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CHAPTER 2

LITERATURE REVIEW

This chapter presents a literature review of Manganese Phosphate

coating, Molybdinum disulphide (MoS2), High Carbon High Chromium Steel,

Pin on Disc wear test, Titanium Nitride (TiN), Titanium carbo nitride (TiCN)

Coatings and the Multi response optimization technique. It mainly focuses on

manganese phosphate coating characteristics, wear behavior of coatings on

steel substrate under different lubricate conditions and the wear behavior of

high carbon high chromium steel. It also discusses the usage of multi response

optimization techniques for the optimization of the wear parameters.

2.1 MANGANESE PHOSPHATE COATING

Manganese phosphate coating has the highest hardness and the

superior corrosion and wear resistances of general phosphate coatings. The

coating is formed as a result of a topochemical reaction, which causes the

surface of the base metal to integrate itself as a part of the corrosion and wear

resistant film. This coating is extensively employed to improve the sliding

properties of engine, gear, and power transmission systems. The use of

manganese phosphated coatings for improved corrosion resistance, can be

found in virtually all the areas of the metal working-industry.

Hurricks (1972) expressed some aspects of the Metallurgy and

wear resistance of surface coatings. They mentioned the reduction or

elimination of wear by the use of surface coatings is likely to become a

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widespread technique at a time when industry is becoming more conscious of

the need to reduce its operating costs. They also addressed phosphating is a

chemical conversion treatment producing a deposit of the porous crystalline

type, a surface layer of crystalline phosphate being produced. Fine grained

coatings are considered to have the best wear resistance.

Andrzej Kozlowski & Witold Czechowski (1975) investigated the

wear resistance of manganese phosphate coatings on steel and cast iron. It

was found that Phosphating in manganese-based solutions, irrespective of the

type of chemical pretreatment, prolongs dry sliding life. Better results were

obtained when both parts are phosphated. The wear resistance of un

phosphated and phosphated 17HGN steel determined on the four-cylinder J-

47-K-54 machine at a constant unit load of 5 kg/mm lubricated with gear oil

W-90.The results confirm that the better wear resistance of phosphated parts.

Phosphating increases wear resistance during normal service in terms of the

base metal wear. The initial wear rate of phosphated parts is higher than that

for unphosphated parts but the running-in period is shortened. Under full

lubricating conditions phosphating is more beneficial for lower-grade

lubricants than for high-grade lubricants.

Perry & Eyre (1977) studied the effect of phosphating on the

friction and wear properties of grey cast iron. Three test environments were

used to evaluate the wear properties of phosphate coatings viz unlubricated,

lubricated by drip feeding, dip lubricated prior to testing. They suggested

phosphating was favorable when employed under lubricating conditions. No

improvement was found for the phosphating of materials operating under dry

sliding conditions. Phosphating was most beneficial when used on pins

sliding under marginal lubrication, as confirmed by the dip lubricated tests.

They advised the wear properties of the phosphate coatings are dependent on

the surface finish and the material used for the sliding counter face. The thin

23

coating is suitable for running against smooth surfaces whilst the thicker

coating is greater against coarser surfaces.

Khaleghi et al (1979) studied the characteristics of Manganese

phosphate coatings for wear resistance applications. Three different manganese

phosphate solutions have been used to produce phosphate coatings on steel.

Three series of accelerated solutions were used for investigation, each at

96 - 980C (1) standard solution containing up to 21 g 1-l HNO, as accelerator;

(2) standard solution containing 7.02 g 1-l Ni(NO3).6H2O as accelerator;

(3) solution standard solution containing 7.02 g 1-l Ni(NO3).6H2O as

accelerator with a further addition of 3.1 g 1-l HNO3. From their report the

best wear resistance was found for fine-grained porous coatings which were

produced in a mixed nitric acid/nickel nitrate accelerated solution under

lubricated conditions.

Shigeyoshi Maeda (1983) studied steel surface chemistry affecting

the performance of organic coatings. The surface chemistry of steel sheets

plays an important, role in industrial operations such as cold forming,

phosphatizing and painting. Manganese, silicon and others elements affect

phosphatability and paint performance. The manganese precipitated in

globular form at the grain boundaries of the steel lowers corrosion resistance.

Reinhard (1987) discussed the surface characterization of iron and

steel prior to coating. Higher degree of surface roughness is equivalent to a

high specific surface energy; rough metal surface has many active centres.

They advised that optimum surface roughness gives better adhesion of

organic coatings, which should be dependent on the type of coating material.

Simon Tung et al (1991) investigated tribological behaviour and

surface morphology between electrodeposited and traditional phosphate

coatings. Traditional phosphate coatings are formed by submersing iron in the

24

solution of phosphoric acid and other chemicals without applying an external

voltage. Electro coated iron phosphate films are deposited electrochemically

from oil containing mixed organic phosphates. The lubricated sliding friction

characteristics of both traditional phosphate coatings and electro coated iron

phosphate films were determined in laboratory tests using the R-H friction

apparatus. The results were reported that the iron phosphate film electro

coated on the piston ring specimen provides 10%-20% lower friction than the

traditional manganese phosphate coating on the ring specimens. Surface

analyses indicate that the electro coated iron phosphate film consists of an

amorphous structure, whereas the traditional phosphate coatings are

crystalline.

Weng et al (1996) reported the corrosion and protection

characteristics of zinc and manganese Phosphate coatings on tool steel by

means of physical methods and electro chemical measurements. The

insulation ability of zinc phosphate coating is superior than that of manganese

phosphate, where as the porosity of the Zinc Phosphate coating is inferior to

that of the Manganese Phosphate Coatings. A lower porosity means a smaller

corrosion rate of substrate. On the contrary, considering the adhesion

performance, the porosity of a coating may have some advantages. Phosphate

coating used as a pre-treatment layer between the substrate and a top layer,

the pores in the coating may adsorb oil, wax or paint very well, so that the

bonding ability between substrate and top coating is improved. The protection

ability of phosphate coatings mainly depends on their barrier performance.

Hivart et al (1997) investigated the seizure behavior of manganese

phosphate coatings according to process conditions. The Coating seizure

resistance is analyzed by considering different temperature, concentration and

dipping time values for the main steps of the whole Phosphating process such

as degreasing, refining and Phosphating. The result confirms that carbon

25

percentage between 0.35 to 0.47 normalized steel dissolution reactions is easy

and germination sites are numerous and result in smaller crystals, quicker

surface coverage and finally higher seizure resistance.

Hivart et al (1998) examined the annealing improvement of

tribological properties of manganese phosphate coatings on steel. Huralite is a

manganese phosphate used as an anti-friction coating on steel parts in relative

motion. The result confirms that the annealing of a phosphate part from room

temperature to 7000C obviously leads to dehydration and modifications of the

coating. The result of the treatment increases the ability of the coating to

retain lubricant.

Fedrizzi et al (2001) reported on the study of the corrosion

behaviour of phosphatized and painted industrial water heaters in order to

improve paint adhesion, the iron phosphate pre-treatment was optimized and

some zinc phosphate pre-treatments were also studied. The result confirms

that both electrochemical tests and cathodic delamination tests showed that

zinc phosphate treatments and in particular phosphatization baths containing

manganese greatly improve the metal–paint adhesion under the very stressful

condition typical of the water heaters.

Guangyu Li et al (2004) investigated a black phosphate coating for

C1008 steel. The black conversion coating obtained on steel and cast iron was

dense and uniform with a thickness up to 18 mm. The coating shows better

corrosion resistance, lubricating ability and higher efficiency of light-

absorption than the traditional phosphate coatings. In black phosphate coating

Sodium molybdate added to the black phosphate treatment bath can refine

microstructure. They reported number of advantages with the black

conversion coating in comparison with the traditional phosphate conversion

coating viz (1) More even and finer grain structures were obtained (2) The

thickness of the black phosphate coating is nearly twice the thickness of the

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traditional phosphate coating. (3) The black phosphate coating shows

excellent corrosion resistance (4) The black phosphate coating satisfactorily

increases the efficiency of light-absorption during laser heat treatment ,and

the black phosphate can be used as a thick lubricating film to modify the

friction property.

Yasar Totik (2006) studied the corrosion behaviour of manganese

phosphate coatings applied to AISI 4140 steel subjected to different heat

treatments. It result concluded that the corrosion resistance of the coatings on

the quenched and tempered substrates is higher than that of non heat-treated

substrates and the corrosion behaviour of the coatings on the quenched

substrates was better when compared to the tempered substrates.

Jegannathan et al (2006) investigated Evaluation of the corrosion

resistance of phosphate Coating obtained by anodic electrochemical

treatment. They suggested that the visual appearance and adhesion of these

coatings are quite similar to those obtained by chemical treatment. The

current density due to oxygen reduction at the pores indicates an increase in

porosity with increase in current density employed for deposition. The surface

morphology of the coatings indicates crystal refinement caused by the

regenerated phosphoric acid under the influence of anodic current.

Polarization and EIS studies reveal that the corrosion resistance of phosphate

coatings obtained by anodic treatment decreases with the increase in current

density employed for deposition. The porosity or discontinuities created due

to the dissolution of the coating under the influence of anodic current are

considered responsible for the inferior corrosion resistance of these coatings.

Chao-Min Wang (2006) reported the effects of temperature and

applied potential on the microstructure and electrochemical behavior of

manganese phosphate coating on CrMoV steel surface. Material characteristics

and corresponding corrosion resistances were also evaluated in this study. The

27

experimental results showed that the manganese phosphate formed at 90 0C

but not at 70 0C or 80 0C in the solution used in this study. At 90 °C, the

phosphate consisted of two distinct layers, with a Fe-rich inner layer and a

Mn-rich outer layer. A significant amount of substrate dissolution occurred

during the phosphating treatment at 90 0C. Figure 2.1 Shows the X-ray

diffraction patterns of phosphate coating after annealing at different temperatures

for 30 min. The diffraction peaks from the as-deposited specimen were

consistent with those of hureaulite (Fe, Mn)5H2(PO4)4·4H2O. Heat treatment

in the temperature range 100–300 C for 30 min did not significantly change

the diffraction pattern of the manganese phosphate coating.

Figure 2.1 X-ray diffraction patterns of manganese phosphatecompounds with various heat treatment deposited on steelsubstrate (Chao-Min Wang et al 2007)

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Figure 2.2 SEM micrograph showing the surface morphology ofmanganese phosphate on steel substrate(Chao-Min Wang et al 2007)

Figure 2.2 shows a SEM micrograph of the surface morphology of

the as-deposited specimen. The granularity of the coated surface indicates that

the phosphate compound that was deposited on the substrate surface was

crystalline. The micrograph reveals that the coarse particle size gave rise to a

rough surface appearance.

Rout et al (2006) investigated Enhanced forming properties of

galvannealed steel sheet by Poly manganese phosphate coating Poly

manganese phosphate coat on galvannealed steel sheet can be made dense

with uniform crystallite size of 1–2 m. The result confirms that

Polymanganese coated galvannealed (GA) steel sheets with 1000 g/m2 oil

helps in reduction of coefficient of friction with the die surface from 0.22 to a

value of 0.11 indicating superior lubricating property. Granular phosphate

coating act as a lubricating base for reduction of coefficient of friction and

manganese phosphate acts as an anti-sticking base to make the surface smooth

during forming operation.

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Jose Daniel et al (2007) analyzed friction and wear behaviour of

steam-oxidized sintered iron components coated with manganese phosphate.

Manganese phosphate coatings are intrinsic lubricant properties and very low

friction coefficients. They reported that the steam oxidation treatment

produced homogeneous oxide layers covering the substrate surface, including

the surface and internal pores, the subsequent phosphating treatment reduced

the thickness of the oxide layer, which became porous and eventually

discontinuous in some areas, reducing the load bearing capacity, the

phosphated samples presented poorer abrasive and dry sliding wear resistance

than the non-phosphated. This effect was more significant for samples with

thinner oxide coatings.

Jegannathan et al (2009) studied the formation and characteristics

of zinc phosphate coatings obtained by electrochemical treatment. A

comparison of the deposition mechanism, characteristic properties and

corrosion resistance of phosphate coatings obtained by cathodic and anodic

treatments during phosphating was addressed. The comparative study

provides an insight on the cathodic and anodic treatments can manipulated to

produce tailor made coatings with the desired characteristics.

2.2 MOLYBDENUM DISULPHIDE

Molybdenum disulphide is an inorganic compound with the

formula MoS2. MoS2 is relatively unreactive, being unaffected by acids . In its

appearance and feel, molybdenum disulfide is similar to graphite. It is widely

used as a solid lubricant because of its low friction properties and robustness.

Lovell et al (1996) studied a finite element analysis of the frictional

forces between a cylindrical bearing element and MoS2 coated and uncoated

surfaces. A two-dimensional cylinder-plate finite element model was

developed to analyze the frictional characteristics of MoS2 coated and

30

uncoated surfaces. The result confirms that the maximum stress in the normal

direction was greater for a ceramic cylinder than for a steel cylinder in

normally loaded coated and uncoated systems. Due to enlarged contact area

effects, the maximum stress in the normal direction was significantly less in

coated surfaces than uncoated surfaces.

Arslan et al (2005) discussed the effect of deposition parameters

and Ti content on structural and wear properties of MoS2- Ti coatings. In this

studies AISI 440C steel substrate was selected for tribological analysis and

silicon wafer substrate for structural analysis of MoS2 -Ti films .At 440 0C

substrates were polished to a roughness value of Ra 0.12 microns by using

SiC emery paper with1200 mesh grit, then with Alpha -alumina having

0.05micron grain size. The content of sulfur and molybdenum in the coating

increased with increasing MoS2 target current. Due to resputtering, the

stoichiometry ratios NS/NMo of the number sulfur atoms to the number of

molybdenum atoms for films increased with increasing working pressure.

Martins et al (2006) investigated MoS2/Ti low-friction coating for

gears. The applicability of a multilayer composite surface coating in gears

was discussed in this work, the average friction coefficient between gear teeth

was discussed and compared with uncoated steel gears. They reported that

MoS2/Ti surface coating applied to gears promotes a significant decrease of

their operating temperature. MoS2/Ti coating promotes a decrease of

coefficient of friction between gear teeth, putting into evidence by the

reduction of load exponent on coefficient of friction equation. MoS2/Ti-

coated gears generate a larger wear volume than uncoated gears.

Shankara et al (2008) reported the study of solid lubrication with

MoS2 coating in the presence of additives using reciprocating ball-on-flat

scratch tester. In this study molybdenum disulphide (MoS2) based solid

lubricant mixtures containing zirconia and graphite were prepared in the

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laboratory and coated on steel specimens. The experiments were done using

reciprocating scratch test for various numbers of cycles. The results showed

that the addition of zirconia and graphite into the MoS2 lubricant has

improved its properties in terms of both friction and wear

The result also confirms that the moisture present in air also plays

an important role in terms of reducing friction coefficient and wear rate. At

high temperature the moisture evaporates and enhances the coating

performance of the film.

Zhou Hui (2011) analyzed the effect of Ti content on the structural

and mechanical properties of MoS2-Ti composite coatings deposited by

unbalanced magnetron sputtering system. The structural and mechanical

properties of these coatings as a function of Ti content were studied. SEM

analysis showed that the pure MoS2 coating reveals a typical porous and

worm-like surface structure, the MoS2 -Ti composite coatings appeared in

compact microstructure and coating porosity decrease with an increase of the

Ti content. They suggested that Pure MoS2 coating reveals a typical porous

and worm-like surface structure, the MoS2 -Ti composite coatings appeared

more dense and compact microstructure and coating porosity decrease with an

increase of the Ti content. The friction coefficient of composite coatings was

between 0.02 and 0.04, and the endurance life of them improves apparently

compared to the pure MoS2 coating.

2.3 HIGH CARBON HIGH CHROMIUM STEEL

A high carbon high chromium tool steel (D2 steel) offering very

high wear resistance and toughness. D2 tool steel hardens in air with a low

order of movement and offers a measure of corrosion resistance. Commonly

used for tools operating under conditions of severe wear and abrasion or as an

alternative to oil hardening tool steel grades. D2 is used in a wide variety of

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tool making applications. Typical applications include blanking dies and

punches for sheet in stainless steel, brass, copper, zinc and hard abrasive

materials generally. Other application include deep drawing dies, cupping

dies, forming dies, sheet metal forming rolls, shear blades for strip and sheet

including flying shears, circular cutters for cold rolled strip, trimmer dies,

thread rolling dies, cold extrusion dies, broaches, plug gauges, ring gauges,

special taps, brick and tile mould liners, master hobs for cold hobbing plastic

moulds and cut moulds for plastics.

Chena et al (1999) reported the corrosion behavior of TiN-coated

AISI D2 steel. The corrosion properties of the TiN-coated D2 steel are

primarily determined by the synergetic effect of the packing factor and

thickness associated with the coating. The beneficial effect of both packing

factor and TiN thickness was consistent with the result of a 500 h salt spray

test. Based on the corrosion values in the polarization test and the results of

the salt spray test, it is understood that for an adequate corrosion protection of

a TiN-coated metal substrate a minimum value of packing factor and TiN

thickness is required.

Helen Coldwell et al (2003) studied the rapid machining of

hardened AISI H13 and D2 moulds, dies and press tools. Tools and dies for

the forging, die casting and plastics moulding industries are commonly made

from AISI H13, heat treated to 48–52 HRC, while the press tool sector

predominantly uses AISI D2 at a significantly higher hardness of 60–62 HRC.

The result confirms that the drilling of AISI H13 (52 HRC) was shown to be

successful using AlTiN coated carbide tools with both soluble oil cutting fluid

and water-based dielectrics applied at high pressure.

Ahn et al (2003) investigated the corrosion behavior of multilayered

coatings on AISI D2 steel. Ti and TiN base layers were deposited on the

substrate prior to the multilayer. Coatings with variable Al content were

33

deposited onto a high speed steel substrate by the cathodic arc deposition

method. The corrosion current density values were low for WC–Ti0.5Al0.5N

and WC– Ti0.43Al0.57N. From the results of EIS measurements after 168 h

immersion, the Rct value of coating was also low because galvanic coupling

effect on the corrosion behavior. On the other hand, the impedance of the

WC–Ti0.5Al0.5N coating showed a higher value.

Lima et al (2005) analyzed Hard turning AISI 4340 high strength

low alloy steel and AISI D2 cold work tool steel. The work was focused on

the machinability of hardened AISI 4340 high strength low alloy steel and

AISI D2 cold work tool steel. The tests involving the AISI 4340 steel were

performed using two hardness values 42 and 48 HRC. In the former, a coated

carbide insert was used as cutting tool, whereas in the latter a polycrystalline

cubic boron nitride insert was employed. The result revealed the machining

forces were reduced as cutting speed was increased and increase with feed

rate and depth of cut.

Bourithis et al (2006) reported comparison of wear properties of

tool steels AISI D2 and O1 with the same hardness. Two commercial cold

work tool steels, AISI D2 and O1, were heat treated in order to obtain the

same hardness 700 HV (60 HRc) and were subsequently tested in three

different modes of wear, namely in adhesion, three-body and two-body

abrasion, by using pin-on-disc, dry sand/rubber wheel apparatus and pin

abrasion on SIC respectively. Even though AISI O1 and D2 steel are heat

treated to the same hardness, they perform differently under the three modes

of wear examined. The results showed that relatively low sliding speeds of

AISI O1 steel performs up to 12 times better than AISI D2 steel in adhesive

wear. For higher sliding speeds, this order is reversed due to oxidation taking

place on the surface of the AISI D2 steel. The result confirms that AISI O1

and D2 steel are heat treated to the same hardness, 700 HV 60 HRc, they

34

perform differently under the three modes of wear examined in this work:

adhesion, three-body and two-body abrasion. The friction coefficient of the

AISI O1 tool steel against Al2O3 is constant regardless of the conditions

applied and has a value of 0.55. The wear rate of both tool steels in three-

body and two body abrasion wear is proportional to the applied load. In three-

body abrasive wear, AISI D2 exhibits a normalized wear rate about two times

lower than the AISI O1 tool steel, and this is due to the plate-like hard

carbides present in its microstructure. The primary wear mechanism in three-

body abrasive wear of AISI O1 tool steel is ploughing, while that of AISI D2

wear tool steel is carbide fracture and exfoliation. In two-body abrasive wear,

AISI D2 has a more than two times lower normalized wear rate than AISI O1

tool steel. Both tool steels perform 3–8 times better in three-body abrasive

wear conditions than in two-body abrasive wear.

Cord Henrik Surberg et al (2008) studied the effect of some heat

treatment parameters on the dimensional stability of AISI D2. The tool steel

AISI D2 is usually processed by vacuum hardening followed by multiple

tempering cycles. They suggested that a deep cold treatment in between the

hardening and tempering processes could reduce processing time and improve

the final properties and dimensional stability. Hardened blocks were then

subjected to various combinations of single and multiple tempering steps

(520 0C and 5400C) and deep cold treatments (900C120 0Cand 1500C).The

result showed that in AISI D2 the amount of retained austenite present could

vary according to position. Deep cold treatment at -1200C and below allowed

the processor to reduce post hardening treatments to a short cryogenic

treatment followed by a single temper. The greatest dimensional stability was

achieved by deep cold treatments at the lowest temperature used, which was -

150 0C. The dimensional stability is independent of the time of deep cold

treatment.

35

Debdulal Das et al (2010) investigated Sub-zero treatments of AISI

D2 steel .Wear behavior of AISI D2 steel specimens subjected to varied sub-

zero treatments, namely cold treatment, shallow cryogenic treatment and deep

cryogenic treatment was studied with respect to that of the conventionally

heat treatment. The obtained results revealed that sub-zero treatments improve

the wear resistance of the selected steel, the degree of improvement varies in

the ascending order of cold treatment, shallow cryogenic treatment and deep

cryogenic treatment, and is function of normal load. The operative mechanism

of wear under the investigated conditions was severe delamination and the

process of wear was found to proceed with the formation of white layer

followed by its delamination, governed by the associated extent of plastic

deformation of subsurface. The wear rates were governed by the type of sub-

zero treatments and the wear test conditions, and these were in conformity

with the characteristics of the worn surfaces, sub surfaces and generated wear

debris.

2.4 PIN ON DISC WEAR TEST

A tribometer is an instrument used to measures tribological

quantities, such as coefficient of friction, friction force, and wear volume

between two surfaces in contact. A pin on disc tribometer consists of a

stationary pin under an applied load in contact with a rotating disc. The pin

may have any shape to simulate a specific contact. The pin on disc test has

proved useful in providing a simple wear and friction test for low friction

coating on valve components in international combustion engines.

Yang (1999) Investigated pin-on-disc wear testing of tungsten

carbide with a new moving pin technique. The experiment was carried out on

computer numerical control (CNC). Lathe with a G96 constant speed

command. Tungsten carbide inserts were used as pins and three types of disc

materials, namely low carbon steel, medium carbon steel and hardened tool

36

steel, were employed. Both the moving pin and the stationary pin wear testing

methods were carried out. The weight loss of the inserts from each test was

measured. The result confirmed that wear rate of tungsten carbide varied from

0.243X10-7 to 1.073X10-7 mm3/mm, with a mean value of 0.656X10-7

mm3/mm, while the wear coefficient from 1.02X10-6 to 1.09X10-6, with a

mean value of 1.05X10-6 depending on the disc material used. With the

stationary pin technique, the wear rate of tungsten carbide varied from

0.18X10-7 to 0.61X10-7 mm3/mm, with a mean value of 0.383X10-7 mm3/mm,

while the wear coefficient varied from 0.58X10-7 to 0.76X10-6, with a mean

value of 0.65X10-6, again depending on the disc material used. The result also

concluded that the moving pin technique caused a higher wear rate and a

slightly higher wear coefficient. This was due to a better work-hardening

effect with the use of more virgin disc surface area in the wear testing.

Psyllaki et al (2000) studied Pin-on-disc testing of PE-CVD

diamond-like carbon coatings on tool steel substrates of different harnesses.

Tribological studies against alumina were performed using a pin-on-disc

apparatus under various normal loads 2 to 20 N. and sliding speeds 0.1 to

0.3 m/s, while the relative humidity of the environment was 25%. The

influence of the testing parameters (normal load and sliding speed) and the

mechanical properties of the substrate on the wear lifetime of the coatings

were determined and the involving wear mechanisms were identified. The

result confirms that the wear of the coating was first taking place through the

partial spalling of a superficial layer, localized at the protrusions of the

surface asperities of the coating, after a short interval, the wear was occurring

by a combination of abrasion and micro ploughing and it was accelerated by

the crack initiation and propagation at the borders of the contact area. The

apparent wear lifetime of the coating was found to increase when decreasing

the normal load applied and with increasing sliding speed and substrate

hardness. Among all the parameters examined, the mechanical behavior of the

37

substrate was found to have a dominant influence on the degradation of the

DLC coating. The final failure of the coating was a result of both its thickness

reduction due to wear, as well as of its forced bending deformation due to the

plastic deformation of the substrate.

Urs Thomann et al (2000) analyzed Wear–corrosion behavior of

biocompatible austenitic stainless steels. Pin-on-drum tests were conducted to

determine the dry wear resistance of test materials. Wear–corrosion behavior

was studied in slurry tests and pin-on-disc experiments in distilled water. The

result reported that the new nickel-free austenitic stainless steel P558

assembled excellent mechanical properties, superior electrochemical stability

and outstanding resistance against wear. Based on the results it can be

concluded that P558 is alloyed in a High-pressure-electro-slag remelting

procedure requiring lesser cost than powder metallurgical techniques.

Cockeram, BV & Wilson, WL (2001) reported the hardness,

adhesion and wear resistance of coatings developed for cobalt-base alloys.

The wear-resistance and performance was evaluated using laboratory pin-on-

disc, 4-ball and high-stress rolling contact tests .The result confirmed that

Wear-resistant coatings were successfully developed for cobalt-base alloys by

minimizing differences in stiffness hardness-modulus between the coatings

and the base materials. 4-ball wear testing results showed that the thin

Cr-N(ss)/Cr2N coating had the best wear resistance. This coating could be

used to reduce cobalt wear debris release in applications that are similar to

these test conditions. The wear test results indicated that the thick

Cr-N (ss)/Cr2N/Cr-N(ss)/Cr2N coating and thin duplex coating had excellent

wear resistance with the best performance observed for the thin duplex

coating.

Malcolm Stanford & Vinod Jain (2001) investigated the friction

and wear characteristics of hard coatings, the friction and wear behavior of

38

four hard coatings (Metco, Diamalloy, Stellite and Zn–SiC) was determined

using a pin-on-disc apparatus. The coatings were thermal sprayed on cast iron

discs. The coating compositions were Ni–17Cr–2.5Fe–2.5Si–2.5B–0.15C

(Metco), Fe–30Mo–2C (Diamalloy), Co–30Cr–12W–2.4C (Stellite), and Zn–

50SiC (Zn–SiC). Sliding was performed between cylindrical pins machined

from non-asbestos organic (NAO) brake lining and the coated and uncoated

discs. The lining, consisting of resin, aramid pulp, zirconia, graphite, calcium

fluoride, rubber and barium sulfate, was developed as a material for

automotive brake pads. The coatings were characterized by measuring their

hardness, porosity, and corrosion resistance. The result reported that the

Stellite coating had the most corrosion resistance. The wear rate for the

Stellite coated and cast iron disc was lowest for all sliding speeds used in this

study.

Bahrami et al (2005) investigated an effects of conventional heat

treatment on wear resistance of AISI H13 tool steel. A pin-on-disc

configuration at speed of 0.07 m/s with two loads of 29.4 and 98N was

employed to study the wear behavior. The result described that at low load

level of 29.4 N, the specimens with martensitic structure have the highest

wear resistance and the mode of wear was mild and debris are fine oxide

particles and plate-like metallic fragments, at high load level of 98N, the

specimens tempered for 30–60 min had the highest wear resistance and the

mode of wear was oxidative and debris were rounded and agglomerated oxide

particles. At high load level of 98N, the rubbing surface temperature was

enough for in situ surface tempering that may result in a transformation of

martensitic structure to a soft tempered structure at low load level of 29.4 N,

because of lower local pressure and temperature. Work hardening was

observed at subsurface level and the depth of hardened zone increases with

applied load. Gradual increase in friction coefficient at 98N load can be

attributed to the in situ surface tempering phenomenon.

39

Ramesh et al (2005) studied the prediction of wear coefficient of

Al6061–TiO2 composites. The investigation deals with preparation of

Al6061–TiO2 composites by liquid metallurgy route. The extent of

incorporation of TiO2 in the composite was varied from 2 to 10 wt%.

Microstructure studies, hardness and wear test were conducted on the cast

Al6061–TiO2 composites. Pin on disc machine was used to assess the wear

resistance of the prepared composites. Load was varied from 10 to 40N while

the sliding distance was from 90 to 540 m. Wear coefficients were evaluated

by using Archard’s and Yang’s theoretical models. Increased contents of

TiO2 resulted in higher hardness and lower wear coefficient of the composites

under identical test conditions. Al6061–TiO2 composites exhibited higher

hardness, lower wear coefficient when compared with the matrix alloy.

Increased loads and sliding distances resulted in higher volumetric wear loss

but lowered the wear coefficient for both the matrix alloy and its composites.

Wilson & Alpas (2005) investigated sliding and abrasive wear of

composite sol-gel alumina coated Al alloys. Alumina coatings, 60-mm thick

were deposited using a novel sol-gel technique on 6061 Al. The samples were

subjected to dry sliding wear tests against hard bearing steel balls and softer

mild steel pins at different sliding speeds and contact loads. When coatings

were subjected to abrasive wear against SiC abrasives of increasing

coarseness, coating wear rates approached those of the substrate alloy as the

abrasion indentation depths greater than 20% of the coating thickness

produced a rapid degradation in wear resistance.

Matsuo et al (2005) investigated sliding wear of spray-formed high-

chromium white cast iron alloys. The sliding wear resistance of high-

chromium white cast iron obtained by spray-forming was studied to determine

microstructures produced by this process, the structure of the matrix, and the

amount and distribution of carbides affect the material. Three alloys

40

containing different concentrations of carbon and chromium, namely

2.4 wt.%C–15 wt.%Cr, 3.5 wt.%C–15 wt.%Cr and 3 wt.%C–19 wt.%Cr, were

spray-formed and conventionally cast. Pin-on-disc wear tests were conducted

according to the ASTM G99-95 standard. White cast iron pins having an

8-mm diameter and 15-mm length were tested against a counterpart VC 131

tool steel disc hardened to 63HRC. The spray-formed alloy C CS (3.0%C–

19.0%Cr) showed a superior wear resistance due to its refined microstructure,

as well as a better balance of the austenite, martensite and carbide phases and

greater oxidation resistance.

José Rendón & Mikael Olsson (2006) investigated abrasive wear

resistance of some commercial abrasion resistant steels evaluated by

laboratory test methods. The abrasive wear resistance of the steels was

evaluated using two different laboratory test methods such as pin-on-disc

testing and paddle wear testing that expose the materials to sliding abrasion

and impact abrasion, respectively. All tests were performed under dry

conditions in air at room temperature. They reported that in the pin-on-disc

test in two-body abrasion the wear rate of the steels was to a large extent

controlled by the hardness and toughness values of the steels. In the paddle

wear test, resulting in impact abrasion and the generation of a pronounced and

relatively thick sub-surface layer of heavily deformed material with the

presence of embedded abrasive particles, the wear rate was believed to be

controlled by the properties of the above tribolayer.

Jose Divo Bressan et al (2006) investigated the wear on tool steel

AISI M2, D6 and 52100 coated with Al2O3 by the MOCVD process. The

wear tests by sliding and abrasion were performed in a pin-on-disc and ball-

on-disc apparatus whose pin and ball substrates were steels fabricated from

AISI M2,D6 and 52100. The wear performance of AISI 52100 steel coated

with Al2O3film has been improved when measured by the wear track width

41

versus sliding distance instead of calculating the lost volume versus sliding

distance. Nitrided AISI M2 tool steel and coated with Al2O3 has superior

wear resistance.

Grimanelis & Eyre (2007) investigated wear characteristics of a

diffusion bonded sintered steel with short term surface treatments. A pin on

disc machine was used to investigate the tribological behavior of a diffusion

bonded sintered steel, with and without surface treatments of steam oxidation

and manganese phosphating, over a wide range of speed (0.2–4 m/s) and

applied load (4–500 N) in conditions of dry sliding and starved lubrication by

oil impregnation of the porous structure of the materials. The regimes of mild

and severe wear were identified. Mild wear was associated with the

development of oxide layers on the rubbing surfaces and the production of

oxidized powder-like debris through an oxidation wear mechanism. Oil

impregnation of the sintered steel was beneficial in increasing the load

bearing ability by as much as 100N and reducing the severe disc track

roughness as compared to dry sliding.

Bressana et al (2008) investigated an influence of hardness on the

wear resistance of 17-4 PH stainless steel evaluated by the pin-on-disc testing.

The wear tests by sliding and abrasion were performed in a pin-on-disc

tribometer whose pins had three different hardness levels (43, 37 and

33 HRC) obtained by varying the precipitation hardening treatment. The

counterface discs were machined from the same steel composition and aged to

the hardness of 43 HRC. The result confirms that the trend of the wear rate

curve for discs versus the sliding distance was constant and linear after the

initial stage. The instantaneous wear ratio was approximately constant. The

discs plotted curves shows two distinct stages or regimes such as initial stage

1m to 200m or initial run in phase with accelerated wear and the second stage

of constant wear rate up to the test end the disc wear rate increased with the

42

decrease of the pin hardness. In this case, for the harder material, the disc, the

Archad Equation for wear rate has to be reformulated, possibly substituting

the hardness H by an equivalent hardness He (1/He =1/Hdisc +1/Hpin), i.e.,

Q= KFN/He, the disc wear rate increases with the increase in the hardness

difference between pin and disc. The trend of the pin wear rate curves with

the sliding distance was approximately constant and linear.

Qunguo Tang et al (2010) investigated tribological behaviors of

carbon fibre reinforced PEEK sliding on silicon nitride lubricated with water.

Research on the tribological characteristics of carbon fibre reinforced

polyetheretherketone (CFRPEEK) sliding on sintered silicon nitride (Si3N4)

lubricated with water was conducted on a surface contacted tribo tester. The

main wear form of CFRPEEK was adhesive wear, and was transfer to the

Si3N4 surface. The formation of transfer film was beneficial to reduce friction.

Chowdhury & Nuruzzaman (2013) investigated on experimental

Investigation on friction and Wear Properties of different Steel Materials. The

obtained results show that friction coefficient varies with duration of rubbing,

normal load and sliding velocity. In general, friction coefficient increases for

a certain duration of rubbing and after that it remains constant for the rest of

the experimental time. The obtained results revealed that friction coefficient

decreases with the increase in normal load for all the tested materials. It is

also found that friction coefficient increases with the increase in sliding

velocity for all the materials investigated.

Agunsoye et al (2012) investigated on effect of manganese

additions and wear parameter on the tribological behaviour of grey cast iron .

The results from linear regression equation and Analysis Of Variances

(ANOVA) showed that manganese additions, load and speed variable were

more pronounced on the wear behaviour of the Grey cast iron. The result

showed that the additions of the 75 % ferro manganese grade decreases the

43

Carbon Equivalent (CE) and fortify the matrix with the formation of tough

(FeMn)3C inter-metallic leading to increased wear resistance of the examined

composition.

Merklein et al (2012) investigated wear behavior of PVD-Coatings.

The obtained result showed that the cyclic load causes initiation and growth

of micro cracks leading to chipping on the coated surface. In contrast the

surfaces coated by TiC, TiAlCN and Si3N4/AlTiN revealed little signs of wear

like tiny pitting and adhesion in few sections. The coatings TiAlCN, TiC and

Si3N4/AlTiN revealed a higher wear resistance than the coatings TiN, TiAlN

and AlCrN. Due to their higher hardness the occurrence of wear grooves on

the coatings Si3N4/AlTiN, TiAlCN and TiC decreased resulting in a reduced

tendency for adhesion.

Agunsoye & Ayeni (2012) investigated an effect of heat treatment

on the abrasive wear behavior of high chromium iron under dry sliding

condition. The hardened specimens have the greatest resistance to wear within

the limits of speed, applied load and time for which the investigation was

carried out. The comparison among the wear coefficients has revealed the

excessive wear rate of the annealed specimens. It also reveals the average

wear severity of the as cast specimen and the competitive wear resistances of

the hardened and tempered specimens.

Wieland & Merklein (2012) investigated on wear behavior of

uncoated and coated forming tools under complex loading conditions.

Aluminum silicon pre-coated semi-finished products within the hot stamping

process automotive industry was taken in this study. They suggested that after

50 strokes it was shown that the surface roughness increased on the coated die

was lesser than uncoated die in areas with low sliding distance and low

contact pressures respectively.

44

Chowdhury et al (2012) investigated on friction coefficient of

different material pairs under different normal loads and sliding velocities.

The result confirms that the friction coefficient decreases with the increase in

normal load, the values of friction coefficient increase with the increase in

sliding velocity and the magnitudes of friction coefficient are different for

different sliding pairs, therefore maintaining an appropriate level of normal

load, sliding velocity as well as appropriate choice of sliding pair, friction

may be kept to some lower value to improve mechanical processes.

Roy & Chowdhury (2013) investigated the effect of contact

temperature rise during sliding on the wear resistance of TiNi shape memory

alloys, the result confirms that wear decreases with the rise in contact

temperature over a wide range of load, speed and surface roughness

combination during sliding. The wear resistance of these alloys normally

responsible for the increased wear and seizure of common engineering

materials.

Roy & Sahoo (2012) investigated the multiple roughness

characteristics of chemically deposited Ni-P-W Coatings. Optimization of the

coating process parameters based on Taguchi method and Grey relational

analysis in order to obtain the particular bath composition which may be used

to deposit Ni-P-W coatings with optimum roughness characteristics.

Experiments were carried out based on the L27 Taguchi orthogonal design

using the combination of three process parameters, namely, concentration of

tungsten ion, concentration of reducing agent and concentration of nickel

source. It was observed that concentration of tungsten ion has the most

significant influence in controlling roughness characteristics of Ni-P-W

coating.

Florea & Antonescu (2003) investigated friction coefficient and

wear variation for grease with different additives. The result confirms that the

45

wear and friction coefficient values were affected by a number of parameters

depending upon the lubricant. The material of the friction couplings and upon

the physical and mechanical conditions, the friction coefficient was measured

at reduced values for load and reduced duration, the wear of the metallic

surfaces was not appreciable, particularly at relatively low loading but at

increased durations of tests, the friction coefficient variations showed more

exactly the comportment of the lubricant, especially additivated.

2.5 TITANIUM NITRIDE AND TITANIUM CARBO NITRIDE

COATINGS

Titanium carbide is an extremely hard ceramic material similar to

tungsten carbide. It is also used as a surface coating. It is mainly used in

preparation of cermets which are frequently used to machine steel materials at

high cutting speed. Titanium nitride is a hard ceramic material, used as a

coating on titanium alloy, steel, carbides and aluminium components to

improve the substrate’s surface properties. TiN is used to harden and protect

cutting and sliding surfaces and as a non-toxic exterior for medical implants,

its coating thickness around 5 microns. The TiCN-coating is used in various

industries such as fabrication of cutting tools and die engineering, to provide

wear resistance and corrosion resistance. The TiCN coating technique has

numerous problems such as film debonding and cracking. These faults may be

due to the heat effect that occurs while using and making these products.

TiCN-coated materials are expected to be used at high temperature, due to

their tolerance to high temperature.

Hintermann (1984) investigated adhesion, friction and wear of thin

hard coatings. chemically vapour-deposited and physically vapour-deposited

coatings of hard and wear-resistant materials such as TiC, TiN, Ti(C, N) as

well as other carbides, nitrides, borides, oxides and combinations thereof are

increasingly used in industrial applications to protect metal, ceramic and in

46

certain cases polymer parts against mechanical and chemical attack. The

result confirms that thin hard coatings deposited by CVD or PVD on

functional surfaces of steel, special alloys, cemented carbides and ceramic

materials provide significant improvement in the tribological behaviour not

only of tools but also of bearings and machine elements. Any protective

coating is only as good as its adhesion to the substrate.

Wilson & Alpas (1988) examined TiN coating wear mechanisms in

dry sliding contact against high speed steel. Dry sliding wear experiments at

specific loads ranging between 20 and 250 N were conducted on a PVD TiN

coating, are deposited onto an AISI M2 high speed steel substrate. The

coating was worn against AISI M2-type high speed steel pins using a pin-on-

disc sliding configuration at a constant sliding speed of 0.7 m/ s .Wear rates,

coefficients of friction and temperatures of the pin were measured as a

function of load. The result reported that wear rates of the TiN coating and

steel pin showed a linear increase with load in this regime and were combined

with increased friction. The transition was accompanied by smoothening of

surface asperities in the wear track, a reduction in coefficient of friction

together with overall softening and rapid wear of the TiN layer.

Eero Posti & Iikkanieminen (1989) studied influence of coating

thickness on the life of TiN coated high speed steel cutting tools. The

influence of coating thickness on the life of TiN-coated high speed steel

cutting tools has been studied using in machining. In the tests using constant

cutting conditions, the thickness of the coating was found to have a significant

effect on tool life. In the tests a coating of thickness 2 - 3 microns was found

to give the longest tool life. In the turning tests the tool life increased with

increase in coating thickness. The coating thickness influences the life of the

tool. Tools with thin coatings have longer lifetimes than uncoated tools. The

chemical composition of the coating affects the life of the tool.

47

Lim et al (1995) analyzed the effects of machining conditions on

the flank wear of TiN coated high speed steel tool inserts. It was found that

the extent of reduction in the measured wear rates depends strongly on the

conditions of machining. The wear mechanism map showed that the three

main groups of mechanisms fall into three broad areas defined by feed rate

and cutting speed. It also showed that the transition from one dominant wear

mechanism to another was more sensitive to cutting speed than to feed rate.

The amount of reduction in tool wear brought about by the application of TiN

coatings depends strongly on the machining conditions employed.

Su et al (1997) investigated comparison of tribological behavior of

three films TiN, TiCN and CrN-grown by physical vapor deposition. In this

work TiN, TiCN and CrN were comparatively studied with respect to their

wear performance, through wear simulation machine, under various

experimental conditions. The results shown that sliding pairs with CrN

coating possess much better wear resistance than the other two Ti-based

coatings under both dry and lubricated conditions. The CrN coating was a

potential candidate for replacing TiN and TiCN in certain applications. The

result confirms that the surface micro hardness increases with increasing film

thickness. The wear resistance of CrN coating was superior to that of TiN and

TiCN depending on the experimental conditions.

Soliman et al (1997) studied on the improvement of the high speed

steel turning by TiN coatings. A comparison between the cutting edge

durabilities of uncoated and coated tools when oblique turning mild steel at

different cutting speeds was carried out. Dry cutting was used to accelerate

wear which in turn assessed on the tool flank at different cutting speeds and

fixed tool angles, feed and depth of cut. The results have shown that the

Taylor equation for uncoated tools is TV 7.82=9.8X1012 and that of coated

tools is TV3.34= 4.85X l07 where T is the tool durability in minutes and V is

48

the cutting speed in metres per minute. TiN-coated HSS turning tools were

more resistant to flank wear than uncoated tools.

Duk-Jae Kim et al (1999) reported the properties of TiN–TiC

multilayer coatings using plasma-assisted chemical vapor deposition.

A multilayer of TiN–TiC has been deposited on commonly used die steels

(D2) by the pulsed DC plasma-assisted chemical vapor deposition process.

The TiC layer was successfully deposited at 580°C with a gas mixture of

TiCl4, CH4, H2 and Ar. A minimum flow of TiCl4 and CH4 gas were used to

minimize the excess carbon phases and the chlorine content in the TiC

deposited layer. The result confirms that the stable composition range of the

TiC phase with the most dense structure was observed at a TiCl4/CH4 gas

volume ratio of 0.38, at which the Ti/C composition ratio was 1.11.W.

Grzesik et al (2002) analyzed friction and wear testing of multilayer

coatings on carbide substrates for dry machining applications. A modified

pin-on-disc tester was used to conduct experiments in which both the friction

coefficient and the linear wear of the tribo-pair were recorded vs. sliding

distance. The volumetric wear rate was proposed as a parameter for

quantitative comparison of the wear resistance of the tribo-pairs tested. It was

found that the principle stage of the specimen wear takes place during the first

200–240 s of sliding in dependently of the applied speed. The maximum wear

resistance was revealed in the case of a carbon steel TiC/TiN coating tribo-

pair for sliding speeds ranging from 0.5 to 3.0 m/min. The result confirms that

Majority of the specimens wear takes place during the first 200–240 s of

sliding independently on the applied speed, after this time period the intensity

of wear decreases drastically.

Zeghni & Hashmi (2004) studied the comparative wear

characteristics of tin and tic coated and uncoated tool steel. Wear

characteristics of TiN and TiC coatings deposited by magnetron sputtering on

49

D2 and D3 tool steels in contact dry sliding conditions have been investigated

and compared to the uncoated. The thin films were characterised in their

adhesion, hardness and chemically analyzed finally the result confirms that

both coatings applied have been improved the wear resistance of the substrate

materials. TiC coating improved the wear resistance of the substrate much

better than TiN coating. Substrate material has an influence on the over all

tribological properties of the composite.

Sandro Cardoso Santos et al (2004) reported tribological

characterization of PVD coatings for cutting tools. Tool life was measured

during cutting tests when machining a grey cast iron. The parameter used to

measure tool life was the number of holes per thickness of the coating. The

results were then compared with the wear resistance coefficient of the coating,

obtained after a micro-scale abrasive test. The result shown that the best

coating was the TiCN coating, because a crack propagates in a direction

parallel to the coating–substrate boundary.

Polcar et al (2005) studied comparison of tribological behaviour of

TiN, TiCN and CrN at elevated temperatures. PVD-coated instruments were

often used at elevated temperatures. The friction and wear data of these

coatings at temperatures exceeding room temperature were measured up to

500 0C. The coatings were deposited on hardened steel substrates either by

unbalanced magnetron sputtering or arc evaporation deposition. The

measurements were done using a high-temperature tribometer (pin-on-disc,

CSM Instruments). The evolution of friction coefficient with sliding distance

was measured at different temperatures and the wear rate of the ball and

coating were evaluated. The result confirms that Sliding against 100Cr6 ball.

Friction coefficient slightly increases with temperature in case of TiN and

TiCN. For CrN, average friction coefficient reaches its highest value in the

50

temperature range 100–300 0C, then decreases reaching its minimum value at

500 0C.

Xu et al (2006) investigated tribological behavior of a TiSiCN

coating tested in air and coolant. The TiSiCN coating showed higher hardness

than the TiN coating. The sliding tribological behavior of the coatings against

alumimium and alumina counterparts was studied both in air and in a coolant

by pin-on-disc tests. Compared to the TiN coating, the TiSiCN coating

exhibited lower wear rates and lower coefficients of friction (C.O.F.) against

those two kinds of counterparts when tested in air. The cutting coolant

provided a lubricant effect and reduced the adhesive wear and C.O.F. between

the coating and the counterpart. The result confirms that the coolant provided

the coatings with lubricant effects, resulting in less wear and low C.O.F. The

sliding wears of the coatings tested in coolant against the aluminum pins were

negligible. Those results indicated that the cutting coolant could perform

lubrication and thus reduce the adhesive wear and the coefficient of friction

between the coatings and the counterparts.

Morant et al (2007) reported hardness enhancement by

CN/TiCN/TiN multilayer films. In this work using a dual ion beam sputtering

system CN/TiCN/TiN/Si multilayer coating have deposited. The results

shown that combining hard and elastic with hard and brittle materials, like

CN/TiCN/TiN/Si, allows to obtain good mechanical and tribological

properties.

Yahya Isik et al (2007) investigated the machinability of tool steels

in turning operations. The work piece materials used in the experiments were

cold work tool steel, AISI O2 (90 MnCrV8) hot work tool steel, AISI H10

and mould steel. The cutting tools used were HSS tools, uncoated WC and

coated TiAlN and TiC + TiCN + TiN inserts. During dry machining of this

experiments cutting forces, flank wear and surface roughness values were

51

measured throughout the tool life and the machining performance of tool

steels were compared. The result reported that cutting speed was the most

influential parameter on tool life, feed rate was the second most one, and

cutting depth was the least influential parameter. The influence of cutting

depth was negligible compared with those of the other cutting parameters.At

the end of the tool life, considerable increases in cutting forces (Fs) were

observed, but the increase rate varies according to the cutting tool and the

workpiece. The amount of flank wear and the cutting force were appropriate

parameters to determine the tool life.

Qamar et al (2008) studied the simulation of extrusion die life

estimation and prediction of tool life. The two most dominant failure

mechanisms for extrusion dies are fracture and wear. Fracture and wear

usually coexist as failure modes, and final die breakdown occurs due to the

mechanism that becomes dominant. Monte Carlo simulation carried out to

predict the life of an extrusion die. Paris law has been used as the model to

estimate fatigue life of the die in terms of number of cycles to failure (number

of billets extruded). An average die life was observed 759 cycles for a hollow

die box.

Fu & Chan (2009) investigated fatigue life improvement through

the rational design of metal-forming system. In metal-forming industries, die

is an important tool for fabrication of metal-formed products. Die service life

is defined as the maximum product number produced by die before it fails,

and die performance directly determine the quality of metal-formed product

and production cost. In cold forming process, die service life basically refers

to the die fatigue life. The die fatigue life is determined by the design of

metal-formed product and die, forming process configuration, die stress and

the entire metal-forming system. This work reported that die service life is

affected by many factors related to die design, process determination and

52

parameter configuration, material configuration and the entire forming

system.

Rogério Fernandes Brito et al (2009) examined thermal analysis in

coated cutting tools. In this studies the heat influence in cutting tools

considering the variation of the coating thickness and the heat flux. K10 and

diamond tools substrate with TiN and Al2O3 coatings were used .The studies

carried out during the execution of the work showed that for a uniform heat

source varying in time, considering a constant contact surface on the chip-

tool, the temperature on the tool may be slightly influenced by the coatings

when the thermal properties of the coating were very different from those of

the substrate, even for fine 1 ( m) coating. The present heat transfer analysis

in coated cemented carbide cutting tools, using commercial computational

tools, revealed promising features in the study of the tool life, cost reduction

in dry machining processes, reduction of the time spent on the study of

thermal influence of coatings, and reduction of the number of experiments.

Maria Nilsson & Mikael Olssona (2011) investigated tribological

testing of PVD and CVD coatings for steel wire drawing dies .Material pick-

up tendency, friction and wear characteristics of four different commercial

coatings CVD TiC and PVD (Ti,Al)N, CrN and CrC/C in sliding contact

with ASTM 52100 bearing steel were evaluated using pin-on-disc testing.

Based on the results obtained in this study, three different coatings CrC/C,

TiC and dual-layer TiC/CrC/C were recommended for wire drawing

operations. CrC/C and TiC are recommended due to their intrinsic low

friction properties and material pick-up tendency in sliding contact with steel.

The dual-layer was recommended in order to combine the good properties of

the two coatings CrC/C and TiC. The result confirms that CVD TiC coating

showed excellent performance in polished condition.

53

Mingdong Bao et al (2011) studied tribological behavior at elevated

temperature of multilayer TiCN/TiC/TiN hard coatings produced by chemical

vapor deposition. Multilayer hard coatings of TiCN/TiC/TiN on high speed

steel substrates were deposited using a chemical vapor deposition system.

Friction coefficient and wear rates of coatings were investigated using ball-

on-disc tester sliding against a WC ball at a constant load of 20 N. Different

changing tendency of friction coefficient were observed from ball-on-disc

experiments. Results showed that the friction coefficient of coatings increased

gradually to a highest value, then to a relatively constant value at room

temperature dry sliding wear. The result confirms that the friction coefficient

of TiCN/TiC/TiN coatings against a WC ball as a function of sliding time

shows a perfect different variation tendency. At room temperature, the friction

coefficient of coatings follows the general friction rule from running-in stage

to a relatively stable period. The friction coefficient increases from an initial

level of about 0.28 to the stable value of about 0.53. At 550 °C, the friction

coefficient increases sharply from the initial level of about 0.60 to the highest

level of approximately 0.7.

Aleksandar Vencl et al (2011) studied evaluation of adhesion and

cohesion bond strength of the thick plasma spray coatings by scratch testing

on coatings cross-sections. The results showed that scratch testing could be

used as an efficient method for evaluation of thick plasma spray coatings

cohesion. It is a relatively easy and quick test method, and for practical

application it could be also used as a supplement of some standard test

method as a coating characterization and quality control technique.

Bull & Berasetegui (2006) studied on an overview of the potential

of quantitative coating adhesion measurement by scratch testing .The scratch

test has been used to assess the adhesion of thin hard coatings for some time

now and is a useful tool for coating development or quality assurance. The

54

two main adhesion related failure modes in the scratch testing of hard

coatings are wedge spallation and buckling. Buckling occurs for thin coatings

which were able to bend in response to applied stresses. The stresses

responsible for failure were complex due to the fact that buckling was

con ned within the region of pile-up close to the indenter. For thicker, stiffer

coatings wedge spallation becomes the dominant failure mechanism. This

occurs well ahead of the moving indenter and the stresses which are

responsible for failure approximate to a state of pure compression.

Zaidi et al (2006) discussed Characterization of DLC coating

adherence by scratch testing, Coating failure appears in various modes,

particularly propagation of the cracks along the longitudinal edges of the

scratch, propagation in front of the indenter, rupture along the maximum

principal stress lines and detachment in the subsurface by shearing of the

coating.

Allsopp & Hutchings (2001) investigated Micro-scale abrasion and

scratch response of PVD coatings at elevated temperatures Scratch tests were

carried out on the four coatings Viz TiN with two different thicknesses, TiCN,

AlTiN at room temperature and at 350 C. The critical loads, determined by

both optical and frictional criteria, either remained the same (TiN) or

increased at high temperature (TiCN, AlTiN), changing the ranking of the

coatings. The results of scratch testing at room temperature of coatings

intended for high temperature applications may therefore be misleading.

Kataria et al (2010) studied evolution of deformation and friction

during multimode scratch test on TiN coated D9 steel. Three different scratch

modes were used to induce deformation in TiN coating deposited on D9

substrate. The consequent surface damage was analyzed using optical and

scanning electron microscopy. Main deformation mechanisms found during

Progressive Load Scratch Test and Constant Load Scratch Test were cohesive

55

cracking, coating spallation and adhesive failure. Ductile fracture was induced

during Multi Pass Scratch Tests (MPSTs) performed at three different loads.

The trend of evolving coefficient of friction was found to be different for

three kinds of scratch modes and the evolution of coefficient of friction has

been correlated with coating deformation.

2.6 MULTI-RESPONSE OPTIMIZATION AND GREY

ANALYSIS

Multi response optimization involving more than one objective

function to be optimized simultaneously. Multi response optimization has

been applied in many fields of science, engineering, economics and logistics.

The performance of a manufactured product often characterize by a group of

responses. These responses in general are correlated and measured via a

different measurement scale. This problem is regarded as a multi-response

optimization problem, subject to different response requirements. Multiple-

response design problems have been widely studied in the quality

improvement and quality management literature. For such problems, several

optimization criteria have been proposed, including maximization of process

yield, maximization of process capability, minimization of process costs, etc.

Most of the common methods are incomplete in such a way that a response

variable is selected as the primary one and is optimized by adhering to the

other constraints set by the criteria. Many heuristic methodologies have been

developed to resolve the multi-response problem (Gaitonde et al 2009).

Cornell & Khuri (1987) surveyed the multi-response problem using

a Response Surface Method (RSM). Response surface methodology consists

of a group of techniques used in empirical study of the relationship between a

response and several input variables. Most of the work in RSM has been

focused on the case where there is only one response of interest. In product or

process development, however, it is quite common that several response

56

variables are of interest. In this case, determination of optimum conditions on

the input variables would require simultaneous consideration of all the

responses.

Logothetis & Haigh (1988) studied a manufacturing process

differentiated by five responses, they selected one of the five response

variables as primary and optimized the objective function sequentially while

ignoring possible correlations among the responses. Optimizing the process

with respect to any single response leads to non optimum values for the

remaining characteristics.

According to Phadke (1989), it is difficult to optimize

simultaneously responses in complex process by single-response method and

engineering judgment is primarily used to resolve such complicated problems.

An engineer’s judgment often increases the degree of uncertainty during

decision making process, making it most critical to the quality of finished

product.

Tai et al (1992) assigned a weight for each response to resolve the

problem. Pignatiello (1993) utilized a squared deviation-from-target and a

variance to form an expected loss function for optimizing a multiple response

problem. Layne (1995) presented a procedure capable of simultaneously

considering three functions: weighted loss function, desirability function, and

distance function.

Antony (2001) reported that the approach adopted by Taguchi

practitioners to tackle multiple response optimization problems by employing

engineering knowledge together with their experience brings some degree of

uncertainty and, therefore, the validity and robustness of results cannot be

guaranteed. Traditionally, assigning a weight for each response solved this

57

problem. However, the equation pertaining to summing of weighted S/N ratio

is difficult to explain from the view point of Taguchi’s quality loss function.

Liao & Chen (2002) proposed Data Envelopment Analysis Ranking

(DEAR) approach to optimize multi-response problem. The author states that

Taguchi method can only be used to optimize single response problems and

PCA, although considered to solve multi-response problem, itself has

shortcomings. The new approach is capable of decreasing uncertainty caused

by engineering judgment in the Taguchi method and overcoming the

shortcomings of PCA. Two real cases on improving the poly silicon

deposition process and hard disc drives quality process were performed and

the result indicates the feasibility and effectiveness of DEAR approach as

compared to Taguchi method and PCA.

In order to overcome the single response optimization problem of

Taguchi method, Hung-Chang Liao (2003) proposed an effective procedure

called PCR-TOPSIS that is based on Process Capability Ratio (PCR) theory

and on the Theory of Order Preference by Similarity to the Ideal Solution

(TOPSIS) to optimize multi-response problems.

Orthogonal array with grey relational analysis was employed to

optimize the multiresponse characteristics of electric discharge machining of

Al-10%SiCP composites (Narender Singh et al 2004b). The experimental

result for the optimal setting shows that there is considerable improvement in

the process. The application of this technique converts the multi response

variable to a single response grey relational grade and, therefore, simplifies

the optimization procedure. Shibendu Shekar Roy (2006) presents a genetic

fuzzy expert system for predicting surface finish in turning of metal matrix

composites.

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Lee-Ing Tong et al (2004) proposed procedure used the desirability

function and dual-response-surface method to optimize the multi-response

problems in a dynamic system. They established a regression model to obtain

the sensitivity and quality variation for each experimental run and the

desirability function is used to obtain a total measurement for the multiple

responses. Next, the dual-response-surface method was used to obtain a set of

possible optimal factor–level combinations. The optimal factor level setting

proposed to maximize total desirability.

Jayapaul et al (2005) reported a review of literature on solving

multi-response problems in the taguchi method. Twelve unifying approaches

are studied in their work to transform a multi-response design problem into a

single response problem using mathematical transformations. Each of these

methods contains assumptions regarding a risk preference of the user,

response relationship, and the marginal rate of substitution. The user should

understand these assumptions before implementing any of these methods.

Onur Koksoy & Tankut Yalcinoz (2006) presented a methodology

for analyzing several quality characteristics simultaneously using the Mean

Square Error (MSE) criterion when data are collected from a combined array.

They proposed a genetic algorithm based on arithmetic crossover for the

multi-response problem in conjunction with a composite objective function

based on the individual MSE functions of each response.

Jiju Antony et al (2006) used artificial intelligent tool (neuro-fuzzy

model) and Taguchi method of experimental design to tackle problems

involving multiple responses optimization. They proposed a single crisp

performance index called Multi-Response Statistics (MRS) as a combined

response indicator of several responses. MRS is computed for every run by

applying neuro-fuzzy model. ANOVA is carried out on the MRS values to

identify the key factors/interactions having significant effect on the overall

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process. Finally, optimal setting of the control factors is decided by selecting

the level having highest value of MRS.

Hari Singh & Pradeep Kumar (2006) proposed a simplified model

based on Taguchi’s approach and utility concept to determine the optimal

settings of the process parameters for turning process to yield optimum

quality characteristics of EN24 steel turned parts using TiC coated carbide

inserts. The model can be extended to any number of quality characteristics

provided proper utility scales for the characteristics are available from the

realistic data.

Shibendu Shekhar Roy (2006) attempted to design an expert system

using two soft computing tools, namely fuzzy logic and genetic algorithm, so

that the surface finish in ultra-precision diamond turning of metal matrix

composite can be modeled for set of given cutting parameters, namely spindle

speed, feed rate and depth of cut. Jayapaul et al (2008) attempted the

simultaneous optimization of multi-response problems in the taguchi method

using genetic algorithm.

Research shows that the multi-response problem is still an issue

with the taguchi method. Researchers have tried to find a series of theories

and methods in seeking a combination of factors/levels to achieve the

situation of optimal multi-response instead of using engineer’s Judgement to

make a decision in the taguchi method (Hung-Chang Liao 2003).

Grey Relational Analysis (GRA) is based on the grey system

theory.GRA is used to study the relation among various attributes in a system

and for solving the complicated interrelationships among the multiple

responses. It is a kind of measure method focusing on the qualitative

description and comparison of variation. In comparison with the conventional

methods which requires massive amount of samples, typical (e.g. linear

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exponential or logarithmic) distribution of samples and large amount of

calculation work, GRA possesses the following advantages viz Simple and

easy calculation, Reasonable number of samples, Typical distribution of

samples is needless, No contradictory conclusions against the qualitative

analysis, Suitable and effective in dealing with discrete data.

The methodology uses the simultaneous optimization of the mean

and variance, since it considers S/N ratio values as basis for analysis. To

optimize the parameter conditions for multiple quality characteristics

problems, first the experimental output data are converted into S/N ratio

values. The S/N ratios of each quality characteristics are transformed into

normalized values to avoid the effect of adopting different units for all quality

characteristics. This normalized S/N ratio values are considered for GRA.

Next, the grey relational co-efficient values are calculated corresponding to

each response. Then the grey grade is calculated by taking the average of grey

relational co-efficient corresponding to each experiment. The grey grade

values are treated as the overall evaluation of experimental data for the multi

response process. The optimal level of the process parameters is the level with

the highest grade.

Lin & Lin (2002) have explored the optimization of the parameters

for electrical discharge machining process. The findings are verified by GRA.

The study also analyses the effect of data normalization and data integrity in

GRA to predict the rank of the parameter effect in the case of insufficient data

derived from the Taguchi method.

Narender Singh et al (2004) reported the use of orthogonal array

with grey relational analysis to optimize the multi-response characteristics of

electrical discharge machining of Al-10%SiCp composites. The experimental

result for the optimal setting shows that there is considerable improvement in

the process. The application of this technique converts the multi-response

61

variable to a single response grey relational grade and therefore simplifies the

optimization procedure.

Nihat Tosun (2006) used GRA for optimising the drilling process

parameters for the work piece surface roughness and the burr height. Various

drilling parameters, such as feed rate, cutting speed, drill and point angles of

drill were considered. An orthogonal array was used for the experimental

design. Optimal machining parameters were determined by the grey relational

grade obtained from the grey relational analysis for multi-performance

characteristics (the surface roughness and the burr height). Experimental

results have shown that the surface roughness and the burr height in the

drilling process improved effectively.

Noorul Haq et al (2008) applied orthogonal array with grey

relational analysis for the optimization of drilling parameters on drilling

Al/SiC metal matrix composite. Based on the grey relational grade, optimum

levels of the parameters have been identified and significant contribution of

parameters is determined by ANOVA.

Wang & Lan (2008) have presented a new method that uses GRA

and fuzzy clustering to form part families. The main objective is to identify

part families based on a new similarity coefficient which considers processing

time, lot size, machine usability, etc., by using GRA.

Yu-min Chiang & Hsin-Hsieh (2009) reported the use of the

taguchi method with grey relational analysis to optimize the thin-film

sputtering process with multiple quality characteristic in color filter

manufacturing. In this work the weights of the quality characteristics are

determined by employing the entropy measurement method.

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Siddhi Jailani et al (2010) attempted to optimise the sintering

process parameters of Al-SiC (12%) alloy/fly ash composite using grey

relational analysis. Experiments have been performed under different conditions

of temperature, fly ash content, and compacting pressure. Taguchi’s L9

orthogonal array was used to investigate the sintering process parameters.

Optimal levels of parameters were identified using grey relational analysis,

and significant parameter was determined by analysis of variance.

Experimental results indicate that multi-response characteristics such as

density and hardness can be improved effectively through grey relational

analysis.

2.7 OVER VIEW OF THE LITERATURE REVIEW

The following conclusion were derived from the review of

Literature

The benefits of manganese phosphate coatings are partly their

oil retaining capacity, which facilitates low friction motion

and eliminates scuffing and galling. Manganese phosphate

coatings improve the resistance to adhesive wear, and adsorb

the lubricant. Phosphating is a process used to produce a

crystalline oil-absorbing coating with an excellent wear

Resistance.

The initial wear rate of the phosphated parts is higher than

that of the unphosphated parts, but the running-in period is

shortened. Under full lubricating conditions phosphating is

more beneficial for lower-grade lubricants than for high-grade

lubricants.

The wear properties of the phosphate coatings are dependent

on the surface finish and the material used for the sliding

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counter face. The thin coating is satisfactory for running

against smooth surfaces whilst the thicker coating is superior

against coarser surfaces.

The best wear resistance was found for fine-grained porous

coatings which were produced in a mixed nitric acid/nickel

nitrate accelerated solution under lubricated conditions.

The electro coated iron phosphate film consists of an

amorphous structure, whereas the traditional phosphate

coatings are crystalline.

The annealing of a phosphate part from room temperature to

700 0 C, obviously leads to dehydration and modifications of

the coating. The interest of such treatment results from the

increase in the ability of the coating to retain the lubricant.

A chemical conversion treatment produces a deposit of the

porous crystalline type and a surface layer of crystalline

phosphate. Fine grained coatings are considered to have the

best wear resistance.

MoS2 lubricant improves the manganese phosphate coatings

properties in terms of both friction and wear. The moisture

present in air also plays an important role in terms of reducing

the coefficient of friction and wear rate. At high temperature

the moisture evaporates and enhances the coating performance

of the film.

AISI D2 steel dimensional stability is achieved by deep cold

treatments at the lowest temperature used, which was -150 0C.

The dimensional stability is independent of the duration of

deep the cold treatment.

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The failure of the coating is a result of both its thickness

diminution due to wear, as well as of its forced bending

deformation due to the plastic deformation of the substrate.

Al6061–TiO2 composites exhibited higher hardness, lower

wear coefficient when compared with the matrix alloy.

Al6061–8 wt% TiO2 possessed the lowest wear coefficient.

Thin hard coatings deposited by CVD or PVD on the

functional surfaces of steel, special alloys, cemented carbides

and ceramic materials provide significant improvement in the

tribological behaviour not only of tools but also of bearings

and machine elements.

The cutting coolant could perform lubrication and thus reduce

the adhesive wear and the coefficient of friction between the

coatings and their counterparts.

Multiple-response design problems have been widely studied

in the quality improvement and quality management systems.

Several optimization criteria are also solved including the

maximization of the process yield and maximization of the

process capability and the minimization of process costs, etc.

SUMMARY OF LITERATURE REVIEW

Manganese phosphate coatings improve the resistance to adhesive

wear, and adsorb the lubricant. The wear properties of the phosphate coatings

are dependent on the surface finish and the material used for the sliding

counter face. The annealing of a phosphate part from room temperature to 7000 C , obviously leads to dehydration and modifications of the coating. Based

on the literature review it is understood that manganese phosphate coating is

included in the family of wear resistance coatings