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High Temperature Alkali Corrosion of Ceramics in Coal Gas,
Final Report - December 31, 1994

Pickrell, G. R.
Sun, T.
Brown Jr., J. J.

Virginia Polytechnic Institute and State University

In this pdf format, this document has 143 pages and is 5.88MB.

Table of Contents

1 INTRODUCTION 1
2 REVIEW OF LITERATURE 4
  2.1 Silicon Carbide and Silicon Nitride 4
2.2 Alumina 9
2.3 Mullite 12
2.4 Cordierite 14
2.5 Zirconia 15
2.6 Aluminum Titanate 17

3

 EXPERIMENTAL PROCEDURE 19
 

3.1

 Alkali Reaction Products 21
  3.1.1 Soda-Cordierite System 23
3.1.2 Potassia-Cordierite System 23
3.1.3 Soda-Zirconia System 23
3.1.4 Soda-Calcia Stabilized Cubic Zirconia System 24
3.1.5 Soda-Aluminum Titanate System 24

3.2

 Sol-gel material Synthesis of Starting Reagents 25

3.3

 Alkali Reaction Kinetics 26

4

 EXPERIMENTAL RESULTS 34
 

4.1

 Alkali Reaction Kinetics 34
 

4.1.1

 Silicon Nitride 34
  4.1.1.1 Silicon Nitride Alkali Reaction Mechanism and Rate Controlling Step 43
4.1.1.2 Alkali Corrosion Induced Microstructural Changes in Silicon Nitride 50

4.1.2

 Silicon Carbide 53
  4.1.2.1 Silicon Carbide Alkali Reaction Mechanism and Rate Controlling Step 56
4.1.2.2 Alkali Corrosion Induced Microstructural Changes in Silicon Carbide 59
4.1.2.3 Comparison of the Alkali Corrosion Kinetics of Silicon Carbide and Silicon Nitride 61
4.1.3 Alumina 63
4.1.4 Mullite 73
4.1.5 Cordierite 78
4.1.6 Zirconia 83
4.1.7 Aluminum Titanate 88

4.2

 Alkali Reaction Products 91
  4.2.1 Soda-Cordierite 91
4.2.2 Potassia-Cordierite 97
4.2.3 Soda-Zirconia 101
4.2.4 Soda-Calcia Stabilized Cubic Zirconia 105
4.2.5 Soda-Aluminum Titanate 108
5 SUMMARY AND CONCLUSIONS 119
6 FUTURE WORK 121
REFERENCES 123