Electrochemistry for Corrosion Fundamentals (eBook)

Toshiaki Ohtsuka, Professor emeritus, Hokkaido University, Sapporo, JapanTakei Award (Society Award) from The Electrochemical Society of Japan, 2012. Society Award from Japan Society of Surface Finishing Japan, 2014.Society Award from Japan Society of Corrosion Engineering, 2014.President of Japan Society of Corrosion Engineering, 2011-2013.Editor in Chief of “Materials and Environment” Journal published from Japan Society of Corrosion Engineering, 2006-2009.Masatoshi Sakairi, Associate Professor, Hokkaido University, Sapporo, JapanNishiyama Commemorative Prize (Scientific Achievement Commemorative Prize) from The Iron and Steel Institute of Japan, 2015.Special Technical Achievement Award form Suga Weathering Technology Foundation of Japan, 2014.Editor of "Light Metals" Journal published from The Japan Institute of Light Metals, 2011-present.Editor in Chief of “Materials and Environment” Journal published from Japan Society of Corrosion Engineering, 2015-2016Vice-President of the Electrochemical Society of Japan, 2016-PresentKoji Fushimi, Associate Professor, Hokkaido University, Sapporo, JapanYoung Researcher Award from Japan Society of Corrosion Engineering, 2002Chief of Publications Committee of Japan Society of Corrosion Engineering, 2011-present.

Preface 6
Contents 8
1 Electrochemical Fundamentals of Corrosion and Corrosion Protection 11
Abstract 11
1.1 Introduction of Corrosion Electrochemistry 11
1.2 Electrochemical Model of Corrosion 12
1.3 Local Cell Model of Corrosion 14
1.4 Classification of Corrosion 16
1.4.1 Wet Corrosion and Dry Corrosion 16
1.4.2 Homogeneous Corrosion and Heterogeneous Corrosion 17
1.4.3 Enhancement of Corrosion by the Mechanical Action 18
1.5 Corrosion Protection 19
1.5.1 Anodic and Cathodic Protection 19
1.5.2 Corrosion Inhibitor 22
1.6 Atmospheric Corrosion of Steels and Surface Layer of Oxides and Corrosion Products 22
1.7 Hydrogen Entry into Steels and Delayed Failure 24
1.8 Summary 25
References 25
2 Electrochemical Measurement of Wet Corrosion 26
Abstract 26
2.1 Electrochemistry Related to the Corrosion Process 26
2.2 Redox Potential of Metals and Potential-pH Diagram 27
2.2.1 Electrochemical Potential and Equilibrium Potential 28
2.2.2 Equilibrium Potential of Metal/Metal Ion Reaction 29
2.2.3 Equilibrium Potential of Metal/Metal Oxide Reaction 30
2.2.4 Equilibrium of Metal Ion/Metal Oxide Reaction 30
2.2.5 Potential-pH Diagram of Iron 31
2.2.6 Prediction of Corrosiveness from the Potential-pH Diagram 32
2.2.7 Comparison of Current-Potential Relation with Potential-pH Diagram 33
2.3 Estimation of Corrosion Rate from Electrochemical Measurement 34
2.4 Tafel Plot 34
2.4.1 Estimation of Corrosion CD from Extrapolation of Tafel Lines 35
2.4.2 Limitation of Tafel-Line Extrapolation 36
2.5 Linear Polarization Resistance 38
2.5.1 Measurement of Linear Polarization Resistance 39
2.5.2 Requirement of Period (or Frequency) and Amplitude 40
2.5.3 “K” Value for Calculation of Corrosion Rate 42
2.6 AC Impedance 43
2.6.1 Differential AC Impedance 43
2.6.2 Electric Elements Constructing Impedance 44
2.6.3 Equivalent Circuit and Frequency Response 46
2.7 Summary 47
References 47
3 Identification of Passive Films and Corrosion Products 49
Abstract 49
3.1 Detection Techniques of Surface Compounds 49
3.2 In Situ Analytical Methods by Using Optical Reflection Techniques 52
3.2.1 Optical Reflection 53
3.2.2 Ellipsometry and Differential Reflectance 55
3.3 Molecular Vibration Spectroscopy 58
3.4 Photoexcitation Technique 63
3.5 Ex-Situ Measurement by Using Electron Spectroscopy 67
3.5.1 X-Ray Photoelectron Spectroscopy (XPS) 67
3.5.2 Auger Electron Spectroscopy (AES) 68
3.6 Summary 69
References 70
4 Electrochemical Measurement of Atmospheric Corrosion 72
Abstract 72
4.1 Electrochemistry in a Thin Solution Layer on Metal Electrode 72
4.2 Electrochemical Measurement Cell Under Thin Electrolyte Film 73
4.2.1 Electrochemical Cell 73
4.2.2 Control of the Solution Film Concentration and Thickness 74
4.3 Electrochemical Impedance Under Thin Electrolyte Film 75
4.4 Example of Electrochemical Measurement Under a Thin Electrolyte Film 77
4.4.1 EIS Measurement 77
4.4.2 Polarization Curve Measurement Under a Thin Electrolyte Film 80
4.4.3 Pitting Corrosion Monitoring in Wet and Dry Cyclic Condition 81
4.4.4 Corrosion Monitoring in Real Seashore Environment [12] 82
4.5 Summary 84
References 84
5 Hydrogen Embrittlement and Hydrogen Absorption 86
Abstract 86
5.1 Delayed Failure by Corrosion 86
5.1.1 Delayed Failure and Hydrogen Embitterment 86
5.1.2 Hydrogen Absorption Induced by Corrosion 88
5.2 Detection of Hydrogen Absorbed in Metals 89
5.2.1 Methods for Detecting Hydrogen in Metal 89
5.2.2 Electrochemical Detection of Permeated Hydrogen Through Metals 91
5.2.3 Analysis of the Hydrogen Permeation Current 92
5.2.3.1 Evaluation of the Amount of Adsorbed Hydrogen 92
5.2.3.2 Determination of the Diffusion Coefficient of Hydrogen in Steels Under Constant Potential 94
5.2.3.3 Determination of the Diffusion Coefficient of Hydrogen in Steels at a Constant Current 96
5.2.3.4 The Diffusion Coefficient of Hydrogen in the Steel from Decay Curves 97
5.3 Measurement of Hydrogen Through the Steel by a Microelectrode 98
References 101
6 Micro-electrochemical Approach for Corrosion Study 104
Abstract 104
6.1 Heterogeneous Surface and Corrosion 104
6.2 Micro-electrochemical Techniques 105
6.2.1 Reducing Size of Electrode 105
6.2.2 Microelectrode Cell (MEC) 107
6.2.3 Microcapillary Cell (MCC) 108
6.2.4 Integration of Microelectrochemical Data 109
6.3 Scanning Microelectrode Techniques 111
6.3.1 Scanning Reference Electrode Technique (SRET) 112
6.3.2 Local Electrochemical Impedance Spectroscopy (LEIS) and Scanning Vibrating Electrode Technique (SVET) 114
6.3.3 Scanning Electrochemical Microscopy (SECM) 115
6.3.4 Deepening of Scanning Microelectrode Technique for Corrosion Research 119
References 120