Glass: Mechanics and Technology

G lass is a material with essentially unlimited application possibilities. This second edition of a comprehensive reference in glass science, points out the correlation between the performance of industrial processes and practice–relevant properties, such as strength and optical properties. Interdisciplinary in his approach, the author discusses both the science and technology, starting with an outline of history and applications, glass structure, and rheology. The sections on properties include mechanical strength and contact resistance, ageing, mechanics of glass processes, the production and control of residual stresses, high–tech products, and current research and development. Applications include glazing, packaging, optical glass, glass fibers for reinforcement, and abrasive tools. The development of touchscreen technology showed how important were the design and resistance of thin flexible glass and these new thin aluminosilicate glasses are also discussed. Containing a Foreword by René Gy, Saint Gobain.

Foreword XIII Preface to the Second Edition XV Preface to the First Edition XVII Symbols and Definitions (Units in Parentheses) XIX Physical Constants XXV List of Abbreviations XXVII 1 Introduction 1 2 Glass, A Ceramic Material 5 2.1 Four Classes of Materials 5 2.2 Materials Properties 11 2.3 Selecting Materials 14 2.4 Performance Indices 16 2.5 Shape Factors in Mechanical Design 19 3 Glass Prehistory and History 25 3.1 Natural Glasses 25 3.2 Early Glasses 29 3.3 First Optical Glasses 33 3.4 Modern Glasses 34 4 Applications of Glass 41 4.1 Glazing 41 4.2 Containers 47 4.3 Optical Glass 49 4.4 Glass Fibres for Insulation and Reinforcement 50 4.5 Abrasive Tools 52 4.6 Glass Manufacturers 54 5 Glass Structure 55 5.1 Introduction 55 5.2 Silica Glass and Related Glasses 56 5.2.1 Glass Network 56 5.3 Borate Glass and Related Glasses 65 5.4 Organic and Chalcogenide Glasses 66 5.5 Metallic Glasses 67 5.6 Avoiding Crystallization 68 5.7 Vitroceramic Fabrication 78 6 Glass Rheology 85 6.1 Viscosity 85 6.2 Glass Transition and Its Observation 101 6.3 Viscous Response of Glass 107 6.4 Viscoelastic Response of Glass 109 6.5 Thermal Tempering of Glass 121 6.6 Transient Stresses 131 6.7 Chemical Tempering of Glass 133 7 Mechanical Strength of Glass 139 7.1 Theoretical Strength 139 7.2 Tensile Resistance of Glass 140 7.3 Stress Concentration and Griffith Energy Balance 147 7.4 Linear Elasticity Crack Tip Stress Field 149 7.5 SIF under Non–uniform Stress 151 7.6 Toughness Measurement 151 7.7 Influence of Residual Stress on Strength and Fragmentation 153 7.8 Statistical Weibull Analysis 158 8 Contact Resistance of Glass 165 8.1 Sharp and Blunt Contact 165 8.2 Sharp Contact Resistance 185 8.3 Scratch Resistance 189 8.4 Abrasion Resistance 191 8.5 Introducing a Controlled and Critical Surface Flaw 193 8.6 Cutting and Drilling of Glass 194 9 Ageing of Glass 199 9.1 Fatigue in Glass 199 9.2 Stress Corrosion 200 9.3 Charles and Hillig Theory 203 9.4 Lifetime under Static Fatigue 205 9.5 Applications 207 9.6 NiS Phase Transformation 208 9.7 Crack Healing 210 10 Mechanics of Glass Processes 211 10.1 Introduction 211 10.1.1 Batching 212 10.2 Float Process 216 10.3 Fusion Draw 221 10.4 Container Process 222 10.5 Fibre Process 228 11 Production Control of Residual Stresses 235 11.1 Introduction 235 11.2 Residual Stresses in Flat Glass 236 11.3 Basics of Photoelasticity in Flat Glass 237 11.4 Stress Meters 241 12 High–Tech Products and R&D 247 12.1 Market Trend–Driven R&D 247 12.2 Flat Displays 248 12.3 Thin–Film Technology 253 12.4 Residual Stresses in Thin Films 266 12.5 Summary 268 13 Conclusion 271 Appendix A: Light Absorption, Dispersion and Polarization 273 A.1 Electromagnetic Spectrum 273 A.2 Light Absorption 273 A.3 Light Dispersion 275 A.4 Light Polarization 275 Appendix B: Atomic Structure and Bond Formation 279 B.1 Atomic Structure 279 B.2 Mendeleev Table 281 B.3 Bond Formation 282 Appendix C: Thermal Expansion and Elasticity 285 C.1 The α –E Trend 285 C.2 Qualitative Approach 285 C.3 Expansion Modelling 286 C.4 Differential Expansion Measurement 287 Appendix D: Falling Sphere Viscometer and Fining of Glass 289 D.1 Falling Sphere 289 D.1.1 Asymptotic Regime 289 D.1.2 Transient Regime 290 D.1.3 Faxen’s Side Correction 291 D.2 Fining of Glass 291 Appendix E: Theoretical Strength of a Solid 293 Appendix F: Weibull Analysis 297 Appendix G: Photoelastic Set–Up for Lectures 301 G.1 Set–Up for Photoelastic Projection 301 G.2 Example of a Beam under Flexion (Transient Stresses) 301 G.3 Example of Tempered Specimens (Residual Stresses) 302 Appendix H: Instrumented Nanoindentation Applied to Thin Films 305 H.1 Instrumented Nanoindentation 305 H.2 Indentation Strain Field 309 H.3 Hardness, Yield Stress and Representative Flow Stress 310 H.4 Coating–Substrate Composite Response 314 H.5 Time–Dependent Response 316 H.5.1 Viscoelastic Indentation Curves 317 H.5.2 Viscous Elastic–Plastic Indentation F(h) Curves 318 H.6 Elastic–Plastic Ratios 321 Appendix I: Strain and Stress 323 I.1 Stress and Strain 323 I.2 Stress and Strain Tensors 325 I.3 Uniaxial Tensile Test 326 I.4 Simple Shear 327 I.5 Plane Stress 328 I.6 Hydrostatic Pressure and Stress Deviator 329 I.7 Generalized Hooke’s Law 329 I.8 Kelvin and Maxwell Models 330 I.9 Generalized Maxwell Model 331 Appendix J: Flow and Plasticity in Glass 333 J.1 Introduction 333 J.2 From Newtonian to Non–Newtonian Flow 334 J.3 From Homogeneous to Heterogeneous Flow 338 Appendix K: Finite Element Analysis 343 K.1 FEM of the Pressing of a Parison 343 K.2 FEM of the Precision Moulding of a Glass Lens 343 K.3 FEM of Fracture 344 K.4 FEM of Contact Loading 346 Appendix L: X–Ray Diffraction Analysis of Thin–Film Residual Stresses 349 L.1 Thin–Film Stress and Strain 349 L.2 X–Ray Diffraction Method 351 L.3 The ε –sin2 ψ Method 352 Appendix M: Diffusion 355 M.1 Diffusion Laws 355 M.2 Steady–State Diffusion 360 M.3 Non–Steady–State Diffusion 361 Glossary 365 References 367 Index 383

Eric Le Bourhis is professor at Poitiers University (Futuroscope, France). He initially taught at a secondary school in Lima (Peru) between 1989 and 1991. Upon returning to France, he gained his PhD at Paris VII University in 1994. During this period, he started investigations of the thermo–mechanical properties of semiconductors. Then he joined Evry University for one year as an assistant professor and subsequently the Saint Gobain R&D team at Aubervilliers for 4 years as an engineer. During this industrial period, he applied contact mechanics to glass surfaces and coatings developed for glazing, and was also involved in industrial production tasks. He joined Poitiers University in 1998, where he has pursued an activity to promote sol–gel hybrid coatings in close collaboration with glass industrial manufacturers, while his other activities focus on small–scale mechanics.