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Clogging Prevention in Submerged

Entry Nozzles Focusing on CaTiO3 as a

Coating Material

Klara Takei

Felicia Lindén Bergman

Supervisors:

Prof. Pär Jönsson, KTH

Prof. Voicu Brabie, HDa

Jennie Svensson, HDa

Bachelor Thesis 2012

Dept. of Materials Science and Engineering

Royal Institute of Technology

Stockholm, Sweden

Abstract

Clogging of the SEN is a complex problem, which implies large annual costs to the steel

industry. Nozzle clogging leads to interrupted production when the nozzle or tundish need

replacement. Moreover, clogging reduces steel quality, as pieces of the clog may loosen and

give rise to larger inclusions in the cast steel.

The first part of this study presents an overview of the clogging mechanisms. Methods to

address the problem are discussed based on literature and earlier studies. Coatings, which

have been subjected to rather little research, are chosen to be further investigated.

In the second part, an experimental study on calcium titanate is performed. Five samples of -

325 mesh CaTiO3 powder were heated in alumina crucibles at temperatures of 1600°C,

1575°C, 1565°C and 1550°C for 60 minutes. One sample was kept at 1600°C for 12 minutes.

The treated samples were analyzed using SEM, and from the achieved compositions resulting

phases were calculated.

There are strong indications that liquid phases were partially obtained in all samples. As a

result, calcium titanate coating of graphite alumina SENs represents a promising method to

decrease clogging.

Pilot plant experiments are suggested to further evaluate the performance of calcium titanate

coatings during casting. Moreover, research is needed in areas such as: the application

method, the depletion and thickness of the coating, the interaction with the refractory, the

necessary amount of liquid phase, and the environmental as well as economic aspects.

Key words: Clogging, Nozzle, Coating, Calcium Titanate, Refractory, Liquid Phase

Table of Contents

Introduction 1

Purpose 2

Literature study 2

Clogging mechanisms 4

Methods to decrease clogging 5

Induction 5

Dimensional design 5

Argon bubbling 6

Heating 6

Adjustment of the melt 6

Design of the ceramic 7

Coating 9

- Coating materials 10

Experimental 12

Results and Discussion 13

Conclusions and Future work 17

Acknowledgements 18

References 19

Appendix A – SEM analyses for sample 1 A1

Appendix B – SEM analyses for sample 2 B1

Appendix C – SEM analyses for sample 3 C1

Appendix D– SEM analyses for sample 4 D1

Appendix E– SEM analyses for sample 5 E1

Appendix F – The results from SEM analysis plotted in phase diagrams F1

1

Stopper rod

Tundish Tundish Nozzle

Slide Gate

Submerged

Entry Nozzle Mould

Steel from

Ladle

Introduction

At continuous casting, steel flows from the tundish to the mould through a submerged entry

nozzle, SEN, as can be seen in Fig. 1. This protects the molten steel from reoxidizing in

contact with the atmosphere. The flow rate is controlled with a gate or stopper rod to maintain

optimum casting conditions. If the nozzle clogs and the flow control cannot make up for the

reduced flux, the nozzle has to be replaced which means the production is interrupted. The

clog buildup can also result in decreased steel quality as oxide particles may loosen from it,

giving rise to rather large inclusions[1]

.

Different methods can be applied to decrease clogging, including coating the interior of the

nozzle, inducing electromagnetic fields, designing the nozzle ceramic and dimensions, heating

of the nozzle, and argon injection. The cleanliness of the steel also affects the amount of

inclusions available to cause clogging. However, clogging can probably not be entirely

prevented by cleanliness of the steel since only one out of 1500 nonmetallic inclusion

deposited on the nozzle wall will be enough to cause clogging. Changed flow patterns due to

clogging can also reduce the steel quality.[1]

Through coating the nozzle refractory several desired effects can be achieved: decreased

roughness making particles less prone to stick to the surface, a denser surface which decreases

oxygen permeability, and protection of the refractory material from both mechanical and

chemical erosion.[2]

As a result, increased nozzle lifespan as well as higher steel quality is

obtained. Additionally, using coatings rather than a solid nozzle of the same material, could

potentially provide economic advantages. Calcium titanate (CaTiO3) has shown promising

properties as a nozzle material[3]

, and could possibly be applied as a coating. Its ability to

form a liquid phase in contact with alumina (Al2O3) will be further investigated in this project.

This is part of a project funded by VINNOVA and Jernkontoret.

Fig. 1: Schematic picture of the area of interest for this study.

[4]

2

Purpose

This report aims to give an overview of the clogging mechanism and the related problems,

such as shortened lifetime of the nozzle and decreased steel quality, which lead to increased

production costs. In particular coatings will be considered as a method for avoiding clogging.

An experiment with calcium titanate heated in alumina crucibles will be performed. The

presence of liquid phases will be evaluated.

Literature study

To investigate previous work and gather knowledge in the area, a literature study was

performed. Table 1 gives an overview of the results from this study. Clogging is common to

all articles used since it is the central problem in this project. From the table it can be stated

that articles concerning the refractory material are far more common than those discussing

coatings. Also specific refractories are more often treated in more than one article. This is to

be compared to the specific coatings; articles treating the same coating material are rather

unique. The descriptive part of this report is based upon the literature study.

3

Table 1: Summary of the literature study

4

Clogging mechanisms

Clogging may occur in several ways, of which combinations can appear in a single

nozzle. Inclusions formed by deoxidation products, such as oxides of Zr, Al, and Ti, can sinter

together to form a matrix[1]

. This is believed to be the dominant mechanism. The rate at

which this type of clogging develops is dependent on inclusion size. Large inclusions can

stick to the nozzle wall only where the flow is slow, i.e. where the cross sectional area is

large. Thus, they tend to have less effect on the nozzle flow. In the case of small inclusions,

adhesion to the internal of the nozzle is possible even in areas with a high flow rate. The

clogging rate is therefore higher for smaller inclusions, that are probably formed during late

stage reoxidation.[5]

At steelmaking temperatures the sintering process is rather rapid; for two

ten-micron inclusions only about 0.03 seconds are required to form a sufficient neck to

withstand the force of the flow. In some cases the matrix contains steel, especially in steels

with a low concentration of deoxidation products.[1]

Complex oxides may also form accretions. There are a number of theories on how reoxidation

products can be brought in contact with the nozzle wall. The theories include turbulent

recirculation zones, turbulent flow, rough nozzle walls, and external corners. The attachment

to the nozzle walls depend on surface tension and sintered bonds between the particle and the

wall or another particle.[1]

The buildup can consist of solidified steel if the heat transfer from

the nozzle is high. This is one reason why nozzles have to be preheated correctly.[1]

Alternatively, deoxidants in the steel may form a film upon reaction with oxygen present due

to: air leaked in through porosity in the nozzle; oxygen from silica based refractories; oxygen

in the steel resulting from the lower solubility at the lower temperature in the nozzle[1]

. This

film is not believed to have a major impact on the flow rate through the nozzle.[5]

Fig. 2: Schematic picture of accretion layers[6]

In aluminium killed steel, a typical accretion forms when micron-sized alumina particles

attach to the nozzle wall, where they form a friable, powdery layer. Densification may then

5

occur at the nozzle interface, rendering a dense alumina layer between the refractory and the

powdery layer[3]

as pictured in Fig. 2. Sometimes three layers are identified: 1) the dense layer

next to the refractory wall mainly consisting of alumina, 2) an intermediate layer of alumina

dendrites and metal beads, and 3) a loose, powdery layer of mainly globular alumina

inclusions.[7]

The powdery and intermediate layers can be seen in Fig. 3.

Fig. 3: a) Powdery layer next to the steel, b) Intermediate layer. [7]

Methods to decrease clogging

Induction If the flow going into the nozzle separates, a stagnation zone can occur. Inclusions can get

trapped in this zone and cause clogging. Electromagnetic forces can be used to force the melt

in the stagnation zone to move. Calculations using several mathematical models suggest that

induction and injecting DC current would be feasible ways of preventing the formation of

stagnation zones. However, not many of the models have been verified experimentally.[8]

Dimensional design

Nozzle geometry can affect clog buildup; a common way to combat the effects of clogging is

to use oversized nozzle bores. A rounded entrance from the tundish can help reduce clogging

in this area through preventing separated flow. Proper vertical alignment is also important to

avoid flow separation. A 5-mm circular step in the middle of the SEN has proven to reduce

clog buildup in the lower part of the nozzle. Keeping the internal bottom of the nozzle and the

port bottom at the same level (no nozzle well) has also shown beneficial effects.[1]

Increasing the nozzle diameter just below the stopper rod could also decrease the amount of

accretions. Another factor influencing accretion is the joint sealing between the SEN and the

tundish nozzle. A tighter sealing which ensures a minimum of air leakage helps prevent

clogging.[1]

6

Argon bubbling

There are several suggested reasons as to why argon injection into the steel through the nozzle

wall or stopper rod helps prevent clogging. The gas may form a film, which prevents contact

between the melt and refractory wall. Thereafter the flow can flush inclusions off the nozzle

as well as promoting their flotation. The increased pressure in the nozzle caused by the argon

inhibits oxygen aspiration through porosities in the refractory. Additionally, theories have

been presented that suggest the gas flow may increase turbulence, thereby causing more

inclusions to be flushed off. It has been shown that clogging is reduced by allowing the argon

flow to be greater where deposition is more common. Argon injection have some drawbacks

including: decreased quality, level fluctuations in the mould leading to nozzle slag line

erosion, nozzle cracking, and a decreased resistance to thermal shock at the nozzle. It might

be that argon injection only transports the clogging to another area.[1]

Heating In some cases part of the accretion consists of solidified steel, which may freeze in the nozzle

due to an excessive heat transfer through the nozzle wall and a low casting temperature[1]

.

This indicates that a proper insulation of the nozzle along with sufficient preheating may

contribute to a reduced clogging tendency[9]

. However, some research suggests that the

clogging rate is independent of nozzle temperature, except for the initial freezing in a cold

nozzle[5]

. For non-clogging steels, for example Si-killed, the frozen shell could even melt and

disappear during the continued teeming[10]

.

Adjustment of the melt To reduce alumina clogging calcium can be added to the steel, commonly through wire

injection[1]

. This leads to the following reaction:

Al2O3 + 3Ca 3CaO + 2Al (1)[11]

The drawbacks are erosion of refractories and increased clogging if not enough calcium is

added. This treatment will not work for steel with high sulfur content as solid calcium sulfide

(CaS) will be produced rather than liquefied alumina unless the calcium treatment is

performed before the sulfur is added.[1]

The Al2O3-CaO phase diagram, which can be seen in

Fig. 4, reveals that a calcia (CaO) content ranging from 37-54 wt% in the inclusions is

necessary to achieve entirely liquid inclusions at steelmaking temperatures. Solid calcium

aluminate phases are known to agglomerate and sinter in a way similar to that of pure

alumina.[3]

7

Fig. 4: CaO-Al2O3 phase diagram.[12]

Design of ceramics The refractory material can be chosen and designed in order to decrease clogging. If a liquid

phase can be obtained at the interface between inclusions and refractory, the inclusion will be

detached from the refractory thus entering the steel flow and preventing the formation of

accretions. Both calcium zirconate (CaZrO3) and calcium titanate, as well as a mix of the two,

have been reported to perform better in casting experiments than the typical industrial alumina

graphite refractories. This is illustrated in Fig. 5 and Fig. 6. In particular calcium titanate

allowed casting of more steel without clogging. No accretion was found in used nozzles at

microscopy investigation, as a result of the forming of a liquid calcium aluminium titanate

phase during casting.[3]

Clogging Factor is a ratio between the actual mass flow rate at a certain time and the

theoretical mass flow rate calculated from the initial flow rate through the nozzle. CF may be

useful in estimating the effects of clogging from cast mass data and ranges from 1 = no clog

to 0 = completely clogged.[3]

8

Fig. 5: Clogging factor plotted towards cast mass for aluminium killed steel in an alumina graphite nozzle[3]

.

Note that pieces of the accretion have broken loose and followed the steel flow twice, reopening the nozzle

(discontinuous curve). [3]

Fig. 6: Clogging factor plotted towards cast mass, using calcium titanate, calcium zirconate and combined

nozzle. No accretion fragments have broken loose; the curves are continuous. [3]

Tuttle et al. have performed finger dipping experiments as well as industrial trials to

investigate if calcium zirconate could be efficient as calcia addition to nozzle refractories.

Both methods have shown that calcium zirconate nozzles are less prone to form accretions

compared to normal alumina graphite nozzles. Industrial trials have shown that for the same

casting conditions calcium zirconate nozzles formed a 13 mm thick accretion layer, while a

normal alumina graphite nozzle had a 50 mm thick layer. Reported problems with calcium

zirconate nozzles include poor steel quality resulting from zirconia washed into the steel flow,

and hydration when the calcia content of the refractory was higher than 25%. For calcium

zirconate materials with calcia contents exceeding 30%, erosion has been observed.[3]

Calcia containing refractories can produce liquid inclusions, as solid alumina particles in the

steel will react with the refractory calcia to produce liquid calcium aluminate.

A drawback with this method is the formation of solid calcium sulfide, which agglomerates

and sinters similarly to alumina, if the steel has sulfur levels higher than 0.02%. Additionally,

the lime (CaO) transport to the refractory surface may be insufficient to enable modification

of alumina inclusions. Alternatively, hydration of the lime can occur according to equation 2:

CaO (s) + H2O (l,g) Ca(OH)2 (s) (2)[3]

9

This may lead to a volumetric expansion and loss of strength in the refractory, which can

cause crumbling. Lime-stabilized zirconia has been used for adding lime to refractories to

avoid hydration, however this has not solved the problem satisfactory. As a result, the use of

lime containing refractories has been limited.[3]

Zirconium disilicide (ZrSi2) has been proven to reduce decarburization of the nozzle during

preheating if added to the refractory in combination with barium tetraborate (4B2O3 ·BaO).

The carbon oxidation resistance is obtained as a result of the volumetric expansion due to

formation of zirconium silicate, while the barium tetraborate glaze fills up the pores. This

prevents oxygen from penetrating into the refractory material.[2]

Strelov et al. report a decreased clogging tendency in forsterite (Mg2SiO4) nozzles compared

to zirconia (ZrO2) and periclase (MgO) nozzles. The reason is believed to be a combination of

two mechanisms:

1) The deoxidizing capacity of the nozzle material is linked to the formation of a solid phase

upon contact with for example aluminium dissolved in the molten steel. Mg2SiO4 has a lower

deoxidizing capacity than MgO, Al2O3 and ZrO2, and is less prone to form oxides with the

components in the steel.

2) The reduced temperature of the steel in contact with the refractory may cause solidification

of the steel, an effect that is more significant in materials with high thermal conductivity.

Even in this aspect Mg2SiO4 nozzles have an advantage in comparison to ZrO2 and MgO.[13]

Coating A coating may provide several advantages. It protects the nozzle refractory during preheating

and if a smoother surface is obtained, inclusions do not stick as easily. A denser material

lowers gas permeability and inhibits oxidation from air leaking through the nozzle wall. If a

liquid phase is obtained in the refractory/steel interface through reactions with inclusions and

coating, the resulting liquid inclusions will be flushed away rather than being accumulated in

the nozzle, and clogging will be eliminated.

Industrial alumina-graphite SENs are in general coated with a glass-silicon powder to prevent

the graphite from oxidizing during preheating.[2]

The presence of carbon and SiO2 on the

surface of the nozzle facilitates formation of a loose layer of alumina deposits[14]

. It has been

shown that accretion thickness is dependent on the degree of decarburization. The glaze

penetrates the refractory and may react with the graphite to form CO-gas which migrates to

the refractory/metal interface.[2]

Dissociation of the CO leads to reoxidation of alloying

elements, creating an oxide film at the SEN interface with the steel[1]

. Several possible

reactions have been proposed for alumina-graphite SENs such as:

Refractory: SiO2(s) + C(s) SiO(g) + CO(g) (3)[6]

Al2O3(s) + 2C(s) Al2O(g) + 2CO(g) (4)[6]

Interface: Al2O(g) + 2CO(g) Al2O3(s) + 2C (5)[6]

3SiO(g) + 2Al Al2O3(s) + 3Si (6)[6]

3CO(g) +2Al 3C + Al2O3(s) (7)[2]

Furthermore, the interaction of the silicon glaze with refractory alumina may result in a

viscous glaze; thus making the SEN internal surface rougher. This facilitates the attachment

and agglomeration of inclusions. The alumina-rich glaze can also react with steel alloying

elements.[2]

10

Coating materials

Zirconia (ZrO2) has a good chemical resistance to molten steel and has been reported to

reduce nozzle accretions in aluminium killed steels. However, some sintering between the

zirconia and inclusions was reportedly found when a zirconium oxide powder was paint

sprayed to form a coating on an alumina graphite nozzle. It has to be taken into consideration

that this coating method may not have rendered a high density coating, but allowed gas to

pass through the pores.[14]

Yttria Stabilized Zirconia, YSZ, is a ceramic in which the crystal structure of zirconia has

been stabilized at room temperature by addition of yttria (Y2O3)[15]

. The structure of pure

zirconia is monoclinic below 1373 K, tetragonal in the range 1373-2953 K, and cubic at

higher temperatures. The monoclinic-tetragonal phase transformation leads to a volume

expansion of 3-5%, which may induce cracks in the coating allowing oxidizing agents to enter

the base refractory. This problem is avoided through the use of YSZ. Memarpour suggests

that a 250-290 μm thick plasma sprayed YSZ coating would provide an appropriate protection

against decarburization of alumina-graphite nozzles during preheating, as well as increased

surface smoothness. Furthermore, in contact with cerium alloyed steels, an YSZ coating has

proven to eliminate the reduction of alumina by cerium and thereby the formation of the main

clogging product on the refractory wall.[2]

Alumina, as well as pure zirconia, has according to Vdovin et al. shown the best results in

chemical resistance to liquid steel and reducing overgrowth of the SEN. Carbon and silicon

dioxide (SiO2) in the refractory material increases the oxygen potential of the melt causing the

aluminium to become oxidized. Once a reaction layer is created on the nozzle wall the build-

up starts, this can significantly reduce the nozzle radius. Liquid steel in contact with a coating

of alumina graphite will dissolve some of the carbon. Some of the alumina particles will then

leave the coating and enter the steel, where they are unlikely to react with the steel. The

synthetic slag contains calcia, which locally penetrates the refractory coating and forms a

layer of calcium aluminate (Al2O3∙CaO). Carbon and silicon containing coatings lead to

carbon monoxide and silicon monoxide gas formation. Using a dense alumina coating makes

it difficult for gas to penetrate through the pores. This was tested through heat treatment of the

coated nozzle at 1600°C. Tests of the nozzle in contact with nonmetallic inclusions, steel melt

and synthetic slag showed that the nozzle coating was chemically stable in contact with the

liquid steel and did not sinter with the nonmetallic inclusions.[14]

Calcium titanate has, as mentioned earlier, given promising results as a nozzle material due to

its ability to form a liquid phase with alumina which can be seen in Fig. 7. However, the

research on calcium titanate as a coating material has been limited.

11

Fig. 7: Calcium titanate - alumina phase diagram. The eutectic point is at 41 wt% Al2O3.

[16]

Tuttle et al. have made thermodynamic predictions using information from FACTSAGE 5.2

(trademark of Thermfact, Canada and GTT-Technologies, Germany). An isothermal section

for the calcia-titania-alumina system at 1600°C suggests that calcium titanate and alumina are

thermodynamically stable when allowed to react at this temperature, however according to

experimental evidence a liquid phase formed. This led to the conclusion that FACTSAGE

slightly overestimated the melting temperatures, meaning a section at 1600°C as can be seen

in Fig. 8 may give a better representation of the phases at 1585°C. [6]

Fig. 8: Ternary phase diagram of the calcia-titania-alumina system at 1600°C. Regions without liquid phase are

outlined. [17]

12

In this section, all regions except three are predicted to form liquid phases. As a result, almost

any reaction between a calcium titanate refractory and alumina inclusions would liquefy the

inclusions.[6]

Ogibayashi suggests that once a liquid layer is produced in the interface, new inclusions that

come into contact with this layer experience almost no attractive forces and are thus carried

away with the steel flow.[18]

Experimental

A sample was prepared by filling an Al2O3 crucible with CaTiO3 powder of the size -325

mesh packed tightly through pressing with a spoon. The crucible was 40 mm high with an

outer diameter of 30 mm and a thickness of 3 mm. It weighed around 32 g, and was filled

with approximately 13g of calcium titanate powder. The sample was placed in a graphite

crucible for protection. Thereafter sample and crucible were placed into a Labmaster graphite

furnace model no 1000 – 3060 – FP 20 with temperature increase set to 10°C/min. This

furnace model is water-cooled with a temperature accuracy of +/- 3°C. To achieve an inert

environment the furnace was flushed with argon at a flow rate of approximately 4 l/min. The

cooling rate was set to 10°C/min. After cooling, the sample was removed from the furnace,

and a blue colour had appeared inside the Al2O3 crucible as exemplified by Fig. 9. The

calcium titanate powder appeared to have sintered into a hard, graphite-grey lump with a

reduced size compared to the volume of the powder. An example of the sintered contents is

shown in Fig. 10. The initial colour of both powder and crucible was white.

Fig. 9: Crucible after experiment

[19] Fig. 10: Contents of crucible after experiment

[19]

The dwell time and temperature varied between samples as Table 2 shows. For sample 1 the

argon flow was closed soon after the dwell time, for the other ones the flow was maintained

until the temperature had reached about 400°C. For sample 4 a drop in argon pressure was

noticed at 680°C. The flow was returned to the original value. However, a stable flow rate

was not possible to obtain due to the low argon pressure in the gas tube. The temperature was

at 450°C at the end of the program instead of the expected 400°C. At this point the argon flow

was close to 0 l/min. To facilitate the cooling the flow was restored to 4 l/min.

Table 2: Time-Temperature-Reaction for the samples respectively.

Sample Temperature [°C ] Dwell time [ min ] Reaction

1 1600 12 Yes

2 1600 60 Yes

3 1575 60 Yes

4 1565 60 Yes

5 1550 60 Yes

13

The samples were prepared for scanning electron microscope (SEM) by using a Struers

Accutom-50 with a CBN cut-off wheel for cutting. The cutting rate was kept at 5-30 µm/s

depending on the sample thickness.

Sample 1, 3 and 4 were washed ultrasonically using an Ultrasons P Selecta, using acetone for

2 minutes and thereafter ethanol for 2 minutes. They were dried with a Braun Silencio 1600

hairdryer for 5 minutes. A Jeol JFC-1300 Auto Fine Coater was used for gold sputtering of

the samples, with a vacuum pressure of 1mA/Pa. A thin conductive layer was thus applied to

the ceramic samples, prohibiting electric charge buildup on the sample surface in the SEM.

This would otherwise distort the images.

The samples were mounted in the desired angle using conductive clay. A S-3700N Hitachi

SEM with a Bruker AXS Flash Detector, combined with a Quantax 800 software, was used to

analyze the variation in microstructure and composition in 3-5 points for each sample. A line

analysis was attempted. However, the results were inconsistent which may be an effect of the

large fraction of pores in the material. Sample 4 was initially incorrectly mounted, leaving

traces of clay on the surface to be studied. An analysis of the clay revealed that the

composition was, apart from some additional elements such as Fe and Si, close to that of the

samples. This means that the results for the contaminated sample were not reliable. However

the sample and the analysis were kept to see whether calcia and titania had penetrated the

crucible.

Sample 2 and 5 were washed 5 minutes using acetone and 5 minutes using ethanol in a Vico

AB Ultrasonic Steri-Cleaner. After washing the samples were allowed to dry in air and the

crucible samples were covered in tin foil (Al) except from a small area selected for

examination by field emission gun scanning electron microscope (FEG-SEM). A Polaron

Equipment E5400 High Resolution Sputter Coater was used for sputtering the crucible

samples with gold.

The analysis of sample 1,3 and 4 was performed by one team and sample 2 and 5 by another

to rationalize the work. Hence, the work procedures were not identical, and the results are

presented in slightly different ways.

Results and Discussion

The literature study reveals that clogging is a highly complex problem. It is affected by

several factors related to the steel, for example steel grade, alloying elements, deoxidation

elements, casting temperature, and the amount of inclusions. However, the focus of this study

is on the SEN. Numerous approaches may be useful in the attempt to eliminate clogging. To

achieve optimal results, it is likely that the solution should include more than one approach.

Here, an overview of the most common methods has been presented. Out of these methods

coatings, and particularly calcium titanate coating, are chosen for deeper investigation. The

reason for this choice is the limited research in the area despite promising results.

From the industrial point of view, it is not clear whether it is necessary to obtain liquid phase

only. Possibly, a two-phase reaction product would reduce clogging satisfactory. In the case

of calcia containing refractories, it has been suggested that a composition completely within

14

the liquid area is necessary to liquefy inclusions[3]

. On the other hand, when discussing the

calcia-titania-alumina system, a two-phase area has been considered to provide possible

protection against clogging.[6]

If this is the case, all samples in this project do at some point

show that calcium titanate could potentially function as an anti-clogging material.

Experimental evidence indicate that calcium titanate produce a sufficient amount of liquid

phase to drastically decrease clogging tendencies[3]

. However, there might be a risk of

agglomeration and sintering of resulting solid phases at the coating/steel interface.

The application method used for coating the nozzle could also affect the functionality.

According to Vdovin et al, paint sprayed coating (zirconia) resulted in low density coating,

permeable to gas.[14]

This may provide an advantage concerning argon injection, if this is

desired to be performed through the nozzle wall. On the other hand, oxygen leakage through

the nozzle, giving rise to in-situ reoxidation, could possibly be more significant. Additionally,

a low density coating is likely to have a less fine surface, facilitating the adhesion of

inclusions to the refractory interior.

Memarpour proposes plasma spaying as a method for applying an yttria stabilized zirconia

coating[2]

. This results in a relatively smooth and dense surface, and could possibly be suitable

also for calcium titanate coatings.

Depending on the temperature, some or all of a calcium titanate coating is likely to react with

an alumina-graphite SEN. Depletion of the calcium titanate coating due to reaction with

inclusions has not been investigated, and would have to be taken into consideration in the

evaluation of appropriate thickness. However, Ogibayashi suggests that once a liquid layer is

obtained, the attractive forces of new inclusions are too weak to allow these to adhere to the

nozzle[18]

. This could indicate that depletion of the coating may not be a major issue. For

refractories containing calcia, the transport of calcia to the refractory/steel interface has been a

limiting factor[3].

An advantage with coatings could be the higher concentration of clogging

decreasing elements at the surface, creating shorter migration distances. However, if a

calcium titanate coating would react with an alumina-graphite SEN rather than with the

inclusions in the steel, this might be a problem. Possibly the nozzle material has to be chosen

to avoid reaction with the coating, not to limit the lifespan of the coating.

The results from the SEM analysis can be found in Appendix A-E. The results were used to

calculate the percentage of Ca, Al and Ti respectively. As the oxygen content is not easily

evaluated by SEM, the composition was calculated omitting these values, and assuming that

all the elements were in their oxide forms TiO, CaO and Al2O3. The achieved compositions

were plotted in the ternary phase diagram from Fig. 8 and are shown in Appendix F. A

summary of the phases obtained through this procedure is presented in Table 3.

15

Table 3: Summary of the calculated phases from evaluated points and areas. Coloured rows indicate phase

diagram areas containing solely solid phases.

Area Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 T+L T+AT+L 3 2 3 0,5 AT+L 0,5 CT+L CT+AT+L 1 CT+AT+L AT+L AT+A+L CT+L A+L 1

Total evaluated points

CT+A+L 1

57

CT+CA6+A 4 1,5 1 1

CT+CA3+CA6 4 5,5 1 2 4

Total in solid phase

T+CA+CA6

24

CT+CA+L

C3T2+CT+L 2 4 12

Total in liquid phase

C3T2+L

33

C+C3T2+L 2 1

C+L CA+L

The experimental results indicate that in many cases a liquid phase was achieved, despite a

short holding time for sample 1 and a rather low temperature for sample 3-5. However, it has

to be taken into account that the SEM-analysis of the compositions is not very precise as

oxygen is difficult to analyze. Also, the samples were not polished due to their hardness, this

may have contributed further to the uncertainty of the results. Ternary phase diagrams of the

actual temperatures were not to be found in literature, thus the available diagram at 1600°C,

which was suggested by Tuttle et al. [6]

to be valid at 1585°C, was used to investigate the

achieved compositions. The binary diagram in Fig. 7 ranges from pure CaTiO3 to pure Al2O3,

and does not consider the possible cases where calcia and titania have different reaction

equilibria or -kinetics with alumina. There are strong indications in the experimental data that

this may be the case, particularly sample 1, 3 and 4 show a pronounced separation between

calcia- and titania contents. Initially, the mole fractions of these should have been equal.

Sample 5 displays the least separation in calcia- and titania fractions, indicating a more

homogenous diffusion at lower temperatures. Moreover, at higher temperatures calcium may

evaporate, its boiling point being 1484˚C.[20]

However, it should be kept in mind that the used

phase diagram was modeled for a higher temperature. Thus, the calculated phases for the low

temperature samples are less certain.

Sample 4, cross section, was contaminated; hence the composition was not plotted in a phase

diagram. However the results strongly indicate that the composition does not vary much with

the distance to the surface. All evaluated points from the cross section contained almost pure

alumina. As a consequence, only the interface surfaces were analyzed in the following

samples. Sample 1, contents, gives further support to the theory that the changes in

16

composition are very concentrated to the actual interface. In this SEM-picture, one point is

situated on a thin flake that is seemingly broken off from the crucible. This point is composed

mostly of aluminium, in contrast to the points on the surface of the sintered contents. The

composition of the surface points is very close to pure calcium titanate, and includes only a

tiny fraction of aluminium.

In many cases the compositions in points evaluated from the same SEM-image vary

substantially. Thus, area analyses may not be a highly relevant means of investigating the

presence of liquid phases. For example, Fig. 11 shows the area composition in a solid phase

area, despite a majority of points having compositions in liquid phase areas.

Fig. 11: Composition of sample 5 plotted in phase diagram. Five evaluated points are in a liquid phase area. The

evaluated area is not in a liquid phase area.[17]

If applied as a coating, the variation in composition could possibly lead to local sintering of

inclusions in areas consisting of solid phases. This in turn may create a more uneven surface

of the SEN, facilitating further agglomeration. On the other hand, it is possible that solid areas

will be covered by flowing liquid phases from nearby regions, in which case the variations

may not constitute a problem. Empirical tests are likely to be necessary to properly answer

this question.

Another tendency found in cases where the compositions of nearby points are diverse, is that

points situated in areas appearing light in the SEM-pictures contain more titanium and less

aluminium and calcium than points in darker areas. Points within light areas are more often

plotted in liquid phase areas in the phase diagram.

In a number of pictures, particularly from Sample 1, left and right area, a honeycomb-like

structure can be observed. There is no obvious difference in composition between the ridges

and the lower central areas, however a tendency to separation between light and dark areas is

noted.

In Sample 2 and 5 flakes can be noted at the surface. The compositions in these more often

represent a liquid phase area, compared to the points situated on the crucible underneath.

Elongated particles can be seen in Sample 4, left area. These show no clear tendency to have

compositions differing from more round particles. Only point 1, situated on a small spherical

17

particle on the surface, stands out through its significant carbon content. Carbon was not

present in any other evaluated point. The carbon peak was omitted before calculating the

composition, the evaluation of which must be regarded as unreliable. A possible carbon

source may be the outer, protective crucible, from which a particle may have loosened and

entered the alumina crucible during the sample preparation.

A properly functioning coating could probably prolong the lifespan of the nozzle, which

would result in both economic and environmental advantages; every nozzle change means

interrupting the production, which leads to loss of production time as well as increased energy

consumption for keeping the steel at casting temperature. In addition, the amount of material

for deposition is decreased with increased lifespan. The application of a coating involves an

additional production process. The extra cost and environmental stress of this step must be

weighed against the benefits. The cost and environmental influence of the materials must be

balanced in a similar way.

Conclusions and Future work

The literature study and experiments have together led to a number of conclusions and

suggestions of future work. These can be summarized as follows:

Several measurements such as clean steel, inert gas injection, proper design of the

nozzle dimensions, preheating of the nozzle, calcium addition to the melt, choice of

nozzle material, inducing electromagnetic fields in the steel flow, and applying

coatings to the internal of the nozzle may contribute to the reduction of clogging.

It is not fully understood whether a liquid phase only has to be obtained for efficient

clogging reduction. Most likely, a fraction of liquid phase is sufficient to provide some

protection against clogging.

Indications of liquid phases were observed in experiments with calcium titanate

powder in alumina crucibles at all evaluated temperatures. Consequently, coating of

nozzles using calcium titanate has a high potential to diminish clogging problems in

the industry.

Temperatures as low as 1550˚C showed indications of liquid phases. Accordingly,

calcium titanate would be an appropriate coating material at steelmaking temperatures.

Significant local variations in composition were found. This may or may not represent

a problem. Casting experiments are probably essential to investigate this phenomenon

satisfactory.

Pilot plant studies are suggested to evaluate the performance of calcium titanate

coatings during casting.

To enable the industrial application of CaTiO3 further research is necessary in areas

such as: the application method, the depletion and thickness of the coating, the

interaction with the refractory, the necessary amount of liquid phase, and the

environmental as well as economic aspects.

18

Acknowledgements

We would like to thank our supervisors; Professor Pär Jönsson at KTH for his enthusiastic

support and guidance throughout the project, Jennie Svensson at HDa for sharing her work

and knowledge particularly in the experimental part, and Professor Voicu Brabie at HDa.

Thanks also to Anders Tilliander at KTH who have coordinated the bachelor thesis course.

The Swedish Governmental Agency for Innovation Systems (VINNOVA) and Jernkontoret

are acknowledged for their financial support, which made the presented research possible.

We wish to express our appreciation to Dalarna University for the use of equipment, and for

allowing us to perform the experiments at their premises.

Many thanks to Wen-Li Long at KTH for her assistance in using the SEM.

19

References

[1] Rackers, Thomas, ”Clogging in Continuous Casting Nozzles”, 78th Steelmaking Conference

Proceedings, Nashville, TN, April 2, 1995

[2] Memarpour, “An Experimental Study of Submerged Entry Nozzles (SEN) Focusing on

Decarburization and Clogging”, Doctoral thesis, KTH, 2011

[3] Tuttle, Smith, Peaslee, “Casting Simulation of Calcium Titanate and Calcium Zirconate

Nozzles for Continuous Casting of Aluminum-Killed Steels”, Metallurgical and Materials

Transactions B, Volume 38, Number 1, 2007

[4] Picture by: Felicia Lindén Bergman, 2012

[5] Kojola, Ekerot, Jönsson, Andersson, “Pilot plant study of nozzle clogging mechanisms during

casting of REM treated stainless steels”, Ironmaking & Steelmaking, Volume 38, Number 1,

2011

[6] Tuttle, Smith, Peaslee, “Interaction of Alumina Inclusions in Steel with Calcium-Containing

Materials”, Metallurgical and Materials Transactions B, Volume 36, Number 6, 2005

[7] Cui, Bao, Wang, Wu, “Clogging behavior of submerged entry nozzles for Ti-bearing IF steel”,

International journal of minerals, metallurgy, and materials, Volume 17, Number 2, 2010

[8] Lavers, Kadar, “Application of electromagnetic forces to reduce tundish nozzle clogging”,

Applied Mathematical Modelling, Volume 28, Issue 1, 2004

[9] Akselrod, Parshin, Mazurov, “Mechanism of Submersible-Nozzle Clogging in Continuous

Casting of Steel”, Steel in translation, Volume 37, Number 4, 2007

[10] Kojola, Ekerot, Jönsson, “Pilot plant study of clogging rates in low carbon and stainless steel

grades”, Ironmaking & Steelmaking, Volume 38, Number 2, 2011

[11] Jernkontorets utbildningspaket del 1(Historia, grundläggande metallurgi) p. 14

[12] Modified picture from: http://skm96.com/english/etc/prouse01.html 2012-02-25

[13] Strelov, Visloguzova, Kascheev, “Clogging of the channel of a forsterite nozzle in teeming of

aluminum-deoxidized steel”, Refractories and industrial ceramics, Volume 26, Numbers 7-8,

1986

[14] Vdovin, Rusakov, Lisichkina, “Prevention of overgrowth on submerged nozzles during

casting of steel deoxidized by aluminum”, Metallurgist, Volume 52, Numbers 5-6, 2008

[15] David W. Richerson, “Modern Ceramic Engineering”, CRC press, Taylor & Francis, 3rd

ed.,

2006, p. 642

[16] Modified picture from: AISI/DOE Industry Briefing, Pittsburgh, 2005

[17] Modified picture from: Tuttle, Smith, Peaslee, “Interaction of Alumina Inclusions in Steel

with Calcium-Containing Materials”, Metallurgical and Materials Transactions B, Volume 36,

Number 6, 2005

[18] Ogibayashi, “Mechanism and Countermeasure of Alumina Buildup on Submerged Nozzle in

Continuous Casting”, Taikabutsu Overseas, Volume 15, Number 1, 2007

[19] Picture by: Klara Takei, 2012

[20] Jefferson Lab, http://education.jlab.org/itselemental/ele020.html 2012-05-08

http://skm96.com/english/etc/prouse01.html%202012-02-25

http://education.jlab.org/itselemental/ele020.html

A1

Appendix A – SEM analyses for sample 1

A2

Spectrum: 1

Element Series norm. C Atom. C

[wt.%] [at.%]

----------------------------------

Oxygen K-series 42.74 55.79

Aluminium K-series 56.89 44.04

Titanium K-series 0.38 0.16

----------------------------------

Total: 100.00 100.00

Spectrum: 2


[wt.%] [at.%]

----------------------------------



Calcium K-series 8.97 4.98


----------------------------------

Total: 100.00 100.00

Sample 1: 1600°C, 12 min, interface/cross section (results plotted in Fig. 1, Appendix F)

A3

Sample 1: 1600°C, 12 min, left area (results plotted in Fig. 2, Appendix F)

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 2


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 3


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 4


[wt.%] [at.%]

----------------------------------





Total: 100.00 100.00

A4

Sample 1: 1600°C, 12 min, right area (results plotted in Fig. 2, Appendix F)

Spectrum: 5


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 6


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

A5

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 2


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Sample 1: 1600°C, 12 min, contents (results plotted in Fig. 3, Appendix F)

Spectrum: 3


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

B1

Appendix B – SEM analyses for sample 2

B2

Sample 2: 1600°C, 60 min (results plotted in Fig. 4, Appendix F)

Spectrum processing :

Peaks possibly omitted : 2.147, 6.404, 9.703, 11.483 keV

Processing option : All elements analyzed (Normalised)

Number of iterations = 2

Standard :

Al Al2O3 1-Jun-1999 12:00 AM

Ca Wollastonite 1-Jun-1999 12:00 AM

Ti Ti 1-Jun-1999 12:00 AM

Element Weight% Atomic%

Al K 77.87 84.66

Ca K 14.94 10.93

Ti K 7.19 4.40

Totals 100.00

B3



Peaks possibly omitted : 0.795, 2.150, 2.430, 2.630, 2.805, 6.409, 9.705, 11.477 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 2.81 4.53

Ca K 41.79 45.27

Ti K 55.40 50.21

Totals 100.00

B4



Peaks possibly omitted : 2.149, 2.640, 6.408, 8.540, 9.703, 11.468 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 80.57 86.65

Ca K 13.40 9.70

Ti K 6.03 3.65

Totals 100.00

0:

3

B5



Peaks possibly omitted : 0.815, 2.148, 2.790, 9.706, 11.482 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 1.07 1.74

Ca K 42.89 46.94

Ti K 56.04 51.32

Totals 100.00

B6



Peaks possibly omitted : 2.148, 5.905, 6.402, 8.530, 9.710, 11.490, 13.365 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 81.58 87.37

Ca K 12.95 9.33

Ti K 5.47 3.30

Totals 100.00

B7






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 52.86 64.41

Ca K 24.09 19.76

Ti K 23.06 15.83

Totals 100.00

B8






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 80.80 86.85

Ca K 12.92 9.35

Ti K 6.28 3.80

Totals 100.00

B9






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 80.05 86.72

Ca K 9.33 6.80

Ti K 10.63 6.48

Totals 100.00

B10






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 2.26 3.65

Ca K 41.72 45.37

Ti K 56.02 50.98

Totals 100.00

B11



Peaks possibly omitted : 2.147, 9.712, 11.493 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 6.64 10.41

Ca K 41.80 44.09

Ti K 51.56 45.50

Totals 100.00

B12






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 20.13 27.95

Ca K 62.84 58.73

Ti K 17.03 13.31

Totals 100.00

B13






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 21.85 29.92

Ca K 65.13 60.03

Ti K 13.02 10.04

Totals 100.00

B14






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 81.47 87.34

Ca K 12.52 9.03

Ti K 6.01 3.63

Totals 100.00

C1

Appendix C – SEM analyses for sample 3

C2

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 2


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00


D1

Appendix D – SEM analyses for sample 4

D2

Spectrum: 4


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Sample 4: 1565°C, 60 min (not plotted due to the contamination)

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

D3

Sample 4: 1565°C, 60 min, left area (results plotted in Fig. 8, Appendix F)

Spectrum: 1


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 2


[wt.%] [at.%]

----------------------------------




----------------------------------

Total: 100.00 100.00

Spectrum: 3


[wt.%] [at.%]

----------------------------------




----------------------------------

Total: 100.00 100.00

Spectrum: 4


[wt.%] [at.%]

----------------------------------




----------------------------------

Total: 100.00 100.00

Spectrum: 5


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

D4

Sample 4: 1565°C, 60 min, right area (results plotted in Fig. 8, Appendix F)

Spectrum: 6


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

Spectrum: 7


[wt.%] [at.%]

----------------------------------





----------------------------------

Total: 100.00 100.00

E1

Appendix E – SEM analyses for sample 5

E2



Peaks possibly omitted : 7.405, 9.000 keV



Standard :

O SiO2 1-Jun-1999 12:00 AM

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


O K 46.13 70.19

Al K 0.08 0.08

Ca K 24.21 14.71

Ti K 29.57 15.03

E3






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 75.53 83.57

Ca K 9.69 7.22

Ti K 14.78 9.21

Totals 100.00

E4



Peaks possibly omitted : 2.147, 2.435, 2.805, 8.515, 9.704, 11.482, 12.795, 13.342 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.49 0.80

Ca K 43.06 47.31

Ti K 56.45 51.89

Totals 100.00

E5



Peak possibly omitted : 2.131 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 18.96 27.36

Ca K 42.85 41.61

Ti K 38.19 31.03

Totals 100.00

E6






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 3.40 5.42

Ca K 43.96 47.24

Ti K 52.65 47.34

Totals 100.00

E7






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 79.55 85.87

Ca K 14.31 10.40

Ti K 6.14 3.73

Totals 100.00

E8






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 53.88 65.38

Ca K 23.15 18.91

Ti K 22.97 15.70

Totals 100.00

E9






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 69.56 78.48

Ca K 17.54 13.32

Ti K 12.90 8.20

Totals 100.00

E10






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.54 0.88

Ca K 43.31 47.54

Ti K 56.15 51.58

Totals 100.00

E11






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 80.95 87.00

Ca K 12.45 9.01

Ti K 6.60 4.00

Totals 100.00

E12



Peaks possibly omitted : 2.148, 2.800, 8.490, 9.706, 11.496, 13.335, 13.800 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 1.75 2.83

Ca K 42.26 46.08

Ti K 56.00 51.09

Totals 100.00

E13






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.86 1.40

Ca K 45.64 49.78

Ti K 53.50 48.82

Totals 100.00

E14






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.48 0.78

Ca K 44.90 49.16

Ti K 54.62 50.05

Totals 100.00

E15






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 72.37 80.67

Ca K 16.21 12.16

Ti K 11.42 7.17

Totals 100.00

E16






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 51.01 64.77

Ca K 1.35 1.15

Ti K 47.64 34.07

Totals 100.00

E17






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 5.30 8.49

Ca K 34.97 37.67

Ti K 59.73 53.84

Totals 100.00

E18






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.18 0.30

Ca K 43.19 47.54

Ti K 56.63 52.16

Totals 100.00

E19



No peaks omitted



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.28 0.45

Ca K 43.00 47.32

Ti K 56.72 52.23

Totals 100.00

E20



Peaks possibly omitted : 2.615, 8.200 keV



Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.17 0.28

Ca K 43.32 47.68

Ti K 56.51 52.04

Totals 100.00

E21






Standard :

Al Al2O3 1-Jun-1999 12:00 AM


Ti Ti 1-Jun-1999 12:00 AM


Al K 0.19 0.30

Ca K 43.19 47.54

Ti K 56.63 52.16

Totals 100.00

F1

Appendix F – The results from SEM analysis plotted in ternary phase diagrams.

Point analyses are plotted in red, areas in blue.

F2

Fig. 1: Composition of Sample 1, interface/cross section, plotted in phase diagram. No evaluated point is in a

liquid phase area. Point number 4 was not possible to analyze due to the positioning.

Fig. 2: Composition of sample 1 (points 1-4 left area, 5-6 right area) plotted in phase diagram. Three points are

in a liquid phase area.

Fig. 3: Composition of Sample 1, contents, plotted in phase diagram. Two evaluated points are in a liquid phase

area.

F3

Fig. F4: Composition of Sample 2 plotted in phase diagram. Two evaluated points are in a liquid phase area.

Fig. F5: Composition of Sample 2 plotted in phase diagram. No evaluated areas are in a liquid phase area.

Fig. F6: Composition of Sample 2 plotted in phase diagram. All evaluated points except one are in a liquid phase

area.

F4

Fig. F7: Composition of Sample 3 plotted in phase diagram. Two evaluated points are in a liquid phase area.

Fig. F8: Composition of sample 4 (points 1-5 left area, 6-7 right area) plotted in phase diagram. Four evaluated

points are in a liquid phase area.

Fig. F9: Composition of sample 5 plotted in phase diagram. Both evaluated areas are in a liquid phase area.

F5

Fig. F10: Composition of sample 5 plotted in phase diagram. Three evaluated points are in a liquid phase area.

Fig. F11: Composition of sample 5 plotted in phase diagram. Five evaluated points are in a liquid phase area.

The evaluated area is not in a liquid phase area.

Fig. F12: Composition of sample 5 plotted in phase diagram. The evaluated area is in a liquid phase area.

F6

Fig. F13: Composition of sample 5 plotted in phase diagram. The evaluated area and all evaluated points are in

a liquid phase area. The compositions are almost identical.

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