Table of Contents
Preface ix
Glossary of Symbols xiii
Abbreviations and Acronyms xvii
1 The Nature of High Temperature Oxidation 1
1.1 Metal Loss Due to the Scaling of Steel 1
1.2 Heating Elements 4
1.3 Protecting Turbine Engine Components 5
1.4 Hydrocarbon Cracking Furnaces 9
1.5 Prediction and Measurement 10
1.6 Rate Equations 15
1.7 Reaction Morphology: Specimen Examination 22
1.8 Summary 26
References 26
2 Enabling Theory 29
2.1 Chemical Thermodynamics 30
2.2 Chemical Equilibria Between Solids and Gases 34
2.3 Alloys and Solid Solutions 42
2.4 Chemical Equilibria Between Alloys and Gases 46
2.5 Thermodynamics of Diffusion 51
2.6 Absolute Rate Theory Applied to Lattice Particle Diffusion 55
2.7 Diffusion in Alloys 58
2.8 Diffusion Couples and the Measurement of Diffusion Coefficients 63
2.9 Interfacial Processes and Gas Phase Mass Transfer 66
2.10 Mechanical Effects: Stresses in Oxide Scales 71
References 76
Further Reading 77
3 Oxidation of Pure Metals 81
3.1 Experimental Findings 82
3.2 Use of Phase Diagrams 84
3.3 Point Defects and Non-Stoichiometry in Ionic Oxides 85
3.4 Lattice Species and Structural Units in Ionic Oxides 89
3.5 Gibbs-Duhem Equation for Defective Solid Oxides 91
3.6 Lattice Diffusion and Oxide Scaling: Wagner's Model 93
3.7 Validation of Wagner's Model 96
3.8 Impurity Effects on Lattice Diffusion 113
3.9 Microstructural Effects 115
3.10 Reactions Not Controlled by Solid-State Diffusion 127
3.11 The Value of Thermodynamic and Kinetic Analysis 133
References 135
4 Mixed Gas Corrosion of Pure Metals 139
4.1 Introduction 139
4.2 Selected Experimental Findings 140
4.3 Phase Diagrams andDiffusion Paths 147
4.4 Scale-Gas Interactions 154
4.5 Transport Processes in Mixed Scales 168
4.6 Predicting the Outcome of Mixed Gas Reactions 175
References 181
5 Oxidation of Alloys I: Single Phase Scales 185
5.1 Introduction 185
5.2 Selected Experimental Results 187
5.3 Phase Diagrams and Diffusion Paths 193
5.4 Selective Oxidation of One Alloy Component 196
5.5 Selective Oxidation of One Alloy Component Under Non-Steady-State Conditions 202
5.6 Solid Solution Oxide Scales 206
5.7 Transient Oxidation 216
5.8 Microstructural Changes in Subsurface Alloy Regions 226
5.9 Breakdown of Steady-State Scale 237
5.10 Other Factors Affecting Scale Growth 241
References 243
6 Oxidation of Alloys II: Internal Oxidation 247
6.1 Introduction 247
6.2 Selected Experimental Results 248
6.3 Internal Oxidation Kinetics in the Absence of External Scaling 255
6.4 Experimental Verification of Diffusion Model 260
6.5 Surface Diffusion Effects in the Precipitation Zone 267
6.6 Internal Precipitates of Low Stability 273
6.7 Precipitate Nucleation and Growth 278
6.8 Cellular Precipitation Morphologies 284
6.9 Multiple Internal Precipitates 290
6.10 Solute Interactions in the Precipitation Zone 299
6.11 Transition from Internal to External Oxidation 301
6.12 Internal Oxidation beneath a Corroding Alloy Surface 305
6.13 Volume Expansion in the Internal Precipitation Zone 306
6.14 Success of Internal Oxidation Theory 311
References 312
7 Alloy Oxidation III: Multiphase Scales 315
7.1 Introduction 315
7.2 Binary Alumina Formers 316
7.3 Binary Chromia Formers 326
7.4 Ternary Alloy Oxidation 330
7.5 Scale Spallation 341
7.6 Effects of Minor Alloying Additions 347
7.7 Effects of Secondary Oxidants 352
7.8 Status of Multiphase Scale Growth Theory 355
References 356
8 Corrosion by Sulfur 361
8.1 Introduction 361
8.2 Sulfidation of Pure Metals 362
8.3 Alloying for Sulfidation Protection 367
8.4 Sulfidation in H[subscript 2]/H[subscript 2]S 378
8.5 Effects of Temperature and Sulfur Partial Pressure 381
8.6 The Role of Oxygen 382
8.7 Internal Sulfidation 383
8.8 Hot Corrosion 383
8.9 Achieving Sulfidation Resistance 391
References 392
9 Corrosion by Carbon 397
9.1 Introduction 398
9.2 Gaseous Carbon Activities 400
9.3 Carburization 402
9.4 Internal Carburization of Model Alloys 403
9.5 Internal Carburization of Heat Resisting Alloys 415
9.6 Metal Dusting of Iron and Ferritic Alloys 421
9.7 Dusting of Nickel and Austenitic Alloys 435
9.8 Protection by Oxide Scaling 444
9.9 Controlling Carbon Corrosion 449
References 450
10 Effects of Water Vapour on Oxidation 455
10.1 Introduction 455
10.2 Volatile Metal Hydroxide Formation 458
10.3 Scale-Gas Interfacial Processes 468
10.4 Scale Transport Properties 472
10.5 Water Vapour Effects on Alumina Growth 488
10.6 Void Development in Growing Scales 489
10.7 Understanding and Controlling Water Vapour Effects 490
References 492
11 Cyclic Oxidation 497
11.1 Introduction 497
11.2 Alloy Depletion and Scale Rehealing 502
11.3 Spallation Models 506
11.4 Combination of Spalling and Depletion Models 514
11.5 Effects of Experimental Variables 517
11.6 Describing and Predicting Cyclic Oxidation 527
References 530
12 Alloy Design 533
12.1 Introduction 533
12.2 Alloy Design for Resistance to Oxygen 534
12.3 Design Against Oxide Scale Spallation 537
12.4 Design for Resistance to Other Corrodents and Mixed Gases 538
12.5 Future Research 539
12.6 Fundamental Research 544
12.7 Conclusion 547
References 547
Appendix A High Temperature Alloys 549
Appendix B Cation Diffusion Kinetics in Ionic Solids 553
Appendix C The Error Function 561
Appendix D Self-Diffusion Coefficients 565
Index 567
