Physical Ceramics. Principles for Ceramic Science and Engineering. Yet-Ming Chiang Massachusetts Institute of Technology Cambridge, Massachusetts

Transcription

1 Physical Ceramics Principles for Ceramic Science and Engineering Yet-Ming Chiang Massachusetts Institute of Technology Cambridge, Massachusetts Dunbar P. Birnie, III University of Arizona Tucson, Arizona W. David Kingery University of Arizona Tucson, Arizona John Wiley & Sons, Inc. New York Chichester Toronto Brisbane Singapore

2 Contents Chapter 1. Structure of Ceramics 1 Assumed Knowledge Close-Packed Lattices 3 FCC and HCP Lattices 3 Location and Density of Interstitial Sites 7 Sites Between Two Close-Packed Layers 7 Three-Dimensional Arrangements of Interstitial Sites Stability of Ionic Crystals 9 The Madelung Constant 9 Pauling's Rules Ceramic Crystal Structures 19 FCC Based Structures 23 Rocksalt 23 Anti-Fluorite and Fluorite 24 Zincblende 27 Special Topic: Polymorphs and Polytypes 29 HCP Based Structures 31 Wurtzite 31 Corundum 32 Ilmenite and Lithium Niobate 34 Rutile 37

3 x Table of Contents Perovskite 38 Special Topic: Ferroelectrics and Piezoelectrics 42 Spinel 49 Special Topic: Magnetic Ceramics 52 Perovskite/Rocksalt Derivatives: Cuprate Superconductors 59 Special Topic: Structure, Conductivity, and Superconductivity 65 Covalent Ceramics 68 Silicon Nitride 68 Oxynitrides: Charge Compensating Solid Solutions Crystalline Silicates 72 Oxygen/Silicon Ratio 73 Clay Minerals Glass Structure 80 Glass Formation 80 Continuous Random Networks 83 Random Close-Packing Radial Distribution Function 85 Oxide Glasses 87 Borates and Borosilicates 91 Additional Reading 93 Problems 95 Chapter 2 Defects In Ceramics Point Defects 102 Intrinsic Ionic Disorder 104 Concentration of Intrinsic Defects 105 Intrinsic vs. Extrinsic Behavior 107 Units for Defect Concentration 110 Special Topic: Kröger-Vink Notation 110 Defect Chemical Reactions 111 Solute Incorporation 113 Electrons, Holes, and Defect Ionization 115 Oxidation and Reduction Reactions 116 Extent of Nonstoichiometry 117 Electronic Disorder 118 Bandgaps 119 Concentration of Intrinsic Electrons and Holes 119 Example: Intrinsic Electronic and Ionic Defect Concentrations in MgO and NaCl 125 Donors and Acceptors 126 Electronic vs. Ionic Compensation of Solutes 129 Special Topic: Point Defects and Crystalline Density in ZrO2 131 Special Topic: Color and Color Centers 133

4 Table of Contents xi 2.2 Simultaneous Defect Equilibria: The Brouwer Diagram 136 Special Topic: Some Simple Procedures for Constructing a Brouwer Diagram 141 Special Topic: Oxygen Sensors based on Nonstoichiometric ТЮ Defect Association and Precipitation 146 Point Defect Association 146 Precipitation 148 Debye-Huckel Corrections 152 Special Topic: Cation Nonstoichiometry, Disorder, and Defect Energetics in Lithium Niobate Interactions Between Point Defects and Interfaces 155 Ionic Space Charge Potential 157 Intrinsic Potential 157 Extrinsic Potential Line and Planare Defects 165 Dislocations 166 Grain Boundaries 171 Special Boundaries 172 General Boundaries 176 Boundary Films 176 Additional Reading 182 Problems 183 Chapter 3 Mass and Electrical Transport Continuum Diffusion Kinetics Atomistic Diffusion Processes 191 Random Walk Diffusion 192 Diffusion as a Thermally Activated Process 193 Types of Diffusion Coefficients 195 Diffusion in Lightly-Doped NaCl 201 Diffusion in a Highly Stoichiometric Oxide: MgO 202 Diffusion in Cation-Deficient Oxides: the Transition Metal Monoxides 205 Diffusion in a Highly Defective Oxide: Cubic Stabilized Zr Electrical Conductivity 211 Relationship Between Mobility and Diffusivity 212 Ionic and Electronic Conductivity216 Cobalt Oxide: ар-type Electronic Conductor 217 Mixed Electronic-Ionic Conduction in MgO 219 Ionic Conduction in Cubic Zr Conductivity in SrTi Special Topic: Nonlinear Conducting Ceramics: Varistors and Thermistors 225

5 xii Table of Contents 3.4 The Electrochemical Potention 233 The Nernst Equation and Application to Ionic Conductors Ambipolar Diffusion 236 Equilibration of Defect Structures 238 Ambipolar Diffusion in Sintering 242 Special Topic: Diffusional Creep as an Example of Ambipolar Diffusion 245 Special Topic: Kinetic Demixing 251 Additional Reading 256 Problems 256 Chapter 4 Phase Equilibria Thermodynamic Equilibrium 263 Special Topic: Metastability in Carbon: Diamond and Diamond-like Materials The Gibbs Phase Rule Binary Phase Diagrams 271 Complete Solid Solution 271 Limited Solid Solution 273 Binary Eutectic System 273 Intermediate Compounds Special Topic: Free Energy Curves and the Common Tangent Construction 277 Peritectic Diagrams and Incongruent Melting 283 Subsolidus Phase Equilibria 285 Solidus and Liquidus Temperatures 287 Variable Valence Systems: Example in Fe Binary Lever Rule 290 Special Topic: Crystal Growth and Phase Equilibria Features of Ternary Phase Diagrams 293 Reading Compositions 294 Example: Si0 2 -Al "FeO" 295 Primary Phase Fields 297 Congruently and Incongruently Melting Compounds 297 Boundary Curves and Temperature Contours 299 Ternary Invariant Points 300 Compatibility Triangles 301 Solidus Temperatures 301 Liquid-Liquid Immiscibility 302 Special Topic: Reciprocal Salt Diagrams Operations Using Ternary Diagrams 307 Constructing Binary Diagrams from Ternary Diagrams 307 Example: "FeO"-SiC>2 Binary Diagram 308

6 Table of Contents xiii Constructing Isothermal Sections 310 The Ternary Lever Rule Reactions Upon Heating and Cooling 318 Ternary Eutectic Reaction 318 Ternary Peritectic Reaction 319 Reactions Upon Heating 321 Heating Through a Ternary Eutectic 322 Heating Through a Ternary Peritectic 327 Equilibrium Crystallization Paths 332 Eutectic Solidification 332 Crystallization with Partial Resorption 335 Nonequilibrium Crystallization 340 Special Topic: Porcelain 342 Additional Reading 345 Problems 345 Chapter 5 Microstructure Capillarity 351 Pressure Due to Curved Surfaces 354 Chemical Potential Changes at Curved Surfaces 356 Wetting and Dihedral Angles 360 Special Topic: Rayleigh Instability and Microstructures Grain Growth and Coarsening 371 Grain Boundary Migration and Grain Growth 372 Particle Coarsening (Ostwald Ripening) Single Phase Sintering 392 Viscous Sintering 392 Crystalline Ceramics 398 Later Stage Sintering 404 Packing, Agglomeration, and Pore Growth 409 Special Topic: Magnesia-doped Alumina Reactive Additive Sintering Hot-Pressing Glasses and Glass-Ceramics 430 Crystallization and Glass Formation 431 Controlled Crystallization in Glass-Ceramics 430 Phase Separation 449 Multiple Phase Separation 460 Special Topic: Thermal Shock Resistance Composite Properties 466 Rules of Mixing 468 Percolation 474

7 xiv Table of Contents 5.8 Strength and Toughness 477 Brittle Fracture 478 Stress Intensity Factor and Fracture Toughness 481 Variability in Strength 485 Surface Flaws 486 Microstructural Toughening 487 Transformation Toughened Zirconia 488 Other Flaw-Tolerant Microstructures 492 Silicon Nitride 494 Fiber- and Whisker-Reinforced Ceramics 496 Additional Reading 500 Problems 501 Index 515