Corrosion of magnesium alloys Edited by Guang-Ling Song WOODHEAD PUBLISHING pppvr- Oxford Cambridge Philadelphia New Delhi
Contents Contributor contact details xiii Preface xvii Part I Fundamentals 1 Corrosion electrochemistry of magnesium (Mg) and its alloys 3 G.-L. Song, General Motors Corporation, USA 1.1 Introduction 3 1.2 Thermodynamics 4 1.3 Surface film 9 1.4 Anodic process 15 1.5 Cathodic process 30 1.6 Corrosion mechanism and characteristic processes 37 1.7 References 57 2 Activity and passivity of magnesium (Mg) and its alloys 66 E. Ghali, Universite Laval, Canada 2.1 Active and passive behaviors of magnesium (Mg) and its a!loys66 2.2 Passive properties and stability 71 2.3 Improvements and promising avenues of the passive behavior 74 2.4 Specific factors characterizing corrosion behavior 78 2.5 Active and passive behaviors and corrosion forms 84 2.6 Performance of sacrificial magnesium (Mg) and its alloys 96 2.7 Mechanism of corrosion of sacrificial anodes 101 2.8 Examples of actual and possible uses 103 2.9 Evaluation of the sacrificial behavior 105 2.10 Future trends 108
vi Contents 2.11 Acknowledgements 2.12 References and further reading 109 109 Part II Metallurgical effects 3 Corrosion of magnesium (Mg) alloys and metallurgical influence 117 A. Atrens and M. Liu, The University of Queensland, Australia, N. I. Zainal Abidin, University of Malaya, Malaysia and G.-L. Song, General Motors Corporation, USA 3.1 Introduction 117 3.2 Measurement details 118 3.3 Second phase effect 124 3.4 Impurity concentration 137 3.5 Surface condition 149 3.6 Medical implant applications 152 3.7 Concluding remarks 160 3.8 Acknowledgements 161 3.9 References 161 4 Role of structure and rare earth (RE) elements on the corrosion of magnesium (Mg) alloys 166 T. Zhang, Harbin Engineering University, China and Y. Li, Institute of Metal Research, Chinese Academy of Sciences, China 4.1 Introduction 166 4.2 Role of structure on the corrosion process of magnesium (Mg) alloys 166 4.3 Role of rare earth (RE) elements on the corrosion process of magnesium (Mg) alloys 180 4.4 References 204 5 Corrosion behaviour of magnesium (Mg)-based bulk metallic glasses 207 A. Gebert, Leibniz Institute for Solid State and Materials Research, Germany 5.1 Introduction 207 5.2 Magnesium (Mg)-based bulk metallic glasses (BMGs) 209 5.3 Effect of micro-structural refinement on the corrosion of magnesium (Mg)-based alloys 212 5.4 General corrosion and passivation behaviour of magnesium (Mg)-based bulk metallic glasses (BMGs) 214
Contents vii 5.5 Chloride-induced local corrosion behaviour of magnesium (Mg)-based metallic glasses 221 5.6 Effect of hydrogen on the stability of magnesium (Mg)-based glassy alloys 225 5.7 Future trends 226 5.8 Acknowledgements 228 5.9 References 228 6 Corrosion of innovative magnesium (Mg) alloys 234 P. B. Srinivasan, C. Blawert and D. Hoche, Helmholtz-Zentrum Geesthacht, Germany 6.1 Recycled alloys 234 6.2 Amorphous alloys 238 6.3 Alloy coatings 243 6.4 Ion implantation 248 6.5 Laser processed magnesium (Mg) alloys 250 6.6 References 260 Part III Environmental influences 7 Atmospheric corrosion of magnesium (Mg) alloys 269 M. JOnsson and D. Persson, SWEREA KIMAB, Sweden 7.1 Introduction 269 7.2 The atmospheric environment 270 7.3 Electrochemical reactions 271 7.4 The oxide film 272 7.5 The effect of atmospheric gases and particles 273 7.6 Corrosion of magnesium (Mg) alloys during field exposure 275 7.7 Corrosion products 278 7.8 Influence of microstructure on the atmospheric corrosion behaviour 280 7.9 Differences between field-exposed magnesium (Mg) and accelerated tests 293 7.10 Concluding remarks 295 7.11 References 296 8 Stress corrosion cracking (SCC) of magnesium (Mg) alloys 299 A. Atrens, The University of Queensland, Australia, N. Winzer, Fraunhofer Institute for Mechanics of Materials IWM, Germany, W. Dietzel and P. B. Srinivasan, Helmholtz-Zentrum Geesthacht, Germany and G.-L. Song, General Motors Corporation, USA 8.1 Introduction 299
viii Contents 8.2 Alloy influences 301 8.3 Loading 315 8.4 Environmental influences 326 8.5 Proctography 334 8.6 Stress corrosion cracking (SCC) mechanisms 335 8.7 Recent insights 348 8.8 Open issues 352 8.9 Acknowledgements 354 8.10 References 354 9 Corrosion creep and fatigue behavior of magnesium (Mg) alloys 365 Y. B. Unigovski and E. M. Gutman, Ben-Gurion University of the Negev, Israel 9.1 Introduction 365 9.2 Historical review of environmentally enhanced creep and fatigue of metals 366 9.3 Mechanoelectrochemical behavior of magnesium (Mg) alloys 372 9.4 Corrosion creep of magnesium (Mg) and diecast magnesium (Mg) alloys 373 9.5 Corrosion fatigue of magnesium (Mg) alloys 387 9.6 Summary 398 9.7 References 398 10 Magnesium (Mg) corrosion: a challenging concept for degradable implants 403 F. Witte, Hannover Medical School, Germany, N. Hort and F. Feyerabend, Helmholtz-Zentrum Geesthacht, Germany and C. Vogt, Leibniz Universitat Hannover, Germany 10.1 An introduction to degradable magnesium (Mg) implants 403 10.2 The appropriate selection and use of biodegradable magnesium (Mg) alloys 406 10.3 In vivo corrosion of magnesium (Mg) alloys: what happens in living tissue? 409 10.4 Methods to characterize in vivo corrosion 411 10.5 In vitro corrosion test methods 418 10.6 Future trends 422 10.7 References 423
Contents ix 11 Corrosion of magnesium (Mg) alloys in engine coolants 426 G.-L. Song, General Motors Corporation, USA and D. H. StJohn, The University of Queensland, Australia 11.1 Introduction 426 11.2 Magnesium (Mg) alloys and coolants 427 11.3 Laboratory evaluation methodology 429 11.4 Corrosion of magnesium (Mg) in ethylene glycol solution 432 11.5 Magnesium (Mg) alloys in ethylene glycol solution 438 11.6 Magnesium (Mg) alloys in commercial coolants 439 11.7 Corrosion inhibition 444 11.8 Health and environmental concerns 450 11.9 Summary 451 11.10 References 452 12 Numerical modelling of galvanic corrosion of magnesium (Mg) alloys 455 A. Atrens and Z. Shi, The University of Queensland, Australia and G.-L. Song, General Motors Corporation, USA 12.1 Introduction 455 12.2 Boundary element method (BEM) model 457 12.3 One-dimensional (ID) galvanic corrosion 460 12.4 Galvanic interaction 469 12.5 Steel fastener 471 12.6 Discussion 474 12.7 Conclusions 476 12.8 Future trends 476 12.9 Acknowledgements 482 12.10 References 482 13 Non-aqueous electrochemistry of magnesium (Mg) 484 D. Aurbach and N. Pour, Bar Ilan University, Israel 13.1 Introduction 484 13.2 A short review of non-aqueous electrolyte solutions 487 13.3 A short review of the passivation phenomena of active metals in non-aqueous electrolyte solutions 491 13.4 Magnesium (Mg) electrodes in conventional polar aprotic solvents and in Grignard solutions 495 13.5 Ionic liquids (ILs) for magnesium (Mg) electrochemistry 498 13.6 On solutions with a wide electrochemical window (>2V) in which magnesium (Mg) deposition is reversible 500 13.7 On magnesium (Mg) ions insertion into inorganic hosts 505 Woodhead Publishing Limited, 2011
x Contents 13.8 Future trends 511 13.9 References 513 Part IV Corrosion protection 14 Electrodeposition of aluminum (Al) on magnesium (Mg) alloys in ionic liquids 519 W.-T. Tsai and I.-W. Sun, National Cheng Kung University, Taiwan 14.1 Introduction 519 14.2 Basics for ionic liquid plating 521 14.3 Electrochemical characteristics of A1C13-EMIC ionic liquids 523 14.4 Material characteristics 526 14.5 Electrochemical and corrosion resistance of aluminum (Al) and aluminum/zinc (Al/Zn)-coated magnesium (Mg) alloys 528 14.6 Summary 534 14.7 Acknowledgement 536 14.8 References 536 15 Corrosion protection of magnesium (Mg) alloys using conversion and electrophoretic coatings 541 B. L. Luan, D. Yang and X. Y. Liu, National Research Council of Canada, Canada and G.-L. Song, General Motors Corporation, USA 15.1 Introduction 541 15.2 Conversion coating for magnesium (Mg) and its alloys 543 15.3 Electrocoat 554 15.4 Concluding remarks 560 15.5 References 562 16 Anodization and corrosion of magnesium (Mg) alloys 565 G.-L. Song, General Motors Corporation, USA and Z. Shi, The University of Queensland, Australia 16.1 Overview of anodizing techniques 565 16.2 Characteristics of anodizing behavior 568 16.3 Anodized coating/film 572 16.4 Influencing factors 577 16.5 Anodizing mechanism 583 16.6 Corrosion of anodized magnesium (Mg) alloys 591
Contents xi 16.7 Application examples 604 16.8 References 609 17 Corrosion of magnesium (Mg) alloys: concluding remarks 615 G.-L. Song, General Motors Corporation, USA Index 618