platinum metals review · mechanical properties of the solid solution matrix phase (y) in...

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PLATINUM METALS REVIEW

A quartrrl? s u r y /$ rrsearrh on the platinum metals t r r d o j

derJulvpmmts in thrir application in industry

VOL. 26 OCTOBER 1982 NO. 4

Co n ten ts

PI atinum-Enriched Superalloys

Electroplating of Palladium for Electrical Contacts

The Use of Platinum Metals in Modern Thermionic Emitters

Catalysis of One Carbon Molecules

The Story of the Platinum-Wound Electric Resistance Furnace

An Historic Platinum Still

Abstracts

New Patents

Index to \’ohme 26

‘46

‘58

767

‘74

I75

783

‘84

Com.munieatioiis should be addressed to The Editor. Platinum Metnls Review

.lchnson Ma1the.y Publie L.imiied Company. Hairon Cnrden, London ECI N 8EE

Platinum-Enriched Superalloys A DEVELOPMENTAL ALLOY FOR USE IN INDUSTRIAL AND MARINE GAS TURBINE ENVIRONMENTS

By D. R . Coupland, C. W. Hall and I. R. McGill Johnson Matthey Group Research Centre

The initial phase in the development of a new class of high temperature materials based upon the incorporation of platinum group metals as alloy constituents in nickel based superalloys has been reported here previously. It was shown that the new alloys provide enhanced resistance to environmental corrosion when compared with their conventional base metal counterparts, without detriment to high temperature strength. This paper describes the results of more detailed studies of the constitutional and structural aspects of these complex alloys which led to the design of a developmental alloy, RJMZOl2, specifically tailored for operation under the aggressive environmental conditions found in the industrial and marine gas turbine.

Advanced nickel-based superalloys are essentially precipitation strengthened austenitic alloys. They are complex in the sense that they may contain up to fifteen elements, each con- tributing some specific property to the material. The typical phases encountered within the general structure are: [i] the matrix, y , [ii] the coherent y’ (Ni,AI) precipitate and [iii] various refractory element carbideshorides. The latter phases have a wide spectrum of chemical composition and can be compositionally manipulated by control of casting conditions and/or heat treatment schedules. The overall properties with respect to creep strength, thermal and stress fatigue resistance, stress rupture life, oxidation resistance and hot corrosion resistance of this class of alloy depend critically upon the distribution of alloying elements between the phases and upon the relative proportions of these phases. Similarly, the operational temperatures and environments encountered by these alloys when subjected to service stresses for many thousands of hours do cause a significant redistribution of alloying elements throughout their structures.

The ideal superalloy is one with a combination of very high strength together with very

high environmental corrosion resistance. Unfortunately these two properties have traditionally been mutually exclusive as a result of inherent structural instability associated with alloy chemistry, which limits the extent to which the stable oxide formers such as chromium can be utilised. By first considering simple alloys and then proceeding to more complex systems this paper demonstrates that previously unconsidered platinum and platinum group metal additions to this class of materials can be beneficial in producing a more desirable combination of properties. Such improvements have the potential to consolidate and extend-the commercial use of these nickel-based superalloys in aggressive engineering environments (I).

Individual Phase Constitution and Properties The Matrix Phase y

The effect of various elements on the mechanical properties of the solid solution matrix phase ( y ) in nickel-based superalloys has been studied in some depth. Essentially it is now generally accepted that solid solution hardening may be attributed to the degree of lattice expansion, and changes in stacking fault

Platinum Metals Rev., 1982, 26, (4), 146-157 146

energy (SFE) occasioned by the presence of solute elements. The effectiveness of solute elements in modifying the SFE of nickel at room temperature has been shown to be a function of the solute element electronic characteristics or electron vacancy number (Nv), and has been presented by Decker (2) from data published by Beeston and France (3) and by Beeston, Dillamore and Smallman (4). A linear correlation between the 0.2 per cent yield stress per unit lattice parameter change (do.oikX) and Nv for various solute elements in nickel at room temperature has also been proposed by Pelloux and Grant (5) using some data published by Parker and Hazlett (6). Using these two latter correlations as a basis for predicting the effects of the platinum group metals on solid solution hardening of nickel at room temperature, it can be inferred that they should only provide a moderate improvement in yield stress characteristics.

This is also true for a model nickel- zochromium binary alloy containing ternary additions of gold, platinum, palladium and ruthenium as presented in Figure I, and those for the base metal additions, namely niobium, tantalum, tungsten, molybdenum, titanium and

cobalt which are presented above, in Figure 2.

However, an examination of the 0.2 per cent yield stress characteristics of the binary nickel- 2ochromium alloy with additions of selected ternary elements at temperatures from 25 to 12oo0C, suggests that the platinum group metals can provide effective solid solution strengthening at temperatures exceeding 800°C.

A correlation between yield stress and element periodicity for temperatures up to izoo0C, is presented in Figure 3. The curves at each temperature follow a similar profile showing strong interaction effects at Nv values of 5.66 and 1.66. This indicates that the effectiveness of the traditional strengtheners such as niobium and tantalum reduces more rapidly than that of platinum and palladium, to such a degree that the latter elements become more effective strengtheners above 80o"C.

The mechanical properties of the model nickel-2ochromium alloy at temperatures above 800°C will depend primarily upon the relative diffusion characteristics of the solute additions and therefore the effect of the change in SFE with temperature. This can be considered a critical factor in the relative performance of

Platinum Metals Rev., 1982, 26, (4) 147

Platinum Metals Rev., 1982, 26, (4)

these alloys, and ultimately of the more complex )'-phase compositions in nickel-based superalloys. It would seem likely from the data presented in Figure 3, that the platinum group metals, notably platinum and palladium, maintain a low SFE in the 7 matrix at temperatures above 800°C.

The Precipitate ;I'

The intcrmetallic phase y' based upon Ni,AI forms the principle basis for high temperature strengthening of the nickel matrix in most superalloy systems. The composition is complex, containing most of the alloying elements to varying degrees. The mcchanical properties and environmental corrosion resistance of y' are therefore closely related to alloying behaviour and a great deal of work has been undertaken to gain an understanding of these effects. Much of the effort, however, has been directed at resolving the anomalous strengthening behaviour of y' with increase in temperature. Little if any attention has been given to the influence of environmental conditions on the corrosion properties of simple and complex y' compositions, despite the fact that this phase is often considered to be the weak link in the corrosion resistance of the bulk superalloy.

The strengthening and corrosion behaviour of y' alloys are therefore now considered in the following three sub-scctions.

I . Strengthening i n y' Prrcipitates

Although it was of primary interest to examine the effects of platinum group metals on the corrosion properties of simple and complcx y' alloys, a number of comments can be made regarding the possible strengthening effects the platinum group metals may have on the mechanical properties of these alloyed pre- cipitates.

'['he ;+ phase (Ni,Al) together with many other L1,-structured A,B compounds show a significant increase in yield stress with increasc in temperature (7-1 8). The inclusion of platinum as a substitutional element for nickel modifies this anomalous yet valuable behaviour

148

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ent

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RJM

20

12

IN7

92

(C

lOll

IN7

92

(5C

)

B 1

92

5

Mar

-MO

O2

IN73

8C

1n93

9

501 Fig. 3 The correlation X Nb between solute element Mb

x X-X Room Temperature electron vacancy number

(Yv) and the change in 0.2 per cent flow stress per

addition to a nickel-20 wt. per cent chromium alloy. at the four specified lemperalures

S-X nowi

unit atomic per ccnl solute 40. A--- 100O'C

-~ 2 $2W'*

Pt X

4 10-

C O -10-

TI Nb C r Fe Co N I % ---6h-- ad7 L 3 L __ 'ti

6.66 5.66 4.66 2.66 1.66 0.66

SOLUTE ELECTRON VALENCY NUMBER ( N v )

but maintains, nevertheless, a degree of positive temperature dependence.

Overall the effect of platinum would be to maintain the yield stress values at a high level over the temperature range of interest. This inference may be drawn from published hot hardness data (18). Even at the limit of platinum solubility in y' , positive strengthening has been observed with increase in temperature.

The results of published data on the strengthening behaviour of modified Ni,Al alloys

would suggest a beneficial effect of substituted platinum group metal additions.

2. Corrosion of Ternary y' Alloys Although Ni,AI has particularly good oxida-

tion characteristics, the presence of sulphur species and/or alkaline earth metal salts within an oxidising environment causes severe degradation, commonly referred to as hot corrosion. It is known that the simple stoichiometric compound retains the LI


ordered structure at temperatures up to at least 1320°C, and has a narrow range of compositional stability but sufficient solubility for other elements to allow improvements to be made to both mechanical properties and corrosion resistance. Indeed, y’ has been considered sufficiently interesting in ierms of high temperature strength and stability to be used in its own right as a basis for a number of high temperature alloys ( I 9-22). However, unless the environmental corrosion properties of y’ can be improved, particularly within the 700 to 900°C hot corrosion regime, there is little possibility of commercial success. The inherent resistance of platinum to corrosive environments led to a general examination of platinum

group metals as ternary additions to Ni,Al (y ‘ ) in an attempt to improve this situation.

The elements which confer improved mechanical properties on the L I ,structured y‘ phase, such as titanium, tungsten, niobium, vanadium, hafnium and tantalum (23),

generally decrease resistance to hot corrosion attack. The data presented in Figure 4 for molybdenum, tungsten and titanium modifications to stoichiometric Ni,Al, where molybdenum and tungsten were substituted directly for nickel, and titanium for aluminium, provide evidence for this behaviour. Chromium and cobalt have no significant effect on corrosion resistance of y’, as shown in Figure 5. Ruthenium and palladium are similarly neutral


Fig, 7 After subjection to a simulation test at 900°C in the prewnce of sulphur dioxide and sea salt, the dramatic improvement in the hot corrosion resistance ul‘ the platinum-enriched alloy

x9.5 (right) compared with the non platinum containing alloy (left) is clearly viqible

in their effect whereas platinum reduces the corrosion rate almost to zero and the alloy maintains a stable protective oxide throughout the period of the test.

3. Corrosion of Cornplex y’ Alloys In order to verify the corrosion benefits

attributed to selected platinum group metal modifications of stoichiometric Ni,Al, the high temperature hot corrosion resistance of platinum-modified multi-element gamma prime phases was examined. An example of the performance of such an alloy modification is presented in Figure 6 where 2.5 atomic per cent of nickel was replaced by platinum. As distinct from the previous model ternary y’ alloys, shown in Figure 5 , the overall corrosion performance of stoichiometric Ni,A1 has been improved, suggesting some synergistic effect between platinum and the other solute elements. An experimental 7’ alloy designed particularly for strength improvements over conventional y - y‘ alloys, (19) was also modified in composition to include 6.2 weight per cent platinum. This alloy, along with the non-platinum containing y’ alloy, was subjected to a gas turbine simulation test operating at a

gas temperature of 900°C with sulphur dioxide and sea salt contaminants injected at levels of 1.56 litres per hour and 24.2 ppm, respectively. The photomacrographs presented in Figure 7 show the dramatic effect the modification has had upon the hot corrosion resistance of the original platinum-free alloy.

Phase Interaction and Composition y - y’ Alloys

The ternary gamma ( y ) and gamma prime (y‘) model alloys described earlier are partial analogues to the true phases found in complex precipitation strengthened nickel-base alloys. The composition and volume fraction of the y’ precipitate, which ultimately dictates high temperature strength in y - y‘ alloys, are controlled by overall alloy composition and heat treatment and in order to obtain full benefit from alloying additions it is important to establish the chemical relationships between the individual phases. Examples of the latter exercise can be seen in the publications of Knege and Baris (24) and also Donachie and Kriege (25).

Establishing the y and 7’ constitutional


relationships in y - y’ alloys containing platinum group metals has proved to be valuable in designing corrosion resistant alloys and much of the chemical data produced has been obtained using the electrolytic phase extraction and chemical analysis techniques established by Kriege and Baris (24).

Traditionally, partitioning data produced by the latter technique are represented as ratios of the weight percentages of elements found in each phase, and when a series of values for different elements are averaged the error is such as to allow these ratios to represent either weight or atomic percentage data. This type of representation allows comparison of element partitioning for alloys with a wide range of precipitate fraction, but is not readily applicable to the design of novel alloy systems.

In dealing with the partitioning effects of elements in y - 7‘ alloys containing single platinum group metals, partitioning coefficients have been established by identifying the relative proportions of atoms of a particular element associated with each of the two major phases and comparing these values with the atomic percentage levels in the alloy composition. Partitioning coefficients generated by this technique are valid for alloys containing similar volume fractions of y’ precipitate (- 50 to 70 per cent). A series of 1’’ partitioning coefficients are presented in Figure 8 for alloys which contain a single platinum group metal.

The composition of the matrix y in alloys containing a fixed y’ precipitate volume fraction is essentially predetermined by the solubility limits of alloying elements in y’ and the ele- mental partitioning coefficients. I t is essential in the design of any new precipitation strengthened nickel-based superalloy, particularly where different elements such as the platinum group metals are being used, that the y composition is controlled so that detrimental phase precipitation, notably sigma but also other topographically close packed phases, does not occur during extended periods of elevated temperature service.

The partitioning coefficient data generated from the work on complex y - y’ alloys containing single or multiple platinum group elements

were used in a modified “PHACOMP“ programme calculation to produce appropriate alloy average electron vacancy numbers (Rv) for the design of sigma-safe alloys. Nv values for y - j r ‘ alloys containing one or more of platinum, palladium or ruthenium can be deterrnincd using the formula: - Nv o.66(N1 + 1’1 + I’d) + 1.71:Co) + z.66(Ru\

+ 4.66(Cr + Mo + W’I + 5.66(1 a + Nb’l + 6.66(T1\ + 7.66(Al)

where element compositions are in atomic per cent.

The maximum xv for avoidance of sigma phase has been determined experimentally as 2.22.

Apart from osmium, the platinum group elements strongly partition to the y’ precipitate thereby exercising a major influence upon strength and corrosion resistance. Rased upon the fundamental understanding of the effects of platinum group metals on the properties of y, j?‘ and y - y‘ alloys, an alloy designated KJM2012 was designed and developed to achievc a


strength capability at least equal to alloys of the IN792 type but with a low temperature (700 to 900%) hot corrosion resistance approaching

between the two alloys but at I IOOOC after 600 temperature cycles RJM2012 shows a distinct and worthwhile improvement in performance.

that of higher chromium alloys, such as IN939. Table I presents the nominal composition of commercial and developmental alloys.

A Developmental ( y - 7') Alloy The alloy RJM2012 was designed on the

basis of the fundamental understanding that developed from a consideration of the effect of the platinum group metals upon the primary components of y - y' alloys and was formulated specifically to overcome many of the environmental problems known to cause severe degradation of these systems such as hot corrosion attack.

Oxidation Behaviour

A comparison of cyclic oxidation data for RJM2012 and IN792 at peak temperatures ranging from 900 to IIOOOC is shown by Figures 9 and 10. For temperatures up to iooo0C there is little difference in performance

6

5

- n

' 0 4 X

n a 2 I

ffl

:3 E

2

7

R J M 2012(Upper l imi t ) 0 RJM 2012(Lower l imit)

V IN 738C A IN 792 Variants 0 I N 939

~~

3 800 TEMPERATURE *C

Fig. I 1 1000 hour stress rupture data for RJM2012, and a number of commercial alloys


Current studies being carried out on the isothermal oxidation characteristics of RJM2012 at the University of Liverpool have provided some understanding of this effect by demonstrating a distinct morphological difference in the oxidation scales at I IOOOC compared to those at yoo"C. Using IN792 for compar ison , t h e cor ros ion p r o d u c t morphologies of both alloys tested at 900°C over a period of 800 hours show similar characteristics, comprising a duplex non- continuous Cr,O, and a sub-surface A1,0, scale. However, at I IOO'C, although similar oxidation behaviour is observed up to 100 hours of test, RJM2012 develops a continuous protective A1,0, scale by the lateral growth of the initial internal oxidation zone after spallation of the initial non-protective duplex scale. In contrast, IN792 continues to develop a non-protective scale, with the formation of NiO becoming more predominant as the exposure time increases.

The influence of platinum on oxide morphology and oxidation kinetics is as yet little understood. However, the implications of using platinum as an alloying element in high temperature materials is quite evident. Work is continuing in order to explain and further develop many of the beneficial corrosion properties of KJM2012.

Stress Kupture Properties

The 1000 hour stress rupture properties of RJM2012 together with published data on other commercial alloys are presented in Figure I I . L>epending upon thermal history the properties presented for RJM2012 fall within the limits represented in the diagram. Further stress rupture data is currently being generated together with information on the high cycle fatigue performance of the alloy, as part of the overall optimisation process. In general, however, it is clear that the mechanical

Platinum Metals Rev., 1982, 26, (4) 1ss

Fig. 14 The surface degradation of the alloys H J M 2 0 1 2 (left) and the* ( ,I01 niodification of lh792 (right) after 800 hours in the burner rig at ~ ( J O O C shows the improvement resulting from plaiinurrr-c.nrictIrnc.nl x 150

properties of this alloy will match very closely those of the current commercial alloy IN792.

R J M 2 0 1 2 in a Simulated Turbine Environment

The Johnson Matthey burner rig, which simulates the corrosive conditions found in turbines operating under severe environmental operating conditions, has been described in detail elsewhere (26).

RJM2012, together with other commercial and developmental alloys investment cast in

turbine blade form, were evaluated under the programme conditions set out in Table 11. The data presented in Figures 1 2 and 13 describe the results of a full analysis of blade corrosion after 800 hours at temperatures of 760 and 900"C, respectively. Each blade was sectioned at the tip, midspan and base to determine the degree of sulphide and general oxide penetra- tion. Immediately evident from a comparison of the two sets of data is the degree of hot corrosion attack on all the tesi alloys under programme A conditions. That is, degradation

Johnson Matthey Burner Rig Operating Conditions

Fuel Carousel 1 duration, Test h 1 litres/h Contaminants speed rpm

Blade Blade Programme 1 t ip 1 base 1 Natural

A I 780 I 740 I 800 I 1050 I 13,650 I 24.2 I 1.56 I 300


Table I I

Temperature "C

Sea salt PPm (by weight)

Sulphur dioxide litredh

Test

nas

300 0 920 880 800 1250 16,650 24.2 1.56

of blade alloys over the temperature range 740 to 780°C is more pronounced than over the 880 to 920°C temperature regime.

T h e environmental performance of RJM2012, shows however, in both cases a remarkable improvement over that of the more conventional alloys. Although it is appreciated that many alloys receive a full coating treatment (26) prior to service, the performance of the base alloy both in terms of mechanical properties and corrosion resistance is just as important should localised degradation of the coating occur.

The photomicrographs presented as Figure 14 compare the surface degradation of alloys RJM2012 and IN792 (modification C101) after exposure to the lower temperature conditions for 800 hours, and provide clear visual evidence o f t h e improvements gained.

I t is clear from the results of these t w o

specifically developed for marine and industrial gas turbines, the platinum group metal concept can be and is being utilised to provide alloys for a wide range of industrial applications with the precise compositional requiremcnts dictated to a considerable degree by the environment to which the structural material is exposed during service. Environmental and economic pressures are placing increasingly severe demands upon materials of construction; it is anticipated that the selective use of platinum mctals as alloying constituents will provide a cost-effective means of meeting performance targets.

Acknowledgements

We would like to acknowledge thc assistance given to us by Rolls Royce and NGTE in the preparation of samples for burner rig evaluation.

In addition we would like to thank Dr. G. Tatlock and '1'. Hurd of the 1Jniversity of 1,iverpool for valuable comments on aspects of the oxidation

mogrammes that RIM20 12 satisfies the original work. - . , .,

alloy design of achieving a superior corrosion resistance withoui detriment to high

.lhe alloy designation Mar-MOO2 is a trade mark ofthe Martin Marietta Corporation; IN792, IN73XC and IN939 are trade marks ofInco Limited; B1925 is

temperature strength. While this alloy has been a trade mark of Sorcery Metals.

1ieferenrt-s

i C. W. Corti, D. R. Coupland and G. L. Selman, Plarinum Meials Rev., I 980% 24, { I ;, 2

2 R. F. Decker, Proc. Symp. Steel Strengthening Mechanisms, sponsored by Climax Molybdenum Cu., Zurich, 5-6th May, 1969, pp. 147-170

3 B. E. P. Beeston and L. K. France, 3. Insr. Mer.,

4 B. E. 1'. Beesron, I. 1.. Dillamorc and R. E.

5 R. M. N. Pelloux and N. J. Grant, Trans. Met.

6 E. R . Parker and T. H. Hazlett, Trans. A . S. M.,

7 H. Gleiter and E. Hornbogen, Phys. Status Solidi,

8 B. H. Kear, J. M. Oblak and A. P. tiiamei, Mer.

9 J. R . Nicholls and R. D. Rawlings, J. Muter. Sci.,

10 S . J. Liang and D. P. Pope, Acta Metall., 1977,

I T R. B. Schwarz and R. Labusch, J. Appl. Phys.,

12 K. Suzuki, M. Ichihara and S . Takeuchi, A m

13 1'. Suzuki, Y. Oya and D.-M. Wee, Acta Metall.,

1968,96,105

Smallman, Mea. Sci. J., 1968, 2, 12

Soc. AIME, 1960, 218, (4), 232

1954,464 701

1965, 12, ( I ) , 235 and 251

Trans., 1970, 1, (91, 2477

1977, 12, (121,2456

2 5 , (51,485

I978,49, (10)) 5174

Merall., 1979, 27, (21, 193

19x0, 2% (317 301


14 T. Suzuki and Y. Oya, 3. Muter. Sci., 1981, 16,

I 5 B. Reppich, Acra Metall., 1982,30, (I) , 87 16 B. Reppich, P. Schepp and G. Wehner, Acra

17 D.-M. Wee, 0. Noguchi, Y. Oya and T. Suzuki,

18 D.-M. Wee and T. Suzuki, Trans. Jpn. Insr. Mer.,

19 J. E. Restall, Proceedings of the 3rd Int. AIME Symposium on Superalloys, Seven Springs, PA, SePt., 1976, PP. 351-357

20 J. E. Restall and M. J. Weaver, British Parent

21 J. E. Restall and M. J. Weaver, U.S. Patent

22 A. S. Pratt and D. R. Coupland, British Farenr

23 R. D. Rawlings and A. E. Staton-Bevan, J. Muter.

24 0. H. Kriege and J. M. Baris, Trans. A.S.M.,

25 M. J. Donachie and 0. H. Kricge, J. Marer.,

26 R. G. Wing and I. R. McGill, Plarinurn Metals

;Io), 2737

Metall., 1982, 30, ( I ) , y5

Trans. Jpn. Inst. Mer., 1980, 21, (4)) 237

1979, 2% (1 I ) , 634

1,381,859; I975

3,922,168; 1975

2,029,857 B; 1982

Sci., 1975, 10, (31, 5 0 5

1969, 62, (11, 195

1972, 7, (31,269

Rev., IY81, 25, (3)) 94

157

Electroplating of Palladium for Electrical Contacts By Ch. J . Raub Forsctiurigsiristitut f u r Edelmrtallr und Metallrhemie, Schwabisch Gmiind, West Germany

LF h p n pa l ladum is plutrd f r o m an appropriate electrol, t P tlir dc‘posit pow~ssc~s similar physical P I opertim to thow o f hard gold, making it a t e r y

\uitablt. rleclrit u1 contact mntcrial. 77ir relutitiv ~ o 5 t of the two metals h r l p lo rrrc ount for tho growing intrrmt in the c‘lwtrodrposition o/ palladium and the p r o p r t r r s o{ the deposits. which are discussed herc..

In one of the first appraisals of palladium electroplating it was remarked “that from a position of relative obscurity, palladium plating has advanced within a comparatively short time to a place of considerable importance among platinum metal finishes, particularly in the field of electrical contacts” ( I ) . One of the reasons given for this was that some of the gold electrolytes used at that time-1965-to process printed circuit boards attacked the adhesives, lifting the copper foil in the boards. Another reason, favouring the use of palladium in contrast to gold, is the price per volume. Since the density of palladium is roughly one- half, and the price at present one-third to one- quarter that of gold, an equal thickness of palladium costs only one-sixth to one-eighth that of gold. This advantage is reduced if, for example, the higher forming and operating costs of palladium electrolytes and the refining of scrap are considered, but there is still quite an incentive to use palladium instead of gold. This is also probably the main reason why the interest in the electroplating of palladium and in the properties of the deposits has increased as the price of gold has risen. Today nearly all

suppliers of plated connectors and major users have accepted palladium as a reliable connector contact material, and it has been in practical and increasing use for many years (2).

General Properties of Palladium Deposits

In general, one has to keep in mind that palladium is a member of the transition metal group of the periodic system and that gold belongs to the non-transition metals. This is the cause of several basic differences in the behaviour of the two elements, for example, palladium is catalytically very active both in solution and as a metal, while under these circumstances gold is not. Therefore a palladium electrolyte tends to be much more sensitive to impurities or alterations in its composition than a gold bath, and the surface of palladium is well known for exhibiting the so- called “brown powder effect” which origmates from the condensation or polymerisation of organic vapours, emanating from plastics in the surroundings. This brown powder increases the contact resistance to intolerably high levels (3,4,5,6) but the effect can be greatly reduced or avoided if care is taken to use only appropriate plastics in the circuitry, or if the contact pressures are high enough, or if a gold flash (4 0. I ,urn) is applied on top of the palladium (7). A series of tests with plastics showed that polystyrene and PTFE caused the smallest increase in contact resistance of palladium, but that glass fibre reinforced plastic, polyethylene and especially hard paper (Pertinax) critically increased the contact resistance (3).

The electrical resistivity of electroplated palladium is between 10.7 and 1 5 ,uuD cm, this being higher than that of bulk palladium and


Change of Hydrogen Concentrat ion of t h e Pa l lad ium Deposits in Dependence on t h e SO,' : Pd2- Rat io i n the Electrolyte

0.1 0.2

Sulphite concentration 1

1 2

Molar concentration I SO,2-: Pd2+

0.0 1 0.02 0.05

0.1 0.2 0.5

I Hydrogen concentration

1 A/drn2

H : Pd I

0.007 0.75 0.0004 0.041 0.0003 0.037 0.0002 0.025 0.0006 0.063

2 A/dm2

H : Pd

four times as high as that of hard gold (gold- cobalt, gold-nickel, gold-iron alloys) layers, which is 2 to 3 p R cm, but similar to the value of I 8 carat gold-copper-cadmium deposits (8). However for contact applications, the resistivity of the deposits in most cases is not as important as the contact resistance and its change with time under different environmental conditions.

The contact resistance of as-deposited palladium, measured against gold, is in the range of that of hard gold and varies- depending on the measuring method-between I and 7 m a (1,3,8 to 12). In extensive tests carried out in atmospheres containing various amounts of sulphur dioxide, hydrogen sulphide, nitrogen dioxide and hydrogen it was demons- t ra ted t h a t under these conditions electrodeposited palladium shows only a slight increase in contact resistance of up to about 30 mQ, at the most (1,3,8,9,10,12,13). Under the same conditions I 8 carat gold-copper-cadmium layers exhibit much worse behaviour, their resistance becoming about twice as high as that of palladium (4, I 0).

The contact resistance of a 2.5 pm thick palladium layer on copper did not change after a heat treatment of 200 hours at 1 ~ 5 ° C or one of I 5 minutes at 2ooOC (3,9). However, that of a comparable gold layer had doubled under the same conditions (9), a behaviour confirmed for 2 hours at 165OC and 250 hours at IOOOC (12).


'I'his is explained by the lower diffusion coefficients of metals such as copper and zinc through to palladium, compared with gold.

The different diffusion rate also plays a role, in the solderability of palladium layers (1,14). In general, dissolution of palladium is considerably slower than that of gold in 60 tin-40 lead solder, but the intermetallic compounds formed at the dissolving interface may result in fracture. It is therefore suggested that the amount of palladium dissolved in the solder be kept below I per cent by weight (14). The growth of intermetallic compound layers at room temperature is fairly rapid. After six months its thickness has increased to 3 pm (14), while after 25 days at IOOT it is between 3 (15) and 60 pm (14). The compound seems to be a lead-tin phase, with the rejected lead accumulating at the solder interface (14).

The other method of connecting leads to connector pins is by wire wrapping. From practical experience it is known that palladium layers behave in a similar way to hard gold, especially if they are heat treated. The microhardness of the deposits is generally in the range of 140 to 300 HV, this depending on the deposition parameters (8,9, I 6, I 7). I t increases in the first hours after deposition and stays constant at longer times, or even drops slightly. This is due to the out-diffusion of hydrogen and to the correspondifig volume changes ( I 6, I 7, I 8).

0.001 7 0.0004 0.0002 0.0003 0.00 1 5

0.177 0.044 0.021 0.035 0.155

The internal stress in the deposits is strongly dependent on factors such as the type of electrolyte and the deposition parameters @ , I 6 to 20). 'l'ensile stresses observed are in the range of- 50 to zoo N/mm', but they increase during storage of the deposits up to, for example, 400 N h m ' (20).

The wear and friction behaviour has also been studied extensively (1,3,8,9,13,16,17,23). F. H. Reid reports on field tests and production experience up to 1965 ( I ) and G. Schachmann (24) and G. D. Fatzer ( 2 5 ) on the experience of I.B.M. with palladium plated connectors. All investigations showed that palladium deposited in the form of single or duplex layers compares favourably with hard gold in its wear resistance. A thin gold layer on top of the palladium

improves the wear behaviour further, as does a combination of a poor wear-resistant underlayer with a wear-resistant porous top layer (26,27).

Alloys are often heat treated at temperatures of 200 to 3oo0C, in order to reduce stresses and the tendency to crack. This is at least partly due to the removal of hydrogen, during which tensile stresscs change to compressive ones.

Many investigations have been concerned with the porosity of the deposits, but it is very difficult to evaluate the results, since many factors not related 10 the electrolyte are involved. However, i t seems to be established that, if a proper base material and pretreatment procedures are used, a level of porosity can be obtained at a given thickness which is equal to that of cobalt, nickel or iron hardened gold.

Hydrogen in Electrodeposited Palladium

The importance of dissolved hydrogen has been recognised since the earliest deposition experiments, but a method for its quantitative dctermination was only developed in recent years (18): This method was adopted and developed further for investigations on d.c. and pulse plated palladium ( I 8).

Palladium dissolves appreciable amounts of hydrogen as a face centred cubic a-palladium solid solution at hydrogen to palladium ratios up to 0.03, at atmospheric pressure and room


temperature. At higher hydrogen concentrations the face centred cubic ,WdH phase with hydrogen : palladium 0.57 is observed. Its lattice constant is higher by about 3.8 per cent than that for the u-Pd-H solid solution. These data refer to equilibrium conditions. In highly distorted electrodeposited layers solubility is much higher.

of electrodeposits is important insofar as there is a connection between stress in the deposits and the hydrogen dissolved in the as-deposited material. Furthermore, if during storage hydrogen diffuses from deposits with higher hydrogen : palladium ratios, the decomposition of the jl-phase and the accompanying change in volume may cause stresses and cracks in the layers, sometimes even days after deposition took place ( I 8 to 22).

In general, the determination procedure for hydrogen by vacuum extraction is so slow that it catches only part of the hydrogen which is very rapidly diffusing out from the deposit (D,,~,, -1.10 cmz/s in p-PdHj. Therefore an electrochemical method was developed which is very fast, and permits the first hydrogen measurements to be made within a few seconds of deposition ( I 8). It uses the electrochemical oxidation of the hydrogen diffusing from the palladium layers to determine its amount via the charge Q used: Q = Ji(t)dt, where i = anodic current and t = time. Figure I shows the circuitry used. The anodisation of hydrogen is done in I N sodium hydroxide at a constant potential of +0.25V, which is high enough to oxidise hydrogen, but low enough to avoid other electrochemical reactions. l 'he anodic current is dependent upon the diffusion ratc of the hydrogen to the metal/electrolyte interface and the charge can be measured by integration with respect to time; thus via Faraday's law the hydrogen quantity is calculated. Certainly there are limitations to this method, such as the loss of hydrogen in the short time between deposition and measurement, but it has proved to be a simple and reliable method for establishing the influence of deposition parameters, at least relatively, for the various electrolytes. Com-

T h e h y d r oge n con c e n t r a t i o n

parative tests with the vacuum hot extraction analysis gave lower values, since some hydrogen had diffused out before it could be measured.

Palladium Electrodeposi tion Processes

Only a few comparative laboratory investigations have been published which give details of the electrolyte compositions, deposition parameters and properties of deposits (3,9,18 to 23). F. H. Reid ( I ) tested seven electrolytes: (a) 'I'eirammino-palladous nitrate, (b) Sodiurn- pallado-nitrite, (c) Diamniino-dinitrito- palladium (P-salt), (d) Dicyano-diammino- palladium, (e) Acid-palladousi-hloride, (0 Palladosammine-chloride and (g) Palladium- sulphamate (developed by the Automatic Tele- phone and Electric Company). Of these electrolytes he found only (c) and (8) to be commercially interesting. Later, electrolyte prototypes (a), (c), (0 and a newly developed acid type bath ( 1 7,22) were tested at the Forschungsinstitut fur Edelmetalle und


electrodeposited as a compact crackfree layer, even at higher thicknesses, with a microhardness of about 250 to 350 HV. At current densities between 0.1 and i o N d m Z deposition at 10 to 50°C occurs at potentials of +0.5 to +O. I V/NHE, see Figure 2. The activation energy of the reaction Pd”/Pd was found to be AH = 17.1 & I kcaVmol (18). The hydrogen content of the deposits is less than hydrogen : palladium = 0.03. X-ray analysis of such deposits shows only a slight expansion of the f.c.c. a-palladium lattice. The layers are fine, crystalline and non-oriented, with low internal stresses of about 60 N/mm2, which are reduced to 20 N/mmz at 7 ,um thickness. This makes the electrolyte suitable for producing thick layers.

Recently the electroplating of palladium- silver alloys from a LiCl containing PdCIJHCI type electrolyte was reported (29).

Unfortunately the emission of‘ hydrochloric acid vapour and the tendency of these electrolytes to self-decompose makes them unsuitable for industrial production, at this stage of development.

These problems are avoided to a certain extent by a proprietary acid electrolyte based on Pd(NO,),/H,SO, ( I 7,22,30), and containing sodium sulphite. Depending on the sulphite concentration and current density, the current efficiency for palladium deposition varies from roX per cent (0.01 mob‘l Na,SO,, I A/dm2) nominal (electroless deposition) to 63 per cent (0.2 mol/l, 2 A/dm’). The sulphite concentration of the electrodeposits increases from 0.15 per cent (0.01 mol/l Na,SO,, I Ndrn’) to 10 per cent (0.2 moVl Na,SO,, I A/dm2) and the H : I’d ratio

iMctallchemie ( I X,20,2 I ,22) and the Technisch-Chcmisches Laboratorium of the ETH Zurich ( 1 9). ’The sulphamate elcctrolyte has recently been re-evaluated (28).

The Acid Pd(:I,/HCI and Pd( NO:,),/H,SO, Elrctrolytes

In the PdClJHCl electrolyte deposition occurs from an equilibrium I’d2+ + 4Cl + 2H+ e H2PdCI,. ’l‘he palladium is rather loosely bound, so it deposits easily without external current on to less noble metals in a blackish powdery form. At a current efficiency of between 97 and loo per cent palladium is


varies from 0.007 (0.0 I moVl Na,SO,, I A/dm2) to 0.0006 (0.2 moVl Na,SO,, I A/dmz) see the Table. The deposits have a microhardness of 3 5 0 HV, which can be increased to 430 by annealing for I hour at TOO'C. After I hour at 400°C it dropped to 200 HV (I 1,22). Deposits show a fibrous texture, the < I O O > orientation being the preferred crystal axis. Internal tensile stresses are very low at nearly 50 N/mm2 but cven at 10 pm thickness they never exceed I O O

N/nim*. Due to their low hydrogen concentration, deposits do not change their stress values during storage. The deposits made at low sulphite lcvels are bright, but on less noble base metals they need a gold or palladium prestrike.

A common feature of all acid clcctrolytes of low pH values seems to be their current efficiency of about 100 per cent, and the low hydrogen concentration and low tensile stresses of deposits produced from them. A problcm with this type of electrolyte is its tendency to show electroless deposition on base metals, but this can be overcome by using gold or palladium prestrikes.

The Alkaline Pd( NH:,) ,C1, Electrolyte

The alkaline Pd(NH,),Cl, complex seems to be completely stable above pH 7.5, but below pH 6 the Pd(NHJLC1, form is the stable one (18) . Palladium deposits at I to 5 A/dm' and -300 to ~-600 mV at a current efficiency of less than IOO per cent. The potential-current density curves show a strong temperature dependence explained by a decreasing stability of the complex, as can be seen from Figure 3. Current efficiency increases from about 60 per cent at 0.2 Mdmi to yo per cent at 2 A/dm* and from 82 per cent at 25°C to about 85 per cent at 50°C. Deposits are highly stressed (100 to 200 N/mm*) and tend to form cracks at high thicknesses. Stresses and hardness values decrease with deposition temperature and thickness. Layers deposited at temperatures below 30°C show age hardening, during which crack formation is often observed, see Figure 4. The hydrogen concentration of the deposits increases with current densities, but decreases

Fig. 5 The surface of a lOum thick layer drposilrd from a I'd( NH,,) ,C1, solution of pH = 8.5 at current density = 14/dm' and 25°C rxhihits a cauliflower-like structurr: ( Scnnuing electron niicroscopr photograph)

Fig. 6 Surface structure of a deposit from a Pdf hli,~),C12 solutiou pH = 9, 1A/dm2, 25"(: , thicknvss 1 0 p m (SEI\.I photograph)

with deposition tcmperature. It dcpends on the relative movement of the electrolyte with respect to the sample. T h e hydrogen : palladium ratio of deposits from a still electrolyte increases from about 0.1 at I

A/dm' to r at 2 A/dmz. Deposits with hydrogen : palladium bclow 0. I arc bright and e x h i b i t m e t a l l i c l u s t r e , b u t f o r hydrogen : palladium > 0.8 they are powdery black. The layers show a cauliflower-like surface structure shown in Figure j , and are rather sensitive to finger prints. This structure is - rongly influenced by additions of carbonic acias or their derivativcs, see Figures 6 and 7. When benzoic and nicotinic acid and their derivatives are added deposition potentials are shifted to more negative values, Figure 8 (20).


Fig. 7 Surface structure of a deposit from a Pd( NH,) &I, solution + 0.5 niolar sodiuni citrate addition, immtdialt-ly after deposilion. conditions analogous t o Figure 6 (SEM)

Citrates have a similar effect. If the cirrate concentration is 0.5 mol/l, the hydrogen concentration increases from hydrogen : palladium 0.02

to 0.08 at 2 &'dm2. In general citrate reduces the tensile stresses, but the deposits are still highly stressed ( I 50 N/mniL) and tend to crack as illustrated in Figure 9 (20). Sodium salicylates increase the hydrogen concentration

Fig. 9 Surface structure of the deposit in Figure 7 after storage for 1 hour iii the high vacuum conditions, (1OF" bar), of the scann- ing electron niicroscopc

from hydrogen : palladium<o.or to 0.18 (0.5 molar sodium salicylare at 2 Mdm'). Benzoates and salicylates, as well as heterocyclic N- containing compounds result in a sharp fibrous ( I 10) orientation. At concentrations above 5 mmoVl phenacetine reduces the tensile stress of the deposits to values below those of deposits from addition-free electrolytes (20).

The influence of deposition parameters on the porosity of deposits from a palladosammine solution and the influence of saccharin were investigated by Fatzer (25) . Apparently saccharin reduces hardness, but increases the porosity of the layers. The best deposits were obtained at room temperature and 60 g/I Pd(NH,),C12 at a current density of 2.4 A/dm2. Such deposits are glossy or bright and at thicknesses greater than 1.25 ,um are pore free. A soluble anode process with a Na,PdCI, solution produced highly stressed, porous deposits (25).

The Alkaline Pd(NH,3),(N0,), Electrolyte (P-salt Type)

Electrolytes of this type are among the most widely used solutions for palladium electrodeposition. They work at a pH value of between 7.5 and 10, and palladium is electrodeposited at -300 to -700 mV as dense, bright layers. At higher temperatures the deposition potential becomes more positive, and at higher pH values more negative. The current efficiency for palladium deposition increases


from about 40 per cent at 2ooC to nearly 60 per cent at 60°C; correspondingly the hydrogen : palladium concentration drops from about 0.04 (203C, I Ndm’j to 0.005 (7o”C, I Aldm’). Tensile stresses of 250 to 300 N/mmz drop sharply with increasing deposition temperature and thickness, and there seems to be a relationship between hydrogen concentration and stress, see Figure 10 (21). The change in the hydrogen : palladium ratio at various storage temperatures with storage time is shown in Figure 11. It is observed that at pH values between seven and eight, insoluble palladium salts are incorporated in the deposit (21).

The behaviour of a P-salt type electrolyte and the deposits obtained by both pulse and d.c. plating were reported by Locarnini and Ibl ( I 9). In general, the results of Hedrich and Kaub (21)

are confirmed. Under certain conditions pulse plating produces harder deposits than d.c. plating. For thicknesses of less than 2.5 pm, crack and pore free deposits are more readily achieved in pulsed than in d.c. plating (19).

Excellent wear resistance and very low transverse porosity was obtained with doublex coatings consisting, for example, or a I pm base layer from a Pd(NH3),CI, type solution, with low wear resistance of its own, and a top layer (2 ,urn) from an ammonia free electrolyte believed to contain Pd(N0J- as the predominant species. This combination proved better than a single layer from a Pd{NHJ,SO, electrolyte, which worked at a deposition speed of 1 2 p d h o u r and a current efficiency of 75 per cent at 50°C and I A/dmL (26).

An interesting variation of a palladium electrolyte with ammonia as a complexing agent is the use of higher alipathic polyamides, such as tetraethylenepentamin, as complex formers (3 I). Another solution based on P-salt was developed by the Automatic Telephone and Electric Company of Liverpool (32). These electrolytes contain 10 g/1 P-salt, IOO g/1 ammoniumsulphamate and operate at pH 7.5 to 8.3, 32OC and 0.6 to I A/dm2, with a cathode efficiency of 70 per cent. Deposits are milky in appearance at least up to 20 pm, but at this thickness cracks appear. Apparently the current

density of 2 A/dmz is a limit, above which edge blackening of the deposits occurs.

Atkinson patented a process for deposition of palladium and a number of other metals from ammoniacal solutions in a diaphragm-cell (33,34). Further literature on deposition of palladium alloys was reviewed by Brenner (34).

The deposition of a palladium-nickel alloy with 27 per cent nickel from a bath containing


0.05 to 0.1 mol/l Pd(NHJ4C1, is discussed by McCaskie, Nobel and Whitlaw ( I 2). I’alladium- nickel deposits u p to 50 per cent nickel, with o r without a final goId flash, were studied by Pike-Biegunski and Bazzone (35 ) . After ageing one month at 125°C in air, the contact resistance of 50 palladium-so nickel increased

to 1 2 f 8 puR. T h e films with a microhardness of 240 10 450 Knoop show good wear characteristics, comparable to hard gold. These palladium-nickel alloys seem to be quite interesting as underplates for electrical contacts ( 3 5 ) or for decorative applications.

Surntriary T h e electrodeposition of palladium and the

properties of deposits obtained are discussed.

There are two groups of electrolyte prototypes, one operating at pH values below 7 and the other one at values mostly above 10. The

.deposits are similar to hard gold in the properties required for electrical contacts. T h e hydrogen concentration seems to be a critical factor, since it has an influence on both internal stress and porosity. Today, palladium electrodeposits with or without a gold top layer are finding a widening application range as a contact finish for connector contacts.

.4eknowledgrmcrit We want to thank the AIF (Arbeitsgemeinschaft

Industrieller Forschungsvereinigungen, Koln), for their support of the investigations at the For- schungsinstitiit fur Edclnietalle und Metallchemie, Schwabisch Gmund, via funds of the Bundeswirtschaftsministerium, Bonn.

I

2

3

4

5

6

7

8

9

I 0

I 1

1 2

I3

‘4 ‘5

16

F. H. Keid, Plating, 1965, 5 2 , 531 M. Antler, Platirium Metals Reo., 1982, 26) @,), 106 H. Grossmann, M. Huck and G. Schaudt, Galoanotechitik, 1980, 71, ( 5 ) , 484 H. Hermance and T. F. Egan, Bell Syst. Tee. y., ‘9587 37,739 H. J. Keefer and K. H. Gumley, Bzll Syr. Tec. 3., 1958, 37,777 L. €1. Germer and J. L. Smith, Bell Sysr. Tec. 3., 1 9 ~ 7 ~ 3 6 , 769 H. Grossmann, M. Huck and G. Schaudt, Metall (Berlin), 1982, 36, (71, 746 W. H. Safranek, “The Properties of Electrodeposited Metals and Alloys”, American Elsevier Publ., New York, London, Amsterdam, 1974, P. 345 H. C. Angus, Trans. Inst. Mer. Fiizish., 1962, 39,

U. iMayer, MetalloberJfieche, 1978, 32, (I), 3 F. Simon, in Proc. 8th Symp. on Plating in the Eleclronics Industry, Am. Electroplat. SOC., R’inter Park, Fla., I 980 J. E. McCaskie, R. Nobel and K. Whitlaw, in I’roc. AES Symp. on Economic Use of and Sub- stitution for Precious Metals in the Electronics Industry, Am. Electroplat. Soc., Winter Park, Fla., 1980 K. L. Schiff and R. Schnabl, Metalloberflaeche,

W. G. Bader, op. cit., ref. 1 2

P. J. Kay and C. A. McCay, Trans. Ins t . Met. Finish., I 976,54, (I) , 68 E. A. Sauter, in Modcrne Gesichtspunkte der Galvanotechnik, Teil I, ?’A Esslingen, Lehrgang 53 I 5/78.002, Esslingen, 198 I

20

19785 323 423,495

I 7 F. Simon, op. cit., ref. I 6 I 8 H. D. Hedrich and Ch. J. Raub, Meralloberflaeche,

19 J. M. Locarnini and N. Ibl, in Proc. AES 2nd International Pulse Plating Symp., Am. Electroplat. Soc., Winter Park, Fla., 1981

20 H. D. Hedrich and Ch. J. Raub, Merallobei$aeche,

2 1 H. D. Hedrich and Ch. J . Raub, Surj. Technol.,

22 H. D. Hedrich and Ch. J. Kaub, Galoanocechnik,

23 A. W. Grobin and V. Veronesi, Prakt. MetaZloRr.,

24 G. Schachmann, presented at 23rd Annual IPC

25 G. D. Fatzer, Plating, 1963, 50, 1000

26 J . h’. Crosby, op. cit., ref. 1 2

27 A. Keil and K. Klein, Merall, I 978, 32, (4), 352 28 F. Friedrich and Ch. J. Raub, results to be

published in Meralloberfaeche 29 U. Cdhen, K. R. Walton and R. Sard,

Elcctrochem. Soc., Fall Meeting, Extended Abs- . tracts of Electrodeposition Div., Abstr. No. 309,

p. 759, Denver, Col., Oct. I 1-16, 1981 30 DEGUSSA, German Patent, 2,105,626 3 I INOVEN-STROEBE. German Pazent, 2,360,834 32 J. J. Miles, Autom. Teleph. Electr. 3., 1962, IS, 63

33 R. €I . Atkinson, V.S. Patent, 1,981,715; 1934 34 A. Brenner, “Electrodeposition of Alloys”, Vol 11,

Academic Press, New York, London, 1963, p. 542

35 M. J. Pike-Biegunski and R. Bazzme, op. cit., ref.

19777 3’3 ( 1 11, 512

1979, 337 (81, 308

1979, 8, (41, 347

1979, 70, (lo), 934

1981, 18, 181

Conference, Orlando, Fla., April, 1980

cit. in ( I )

I 2


Referenees

The Use of Platinum Metals in Modern Thermionic Emitters By Richard A . Tuck n i o H \ E\Il-Varian Ltd, Hayes, England

The per,formunccJ of dispenser cathodm has been cnnsidwnbly improved over the last quarter n,f u

century. This reuiew considers advances made in thr matcrials uscd either for the matrix o,f (he thermionic emirtrr, or to coat i t s sur,fnce, which hace resulted in loiwr e,/fe‘rC.tii,r work functions. The use 01 iridium, osmitcrn and ruthmiurn has playrd a s i g - nificant role in this irnproverrtent.

In a world where integrated circuits and microprocessers are regularly making new inroads into our daily lives, it is all too easy for those not in the business to assume that the thermionic valve is obsolete; nothing could be further from the truth. The majority of households still have at least one thermionic device, the television picture tube. The U.H.F. signals the television set receives are broadcast using a high power klystron amplifier, another thermionic device. These signals in turn come from a TV camera which uses thermionic pick up tubes. In just the field of communications this list can be extended to include satellite “up- link” and “down-link” electron tubes.

There is no doubt that the triode, tetrode and pentode receiving valves of twenty-five years ago, are, except for a few specialised uses, gone for good. For some uses, however, vacuum devices have remained pre-eminent. One such area is power microwave devices and it is this field that is continually making new demands of thermionic emitter materials.

The devices which are currently stretching the performance of thermionic emitters, are

known as velocity modulated linear beam tubes, the two major variants being the klystron and travelling wave tube. In these devices, which are amplifiers, an electron beam, formed by an electron gun, passes through an interaction space and thence into a collector electrode. ’The interaction space is arranged so that the radio frequency signal to be amplified either slows down or speeds up the electron beam a little; after drifting for a period, the faster electrons catch up with the slower ones, resulting in a bunched beam. The time varying current then interacts with the circuit, causing further bunching, and so on along the device. At the end of the device the energy in the time varying component of the beam is coupled out, leaving the spent beam to be collected.

The physics of these devices dictates that the interaction region, and more significantly for the gun, the tunnel through it, change in proportion to the wavelength at which the device operates. Consequently, if power output Is , to be maintained as the frequency is increased, the current density required from the cathode in the electron gun increases also. To see why this presents a problem we must look at the mathematics of thermionic emission.

At the surface of all solids there is a potential barrier, which the electrons in that material have to overcome if they are to leave. The energy required to overcome this barrier is called the work function, and is traditionally measured in electron volts. When a solid is heated, some of the electrons acquire sufficient energy to escape into the surrounding vacuum. The magnitude of this current is given by the Richardson-Dushman equation:

J = i 2 0 T2 exp ~ ( I 1600 V/Tj

where J is the current density at the emitter


surface i n A/cmL and q the work function in electron volts, T the temperature is measured in kelvins.

Linear beam tubes use convergent Pierce type electron guns, illustrated in Figure I,

which require the emitter to be heated by a separate insulated heater; temperatures above r50oK cannot be used if the device is to have a long life.

The best pure metal thermionic emitter is tungsten which has a work function of 4.54 eV which at I 50oK can provide I .5 x 10-’ A/cm2. Modern microwave tubes operate with cathode loadings of I to 8 A/cmz, so we can see how inadequate pure metal emitters are.

The oxide cathode has been the mainstay of the receiving tube designs for many decades. At direct current densities of 0.3 to 0.5 Ncm2 or pulse loadings of a few amps per square centimctre for all but the shortest duration, problems are encountered with ohmic heating in the thick oxide layer. Modern electron guns are built to exacting mechanical tolerances which oxide cathodes, with their sprayed coatings, cannot meet.

The class of cathodes which have become more or less standard in the microwave tube industry are called dispenser cathodes. l’he evolution of these cathode materials from the earlier oxide is well reviewed by Beck (I). The purpose of this review is to pick up the story

from where Beck finished., During the last two decades or so since Beck’s paper, the use of platinum metals, though not platinum itself, has significantly improved the performance of thermionic emitters.

Dispenser Cathodes 1 . The B-type or Impregnated Cathode

The starting point for the majority of modern developments is the B-type cathode; its invention is usually ascribed to Levi (2) though as with most things many earlier workers made significant contributions.

‘l‘he cathode comprises a porous tungsten matrix made by sintering tungsten powder. The pore diameter is around 5 pm and the interpore separation 5 ,pm to 10 pm. The emitter pellet, or button as it is called, is machined to size with the matrix filled with either copper or plastic. This filler is then removed.

The porcs are then filled with a barium containing ternary mixed oxide, which in Levi’s cathode had the composition:

5 BaO:3 CaO:2 hlzO,

the so called 5 : 3 : 2 mix. Cathodes are also manufactured with other impregnant compositions, 6: 1:2 and 4:1:i being in common use. The material is infiltrated into the matrix at 1600 to 18ooOC in dry hydrogen, the excess removed either mechanically or chemically, and


the emitter mounted together with a heater into the final structure.

The current explanation of its operation is as follows. Reactions between the impregnant and the tungsten produce free barium. This migrates by Knudsen flow and surface diffusion to the surface. A t the surface, and to an extent on the way to the surface, some of this reacts with oxygen to produce what we shall rather loosely call barium oxide. This forms a vertically ordered double layer with barium outermost. The dipole so produced lowers the work function from the 4.54 eV of bare tungsten to around 2.1 eV. Excess activator (Ba/BaO) evaporates from the pore ends and surface, the “BaO” layer being in dynamic equilibrium with the supply. This enables the cathode to repair itself after poisoning by residual gases or positive ions. This virtue is in another way a vice, since the evaporated Ha/HaO coats nearby electrodes, making them more likely to emit stray electrons both by secondary and thermionic emission. The cathode life time is determined by the reservoir of available barium in the matrix.

The effective work function of the B-type cathode is 2.05 to 2.10 eV, equivalent to approximately z A/cm* Lero field emission at I 3ooK; this was considered to be a high current density in 1955.

For nearly two dccades the B-type cathode was the microwave tube industry standard. During this period, however, the power frequency product of new devices increased steadily. This trend, together with the introduction of grid controlled guns on most new tube types, pushed cathode loading up to 7 to 10

A/cmz. To supply this current density a B-type cathode would nced to be operated at temperatures wcll over 15ooK. At such temperatures life is short both for the emitter material and the heater assembly.

2. The M-type Cathode The first improvement to the B-type cathode

is attributable to Zalm and van Stratum (3). They noticed that for alkali metals on crystal surfaces it was the face with the highest bare work function which had the lowest value after adsorption. By analogy they agreed that by

Mean Changta in Electron Emission of H-~ype Cathodrs when ( h t e d with

Various Metals

Coating on cathode

Titanium Nickel Copper Zirconium Molybdenum Ruthenium Ta nt a I u m Tungsten

Rhenium Osmium Iridium

Platinum Gold


Mean emission change

<o. 1 2 .o 0.6

1 .o 2.8 0.4 1 .o

- 1 0 . 5

2.7 3.7 2.7

169

References

24 18 19 16 8

3.20 20 Reference surface 15.17,18.20 3.14,17,20,23 14,17,18.20, 23 17,20 22,24

been used, including vacuum cvaporation, chemical vapour deposition, chemical deposition and, the most widely used, sputtering. The films are normally 0.2 to I pm thick.

Since Zalm’s paper many other workers have duplicated his work, though the results have varied considerably from author to author.

How the Coating Works After Zalm’s paper many metals were coated

onto dispenser cathodes to try their effect; the Table and Figure 2 summarise the results. These are taken from a paper by Skinner, Tuck and Dobson (4); Figure 3 is from the same work, and shows the mean emission change as a fiinction of coating work function. The data would fall on a smooth curve were it not for platinum and gold, which are serious anomalies. The authors present a n alternative model based on the difference between the heat of sorption of oxygen and barium on the surface, Figure 4 shows their data. Their reasoning is that to form a stable vertically ordered dipole layer with oxygen closest to the surface, one needs an

increasing the work function of a matrix surface, thc cathode would have a lower final work function.

It is at this point that the platinum graup metals enter the story. The metals which satisfied the high work function and other criteria were osmium, iridium, ruthenium and rhenium; platinum, palladium and gold were rejected because they formed iniermetallic compounds with barium. The work function of B- type cathodes coated with osmium, ruthenium, iridium or rhenium are approximately 0.1 eV less than the uncoated samples; this represents a threefold increase in emission at the same temperature.

Various techniques for coating cathodes have


Fig. 4 The change in emission of B-type cathodvs az a fuiictiuri of the parameter: Heat of sorption of oxygen - Heat of sorption of barium

c> Exprrimrntal data for hoth AHg, and

0 Experimental AHtla estimate of At10

0 Experimental A H o 2 e s t i m a t e of A H B ~ ( Miedema)

0 Isnth estimated

AH Ba

l o r m s intermetallic with Ba

W

c 4-

oxygedsubstrate bond. If this bond is too strong, as in tungstcn say, an adverse dipole is formed between oxygen and the substrate, reducing the beneficial effects of the “BaO” dipole. Osmium, iridium, ruthenium and rhenium fulfil this condition. However, with platinum and gold the bond is too weak for a stable laycr.

A molecular orbital approach to the bonding is used by Green (5j, drawing on theories of heterogeneous catalysis. He presents a theoretical covalent bonding model of gas phase BaO and then discusses how this might bond to a transition metal surface. He argues that the bonding is via unoccupied d-orbitals at the surface. Using the arguments of heterogeneous catalysis, metals are divided into categories depending on the orientation and number of unoccupied d-orbitals. Tungsten falls into one group: osmium, iridium, ruthenium and rhenium into another, while platinum, the anomaly, falls into a third. The second group, containing osmium, is believed to have unoccupied orbitals which fit with the BaO orbitals. Green’s model and that of Skinner and her colleagues have large areas of compatibility.

Several groups are currently using surface analytical techniques to investigate the nature

of dispenser cathode surfaces, with considerable success. However, the heterogeneous nature of the surfaces involved will mean that a really definitive solution will take some time.

3. Alloy Based Cathodes During the last five years, the use of alloys

both as coatings and matrices, has considerably improved dispenser cathode performance.

The first use of alloys dates back to the beginning of the M-type cathode. There was concern about the volatile and toxic OsO, being formed on pure osmium films. The solution adopted throughout the U.S.A. was to replace pure osmium with an osmium-zo per cent ruthenium alloy, which was claimed to reduce oxidation (6). The author’s company has used pure osmium for many years without hazard, so the problem may be more imagined than real. The performance of cathodes coated with either seems identical.

The use of alloys to actually improve performance was pioneered by Falce at Varian Associates (7) and Green, Skinner and Tuck at THORN EMI-Varian Ltd (8). Falce produced mixed matrix cathodes using iridium-tungsten alloys. In a mixed matrix cathode, the tungsten matrix of the B-cathode is replaced by one of


sintered mixed powders, which is impregnated in the usual way. Matrices with 20 per cent iridium were found to be optimum, though the maximum is rather broad, 40 per cent iridium alloys producing very similar results.

Work at 'I'HORN EM-Varian Ltd (S) on the osmium-tungsten system, correlated improved emission with the formation of the tetragonal u phase. B-type cathodcs coated with this intcrmetallic showed reductions in work function of up to 0.2 eV, a further factor of three in emission, compared to the M-type cathode.

Subsequently, other groups duplicated and expanded upon thc work, trying other combina- tions of metals. Figure 5 shows the published state-of-the-art. Schroff (9) has produced a coated mixed matrix cathode, combining perhaps the best of both worlds.

Why Are the Alloys Better? Currently there is no definitive answer to this

question; theory and experiment are much less advanced than for pure metal coatings, which


Fig. 6 The unreconstructed ( 100) surface of a 0-phase alloy with rims and craters

are still by no means fully understood. There are, however, some ideas. The inter-

metallic compounds which seem beneficial are likely to have atomically rough surfaces, with either “ridges and valleys” or “craters and rims”, Figure 6 shows the probable (100)

surface of a u-phase alloy which is of the craters and rims variety.

A rather elegant experiment by Pankey and Thomas ( I 01 supports this reasoning. They activated recrystallised iridium ribbons with BaO and measured the final work functions of the crystallitcs with an emission microscope. Using a microbeam X-ray diffraction system they then determined the orientation of the crystallites. The activated crystallites with the lowest work functions were from the atomically rough (210) faces.

The reasoning of Smoluchowski ( I I),

recently experimentally supported by Gardiner, Kranier and Bauer (12): says that such rough crystal faces would have low work functions. The benefits of alloys are thus further evidence against the high substrate work function

explanation for the effects of osmium, iridium and ruthenium.

The reason for the superior performance of atomically rough surfaces is not known. The author has suggested ( I 3) that the topography of the surface may control the coverage of “BaO” at a more nearly optimum value. A definitive answer to this question may be a long way away, awaiting adsorbate experiments on single crystals.

The Future At the Tri-Service Cathode Workshop Con-

ference, held at Fort Monmouth, New Jersey, in Spring 1982, the concensus was that while the best samples of alloy based cathodes were quite adequate for current state-of-the-art electron guns, the variations fram sample to sample were not.

Work is now underway at a number of centres to improve the reproduceability, though none of it has yet been published. What we can be sure of, is, that platinum metals will con- tinue to play a significant role in this work.

I A.H.W. Beck, Proc.1.E.E. Nov. 1958, 372 2 R. Levi,J. Appl. IJhys., 1955,26,639 3 P. Zalm and A. J. A. van Stratum, Philips Tech.

4 H. B. Skinner, R. A. Tuck and 1’. J. Ihbson,

5 M. C. Green, Final Report on Contract F30602-

6 P. Zalm, A. J. A. van Stratum and H. H. Peeters,

7 L. R. Falce, U.S. IJatent 4,165,473; 1979 8 M. C. Green, H. B. Skinner and R. A. Tuck,

Appl. Surf. Sci., 1981, 8, ( I and 2), 13 y A. M. Schroff and J. C. Tonnerre, Final Report

on Contract L‘STEC 4086/79/NWDG European Space Agency, I 98 I

10 T . Pankey and R. E. Thomas, Appl. Surf. Sci.,

I I R. Stnoluchowski, P h y . Rev., 1941, 60, 661 1 2 T. M. Gardiner, H. M. Kramer and E. Bauer,

Surf. Sci., 1981, I I Z , (I/z), 181 13 R. A. Tuck, Tri-service Cathode Workshop

Conference, Fort Monmouth, New Jersey, lJ.S.A., 1982

14 G. K. Bhidc and F. E. W’ray, J . Phys. D., 197c,

Reti., 1 9 6 2 7 , (3/4),69

J. Phys. D., 1982, (to be published)

79-C-0220-U.S. Air Force, 198 I

U.S. Paent 3,497,757; 1970

1981, 8, (d2L 50

33 (31, 443

References 15 R. Branscombe and F. J. Weaver, English

Electrical Valve Company, Report No. I 0/36-6, I970

16 G. A. Haas and A. Shih, Appl. Surf. Sci., 1980, 4, ‘04

17 J. M. Housten, U.S. General Electric Company, Report No. 67-C-223, 1967

18 C. E. iMaloncy, Camb. Univ., Report on Project

19 C. E. Maloney, Camb. Univ., Keport on Project RIJ2-10, 1975

20 V. N. Nekrasoo and A. V. Druzhinin, Radio Etzg. Elccr. Phys., 1970, 15, 2, 36

2 1 E. S. Kittncr and K . H. Ahlert, J . AppL Phys., 1958,29,61

22 Yu. G. Shishkin, Sov. Phys. (U.S.A.) SulidState, 196627,185 1

23 R. A. Tuck, unpublished reports 24 J. Vaughn, K. Dudley and I,. I.esenski, Advances

in Electron Tube Techniques, Proc 5th Natl. Conf., Pergamon Press, Oxford, I 968, p. I 40

2 s J. Lotthammer, Advances in Electron Emission, Meeting at the Institudon of Electrical Engineers, London, I I Feb. 1982

26 A. M. Schroff, P. Palluel and J. C. Tonnerre, Appl. Surf. Sci., 1981, 8, ( I and z), 36

KU2- I 0, I 973


Catalysis of One Carbon Molecules T H E ROLE OF PLATINUM METALS IN T H E PROVISION OF CARBONACEOUS MATERIALS FOR T H E CHEMICAL INDUSTRY

As the availability of crude oil decreases the chemical industry will have to change its raw material basis from crude oil to other sources of carbon. The recent international symposium held at Bruges, Belgium under the auspices of the Belgian Inter-University Consortium for Research in Catalysis, the Vlaamse Chemische Vereniging and the SociCtk Chimique Belge provided an opportunity for participants to consider solutions to some of the problems that may arise during this transition. Fortunately almost all carbonaceous raw materials can be converted into synthesis gas which can then be used for a variety of manufacturing applications. Several of the papers presented were concerned with the application of platinum group metal catalysts; a number are reviewed here.

An invited lecture was presented by Dr. M. E. Dry, SASOL, South Africa, on the Fischer- Tropsch process, and several papers set out to elucidate the mechanism of this synthesis. P. Biloen, J. N. Helle, F. G. A. van de Berg and W. M. H. Sachtler, Koninklijke/Shell Laboratory, Amsterdam, reported comparative results obtained with nickel, cobalt and ruthenium catalysts. They concluded that the reaction was limited by the number of active sites rather than by intrinsic activity. K . Liz&, Z. Schay and L. Guczi, of the Hungarian Academy of Sciences, described the correlation between surfacc carbon and carbon monoxide/hydrogcn selectivity on iron and iron-ruthenium catalysts established using in situ Mossbauer spectroscopy and kinetic studies. The effect of the support on the activity and selectivity of rhodium systems was presented by P. MCriaudeau, H. Ellested and C. Naccache, Institut de Recherches sur la Catalyse, France. A metal support interaction between rhodium and titania was proposed to explain the favoured formation of olefins and long chain hydrocarbons over this catalyst.

Professor K. G. Caulton, of the Indiana University, U.S.A. reviewed current progress in our understanding of possible mechanisms of carbon monoxide hydrogenation derived from the studies of homogeneous systems. Model studies with Group VIII transition metals of relevance to methanol synthesis from synthetic natural gas were discussed.

The co3rdination chemistry of formaldehyde iridium complexes was reviewed by D. L. Thorn of E. I. Dupont de Nemours. Later J. C. Conesa, M. T. Sainz, J. Soria, G. Munuera, V. Rives-Arnau and A. Munoz of the University of Seville, described studies of' the effect of carbon monoxide adsorption on RhCIJI'iO, catalysts and its reactivity with hydrogen. The results indicate the possible role of intermediate rhodium oxidation states in catalytic processes with carbon monoxide. The carbonylation of methanol to acetic acid with rhodium and cobalt catalysts was reviewed by Dr. D. Forster of Monsanto, who emphasised the superior performance of the rhodium iodide catalyst. Ruthenium and mixed cobalt ruthenium systems are at present the most selective catalysts for methanol homologation to ethanol. G. Braca, G. Sbrana and G. Valentini, of the University of Pisa, Italy, reported the results of a study of thc role and effect of iodide promoters and ligands on ruthenium catalysed methyl acetate homologation to ethyl acetate.

On the final day R. P. A. Sneeden, Institut de Recherches sur la Catalyse, lectured on the homogeneous and heterogeneous catalytic reactions of carbon dioxide. Others described results pertaining to the hydrogenation of carbon dioxide over supported palladium catalysts and carbon monoxide and carbon dioxide over supported rhodium catalysts.

The papers presented at the symposium will be published in a special issue of the Journal of Molecular Catalysis. F.K.


The Story of the Platinum-Wound Electric Resistance Furnace By R . C. Mackenzie The Macaulay Institute for Soil Research, Aberdeen, Scotland

For many years platinum-wound furnaces have been established as a means of obtaining high temperatures without the complication of a protective atmosphere to surround the resistance elements. Indeed, such electric furnaces were first produced commercially in Germany around the turn of the present century. The history of their early development has, however, never been described, and in this paper the author gives a detailed account of their origin and their gradual development into valuable items of laboratory equipment.

Standard reference books are rather coy about the history of the simple platinum-wound tube or muffle furnace and even extensive reviews are not any more revealing (1,2).

Certainly the Dictionary of Scientific Biogra- phy does attribute its invention correctly (3) , but such a reference presupposes prior knowledge. In actual fact, the history of this common article of laboratory furniture is rather fascinating, if only because of the time lapse between the observations that made it possible and its development.

The Contributions by Volta, Children and Pepys

The story effectively starts with the letter, dated 20th March 1800, of Alessandro Volta (1745-1 827) describing his famous pile (4), which led to a flurry of interest in things electrical and, in T 809 (5) and I 8 I 3 (6), to the development of two large batteries by John George Children (1777-1852). These were enormous: the 1815 development of the 1813 model, for example, had 63 plates of zinc and copper each measuring 6 ft by z ft 8 in dipping into 945 gallons of a 3:1 mixture of fuming nitric and sulphuric acids diluted with water, and the flow of electric current was stopped by raising the plates out of the acid by a system of ropes and pulleys. This battery was located at

his father’s house, Ferox Hall, near Tonbridge, Kent (7), and was also used by several other Fellows of the Royal Society, including Sir Humphry Davy, for electrical experimentation. For his work with his batteries Children was awarded a Royal Society Medal in 1828. He established, among other things, that the heating powers of metals varied with their specific resistance; but the most interesting observation from our viewpoint was that of William Hasledine Pepys (1775-1856) who was in- terested in the controversy then raging on whether diamond could convert soft iron into steel on heating (8), or whether the necessary carbon came from an outside source (9,10,1 I). Usc of Children’s battery ensured that there would be no source of carbon other than diamond and accordingly (6):

“he bent a wire of pure soft iron, so as to form an angle in the middle, in which part he divided it longitudinally, by a fine saw. In the opening so formed he placed some diamond powder, securing it in its situation by two finer wires . . . . All the wires were of pure soft iron, and the part containing the diamond powder, was enveloped by thin leaves of talc [sic, presumably mica]. Thus, arranged, the apparatus was placed in the electrical circuit, when it soon became red hot, and was kept so for six minutes . . . . On opening the wire, Mr Pepys found that the whole of the diamond had disappeared . . . and all that part that had been in contact with the diamond was converted into perfect blistered steel”.


Henry Louis Le Chatelier 1850-1936

So was born the first electrically heated wire resistance furnace, although the heating element was not platinum.

The Lost Years, 181 5-1 893 Why did nearly a century elapse between the

above experiment and the invention of the platinum-wound tube furnace?

The answer is not to be found in lack of technical advance, since continuous current could be obtained from reliable compact batteries before I 840 ( I 2, I 3) and the electrical generator had been developed from the rudi- mentary form of Hippolyte Pixii in I 832 to the commercial model of Ztnole Theophile Gramme (1826-1901) in 1870 (14,15). Fila- ment lamps, which employ a somewhat analogous principle for another purpose, developed over the period 1820 to 1878 from early attempts to use platinum wires in a vacuum to usable glass-enclosed lamps (I 5,16). Moreover, in 1x41, James Prescott Joule ( I 8 18-1 889) quantified the amount of heat


Born in Paris, Le Chatelier came into early contact with eniinent scientists through his father: then Inspector General o f Mines. Educated at the Military Academy. the College Rollin, the h l e Poly1t:chnique and the ficole des Mines, he became in 1875-77 a mining enginecr in Besarieon and from 1877 to his retirement in 1919 was Professor of General Chemistry at the kcole des Mines: he also held sweral other teaching posts. Although best known l o r “Le Chate l ie r ’ s Principle”, he had a wide range of interests, including c:ements, clays and metallurgy. In 1886 he showed that the thermocouple could be made a n accurate temperature-measuring device (hence its then name “Le Chatelier’s pyrometer”) and is generally regarded as the father of thermal analysis

liberated when an electric current is passed through a resisrance ( I 7).

However, the reference by Powell and Schroeder ( I 5) and Jarvis (I 6) to the I 820 work of Warren de la Rue must be treated with caution as de la Rue was then only 5 years old. Comments by Grove (Phil. Mug., 1840, 16, 338-339) suggest the reference might be to de la Rive, and presumably to Gaspard ( I 770-1834), since the first scientific paper of Auguste (rX01-1873j appears to have been published in I 822.

Lack of interest is likewise not a tenable answer as two reviews which appeared about the [urn of the century reveal a continuous interest in certain types of electric furnace. Thus, Street ( I ) in 1895 considered such furnaces could be divided into two main classes: “les uns . . . bases sur l’incandescence d’une fraction rksistante de circuit et les autres sur l’emploi de l’arc tlectrique”, the firs1 referring only to systems where the resistance of the contents was the source of heat. Minet ( 2 ) in 1905

176

Augustin Georges Albert Charpy 1 865- 1945

Born in Ouillins, France, the son of a naval captain. Charpy was edurated there and at Lyon before entering the &ole Polytechnique in Paris. He remained there, after graduating in 1887, until he had acquired his doctorate for work on the volumes and densities of salt solutions. At this time he got to know Moissan, Le Chatelier and Osmond. In 1892 he moted to the Laboratoire Central de I’ArtiIlerie de Marine, in 1898 he joined the Compagnie de Chatillon- Cornmentry, where he rose to be Technical Director, and in 19 I 9 he became Deputy Director of the Com- pagnie des AciCries de la Marine and Professor at both the Eeole des Mines and the h o l e Polytechnique. W hile most of his work w a s concerned with the study of alloys, he was also responsible for introducing scientific methods of problem-solving into tht. companies he was concerned with

lists three stages of development, that in the period 1808 to 1886 being attributed to “laboratory furnaces”, but again refers only to the types recognised by Street. In his final complex classification of furnaces, a type not discussed in the text is given as a “solid resistance not in contact with the material” and under this he has “iron wire round the reaction chamber” and “platinum wire” associated with the names “Charpy ( I 893)” and “Nernst ( I 9001, Howe (1900)” respectively but with no references. In general, therefore, it would appear that electric furnaces were developed with essentially technical and industrial applications in mind-and Street’s two classes would fit these requirements.

Another factor in the delay was undoubtedly the use of coal gas. With the introduction of the Bunsen burner in 1853 (18) gas became the normal source of heat in laboratories and small gas furnaces and muffles (19,20) were adequate for most laboratory purposes. Electricity, in contrast, was not readily available until into the

twentieth century and even then the position varied from laboratory to laboratory, as illustrated by the use of gas heating for ther- mogravimetry as late as J 925 (2 I).

Analysis of these facts suggests that the main causes of delay in the introduction of the wire- wound furnace were the ready availability of laboratory gas furnaces, the familiarity of scientists with gas and possibly the fact that highly accurate temperature control was not then considered essential for many of the opera- tions performed.

Le Chatelier, Osmond, Moissan and Charpy

In the late 1880s, however, interest in metallurgy grew, and convenient temperature control became a reality in 1886 when Henry Louis Le Chatelier developed the thermocouple as an accurate temperature-measuring device (zz), thereby confounding earlier prognostica- tions (23). At about this period too, Floris Osmond (I 849-1 9 I 2) carried out his extensive


The first illustration of a platinum-wound electrical tube furnace, F, complete with tht-rmocouple, a$ depicted hy Georges Charpy in 1895. The recording system ron- sisted of a drum, surrounded hy phntographic paper and rotated by c-lockwork, in a container C. The image of the filament of a n electric lamp in the housing L was pro- jected on to the drum C and the scale E from the mirror of the galvanometer (;

metallurgical investigations (24) and F e r d i n a n d - F r k d k r i c - H e n r i M o i s s a n (1852-1907) was involved in related studies. It was in this climate that Augustin Georges Albert Charpy entered I’lhole Polytechnique in 1887 (25,26). Becoming an Assistant in the Chemistry Course in 1889, he gained his doctorate in 1892 and then, not surprisingly as Henri Moissan had presented his papers to the Academy of Sciences from 1891 on (27), he

Laboratoire Central de 1’ArtiIlerie de Marine. His first paper on this subject, published in 1893 and dealing with the effect of annealing on the physical properties of brass, contains the comment (28):

“Pour effectuer le recuit on employait un four chauffk par une spirale de platine traverske par un courant Clectrique, ce qui permet d’obtenir facilement des tempkratures constantes: les tempiratures ktaient mesurCes avec un pyromktre thermoilectrique Le Chatelier” [that IS a

commenced metallurgical studies at the thermocouple].

Diagram showing details of the internal construction of the large rotating, pivoted furnace of Georges Charpy, the platinum wire being wound round a refractory tube


This is the first record in the literature of a wire-wound electric resistance furnace-and the winding was platinum, not the “iron wire” mentioned by Minet (2), whose notes, regrettably, are not always accurate. BerthClemy was thus quite correct in stating in 1947 (26) that “il a construit le premier four A risistance Clectrique, i iliments de platine, qui nous parait t r b simple, mais qui fut et qui reste un outil extrkmement prCcieux pour les mesures”. For a study of the allotropic forms of iron, in I 894, Charpy used a similar furnace of which he gives more details (29). The platinum wire was wound around a refractory tube 20 cm diameter by 60 cm long, giving a zone 20 cm long in which the temperature, as measured by a thermocouple, remained constant for several hours over the range 500 to 13oo0C. The furnace tube was insulated with asbestos, the current was regulated by a rheostat and the furnace was pivoted so that it could be quickly tilted vertically to allow the iron bar being heated to fall into the tempering bath without its temperature falling significantly in transit.

On 25th November 1892 the Council of La SociCtk d’Encouragement pour 1’Industrie Nationale offered a grant of 3000 francs for studies on the tempering and annealing of steel to Floris Osmond, who at first accepted but later withdrew as his research had taken a different direction. Thereupon the Council approached Georges Charpy who, with the approval of his superiors at the Laboratoire de la Marine, entered into an agreement with the Society in June 7894. After visiting his laboratory, a Committee of Council, who were most impressed by his research, handed over to Charpy the 3000 francs previously set aside for Osmond (30). On 25th January 1895, Charpy described his work to a meeting of the Society and this was published in their Bulletin for June I 895 ( 3 I ) . This remarkable piece of work for such a short period deals not only with the tempering of steel in detail but also describes several platinum-wound electric resistance furnaces and was very highly praised by the Society’s assessors, who refer to “la profondeur de ses recherches, la vigeur et la prkcision de

ses methodes et I’originalitk de ses procCdts d’investigation” (30). Apparently Charpy also exhibited one of his furnaces at the meeting on 2 5th January; as this excited great interest (321, one wonders why it is not referred to in Street’s review ( I ) and how Minet (2) got his facts wrong.

The first illustration of such a furnace and its associated temperature measuring and recording arrangement is reproduced herewith; Charpy describes its construction as follows:

“[Le four] comprend un tube en terre rhfractaire de Om,2o de diametre et 10

centimetres de long. Autour de ce tube, est enroul6 un fil de platine de Omm,5 de diametre recouvert hi-mCme d’une ipaisse couche d’amiante. Le tout est enferm6 dans un cylindre mktallique port6 sur un pied . . . Avec un courant de 6 amperes environ, on arrive rapidement et d’une facon tres rkguliere B une tempkrature de I zoo0 et I 300””.

A rather more complex furnace was used by Charpy in his studies on the tempering of steel. It consisted of a platinum-wound refractory tube 60 cm long by 2.5 cm diameter insulated with asbestos inside a brass tube sealed with end-pieces. The refractory tube was extended at each end by cooled bronze tubes forming axles set in bearings fixed to the outer frame: one axle had a pulley attached and the other the electrical contacts. This arrangement was rotated by an electric motor attached to the outer frame and again the whole system was pivoted so that it could be rapidly brought to the vertical position, allowing the metal bar sample to drop into the tempering bath. Temperature profiles, obtained using a thermocouple, showed that the sensibly “constant- temperature” region tended to become smaller as the temperature increased up to IOOO~C, although, even at this temperature, the variation was less than 10°C over 15 cm in the centre of the tube. Temperature control was by manual adjustment of a rheostat. The winding used consisted of four platinum wires 7 m long and 0. I 5 rnm diameter arranged in parallel; two wires were wound directly on the refractory tube and were covered with a sheet of asbestos on which were wound the other two. In an


appendix to the paper, Charpy gives instruc- tions for constructing a similar furnace 40 to 50 cm long but without the rotating arrangement or water-cooled ends, indicating that this can be used when great temperature precision is not required. In this furnace, constructed for Charpy by M. Jobin, precision instrument maker, Paris:

“Une feuille de cuivre double I’intirieur du tube, et facilite I’igalisation de tempkrature . . . Une dirivation montie sur les spires centrales du fil de platine (dam la region oh la temperature est uniforme) communique avec un volt-mitre assez sensible; si l’on connait l’intensiti du courant qui traverse le fil de platine, on a . . . un mesure approximative de la resistance . . . [et] on arrive facilement B ivaluer la temperature B I 5 O ou 20° pr W.

Thus, not only did Charpy construct the first platinum-wound furnace in 1893, but in the next year he arranged it on a pivot so that it could be turned rapidly from the horizontal position to the vertical, and in 1895 he produced a rotating, pivoted version with water-cooled ends that seems complex even today. He also used part of the winding as an inbuilt platinum resistance thermometer for less precise work. Clearly he was an engineer of resource and ingenuity and it is little wonder that, later in 1895, he was awarded a gold medal of the SociCtC d’Encouragement pour 1’Industrie Nationale for his efforts (33).

Developments in the Period to 1900

An interesting electric resistance furnace with a spherical cavity, heated by coils of iron wire, rotating on axles and fitted with an inner iron sheath was constructed by K’illiam Chandler Koberts-Austen ( I 843-1 902) in I 897 and was used for calibrating thermocouples against an air thermometer (34). Iron wire could not give the temperature stability or reproducibility of platinum-although Le Chatelier, by packing the space around an iron winding with charcoal, claimed long life when used up to IOOOOC (35)-but Robert-Austen’s furnace was as carefully constructed as Charpy’s and was perfectly adequate for the

purpose for which i t was made. In 1899, Holburn and Day constructed a tube furnace, also for calibrating thermocouples against an air thermometer, using a winding of nickel wire (36). Rase metal windings were thus introduced at an early stage; obviously these were cheaper than platinum, but a contributory factor may have been the difficulty of obtaining pure platinum wire. Many of the papers at that period comment on the fact that specially purified metal must be used for windings and claim that the iridium, which was apparently then a normal impurity, tended to evaporate during heating, contaminating the furnace. Although this seems most unlikely, furnace tubes certainly tended to become conducting after a period of use and poor quality materials gave rise to much trouble. For example, in I 898 a batch of commercial rhodium for the construction of thermocouple wires was found to contain 30 per cent iridium (37) and, up to at least ryo8, the quartz present in British porcelain refractory tubes (but not in Berlin porcelain) gave rise to spurious thermal analysis effects (38).

Early Commercial Manufacture Platinum-wound laboratory resistance fur-

naces, both tube and muffle, were first produced commercially by the firm of W.C. Heraeus, Hanau, Germany, around I 900. Repeated heating and cooling caused the thin platinum wire spiral on early models to expand and separate in places from the ceramic tube with resultant non-uniformity of temperature distribution and development of local hot-spots where the wire eventually fractured. To overcome this, Heraeus in I 902 developed a furnace using a very thin platinum ribbon (0.007 mni thick) in place of the wire (39). This ribbon required only about one-sixth of the amount of platinum, that is 6 g for a furnace 20 cm long (40). As the coils were laid I mm apart there was virtually a complete platinum cylinder around the ceramic tube. Because of their advantages of uniformity of heat supply and long winding life, these furnaces were highly regarded and were extensively used during the


One example of thr furnaces supplied by W. C. Herarus. Hanau, Germany in 1902, the element consisting of thin foil platinum windings. This particular furnace has an extra long tube sealed with mica end-pieces and is fitted w i t h thermocouple and galvanornctcr for work in mntrnlled atmosphere*

early part of this century. An example is illustrated herewith (4 I) .

Heraeus claimed that furnaces with tubes 2.5 cm in diameter could be heated to 1400°C in about 5 minutes and could attain 170oOC without fusion of the winding (39). The refractory material available for the tube, however, became electrically conducting above about I 500°C. Haagn (42) confirmed that, for 6 to 8 hours’ operation, the practicable maximum was I ~ o o O C , although the furnace could be heated to ~7ooOC for a short period without permanent damage.

Later Developments Despite the ready availability of these fur-

naces, many laboratories still preferred to make their own, sometimes for financial reasons but sometimes because the sizes available were inappropriate for the work to be performed. For example, in 1902 the Physics Division at the National Physical Laboratory, Teddington, constructed two large electric furnaces for a McLeod, gas thermometer reading up to I 200°C, two large furnaces for thermocouple comparison and two smaller furnaces for mis- cellaneous work. By 1904 the Thermometry


Department of the Physics Division had 5 wire- resistance furnaces. ‘l’he winding material is not known with certainty but it would appear to have been platinum or nickel; manganin or eureka wire then being used for low- temperature studies.

Graded windings, to lengthen the uniform- remperature zone, appear to have been first introduced with nickel wire in 1903 (43). In 1904, at the US. Geophysical Laboratory, where much early development took place, platinum-iridium windings were placed inside the furnace tube to obtain temperatures 20o0C higher than those obtainable with a conventional system (44); in 1908 this arrangement was further improved by using graded windings along with supplementary end-coils to give temperatures varying by not more than 1°C over the central 20 cm of a tube 30 cm long by 6 cm internal diameter (45). Within fifteen years from its introduction, therefore, the wire- wound resistance furnace had developed into a precision tool and its technology was highly advanced.

The usual sources of power for these furnaces were high-capacity accumulators of 70 to 100 volts output, or occasionally dynamos, as

181

these provided a more reliable output than mains electricity, where this was available (43,44). By 1912, however, local mains supplies were apparently sufficiently stable in some places to be useful (46). Power consumption is only very rarely stated, but seems to have varied enormously-for example, that of the Heraeus range is quoted as 400 to 2000 watts (42), but 3000 and even 4000 watts are mentioned elsewhere (44,47).

Temperature control was normally effected as described above by Charpy (3 I) , that is using visual observation of the galvanometer deflec- tions and manual adjustment of a rheostat. Temperature indicators for use with thermocouples were introduced at an early stage and in the 1900s control at a fixed temperature was effected by using the needle of the indicator as a relay contact. T h e first automatic control system for continuously increasing temperature seems to have been introduced in 1912 (46); despite the mechanical nature of this, the linearity of the temperaturehime curve is impressive.

Replacement of gas furnaces by electric ones was generally slow. Evidence in the literature suggests that by 1906 gas and electricity were fairly equally utilised, whereas by 1909 electricity had probably become more common. Yet the preference for gas was very strong in some countries and gas furnaces remained in use for purposes where electricity would have been more convenient well into the 1920s ( 2 ~ ) .

Moreover, visual temperature observation with manual control persisted until the 1950s (48).

Perhaps it is because of this gradual transition that the history of the platinum-wound electric resistance furnace has been so neglected.

Acknowledgements The author wishes to thank the Librarian of the

Macaulay Institute and various libraries- particularly those of the Universities of Aberdeen and Cambridgethat provided literature and facilities; also Mr W. E. Carrington, late of the Metallurgy Division of the National Physical Laboratory, and Dr R. C. Chirnside, late of the GEC Research Laboratories, for reminiscences and information.

References

I

2

3

4

5

6

7

8 9

1 0

I 1

I 2

’ 3 ‘4

C. Street, Bull. Soc. Int. Electriciens, 1895, 12,

A. Minet, Trans. Faraday SOC., 1905, I, 77-84; 1906,z, 1-31 “Dictionary of Scientific Biography”, ed. C. Gillispie, Scribner, New York, 1973, 3, pp.

A. Volta, Phil. Trans. Roy. Soc., 1800, 90, 403-431 J. G. Children, Phil. Trans. Roy. SOC., 1809, 99, 32-38 J. G. Children, Phil. Trans. Roy. SUC., 1815, 105, 363-374 A. E. Gunther, Bull. Br. Mus. Nut. Hisi. (Hisi. Ser.), i 978, 6, 75-1 08 I,. B. Guyton, Ann. Chim., 1799,31,328-336 D. Mushet, Phil. Mag., 1799,5,201-205 Sir George Mackenzie, Trans. Roy. So&. Edinb., 1805, 59(3), 11-14 D. Mushet, Phil. Mag., 1801, XI, 289-294 J. F. Daniell, Phil. Trans. Roy. Soc., 1836, 126,

W. R. Grove, Phil. Mag., 1839,15,287-293 C. M. Jarvis, in “A History of Technology”, ed. C. Singer, E. J. Holmyard, A. A. Hall and T. I . Williams, Clarendon Press, Oxford, 1958, 5, pp. 177-207

246-273

211-212

107-124, 125-129


15 J. W. Powell and H. Schroeder, “History of the Incandescent Lamp”, Maqua Co., Schenectady,

16 C. M. Jarvis, in “A History of Technology”, ed. C. Singer, E. J. Holmyard, A. A. Hall and T. I. Williams, Clarendon Press, Oxford, 1958, 5, pp.

N.Y., 1927

208-234 17 J. 1’. Joule,Phil. Mag., 1841, 19,26*277 I 8 Sir Arthur Elton, in “A History of Technology”,

ed. C. Singer, E. J. Holmyard, A. A. Hall and T. I. Williams, Clarendon Press, Oxford, 1958, 4,

19 L. Fourquignon and A. Leclerc, C. R . Hebd. Skanc. Acad. Sci., Paris, 1873, 75, I 16-1 18

20 WJ. C. Roberts-Austen, Proc. Inst. Mech. Eng., 1891, 543-604; see also F. T. Addyman, “Agricultural Analysis”, Longmans Green, London, 1904, p. 16 (illustration)

21 M. Guichard, Bull. SOC. Chim. Fr., 1925, 37, 251-253

22 H. Le Chatelier, C. R. Hebd. Sianc. Acad. Sci., Paris, r886,1oz, 819-822

23 H. V. Regnault, Ann. Chim. Phys., 1842, 4,

24 F. Osmond, Ann. Mines, I 888,14,5-94 25 A. Portevin, Noi. Discours Acad. Sci., 1949, 2,

pp. 258-276

5-63964-67; 5,52-83,83-104

471-476

182

26 R. Barthilemy, Not. Discours Acad. Sci., 1949, 2,

27 G. Charpy, C. R. Hebd. Slanc. Acad. Sci., Paris,

28 G. Charpy, C. R. Hebd. Se‘anc. Acad. Sci., Paris,

29 G. Charpy, C; X. Hebd. Sianc. Acad. Sci., Paris,

30 J. Hirsch, Bull. Soc. Encouragement, 1895, 10,

31 G. Charpy, Bull. Suc. Encouragemenl, 1895, 10, 660-726

32 Bull. Soc. Encouragemenc, I 895, 10, 204 33 Bull. Soc. Encouragement, 1895,10, 807 34 W. C. Roberts-Austen, Proc. Insr. Mech. Eng.,

35 H. 1.e Chatelier, K i v . Metall., 1904, I , I 34-140

633-638

1891, 112, 1451-1453

1893, 116, I 131-1 I33

1894,118,418-421

655-660

1 m 3 1-67

36 L. Holburn and A. L. Day, Am. J . Sci., 1899, 8,

37 A. Stansfield, Phil. Mag., 1898, 46, 59-82 38 W.Rosenhain,Proc.Phys.Soc., 1908,21,180-209 39 W.C.Heraeus,Z. Elekrrochem, I 902,8,201-203 40 B. Blount, Anal. Land., 1905,30, 29-3 j

41 H. Daneel, Z. Electrochem., 1902, 8, 822-828 42 E. Haagn,Z. Elektruchem., 1902, 8, 509-512 43 A. Kalahne, Ann. Phys., I 903,11,2 57-269 44 A. L. Day and E. T. Allen, P h y . Rev., 1904, 19,

45 A. L. Day and J. K. Clement, Am. 3. Sci., 1908,

46 K. Friedrich, Cenrrbl. Miner. Geol. Palaont.,

47 W. P. White, Am. 3. Sci., iyo9, 28,474-489 48 M. Linseis, Sprechsaal, 1952, 85, 423-427

165-19 I

177-186

26,405-463

1912, 174-184

An Historic Platinum Still Preserved for a great many years in the care

of the Society of Chemical Industry in London, a severely damaged small platinum still was recently returned to Johnson Matthey for restoration to something like its original condition. Made for Dr. Rudolph Messel in the 187os, it was used in the development of his process for making fuming sulphuric acid, or oleum, then much in demand by the growing British dyestuff industry. Messel, born in I 848, had originally come to London as secretary to Professor H. E. Roscoe after studying chemistry in Zurich, Heidelberg and Tubingen, but then joined William Stevens Squire o f D u n Squire & Company, this firm later being succeeded by the well known acid manufacturers Spencer Chapman and Messel.

Messel’s complicated process involved the heating of sulphuric acid in a platinum still to contact process originally devised by decompose it into water, sulphur dioxide and oxygen, condensing out the water and then passing the mixed gases in stoichiotnetric proportions-a concept later shown to be quite unnecessary-over finely divided platinum con- tained in a heated platinum tube to form sulphur trioxide. This was then dissolved in sulphuric acid to give oleum. This replaced the old-established lead chamber process and had the further advantage that it eliminated catalyst poisoning from the raw materials he had previously tried in his attempts to operate the

.~

Peregrine Phillips in I83 I .

A British patent, No. 3278 of 187 j , was filed for the process by Messel’s partner Squire, and on April 20th 1876 a short paper was read to the Chemical Society, again by Squire, “On the Manufacture of Sulphuric Anhydride”.

Messel became managing director of the company in I 878, holding this position until his retirement in 1915, by which time some thousand tons a week of oleum were being produced by the process he had originally developed with this experimental still.


ABS TRA C T S of current literature on the platinum metals and their alloys

PROPERTIES Structure of Platinum Aggregates Encaged in Y-Type Zeolite. Effect of CO Adsorption and of CO-H, Co-adsorption

The structure of 10 A Pt particles encaged in Y-type zeolite was determined from the radial electron distribution method from X-ray diffraction data. CO adsorption at 300K on bare Pt leads to an average f.c.c. lattice with normal bond lengths, but with a displacement disorder of the Pt atoms around the nodes. Thus Pt-Pt distances are contracted or elongated compared to their average lattice. Similar observations in molecular Pt carbonyl clusters could provide good modes for these defects appearing in response to CO bonding.

P. GALI.EZOT,ZeOliZeS, 1982, 2, (Z), 103-108

Strength and Plasticity of Palladium- Platinum-Hydrogen Alloys

Fiz. Mer . Meralloved., 1982, 53, (6), I 189-1 193 Studies of the changes in mechanical characteristics of 5-60at.% Pt-Pd alloys under H, saturation showed an increase in strength and plasticity for Sat.% Pt-Pd alloys with an occurrence of phase conversion by H, saturation. Alloys containing 315at.47, Pt showed increased strength and some increase in relative pressure during elongation tests of H, saturated material.

N. T. TIMOFEEV, F. N. RERSENEVA and V. 1. GROMOV,

Overview 19: Hydrogen in Amorphous Metals-I

Metall, 1982,30, (6), 1059-1068 The solubility and diffusivity of H, in amorphous Pd,,,Cu,Si,,,, and Ni,,$d,,,,P,,,, were measured electrochemically. The pressure-concentration isotherms had remarkable deviations from Sievert’s Law, while the amount of H, dissolved lies in- between the solubility of the alloy components. H, diffusivity is high (io-*crn*/s) and depends on temperature and concentration, even at very low H1.

R. KIRCHHEIM, F. SOMMER arid G. SCHLUCKEBIER, Acta

Wear Characteristic of the Sandwich System Nickel-Palladium-Gold

36, (71, 746-752 H. GROSSMAN, M. HUCK and G. SCHAUDT, Merall, 1982,

Microscopic, microanalysis and X-ray diffraction studies of friction-wear of sandwiched Ni-Pd-Au electrodeposits on connectors with thin A u layers between 0.05-0.5 pm were performed. Hard gold alloy (AuCo) on Pd with a Ni underlayer shows more favourable friction and wear conditions even as a

thin layer, than pure Au. With hard gold the insertion forces are nearly independent of thickness of the Au deposit, whereas with fine Au the insertion forces become more pronounced with increasing thickness of the pure Au layer.

Growth Mechanisms and Thermal Stability of Ion-Beam-Induced Epitaxial Pd,Si Films H. ISFII\Y’ARA, Thin Solid Films, 1982, 92, (1/2),

147-1 53 Growth mechanisms and thermal stability of ion- beam-induced epitaxial Pd,Si films were studied by Rutherford backscattering and channelling techniques. Epitaxial growth of Pd,Si films was observed at room temperature by Ar ion implantation into as- deposited PdSi(l1I) structures and furnace-annealed Pd$i(polycrystalline) / Pd,Si(epitaxial) / Si(II1) structures. The stability of the ion-beam-induced epitaxial Pd,Si films on subsequent furnace annealing is studied.

The Diffusion of Hydrogen through Palladium-Titanium and Palladium- Vanadium Solid Solutions M. YOSHIHARA and K. R. MCLELLAN, J . Phys. Chem. Solids, 1982~43, (61,539-545 An electrolytic method was used to measure the diffusivity of H, through substitutional Pd-Ti and Pd-V alloys containing up to roat.% Ti or V in the temperature range 273-3 joK. The diffusivity obeyed the Arrhenius relation. Both Ti and V atoms create trapping sices for H and the mobility of H decreases as the ‘ l i or V increases.

Paramagnetism in High-Nuclearity Osmium Clusters R. E. RENFIEI.D, P. P. EDWAKDS and A. M. STACY, J . Chem. Soc., Chem. Comrnun., 1982, (IO), 525-526 The cluster H,Os,,C(CO),, exhibits intrinsic paramagnetism at iemperatures below 7oK; such behaviour is characteristic of a particulate metal in the quantum size effect regime.

ELECTHOCHEMISTRY Platinum Corrosion in Alkaline Solu- tion in the Presence of Ba” and C1-ions

and K. A. SHUMILOVA, Elektrokhimiya, 1982, 18, (6), 848-850 Studies of the corrosion behaviour of Pt black in alkaline solutions were made at 0.85-1.37V. The dependence of the rate of corrosion of Pt on the potentials, and the effect of preliminary treatment

E. 1. KHRUSHCHEVA, M. P. TARASEVICH, G. P. SAMOILOV

Platinum Metals Rev., 1982, 26, (4),184-187 184

and electrochemical reduction of Pt on the rate of corrosion were studied. 0, adsorption and desorption data on Pt in alkaline solution showed that the process of Pt dissolution proceeds through the formation of intermediate surface oxides.

Reduction of Surface Oxide of Platinum and Cold Electrodes in Aqueous Sulfuric Acid. Local Cell Mechanism and Reactive Species z. H. GUO? -r. hmsLuA and K. SASAKI, Nippon Kugaku Kaishi, 1982, (41, 574-578 ' lhe surface oxides of Pt and Au electrodes, formed anodically, were gradually reduced at open circuit in aqueous H,SO,. The reaction proceeds by the galvanic cell mechanism when the bare surface of the metal acts as an anode which oxidises certain contaminants, and the oxide covered surface acts as a cathode. The formaldehyde used as a contaminant was effective for Pt oxide, but not for Au oxide.

Activation of RuO, and PtO Electrode Surface for Immobilization Reactions Using Thionyl Chloride K . N. KuO and K. W. MURRAY, 3. Elecrrochem. Soc.,

RuO, and superficially oxidised Pt electrodes are reacted with thionyl chloride in an attempt to produce activated chlorinated surfaces which bind and immobilise appropriately substituted reagents. The activated surfaces stably bind reagents such as aminophenylferrocene, tetra(paminopheny1)- porphyrin and [R~(bpy)~4,4'-bipyridine)J'+, which then display electrochemical reactions similar to those of the surfaces. (43 Refs.)

1982, 129, (41,756-761

PHOTOCONVERSION

Photoeatalytic Hydrogen Evolution from Alcohols Using I)odecawolframosilicic Acid and Colloidal Platinum J. R. DARWENT,?. Chem. soc., Chem. Commun., t 982, (141,798-799 Photocatalytic H, evolution from alcohols using Si W;, and colloidal Pt, prepared by boiling aqueous Na citrate and H,PtCI, for 4h, and illuminated with a 9oo'x' xenon lamp was studied. Illumination of SiW';, and colloidal Pt leads to photocatalytic H, evolution with a quantum yield for H, of o.rmol/einstein.

A liechargeable Photo-Electrochemical Solar Cell M. SHARON and A. SINHA, Int. J . Hydrogen Energy, 198297, (71,557-5'52 A rechargeable photoelectrochemical solar cell based on then-typeRaTiOJCe3; Ce'+//FeZ', Fe3'/Pt system has been made. The cell has 0.6V open circuit voltage and 0. I zmA/cmz short-circuit current when fully charged. The power conversion efficiency of the

cell is 0.01% under AMz-sunlight irradiation (75mWkm2). The fill factor of the cell is 0.26. Charg- ing and discharging were characterised; flat-band potential and carrier concentrations of the BaTiO, were calculated and effects of pH and different electrolytes were studied.

Visible Light Induced Water Cleavage in Colloidal Solution of Chromium-Doped Titanium Dioxide Particles E. BORGAKELLO, J. KIWI, M. GRATZEL, E. PELIZZETTI and M. VISCA, J. Am. Chem. Sac., 1982, 104, ( I I), 2996-3002 Surface doping of colloidal TiO, particles with Cr ions precipitated from aqueous H,SO, solution produces very small ((0.1 pm) mixed-oxide particles which absorb light in the 400-50onrn region in addition to the band-gap adsorption of anatase. Ultrafine deposits of I't or RuO, are necessary to promote H 2 0 decomposition. A pronounced synergistic effect in catalytic activity is noted when both RuO, and Pt are codeposited onto the particles.

HETEROGENEOUS CATALYSIS

Study of the Effect of Hydrogen on C,- Hydrocarhon Transformations in the Presence of Platinum-Alumina Catalysts s. A. KKASAVIN and 0. v. BRAGIN, Izv. Akad. Nauk SSSK, Ser. Khirn., 1982, (6), 1314-1320 Studies of the effect of I, on the conversion of C6- hydrocarbons in the presence of o.6%Pt/Al,03 and 0.55% Pt-o.o02?K Re-o.3%F/Al,03 catalysts showed that activity, selectivity and conversion mechanism depend on partial H, pressure in the gaseous phase. Skeletal isomerisation of alkanes proceeds through a predominantly C,-cyclic mechanism at high H, concentration and through a bifunctional mechanism at low H, concentrations.

n-Heptane Transformations on Modified Reforming Catalysts

22, (313 335-338

I. M. KOLESNIKOV, S. G. GORLOV, N. N. BFI.OV, A. P. FEDOROV and E A. SHKLIRATOVA, Nefiekhimiyu, 1982,

Studies of the effects of additions of small amounts of metal containing Si organic compounds on the catalytic activity of PdAI,O, reforming catalysts were made during n-heptanc transformation. Modification of the catalysts by Si-organic compounds was found to increase their activity, selectivity and stability.

Ceria-Promoted Three-Way Catalysts for Auto Exhaust Emission Control G. KIM, Ind. En#. Chem., Prod. Res. Dev., 1982, 21,

(215267-274 Studies were made of the effects of Ba, Mg, Cr, Mn, Co, Ni and Ce promoters on the performance of a typical three-way catalyst (TWC) Pt-Pd-Rh/Al,O,


during CO removal under 0, deficient conditions. Ce was found to be the best promoter largely because it increased the water gas shift reaction (CO + H,O = CO, + HJ and possibly also due to the additional 0, storage it provides to the TWC.

Heterogeneous Water Gas Shift Reaction Catalyzed by Titanium Dioxide Supported Noble Metals R. RUPPERT, J.-P. SAUVAGE, J.-M. I.EHN and K. ZIESSEL, Nouv.3. Chim., 1982, 6, (s), 235-239 Various transition metal catalysts supported on SiO,, PVA, TiO, and zeolite were studied for the water gas shift reaction in the liquid and gas phases at L O O to 285OC and CO pressures QI arm. Parameters such as pH, temperature and preparation method have a drastic effect on catalytic activity. The catalyst Pt,K,CO,/TiO, was the most efficient catalyst for the reaction, its turnover frequency varied from 360/h at 200°C to 3600h at 268°C.

Catalytic Combustion of Hydrogen. 11. An Experimental Investigation of Funda- mental Conditions for Burner Design M. HARIJTA, Y. SOUMA and H. SANO, Inr. 3. Hydrogen Eneru, 1982~7 , (91,729-736 The performances of catalysts, consisting of a ceramic honeycomb impregnated with Pt, Ni metal foams coated with Pd powder, and ceramic foam coated with Co-Mn-Ag oxide powder, were studied for the design of a catalytic combustor using H, fuel. In the diffusive mode of operation the Pd coated Ni foam with larger pores exhibited the highest combustion efficiency. Combustion efficiency was improved by increasing the amount of premixed air.

Fischer-Tropsch Studies over Well- Characterized Silica-Supported Pt-Ru Bimetallic Clusters n. MlUKA and R. D. GONZALEZ, Ind. Eng. Chem., Prod. Res. Deo., 1982, 21,(2), 274-278 A Fischer-Tropsch (F-T) study over a well- characterised series of SiO, supported Pt-Ru bimetallic clusters showed that the increase in surface concentration of Pt has a marked effect on methane selectivity. The F-T reaction was shown to be structure sensitive, occurring predominantly on Ru surface sites. It is concluded that Pt surface sites are inactive in the CO-H, reaction under the studied conditions and the role of Pt is, therefore, reduced to that of a surface diluent.

Transformation of 1,3-Pentadiene on Membrane Catalysts Made of Binary Palladium Alloys A. 1'. MISHCHENKO, V. M. tiKYAZNOV and M. E. SARYLOVA, Izw. Akad. Nauk SSSK, Ser. Khim., 1982, (711 '47 1-1 473 Studies of catalytic conversion of I ,ypentadiene under H, pressure through membrane catalysts made of Pd-9.8W Ru and Pd-2.03, Srn alloys showed an

increase in rate of H, transfer through the catalyst. The effect of (1- and P-hydride phases on selectivity of the hydrogenation process is discussed.

AlPO,-Supported Rhodium Catalysts. I . Effect of the Preparation Variables on Cyclohexene Hydrogenation J. M. CAMPELO, A GAKCIA, L, LUNA and J. M. MARINAS, Gazz. Chim. Ira/., 1982, 112, (5-6),221-225 The liquid phase catalytic hydrogenation of cyclohexene over Rh/AIPO,SiO, catalysts in I wt.% methanol solvent and initial H, pressure of 5.6 bar and 4ooC is reported. Catalytic activity was strictly dependent on the conditions of reduction of the pre- cursors. The highest catalytic activity was obtained when the precursor was reduced under mild conditions; at higher temperatures, or if the precursor was calcined, activity was lower.

Hydrogenation of CO and CO, over Rhodium Catalysts Supported o n Various Metal Oxides T. IIZIJKA, Y. TANAKA and K. TANABE, J . Catal., 1982, 76,144 The formation of hydrocarbons in the reaction of CO+H, and CO,+H, was studied over Rh catalyst supported on ZrO, A1,0,, SiO, and MgO. In the studied teaction, Rh/ZrO, was the most active and Rh/MgO was least active. The activity for the CO+H, reaction over the oxidised Rh/ZrO, and Rh/AI,O, catalysts was 2-10 times higher than that on the reduced catalyst.

Improvement of the Catalytic Perfor- mance of an Osmium Powder in Ammonia Synthesis by the Use of a Cyclic Procedure G. RAMBEAU, A. JORTI and H. AMARIGLIO, Appl. Catai., 1982, 3, ( 3 1 9 273-282 The catalytic activity of 0 s in NH, synthesis is greatly impeded by H, under the usual reaction conditions. Decreasing the H, content of the reactant mixture reduces inhibition and increases the reaction rate. The reaction is also inhibited by NH,. Decreas- ing the H, shifts the synthesis equilibrium to lower NH, contents. Cycling with pure N, and H, increases 0 s activity and the best average rate is 5-50 times higher than the best steady rate, depending on temperature in the range 4oo-250°C.

Mechanistic Study of Carbon Monoxide Hydrogenation over Ruthenium Catalysts Y. KOBORI, n. YAMASAKI, s. HAITO, T. ONISHI and K. TAMARIJ, 3. Chem. Sac., Faraday Trans. I , 1982, 78, (S?> J 473-1490 The mechanism of the hydrogenation of CO over 4.~wt.%RdSiO, catalyst prepared by impregnation of SiO, with an aqueous solution of RuCI, hydrate was studied. It is concluded that all the hydrocarbon products are produced via dissociatively adsorbed CO with no CO insertion. The rate-determining step comprises the conversion of C, intermediates.


HOMOGENEOUS CATALYSIS Novel Pa l lad ium( 11)-Catalyzed Copolymerization of Carbon Monoxide with Olefins A. SEN and T.-\Y’. LAI, 3. Am. Chern. Soc., 1982, 104, (12),352*3522 The series of cationic Pd(I1) compounds [Pd(CH,CN),](BF&.n PPh, (n = 1-3) which catalyse the cepolymerisation of CO with a range of olefins under unusually mild conditions is reported. The species prepared by reactions of AgBF, with Pd(PPh,)flel and Pd(Ph,),(C(O)Me)Cl and I’d(PPhJXC(O)Me)(solv)+ were also active catalysts for the co-polymerisation of CO and C p , under similar conditions. Catalysts prepared with a PPh, : I’d2+ ratio of 1-3 were active but those with ratios 4 and 6 were found to be inactive, which shows the need for easily accessible co-ordination sites.

Activation of Molecular Hydrogen by Transition Metal Complexes. 6. Role of Molecular Oxygen in Forrnatiun uf Palladium Complexes Active in Hydrogenation of Unsaturated Com- pounds A. s. BERENBLIUM, A. G. KAIZHNIK, s. I.. MIJND and I. I. MUISEEV, Izv. Akad. Nauk SSSR, Ser. Khim., 1982, (61,1249-1253 Studies of the interaction of [Ph,PPd(OAc)J, with H, showed the formation of intermediate complexes (Ph,Pj,PddOAc), and final yields of (Ph,P),Pd, and (Ph,P),PdpH,. The cluster [(PPh),Pd,], was found to be active in the hydrogenation of unsaturated hydrocarbons.

Mechanism and Stereoselectivity of Asymmetric Hydrogenation J. HALPEKN, Science, 1982, 217, (4558), 401--407 Rh complexes containing chiral phosphine ligands catalyse the hydrogenation of olefinic substrates such as cu-aminoacrylic acid derivatives, giving chiral products with very high optical yields. It is concluded that the stereoselection is dictated by the much higher reactivity of the minor diastereomer of the catalyst-substrate adduct, corresponding to the less favoured binding mode.

Selective Homogeneous Transfer Hydrogenolysis of Trihalomethyl Cum- pounds by Alcohols and Rutheniurn- Phosphine Catalysts J. BLUM, s. SHTELZER, P. AI.BIN and Y. SASSON, J . MoZ. Card., 1982, 16, (21, 167-1 74 RuC1,(PPh,)3 was shown to catalyse H, transfer from halogen-free alcohols to m-trichloromethyl- and tx- tribromomethyl carbinols and to give selectively dihalomethyl derivatives. Benzyl alcohols proved to be very efficient H, donors. The catalytic process was affected by the electronic structure of‘ the catalyst and of the H, acceptor but not by H, donor.

The Cluster Anion [ HRu,(CO) 11]- as Catalyst i n H y d r o f o r m y l a t i o n , Hydrogenation, Silacarbonylation and Hydrosilylation Reductions of Ethylene and Propylene G. SOSS-FINK and J. REINER, J . Mol. Caral., I 982, 16, The trinuclear cluster anion [HRuJCO),,] ~ was found to catalyse hydroformylation, hydrogenation, silacarbonylation and hydrosilylation reactions. Ethylene and propylene were hydroformylated with CO and H, to give the corresponding aldehydes; in the case of propylene a high yield of the unbranched butyraldehyde was obtained. The catalytic turnover of these reactions was observed to be 50-400.

ELECTRICAL AND ELECTRONIC ENGINEERING

Dynamics of Interfacial Electron- Transfer Processes in Colloidal Semiconductor Systems D. DIJONGHONG, J. RAMSDEN and M. GRATZhL, J. Am. Chem. SOC., 1982,104, ( I I ) , 2977-2985 The dynamics of interfacial electron-transfer reactions were studied with colloidal ‘l’i02 and CdS particles, which form transparent aqueous disper- sions. Experiments with Pt-loaded CdS established catalytic H, production by conduction-band electron with electron transfer to adsorbed MV2+. RuO, deposits enhance hole transfer from the valence band to solution species.

Hydrogen Detection by Schottky Diodes K. ITO and K. KOJIMA, Inr. 3. Hydrogen Energy, 1982, I? 495-497 A Schottky diode was made from a 20 nm evaporated Pd film, a very thin SiO, film and n-type Si substrate. Two diodes were obtained on the Si substrate, one was used for H, detection and the other as a reference diode. The detector, operating at room temperature was able to detect 2000 ppm H, in air within 10s. There was no degradation found over an 8 month operating period.

TEMPERATURE MEASUREMENT Measuring Low Temperature in the 13 through 80K Range Using ZPA, NIT-100 Platinum Temperature Sensors I. \w>REK, Slaboproud. Obzor, 1982,43, (51, 216-220 The basic thermometric properties of the ZPA Pt temperature sensors of the MT-IOO type are described for the temperature range I 3-80K. The dependence of electrical resistance, sensitivity and temperature resistance coefficients on temperature are described. The dynamic stability of the electrical resistance is tested by the cycling mcthod.


N E W PA TENTS

METALS AND ALLOYS ZGS Au-Pt Bushing Baseplate JOHNSON MATTHEY & CO. LTD.

British Appl. 2,085,028 A Alloys for USK in glass handling equipment and for X-ray fluorescence sample preparation, having improved wetting properties, contain 2-1 0% Au, one or more platinum group metals and a grain stabilising agent which may be Sc, Y, Th, Zr, Hf, Ti, Al or other lanthanide oxides, carbides, silkides or nitrides. %rO, or T h o , stabilised Pt-S%, Au alloys are preferred. The particles of the grain stabilising agent are preferably in the size range of 200-1000 A.

ELECTROCHEMISTRY Urea Oxidation SIEMENS A.G. European Appl. 50,803 A process for the indirect oxidation of urea, in blood, uses an electrochemical cell having electrodes coated with Pt, a Pt-Ir alloy or Ru oxide.

Oxygen Electrodes DIAMOND SHAMROCK CO. European Appl. 52,446 Active electrodes for use in brine electrolysis are resistant to corrosion and have extended service life when they contain particles of partially-fluorinated active carbon supporting a Pt or Ag catalyst.

Thermionic Cathodes THORN EMT-VARIAN 1.TD. European Appl. 53,867 A thermionic cathode consists of a porous W matrix impregnated with a Group IIA metal activator such as Ra Ca aluminatc and coated with a film of alloy such as Mo-Os, Ir-Ta, Ir-Nb, Rh--la or Rh-Nb.

High Voltage Electrolytic Cell C.D. THEMY U.S. Paten1 4,3 16,787 A method of electrolysing brine solution to chlorine and ozone USKS full line unrectified electricity which has passed through a solid state rectifier unit. High yields are obtained using a laminate anode composed of a platinum group metal foil bonded to a T a or Nb layer on a Ti substrate.

Catalysed Chloralkali Cathode JOHNSON MKITHEY & CO. LTD.

German Offeen. 3,116,032 A cathode for use in brine or water electrolysis cells is made from an electrically conductive matrix carry- ing a surface deposit of a platinum group metal, preferably Pt and/or Ru. The matrix may be made of Ni, Cu, austenitic steel or another base metal on to which the catalyst is deposited by chemical displacement. A mild steel cathode may be plated with Ni, etched and then chemically plated with Pt and Ku.

ELECTK0L)E;POSlTION AND SURFACE COATINGS Sputter Ion Metal Plating V.K. SECRETARY OF STATE FOR DEFENCE

British Appl. 2,090,291 A Smooth, dense, pore-free coatings are produced without developing high substrate temperatures by sputter ion plating using mixtures of the required refractory metal and another metal or metals and reducing the substrate bias potential. The platinum group metals (excluding Pd) are among the refractory metals that may be deposited.

Palladium Plating Bath BLJNKEK KAMO COW. South African Appl. 8017609 Ductile, non-porous coatings are deposited from a bath containing a palladosaniine salt, sulphamic acid and ammonium chloride.

LABORATORY APPARATUS AND TECHNIQUE Leak Detector M A ISUSHII'IZ EI.ECI'KIC WOKKS L I D .

British Appl. 2,086,583 A The presence of H , methane and butane gas leaking from a I.PG or another gas container, is detected by a double sensor system. The sensing elements used are mixtures of metallic oxides, such as Pd, In, Sn and FK oxides and the main sensor may also contain PtO, and Rh,O, to improve its hydrogen selectivity.

Hydrogen Sensor GRNERAI. EI.ECTRIC CO. British Appl. 2,090,050 A The concentration of hydrogen in a Huid is sensed by electrodes in a chamber having a hydrogen- permeable window, made of Pd-Ag.

Oxygen Partial Prvssure Electrode .MI1S~IRISIII RAYON CO. LTD.

European Appl. 56,178 An improved electrode for continuously measuring the 0, partial pressure of blood consists of a fine metal wire coated with a cellulose acetate or other porous membrane. The preferred wire is Pt.

Thick Film Sensor for Hydrogen and (:arbon Monoxide W'ESTINGHOL'SE EIXC'rRIC CORI'.

European Appl. 56,339 The sensitivity of a thick film stannic oxide sensor to CO is enhanced by adding 1.a-oxide or another lanthanide oxide to the filtn instead of T h oxide as before. Pt and Ru chloride catalysts are introduced into the SnOZ to increase its reactivity.

Platinum Metals Rev., 1982, 26, (4),188-190 188

Bacteria-Sensing Probe G.R. INTERNATIONAL ELECI KONICS L I T .

U S . Parenr 4,322,279 Thick film printing technology is used to produce Pt and Au conductive tracks in an electrode assembly for sensing bacterial activity.

HETEROGENEOUS CATALYSIS

Catalyst fur Ethanol Production ~MITSlIBISI11 GAS CHEMICAL CO. INC.

Brirish Appl. 2,087,393 A Ethanol is prepared with a high selectivity and yield from methanol, C:O and HZ using a catalyst consisting of Ru and Mn promoted with an iodine source. A typical catalyst contains Mn acetate, Ru chloride, iodine and methyl acetate.

Ultraviolet Stahle Polymers JOHNSON MATTHEY & CO. I.TD.

Bricish Appl. 2,087,403 A 'l'he chemical and thermal stability of butadiene polymers and co-polymers are improved by hydrogenation using a new method. The polymer is dispersed in a non-polar solvent such as cyclohexane and contacted with gaseous or dissolved hydrogen in the presence of a heterogeneous solid particulate catalyst consisting of Pd on a solid, porous, particulate C: support.

Paraffin Dehydrocyclisatiun Catalyst ELF FRANCE French Appl. z,484,40 I

Aromatic hydrocarbons may be prepared at relative low pressure from paraffins using a catalyst containing 0,1-1.5r~, Pt, Ir, Ke, Sn a n d o r Ge on a Leolite support which has been exchanged with a Group IA metal. Pt and Pt-Re catalysts are used.

Coating Catalyst Tubes with Metal Ub.C;LSSA A.G. German Offen. 3,034,957 A homogeneous layer of catalytic metal is obtained on the internal surface of a catalyst tube, such as A1,0,, by filling the tube with an aqueous solution of an appropriate metal derivative, such as Pt chloride optionally together with I r chloride, evaporating the solution at elevated temperature and reducing the metal compound in a stream of hydrogen.

H OM 0 G EN EO U S CAT A LY S I S Phase Transfer Hydrogenation of Olefiris JOHNSON MAI.I H ~ Y P.L.C. Brirish Appl. 2,085,874 A A new two phase olefin hydroformylation process operates at moderate conditions and makes recovery of the catalyst easier. The catalyst consists of a water- soluble platinum group metal complex, such as a Rh complex of a sulphonated or carboxylated phosphine, and, an arnphiphilic reagent, such as a phase transfer agent or surfactant.

Hhodium Carbonylation Catalysts EXXON RESEARCH iyr tNGlh 'EERING CO.

Brirish Appl. 2,086,906 A Highly stable and selective catalysts for the hydroformylation of olefins at relatively low pressure to obtain, predominantly, aldehydes, are non-charged non-chelated bis- and trisjalkyldiarylphosphille~ Rh carbonyl hydrides. AlkyI group substituents include hetero-organic radicals containing silane, silicone, ether, ester, keto, phosphine oxide, amide and amine groups.

Ruthenium Catalysts KHONE-POIJLENC I N D l ~ S r R I B S Europeun Appl. 49,674 A catalyst system for the formation of carboxylic acid esters by reaction of olefins with alcohols and CO contains a tertiary amine, a Co derivative, such as dicobalt cclacarbonyl, and a Ru derivative such as triruthenium dodecacarbonyl.

Carbonylation Catalysts EXXON RESEARCH iyr ENGINEERING cn.

U S . Pateni4,321,211 New carbonylation catalysts are obtained by reacting a Rh, Co or other Group \:I11 metal carbonyl with a Group 1IA metal in the presence of a Lewis base. A typical catalyst is (C,H,0)$4g(Rh(CO),(PPh3,/L.

Iridium-Catalysrd Preparation of Aniline 'I'EXACO TNC. U.S. Parent 4,322,s 56 Aniline may be prepared, in good yield, by reacting nitrobenzene with vinyl cyclohexene in the presence of a homogeneous hydrogen transfer caralyst. The original filing suggested IrCI(CO)(Ph,P), as a useful catalyst but the claims describe a noblc metal complex catalyst containing Pt, I'd, Rh or Ru.

FUEL CELLS


Fuel (:ell Electrodes tLEC'I'ROCHFMISCHE ENFRGIECONVEKSIli N.V.

European Appl. 54,984 Electrodes of considerably improved stability are obtained from mixtures of a C of relatively low specific surface, such as graphite, supr lrting 1 ~ 1 0 % of a noble metal, preferably Pt, a C of ,latively high specific surface such as activated C and a binder which is preferably PTFE.

Dry Method for Preparing Fuel Cell Electrodes I I N I I E L ) TECHKOI.UGIES C o R r U.S. Pareni 4,3 I 3,972 A method of manufacturing gas diffusion electrodes on a continuous basis deposits a layer of dry C, preferably catalysed with Pt, and hydrophobic polymer powder on a substrate by dispersing the powder as a cloud in a chamber and vacuum depositing the powder cloud on to the substrate. ' Ihe coated electrode is then compacted and sintered in the normal way.

Fuel Cell Electrode STE. GENERAI.E DE CONSTRUCTIONS E L E C ~ . R I Q ~ J E ET M E C H A N ~ Q U E ~ 'ALSTHOM~ U.S. Patent 4,3 17,867 Extremely thin (roo-zgo pm) flexible fuel cells electrodes may be formed from only two layers, such as a support layer and an active or catalytic layer, when high amounts of a hydrophobic binder are included in similar amounts in both layers. An electrode described includes a Pt-catalysed c layer.

trate. A thin layer of Pt covers a central layer of the substrate to form a Schottky barrier layer and is surrounded by the insulated shield structure.

Reversible Optical Storage Medium U S . PaLen1 4,320,489 R.C *. 'OKP.

A recording marerial consisting of a thermoplastic layer containing a light absorptive I't, Pd or Ni- substituted ethylene dithiol complex supported on a conductive layer of A1 enables information to be stored in a reversible manner. The substrate is charged to store and heated to erase information. ELECTRICAL AND ELECTRONIC

ENGINEERING

ENERGY CONVERSION DEVICES INC. MEASUREMENT Programmable Cells for PHOM Devices TEMPEHATURE

British Appl. 2,086,654 A Programmable cells are formed from amorphous Temperature Conditioning Apparatus

European Appl. 50,287 doped Si and II, alloys, in which the doped areas are HONEMVEI.~. INC. settable into a highly conductive state. pt and I'd A temperature conditioning apparatus of improved silicide Schottky diodes may be included in the efficiency is controlled by a microprocessor to which memory device. are connected a multiplicity of temperature-sensing

elements such as Pt resinate sensors. Conductive Palladium-Polyimide Films K. A. FROSCH ET AL 'Temperature Sensor for (:oal Gasification Light-weight, high temperature-resistant, electrically Reactors conductive films for use in aviation and space KUHRCHEMIEA.G U.S. Paten1 4,305,286 applications are polyamic acids containing Pd ions pt : pt-Kh thermocouples may be used in such which subsequently are formed into thin) flexible reactors which reach temperatures of up to 1,700CC polyimide films. The acids are prepared by reacting when the thermocouples are protected by a sealed an aromatic dianhydride with an aromatic diamine sheath and are retracted from the reactor when not in the Presence of Li,pdC1,, pd\SMe,l,C12 or I'dCl2 in use. A bore arrangement facilitating the retraction salts. is described.

Thick Film Resistor Pastes GENERAL MOTORS COW. U S . Patent 4,3 I 2,770 Resistor pastes for producing stable fired resistors which are economical in the use of noble metals contain 5-24%, Ru dioxide, IO-ZO'X Ag, up to 4%' T a oxide, 3-857, Sb oxide, 8-12% Cd oxide, 35-70% glass frit and up to zY(, thermistor powder (such as Mn,03, NiO, CuO, Cr,03 or ZnO).

Low Barrirr-Height Epitaxial Ge-GaAs Mixer Diode t:,s, S,;(-RETARyOFT"E NAVY

Low barrier height (0.4 eV) Schottky diodes are obtained by depositing a very thin heterojunction epitaxial layer of Ge on a GaAs substrate using specified deposition rates and substrate temperatures. .I'hen Pt-,,i-Mo-Au metallisation is deposited on the epitaxy layer. Conract layers are finally Au plated.

Platinum-Cadmium Sulphide Schottky be improved by the addition of o.2-.o,7m, R ~ ~ , Barrier Photovoltaic Detector GENI:RAI. DYNAMICS U.S. Parent 4,319,258 Water-Soluble Salts of Platinum A detector capable of sensing U.V. and short HydroxymaIonate Complexes wavelength visible radiation with extremely small HKrS101.,2.1YHKS co. U.S. Patent 4,322,362 response to longer wavelengths is used in missile Animoniurn and Na salts of known anti-cancer l't guiding systems. It has a Ti-Au-li infrared shield complexes, such as hydroxymalonatd't diammine, structure deposited directly on to a Cd sulphide subs- possess high solubility for intravenous use.

U.S. Patent 4,3 I r,6 I 5

MEDICAL USES Anhydrous Chip JOHNSON MAITHEY P.I..C British Appl. 2,085,440 A Cisdichloro-trans-dihydroxy-bis (isopropylamine) Pt (TV) is useful for the treatment of cancer or malig- nant neoplasms. Hitherto, its preparation has resulted in formation of the I : I hydrate. The anhydrous form may now be prepared by oxidising

adduct with dimethylacetamide.

Palladium-Based Dental tl, ti, U.S. I'acent 4,319,887 A non-discolouring dental alloy, free from Ag and Au, contains 7 5-85'6 I'd, 5 - 1 0 7 In, 5-1o.jr& Sn, up to 7.5%) Co, Cr or Ni and up to 0.25% Si. T h e physical and mechanical properties of the alloys may

u,s, palent 4,316 ,201 the Pt(II) complex with peroxide and purifying via an


AUTHOR INDEX

Page Ad&, R. R. 135 Albin, P. 187 Alexandrov, E. P. 39 Alnot, M. 134 Amariglio,H. 43.91, 186 Andersson, S. L. T. 139 Angerstein-Kozlowska,

H. I 36 Anthony, R. G. 138 Antler, M. 106 Antonov, P. G. 39,44 Anufriev, V. 1. 39 Apple, 1. M. 138 Arakawa, H. 89 Ardizzone, S. 87 Arzamaskova, L. N. 89 Asakura. Y. 41 Attwood, D. Aubke, F.

Baidus, 0. V. Bard, A. J. Barrell, J. D. Bashilov, K. V. Battezzati, L. Bauer, E. Beden, B. Bell, A. T. Belov, N. N. Bemiller, J. N. Benedek. R. A. Benfield, R. E. Bed, G. Bereublium, A. S. Berger, R. Bernhard, P. Berseneva, F. N. Bettoni, G. Blum, J. Boberg, G. Borgarello, E. 40, Borunova. N. V. Bossi, A. Boswell, P. G. Boyar, E. B. Bradley, D. 1. Bradley, P. Bragin, 0. V. Branik, M. Brener, R. Bricker, J. C. Brotherton, S. D. Budd, A. E. R. Bune, N. IA. Burch, R. Burmester, W. L. Byvik, C. E.

41 88

42 39,89

13 39

134 I34 88 42

185 140 98

184 92

187 91 88

184 88

187 44

136. 185 44

138 16 65 87

1 40 185 41

140 136 140 104 136 90

I34 40

Page

Chevalier, B. 134 Chitnis, G. K. 137 Christenson, J. R. 91 Clark, R. W. 87 Cleare, M. J. 33, 1 I8 Cole, A. 134 Cde-Hamilton, D. J. 89 Conway, B. E. 136

Cort, B. I34 Cottington, I. E. 105 Coupland, D. R. 146 Courbon, H. 89 Cox, F. F. 41 CNZ, M. 40 Czerwinski. A. 135

Cheryshev, G. A. 88

Cooper, G. 88

Darwent, J. R. Dautremont-Smith, w. c.

Day, J. G. De Asmundis, C. De Wit, N. Disdier, J. Dombek, B. D. Drago, R. S. Ducros, R. Dumesic, I. A. Dunn, W. W. Duonghong, D. Duprez, D. Duwez, P. E.

Edwards, P. P. Ehrhardt, J. J. Eizenberg, M. El A’mma, A. G. Enga, B. E. Ermakov, IU. I. Ermoiaev, V. N.

Fajula, F. Fasman, A. B. Fedorov, A. P. Fedoseeva, T. A. Fisher, G. L. Foglia, T. A. Foost, D. S. Formichev, V. G. Franchini, C. Frank, A. J. Frew, A. A. Friedlin, L. KH. Fripiat, J. Froment, G. F. Fujitsu, H.

Galeev. T. K.

185

92 57 87 88 89 44 43

134 43 89

40.187 I37 39

I84 I34 140 43 50 89

139

138 139 185 40

135 139 92 88 88 88 91 44 40

137 139

90

TO VOLUME 26 Page

Gil’chenok, V. P. 42 Giorgi, A. L. 134 Gobolos, S. 42 Godoy, J. 92 Gonzalez, R. D. 137.186 Gorlov, S. G. 18.5 Gorodetskii, V. V. 136 Gorodyskii, A. V. 89 Grant, N. J. 39 Gratzel, M. 40.136,185,187 Green, M. C. 32 Grigg. R. 91 Gromov, V. 1. 184 Grossman, H. 184 Gryaznov, V. M. 186 GuCnault, A. M. 87 Guo, Z. H. 185 Guthrie, W. L. 38

Hackwood, S. 92 Haito, S. 186 Hall, C. W. 146 Halpern, J. I87 Hamaker, H. C. 39 Hardwick, S. J. 92 Haruta, M. 186 Hashimoto, K. 136 Hayasaka, T. 138 Hegedus, M. 42 Heindl, R. I36 Herrmann, J.-M. 89 Heywood, A. E. 28,98 Hicks, R. F. 42 Hinckley, C. C. 140

Hlavacek, V. 90 Hoffman, M. Z. I36 Hoflund, G. B. 41 Hou, X. 40 Huck, M. 184 Humphry-Baker, R. 136 Hunt, D. J. 90 Hunt, L. B. 79. 183

Hjortkjaer, 1. 43

landelli, A. Iizuka, T. Inoue, H. Isaguliants, G. V. Isakov, IA. I. Ishida, H. Ishiwara, H. Ito, K. Ivanov, V. A. Iwasawa, Y.

Jackson, D. Jacobsen, T. Johnson, B. F. G.

38 186 90 41 90 90

184 187 39

138

90 42

135

Katsuki, T. Kauffman, G. B. Kawai, T. Kawakami, T. Keim, W. Keith, V. Kelemen, S. R. Kemmitt, R. D. W. Keramati, B. Khidekel, M. L. Khrusbcheva, E. I. Kil’dibekova, G. A. Kim, G. Kimura, T. King, F. Kirchheim, R. Kiwi, J. Kleppa, 0. J. Klos4 J. Klyuev, M. V. Knifton, J. F. Kobori, Y. Kojima, K. Kolbasov, G. IA. Kolesnikov, I. M. Kondrat’ev, S. I. Kornienko, L. P. Kosaki, Y. Krasavin, S. A. Kravchenko, N. IA. Kravchuk, L. S. Kroger, H. Krulik, G. A. Ku, R. C. Kudo, K. Kukushkin, IU. N. 39.4 Kulak, S. Kummer, F. Kuo, K. N.

Lai, T.-W. Laitinen, H. A. Lalevic, B. Lamy, C. Lationova, T. I. Lee, K. C. Leger, J. M. Lehmann, H. h h n , J.-M. Lejay, P. Levy, F. Lewis, F. A. 20.70, Lewis, J. Liao, P. C. Liashenko, A. 1. Lilic, J. Lodi. G.

Page 43

129 I36 43 43 87 87

135 92

138 184 139 185 139 I74 184 185 87 92

138 92

186 187 89

185 138 40

137 185 88

138 92 58 38

139 4.9 1

42 41

185

187 41 89 88

138 88 88 88

186 134 135 121 135 137 139 136 87

Campelo, J. M. 186 Gallei, E. 42 Jones, R. F. 89 Losev, V. V. 136 Carbonara, G. 88 Gallezot, P. 184 Jorti, A. 186 Lucci,A. 134 Carlsen, P. H. 3. 43 Garbassi, F. 138 Ludi, H. 88 Cassuto, A. 134 Garcia,A. 186 Kadirgan, F. 88 Luft,G. 91 Chaston, J. C. 3 Gaube,V. 91 Kaizhnik, A. G. 187 Luna,D. 186 Chaudhury, Z. A. 135 Genesca, J. 40 Kalyanasundaram, K. 136 Luudin, S. T. 91 Chernova, G. P. 40 Georg, C. A. 135 Karakeev, B. K. I39 Lunsford, J. H. 138


McBreen, J. McGill, I. R. Mackay, H. B. Mackenzie, R. C. McLellan, R. B. McNicol, B. D. Maestri, M. Mague, T. J. Makarova, E. A. ManojloviC-Muir, L. Marin, G. B. Marinas, J. M. Marnot, P. A. Martin, N. Martin, V. S. Maslianskii, T. N. Masuda, T. Matsuda, S. Matsuda, Y. Matsui, Y. Matsumura, E. Matzke, H. Maurel, R. Maxwell, K. W. Megusar, J. Menon, P. G. Meyer, 0. Mill, R. H. Miloudi, A. Minachev, KH. M. Mishchcnko, A. P. Misono, M. Mitchell, T. R. B.

Miura, M. Miyamoto, A. Moger, D. Moiseev, I. I. Moon, S. H. Moshkevich, A. C. Moyes, R. 6. Muetterties, E. L. Muir, K. W. Mulazzani, Q. G. Muller, P. Mund, S. L. Murakami, Y. Murakawa, K. Murray, R. W. Musaev, A. A.

Page 137 146 3Y

175

41 89

135 138 91

137 186 91 41 43 42

I85 41 87 44

139 38

137 10 39

137

184

38 91

137 YO

I86 139 91

Miura, H. 137. 186 43

137 42

I87 42 42 YO 87 91

136 92

187 137 . .

Nagamoto, H. Nagel, C. C. Nakano, Y. Naruse, Y. Nis, H. Nizova, G. V. Norde, H. Noufi, R. Nozik, A. J. Nyberg, E. D.

Odenhrand,

Olendcr, A. Omashev, KH. Onishi, T. Ono, Y. Orehotsky, J. Oshima. R.

I G.

Paek, I.-B. Palenzona, A. Parsons, R. Paseka, I. Pecherskii, M. M. Peebles,, D. E. Pelizzetti, E. Pereira, P. Petrini, G. Phutela, R. C. Pichat, P. Pickett, G. R. Popova, N. M. Poppa, H. Poteat, T. L. Pratt, W. P. Pringle, P. G. Puddephatt, R. 1.

136.

Page 137 139 186 90 40 38

88 38

136 YO

136 135 I85 137 138 87 89 87 YO

134 89 8 7 88 91

Rahette, P. 38 Rambeau, G. 4 3 , 9 l . 186 Ramsden, J. 187 Raspopin, S. P. 39 Rathousky, J. 90 Raub, C. J. 158 Redon, A. M. I36 Reichman, B. 40 Reiner, 1. 187 Reutov, 0. A. 39 Rius de Riepen, M. 40 Robinson, S. D. 65 Rodin, A. P. 90 Romanenko, A. V. 89 Roper, M. 43 Rosenberg, B. 140 Rubinstein, I. 39 Ruppert, R. 91. 186 Russell, D. R. 135 Russell, L. D. 140 Ryndin, YA. A, 42

38 44 Rytvin, E. 1. 185

39 Saitho,F. 90 Sakata,T.

136 Sandrini, D. 139 Samoilov, G. P. 87 Sano,H. 40 Sarylova, M. E. 39 Sasaki,K. 44 Sasson,Y. 88 Sastry, G. V. S. 88 Sato,T. 43 Sauer,R.

Sauvage, J.-P. Savel'eva. G. A.

c. u. 1. 9 I , 139 Scarpellino, A. J. Ogasawara, S. 138 Schaudt, G. O'Gtady, W. E. 135, 137 Schreifels, J. A. Okada, M. 44 Schiavone, L. M. Okuhara, T. 139 Schluckebier, G.


43 136 89

184 186 186

87.185 187 135 44

117 91, 186

YO 135 184

Schrod, M. Schulze-Berge, K. Scurrell, M. S. Sckirin, I. V. Sellmyer, D. J. Sen, A. Shapley, J. R. Shapovalova, L. B. Sharon, M. Sharpless, K. B. Shaw, B. L. Shiflett, W. K. Shih, H. D. Shimizu, T. Shinohara, T. Shiiahama, S. Shkredov, V. F. Shore, S. G. Short, R. T. Shtelzer, S. Shul'pin, G. B. Shumilova, N. A. Sibhett, W. Simonsen, P. Sinha, A. Sivieri, E.

Page 91 41 43 89

134 187 92

139 185 43 88 43

134 87 87

139 39

136 41

187 39

184 40 4 3

185 87

Skinner, H. B. 32 Snyder-Robinson, P. A. 88 Sobkowski, T. 135 Sokok, J. D. 38 Sokolov, V. 1. 39 Sokol'skii, D. V. 138 Sommer, F. 184 Somorjai, G. A. 38 Soria, F. 134 Souma, Y. 186 Srinivasan, S. 40, 135. 13 7 Stacy, A. M. 184 Stepanova, G. S. 38 Stewart, G. R. I34 Stolt, L. 44 Strack, L. E. 140 Stucky, G. D. 92 Sugi, Y. 89 Sugita, N. 139 Suryanarayana, C. 135 Suss-Fink, G. 187 Sutthivaiyakit, S. 91 Sutyagina, A. A. 42 Suwa, K. 139 Svendsen, H. 43 Szabo, S. 42 Szklarczyk, M.

Takeshita, K. Tanahe, K. Tanaka, Y. Tad, K. Tanigawa, E. Taranenko, N. 1. Tarasevich. M. P. Taylor, E. 1. Teo, 6.-K. Thompson, D. T. Tien. J. K.

135

I39 186 186 139 139 89

184 135 88 IY 87

Tomashov, N. D. Tonomura, S. Torikachvili, M. S. Tortorella, V. Tove, P. A. Tributsch, H. Triggs, P. Tripkovic, A. V. Trost, B. M. Tsai, M.-C. Tsubomura, H. Tsuchiya, H. Tsuji, 1. Tu, K. N. Tuck, R. A. Turos, A.

Ualikhanova, A. Uematsu, T. Unruh, J. D. Urvain, H. Usachev, N. [A. Usikov. M. P. Ustinski, E. N.

Vaiieva, S. V. Van Baar, J. F.

Page 40

134 39 88 44

136 135 135

87 134 41 91 87

32. 167 38

138 43 91 41 90 38 40

138 88

9P

Van Damme, H. Vannice, M. A. Van Veen, J. A. R. Vasin, B. D. Venturi, M. Vepkk, J. Victori, L. Visscher, W. Vlasse, M. Vovchenko, G. D. Vozdvizhenskii, V. F. Vukovif, M.

Wang, S.-Y. Watanabe, H. Weekley, B. Weindling, P. J. Wells, P. B. White, J. M. Whyman, R. Wolf, E. E. Woolf, L. D. Woollins, J. D. Wrzyszcz, J. Wynblatt, P. Wysocki, J. A.

Yamaguchi, S. Yamamoto, N. Yamasaki, H. Yamauchi, H. Yeo, R. S. Yermakov, YU. Yoneda, Y. Yoshida, H. Yoshida, T. Yoshihara, M. Yursha, I. A. Yasa, H.

I.

40 42 88 39

I36 187 40 40

134 42 YO

I36

42 87 40 34 90

I35 YO

137 39

I40 42

38,87 39

138 134 186 87 40 42

139 87

139 184 I38 41

135 Timofeev, N. T. 184 Zakumbaeva, G. Z. 139 92 Timofeeva, E. A. 41 Zemel, J. N. 92

184 Tiunaev, A. P. 41 Ziessel, R. 186

192

SUBJECT INDEX TO VOLUME 26 a - abstract Page Acetylene, chemisorptipn on Pt( 100) and Pt(l1 l), a 87

oxidation over RuCI,(PPh,),, a 92 Air Flow Meter I I 7 Alcohol, ethyl, oxidation on single crystal Pt

electrodes, a 135 44 88

catalyst, a 41 I 3 9

oxidation on single crystal Pt electrodes. a 135 synthesis, u 42,44,138

Pt!anatase. a 89 89

Aldehydes. amination, o 1 % Alkanes, reactions over platinum metals, a 42,89 Alkynes, hydrogenation over collodial, Pd. Pt. a 138

Amines, tertiary polycyclic, reaction with RuO, a 88 Ammonia conversion to amines by Pd

decomposition on Pt(ll1) and Pt(557). a

synthesis rrom CO by Ru catalyst, a mcthyl, clcctro-oxidation on Pt catalyrts, a

homologation to ethyl over Ru-Co, a

electro-oxidation by Pt/C-fibrc paper

primary aliphatic, dehydrogenation over

2-propanol? dehydrogenation by RhCI(PPh,),, a

Amination of aldehydes, a 138

acetylacetonate. a 43 38

28, 137 43.91.186

oxidation over platinum mctals. a synthesis over 0 s and Ru, a

Analysis, microsampling in flame atomic

Arthritis drug, 0s carbohydrate polymers, a adsorption. a 4 1

I 4 0

Banks, Sir Joseph, history 34 Benzene, hydrogenation over platinum metals, a

Book Review, Platinum Group Elements:

Booklet, Homogeneous Catalysts or the Platinum Metals 15

Bromine, photoproduction by Pt~TiO,. a 40 Rursting Discs 13

Butene, reactionz, over platinum metals, a 43.92

Cancer, anti-tumour drugs Capacitors, MOS. to detect H,, CH,, C,H,,, CO, a Carbon Oxides. CO. adsorption on Pt. Rh. a

42.89, 91. 137. 138, 139

Mineralogy. Geology. Recovery 57

Bushveld Igneous Complex 5 7

33,65, 88,92, 140 89

90. 138, 184 co-adsorption with H, and DI on Ru(OOl), a 135 conversion to ethylene and propylene

over Rh/SiO,, a 138 co-polymerisation with oletins by

Pd(I1) complexes, a 187 detector 89 dicsel emission control 50 electro-oxidation with Rh-/ and

Ir-porphyrinIC catalysts. a 88 hydrogenation over platinum metals. a 44. 186 interaction with N, over Ru/AI,O,,

RuiMgO. Ru/SiOl, a 138 interaction with NO and 0, on Pt-Re, a 134 interaction with 0, on thin Pd islands, a 134 oxidation over platinum metals. a 90, 137

CO?. hydrogenation over Rh/support catalysts, a 186 Carbonylation, methyl acetate over RhCI, hydrate. a 91 Carhoxylic Acids, production. a 92 Catalysis, homogeneous, booklet 15 Catalysts, three-way. a 185

shift reaction. a 91

hydrogenolysis of-n-butene, a 92

Iridium Complexes. for water gas

CplW,lr,(CO),z. CpWIr,(CO), synthesis.

Osmium. powder for NH, synthesis by cyclkg. a

Os,(CO),.iAl,O,. SiO,, 50,. a Os,(CO),,iAl,O,, SO,, TiO,, a

186 90 90

Catalysts (contd) Palladium black, methanol %ynthesis.

metal-support effect, a colloidal, hexyne hydrogenation, a for natural products’ syntheses, a H,-permeated membrane. for ethylene

permanent, for petrochemistry, a templates for allylic alkylation, a

hydrogenation. a

Palladium Alloys. Pd-Ru. Pd-Sm membranes, for 1.3-pentadiene conversion, a

Palladium Complexes, Pd acetylacetonate + tributyl phosphite for amine synthesis. a

IPd(CH,CN),l(BF,),.nPPhl, CO

IPd(OC,H,CH=NC,H,)I1 for isoprene

[(PPh),Pd<l,?, for hydrocarbon

co-polymerisation with olefins, a

reactions, a

hydrogenation. a (Ph,P),Pd,, (Ph,P),Pd-(OAc),, a K lPd(C,H:SO,),(H,O)Cll for isoprene

reactions, a

metal-support effect, a Pd/AI,O,, CO adsorption spectra.

for methanol synthesis,

for phenol amination with NH,. a Pd/< t-Al,O,/honeycomb, a Pdb)-AI,O :, for benzene hydrogenation, a

Pd-Au/Al,O, for phenol amination, u Pd-Pt-Rh/Al,O,, three-way, Ce promoted, a Pd-Pt~-Al,O,, for n-pentane isomerisation, a Pd/AI,O, + A, for benzene hydrogenation. a Pd/AlIO,-SiO2, for benzene hydrogenation, a

metal-support effect, a

solubility in HCI, a

CO adsorption spectra. metal support effect, a

Pd/LaO,, -/MgO, for methanol synthesis,

Pd/Ni foam, for H, combustion, a Pd/SiO,, CO adsorption spectra,

metal-support effect. a

metal support effect, a for CO hydrogenation. a for methanol synthesis. metal-aupport

interaction, a

metal-support effect. a Pd/TiO,. CO adsorption spectra,

for benzene hydrogenation, a for methanol synthesis,

metal-support effect, a PdCI,.CuCl,/zeolite. for olefin oxidation, a Pd/HY reolite, for CO hydrogenation, a Pd/NaY zeolitc, for CO hydrogenation, a Pd/ZnO. for methanol synthesis,

Pd/ZrO,, for methanol synthesis.

Platinum, colloidal. for hexyne hydrogenation,

metal-support effect, a

metal-support effect. u

colloidal, and SiW;,, for H,

electrocatalvsts in fuel cells photoproduction. a

for oil refining Pt/EDTA/Ru(bpy):/MV*’, for H,

(Pt/Fei+, Fe’+//Ce‘+, Ce’+/n-RaTiO,) in photoproduction. a

solar cell, a

H,O photocatalysis. a Pt/RuO?, TiO,, MV: for H,

photoproduction. a

Pt!RuO,/Cr ions/colloidal TiO,. for

Platinum Alloys, recovery in NH, oxidation Platinum Complexes, [Pt,H,(u-HXpdppm),l

[PF,] for water gas shift reaction, a IHPt(PEt,),l*, a

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Catalyst3 (contd) Pt/AI,O,, CI modified, for oil refining

effect of heat, atmosphere on, a for hydrocarbon conversion, a S poisoning, a

CO oxidation on, oscillations. a Pt/y-AI,O,, CO adsorption on. a

Pt-Re-F/AI,O,, for hydrocarbon

Pt/AI,O, + Li, Pt concentration effects, a Pt-metal oxide/Al,O,, for NH, oxidation, a Pt-metal-Si organic compounds/Al,O,, for

n-heptane transformations, a Pt-Pd-Rh/Al,O,, three-way, Ce promoted, a Pt-Rh/Al,O,; reactions over, a P(-Ru/AI20,, microsampling, u Pt-Sn/AI,O,, for H: adsorption. a Pt-Bi/pAl,O, for n-pentane isomeristion. a Pt-PdP]-Al,O,, for n~pentane isomerisation, a Pt/anatase, for H, production from alcohols, a Pt/CdS, RuO,, f i r H, production, a PdC, for NO hydrogenation, a Pt/C-fibre paper, for CH,OH. HCOOII

Pl/Cu.Cr,O,, CO oxidation over. a Pt-Ru/SiO,, for Fischer-Tropsch reaction. a

Pt/porous Teflon, D,-H, exchange, a Pt/TiO,, for benzene hydrogenation, a

photocatalytic activity, a Pt/K,CO,/TiO?, for water gas shift reaction, a P thT iO, powder, for Hr?. CI,. I,

PtlY-zeolite, CO adsorption on, a Pt-Re/zeolite, for coal liquefaction, a Platinum Metals, for coal liquefaction, a

for diesel emissions control, a for one carbon molecules. conference poisoning by Hg,S.Pb, a

Pt Metals + chloranylic acid

Rhodium Alloys, Rh-Pt gauzes, in NH,

conversion, a

electro-oxidation, a

methanations over, a

photoproduction, a

complexeshpport, a

oxidation Rhodium Complexes, for hydrogenation, a

for carboxylic acid production, a for ester production, a for 3,4-epoxy but- I-ene hydrogenation, a for water gas shift reaction. a RhCI, hydrate. for carbonylation, a RhCI(PPh,),, polymer bound, for olefin

hydrogenation and isomerisation, a RhCI(PPh,),, for dehydrogenation, a RhH(COXPPh,),. for cster synthesis. a Rh phosphine, for hvdroformylation, a IRlll(i-Pr):P(CH,),P(i-Pr),J(NBD)l CIO,.

tris(2,2’~bipyridine)Rh(lIII), for water for hydrogenation, a

photoreduction, a

-bpyRh, for hydrogenation, a Rh/AI,O,, for CO hydrogenation, a Rh-Pd-PdAI-0, three-way. Ce promoted. a RhPt/Al,O,,kaotjons over, a Rh/AIPO,-SiO,. for cyclohexene

Rh/SiO,, for CO conversions, a HRh(CONPPh,),/SiO,, PPh3, for propcne

I’#support, for C oxides hydrogenation, a Rh/TiO:, adsorption of H, and CO on, a Rh/ZrO,. for CO hydrogenation, a Ruthenium, for NH, synthesis, a

IRh(X)(CO)CIZl~bpyPdC1,, -bpyPtCI,,

hydrogenation, a

hydroformylation, a

for benzene hydrogenation, a for CO hydrogenation, a RuO,, RuO- Rue,-. for oxidation, a RuO,. for ozdations, a Ru oxides, for 0, evolution, a


PURL? 19 42

I 8 5 137 90

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185 185 137 41 90 42 42 89

I87 YO

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28 187 92 91

134 91 91

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43 156 185 137

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194

Catalysts (conrd) poisoned, for benzene hydrogenation, a powder, for NH, qynthesis, a skeletal. a RuO,/CdS, for H, photoproduction, a RuO,/Pt/Cr ionsicolloidal TiO,, for

RuD,/Pt/’TiO,. MV. for 11,O

RuO,/colloidal TiO,, for H 2 0

H,O photocatalysis, a

photocatalysis, a

photocatalysis, u Ruthenium Alloys, Ru-Co, for homologation, c

Ru-Co, properties and structure, a Ru-Fe, properties and structure. a Ru-Ni, properties and structure, a

Ruthenium Complexes, for carboxylic acid

Ru(bpy):+, for 11,O photoreduction. a rrans Ru(bpy),(lH,O):+. for H,O

EDTA/Ru(bpy):/MV2+/Pt, for H,

RuCI,(PPh,),, for acetylene oxidation, a RuCI,(PPh,),, for hydrogenolysis, a IRu(PPh,i,(SnCI,)CIl. for

IHRu3(CO),,1-, rcactions over. a

production from syngas, a

photoreduction. u

photoproduction, a

hydrogenation, a

Ru/AI,O,, CO and N? isotopic equilibration, a R I I - P ~ / A I ~ O ~ , microsampling, a X4:A1203 + CI-, for NH, synthesis. a RU,(CO),~/~AI,O,. i.r. study of, a RdMgO, CO and N, isotopic equilibration. a Ru,(CO),,/MgO, i.r. study of, a RdSiO,, CO and N, isotopic equilibration, a

for CO hvdrogenation, u Ru-PdSiO,, f& Fischer-Tropsch reaction, a

for methanation, a RdSiO, i CI-, for NH, synthesis. a Ru(CO),,/SiO,. i.r. study of. a R u K O ) ~ ? / A I , ~ , , SiO,, TiO,, a Ru,(CO),l/ZnO. i.r. study of, (i

Charpy, Georges, history Chemisorption, acetylene on Pt(100), Pt(lI1);a Children, John George, history Chlorine, effect on catalysts. a

Coal, liquefaction, a Conference, Catalysis, Bruges, 1982

Fuel Cells, Montreal. 1982 NO, Emission Control, Maastricht, I982

Corrosion, of platinum black. a resistance, Pd-steel alloys. a resistant polypyrrolc films/Pt-Ta> anodes, a Cr-Ru alloy in €€,SO,. u

production over platinum metals, a

Creep. high temperature of Pt alloys. a Cyclohexene, a

Dehydrogenations, over platinum metals, a Detector, H,, using Schottky diodes, a

Deuterium, a Dienes, hydrogenation by I Ru(PPh,),(SnCI,)CIl. a Diesel Fuel, emission control Diodes, Pd-thin-30,-Si. a

MOS capacitors, for H?, CH,. C,H,,,, CO, a

Pd~TiO?, vapour sensitive, a Pt killed. compared to Au, a

Editorial, twenty-fifth anniversary issue Electrical Contacts, palladium plated

Pd, sliding, a Au/Pd, sliding, a Pd alloys. review, (I

Pt silicide, on n Si, p Si. a Pt~Si/Si. Schottky contacts, a

Pd Ni alloy, a Electrodeposition. Pd

Page 9 1 91

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174 118 104 I84 40 88 40 38

91, 186

41,89 187 89

41, 135 44 50 92

134 I 4 0

2 158 44 44

106 44

I40 158 41

Electrodeposition (conld) Pd-Sn, catalysts Pt on Sn oxide, Sb doped films, a precious metals, review, 1966 to 1982, a Rh, a

Electrodes, anode, Ru-Ir + noble metal coated/Ti, for Ni electrowinning. a

anode, Ru/Ti, kinetics in chloride solution, a cathode, l r - W coated thermionic cathode, 0s-Ru coated, thermionic cathode, W-0s coated, thermionic Ir-porphyrin/C for CO electro-oxidation, a Nafion/Pt containing Ru(bpy):+, a Pd, PdO, coloured films on, a Pd-H Pd-Ag-0-Cs, photocathode, a Pt, laser photoeffects on, a Pt, platinised. SO, adsorption, a Pt, reduced, a Pt, rotating, anodic oxidation of H,O,, a Pt, single crystal, oxidation kinetics on, a Pt, surface oxide reduction, a Pt/C, in fuel cells. a PtO, activation with thionyl chloride, a Pt + Pb, for methanol oxidation, a Pt + Re. for methanol oxidation, a Pt + Ru. for methanol oxidation, a Pt-polypyrrole-Ta photoanodes, a Pt + Sn. for methanol oxidation, a Rh-porphyrinsiC for CO electro-oxidation, a Ru, oxidised, cycled CI, and 0, evolution, a RuO,. activation with thionyl chloride, a RuS,. photoreaction for O2 production, a

Electrolytes, Pd complexes for electroplating

Electronic Connectors. palladium based, review Emission Control, car exhaust catalysts for. a

diesel engines Energy, solar. conversion and storage, a Engines, catalytic

Esters, production, a

electrical contacts

petrol, air flow meter for

Page 58 41

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135 136 167 167

32. 167 88 39 4 0 20 40 89

135 135 88

135 185 137 185 88 88 88 88 88 88

136 185 136

158 106 185 50 40

105 117 9 1

Ethylene, reactions over platinum metals, a 90, 138, 187 Ethylene Glycol, synthesis, a 144

Fatty Acids, oxidation by RuO, and Ru oxyanions. a 139 Filters, catalytic. for diesel emission control 50 Fire Extinguisher, using bursting disc 13 Fischer-Tropsch reaction, a 138. 186 Formaldehyde, oxidalion on Pt electrodes, a 135 Formic Acid. electro-oxidation by PtK-fibre

Fucl Cells, a 147 Pt electrocatalysts, conference I18 for spacc shuttle 105

175

I 3 4 detectors. a 89, 189

paper catalyst, a 41

Furnaces, Pt-wound, electrical resistance, history

Gases, detection by Pd-TiO? diode, a

George 111, history Glass. industry. dispersion strengthened Au-Pt

metallic. amorphous Pd-B. a Pd,,Si,,, with B and Zr additions, a

Heptane, Transformation on Pt + metal Si

Heraeus, W. C., history History, Kurnakov. Russian Platinum Industry

organic compounds/A120,, a

melting platinum, first time platinum gift to George 111 platinum still platinum-wound electrical resistance furnace rcvicw. 1957-1982, for platinum metals

Hydrocarbons, C,-conversion over Pt/AI,O,, a oxidation, Pt/A1,0, effect of heat, a unsaturated, hydrogenation by [(PPh),Pd,l,, a

Hydrocracking, during coal liquefaction, a


34 98

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185 175 129 79 34

I83 I 75

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195

Page Hydrodealkylation over RhPt/AI2On a I 3 7 Hydroformylation over platinum metals. a 43. 91, 187 Hydrogen, adsorption over platinum metals. a 90, 138

co-adsorption with D, and CO on Ru(001), a 135 combustion. by catalytic burner. a I 8 6 detectors, a 89,187 diffusion in Pd alloys, a 184

41 for NH, synthesis. a 43, 186 for hydrocarbon conversion over Pt/AI,O,, a 185 in Pd and Pd alloys 20, 70, 87, 121 isotope permeability through Pd-Ag membrane, a 87 permeated in Pd catalytic membrane, a 90 photoproduction from alcohols, a 40. 89, 136. 185 production by Pt/CdS, with RuO,. a 187

Hydrogenation, alkynes over colloidal Pd, Pt, a 138 asymmetric. by Rh complexes, a 187 benzene, over platinum metais, a 42, 89. 137, 138, 139

by IHRu,(CO),,l-, a 187 CO. over platinum metals. u 44, 138, I86 carbonyl compounds by Rh(1) complexes, a 139 coal oil from coal, a 42 cyclohexene, over Rh/AIP0,-Si02, a 186 3.4-epoxybut-1-ene by cationic Rh complexes. a 139 ethylene over H permeated Pd membrane, a 90 NO over Pt/C. a 90

92. 137.187

D,-H, exchange over Puporous Teflon. a

by IRh(X)(CO)Cl,l-bpyY. a 43

olefins, by RhCI(PPh,),, a 43 Hvdroeenolvsis over olatinum metals. a Hidrogen Peroxide, anodic oxidation: a

Iodine, photoproduction on Pt-TiO, powder. a Iridium, Annual Surveys for 1979, 1980, a Iridium, compounds. H(Nblr0). specific heat. a

LaIrSi. NdlrSi, characteristics, a Ruorosulphates. a

Iridium Alloys, Iridium-Tungsten cathodes Iridium Complexes, llrClh12-, a Iridium Oxide, IrO, single crystals, a Isomerisation over platinum metals, a Isoprene, a

Johnson Matthey, technology exhibition

Kurnakov, N. S., history

Lavoisier. first melting of Pt, using 0, Lead poisoning of platinum metal catalysts, a Le Chatelier, history

88

40 I 3 5 134 134 88

167 89

135 42,43 43,91

105

129

79 42

175

Magnetism, H,Os,,C(CO),,, paramagnetism in, a VPd,. NbPd, properties, a LalrSi, LaKhSi, NdIrSi, properties, a

Medical. anti-arthritis drug. a anti-tumour drugs

Mercury poisoning of platinum metal catalysts, a Mcrcnsky Reef, mineralogy. book review Methanation over Pt-Ru/SiO,, a Methane. detector, a Methyl Acetate, carbonylation over RhCI, hydrate, a Mineralogy of platinum metals, book review

33, 65. 88, 92,

184 134 I 3 4 140 140 42 5 1

137 89 91 57

Nickel, electrowinning, electrodes for, a 135 Nitric Acid, production 28 Nitrogen, for NH, synthesis, a 43, 186

138 Nitrogen Oxides, emission control, conference I 0 4

90 134

19 187

C,-C,. oxidation by Pd,.CuCl,/zeolite, a 90 hydrogenation by platinum metal complexes, a 43,44

Osmium compounds. cluster, 1979, 1980 surveys. a 135 Osmium Alloys, Osmium-Tungsten cathodes 32, 167

reaction over Ru/A120,, RuiMgO, RuiSiO,, a

NO, hydrogenation over Pt/C, a reaction with CO and 0, on Pt-Re, a

Oil, refining over modified Pt/AI,O, Olefins, co polymerisation with CO, a

Page I40

osmium carbonyl cluster, a 135 Au-0s complexes. a 135 H,Os,,C(CO),,. paramagnetism in. a I84

43, 88, 89. 90, 137, 139 135

40, 88, 92. 136 19

89. 136, I85 134

134 compounds, NbPd,, VPd,, magnetic properties, a 134 electrical contacts 43, 106, 158 electronic connectors 106

stress-rupture at high temperatures 16 134

Palladium-Copper-Silicon, amorphous, H, solubility in, a 184

Palladium-Gold, low temperature alloying, a 134 Palladium-Cold-Nickel, electrodeposits, wear, a I84 Palladium-Hydrogen, properties 20, 70, 121 Palladium-Iron, martensites, phase diagram, a 38

Palladium-Manganese, HI in, thermodynamics of. a 87 Pd,MnSn, cold working, magnetisation, a 87 Palladium-Nickel. electrodeposited coatings. a 4 I Palladium-Nickel-Phosphorus, amorphous, Hz

solubility in. a 184 Palladium-Platinum particles. coarsening. a 87 Palladium-Platinum, H, saturated, properties, a 184 Palladium-Silicon, phase diagram, a 39 Palladium-Silver, for electronic connectors 106 Palladium-Silver, membranes, a 87 Palladium-Steel, corrosion resistance, a 40 Palladium-Titanium, H2 diffusivity in, a 184 Palladium-Vanadium, H2 diffusivity in, a 184

39 Pd-Pt mixed, the first, with dppm, a 88

Palladium Silicides. u 39, 184 Paraffins, dehydrogenation. over Pt/AI2O1. a 41 1.3-pentadiene, conversion over membrane catalysts, a 186

Petroleum, from coal, a 42 Petroleum Reforming. Pt, Pd catalysts for 138 Phase Diagrams, for Pt and Pd alloys, a 38,39. 135 Phenol, amination with NH, over Pd/AI,O,, a 90 Photocatalysis, a 40.89, 136. 185 Plastics, printing on 58 Plating, electroless, by Pd-Sn catalysts 58

electroplating. Pd 158 PI, Pd. Rh. Ir, Ru. a 137

Platinum, black, corrosion in, a 184 compounds, R(NbPt0). a I34 drugs, anti-cancer 33, 88,92, 140 electrical contacts, a 44, 140 first melting by Lavoisier 79 ions implanted in MgO. radiation damage, a 38 Pt(l11) and Pt( loo), acetylene chemisorption, a 87 Pt( I 1 1 ) and Pt(557), NH, decomposition on, a 38 Pt(ll0). SO, adsorption on, a 38 stress-rupture at high temperatures I6

Platinum Alloys, Platinum-Europium, phase diagram, a 38 Platinum-Gold, dispersion strengthened 98

phase diagram, a 38 Platinum-Iridium, plastic deformation in, a 38 Platinum-Palladium particles, coarsening. a 87

H, saturated, properties, a I84 plaslic deformation. a 38

and NO, a 134 Platinum-Rhodium, plastic deformation, a 38

Osmium Complexes, anti-arthritis drug, a

Oxalic Acid, photo-oxidation, a 39 Oxidation over platinum metals, a Oxygen, electroreduction in H,PO, on reduced Pt, a

evolution on platinum electrodes, a for first melting of platinum photoproduction from H,O, H,SO,, a reaction with CO on platinum metals, a

Palladium, adsorption of CO and 0, on, a

hydrogen in, properties 20.70,121

Palladium Alloys, Palladium-Boron, amorphous, a

Palladium-Gold, catchment gauzes 28

Palladium-Iron, thermoelectric power. a 87

Palladium Complexes, Pd(0)-Hg salts, a

Pepys, William Hasledine, history 34

Platinum-Rhenium, reaction of CO with 0,

Platinum Alloys (contd) Platinum-Ruthenium, plastic deformation, a Platinum-Enriched Superalloys

Platinum Complexes, a-aryl Pt(TI), a bis(cis-dichloro(diamine)Pt(II)), a caffeine 8-ether-Pt. carcinostatic effect, a Pt(0)-Hg salts of Co, Mn, Re carbonyls, a Pt-Pd mixed: the first, with dppm, a

Platinum Silicides, electrical contacts on n-Si, p-Si, L

Platinum Metals, advances over last 25 years Platinum Metals Complexes, a Platinum Metals Alloys, in thermionic emitters Platinum Still, for HISO, production. history Pollution Control, NO, emissions 50, Printed Circuits Prnpene, hydroformylation, a Propylcne, reactiona over platinum metals

Page 38

146 39 88 92 39 88

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39 167 183

104, 185 58 43

138, 187

Review, syntheses of natural products over Pd, a

Rhodium, Annual Surveys for 1979, 1980, a Pd in electronic connectors

compounds, LaRhSi, characteristics. a TmRh,B,, a

drugs. anti-cancer electrolytic deposition, a Rh(1 lo), SO: adsorption on. a

Rhodium Chlorides, spectra, a Rhodium Complexes, anti-tumour activity Russia, foundation of the platinum industry Rustenburg, platinum metals Ruthenium, co-adsorption of H, and D, with CO: a

Ruthenium Alloys, Ruthenium-Aluminium, phase compounds, Ru carbonyl clusters. a

transformations, a Ruthenium-Chromium, corrosion in H,SO,, a

IRulHIO),l’-, a II-IRu ,(CO), , I ~. in water gas shift reaction, a

Ruthenium Oxides, electrocatalyst for O2 evolution, a RuO,, layers on quartz, resistivity and T.C.R., a RuO, and Ru0?:Ir02 single crystals. a RuO,, oxidation of tertiary polycyclic amines, a

Ruthenium Complexes, for alkane oxidation, a

Schottky Diodes, in 111 detector, a SIROF’s, 0: evolution on, a Solar Cell, a Specific Heat, of H(NbIr0) and R(NbPtO), a Sulphur, catalyst poisoning by, a Sulphur Dioxide, adsorption on Pt and Rh. a Superalloys, platinuin-enriched Superconductivity, LaKhSi, LaIrSi, NdIrSi. Q

Syngas, for carboxylic acid production, a TmRh,B,, a

Temperature Measurement, a Thermionic Emitters, cathode materials Thermoelectric Power, of Pd and Pd-Fe alloys, Q

Thick Films, PdOJPd electrodcs, coIourc4 a Pd-Ag-0-Cs photocathode, a RuO, on quartz, resistivity and T.C.R., u

Ir oxide, sputtered. properties, a PdSi. Pd,Si, thermal stability, a Pd,Si. epitaxial growth and stability. a Pt~SVSi, a Sn oxide, Sn doped, platinised, a

Thin Films, .4u Xi-Pd electrodeposits, wear of, a

Turbines. gas, superalloys for

Water Gas Shift Reaction, a by Ir and Rh complexes, a in car exhaust, a Pt. K,CO,/TiO, catalyst for. a using IPtIH(~-ll)(~~dppm),ll PF,I, a

Wear, in Pd-Ni-Au electrodeposits, a

91 106 135 134 39 65 41 38 39 65

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135 135

135 40 89 88

136 40 87

135 88

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185 I34

42,137 38, 135

146 134 39 92

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platinum metals review · mechanical properties of the solid solution matrix phase (y) in...

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