Corrosion and Corrosion Control: An Introduction to Corrosion Science and Engineering, 4th Edition

Preface xvii

1 DEFINITION AND IMPORTANCE OF CORROSION 1

1.1 Definition of Corrosion 1

1.1.1 Corrosion Science and Corrosion Engineering 1

1.2 Importance of Corrosion 2

1.3 Risk Management 5

1.4 Causes of Corrosion 6

2 ELECTROCHEMICAL MECHANISMS 9

2.1 The Dry-Cell Analogy and Faraday's Law 9

2.2 Definition of Anode and Cathode 11

2.3 Types of Cells 13

2.4 Types of Corrosion Damage 15

3 THERMODYNAMICS: CORROSION TENDENCY AND ELECTRODE POTENTIALS 21

3.1 Change of Gibbs Free Energy 21

3.2 Measuring the Emf of a Cell 22

3.3 Calculating the Half-Cell Potential—The Nernst Equation 22

3.4 The Hydrogen Electrode and the Standard Hydrogen Scale 24

3.5 Convention of Signs and Calculation of Emf 25

3.6 Measurement of pH 28

3.7 The Oxygen Electrode and Differential Aeration Cell 28

3.8 The Emf and Galvanic Series 30

3.9 Liquid Junction Potentials 33

3.10 Reference Electrodes 34

4 THERMODYNAMICS: POURBAIX DIAGRAMS 43

4.1 Basis of Pourbaix Diagrams 43

4.2 Pourbaix Diagram for Water 44

4.3 Pourbaix Diagram for Iron 45

4.4 Pourbaix Diagram for Aluminum 47

4.5 Pourbaix Diagram for Magnesium 48

4.6 Limitations of Pourbaix Diagrams 49

5 KINETICS: POLARIZATION AND CORROSION RATES 53

5.1 Polarization 53

5.2 The Polarized Cell 54

5.3 How Polarization Is Measured 56

5.4 Causes of Polarization 58

5.5 Hydrogen Overpotential 63

5.6 Polarization Diagrams of Corroding Metals 66

5.7 Influence of Polarization on Corrosion Rate 68

5.8 Calculation of Corrosion Rates from Polarization Data 71

5.9 Anode–Cathode Area Ratio 73

5.10 Electrochemical Impedance Spectroscopy 75

5.11 Theory of Cathodic Protection 77

6 PASSIVITY 83

6.1 Definition 83

6.2 Characteristics of Passivation and the Flade Potential 84

6.3 Behavior of Passivators 88

6.4 Anodic Protection and Transpassivity 90

6.5 Theories of Passivity 92

6.6 Critical Pitting Potential 97

6.7 Critical Pitting Temperature 99

6.8 Passivity of Alloys 100

6.9 Effect of Cathodic Polarization and Catalysis 108

7 IRON AND STEEL 115

7.1 Introduction 115

7.2 Aqueous Environments 116

7.3 Metallurgical Factors 138

7.4 Steel Reinforcements in Concrete 143

8 EFFECT OF STRESS 149

8.1 Cold Working 149

8.2 Stress-Corrosion Cracking 150

8.3 Mechanism of Stress-Corrosion Cracking of Steel and Other Metals 156

8.4 Hydrogen Damage 166

8.5 Radiation Damage 172

8.6 Corrosion Fatigue 173

8.7 Fretting Corrosion 180

9 ATMOSPHERIC CORROSION 191

9.1 Introduction 191

9.2 Types of Atmospheres 192

9.3 Corrosion-Product Films 192

9.4 Factors Infl uencing Corrosivity of the Atmosphere 195

9.5 Remedial Measures 201

10 CORROSION IN SOILS 205

10.1 Introduction 205

10.2 Factors Affecting the Corrosivity of Soils 206

10.3 Bureau of Standards Tests 207

10.4 Stress-Corrosion Cracking 210

10.5 Remedial Measures 211

11 OXIDATION 215

11.1 Introduction 215

11.2 Initial Stages 216

11.3 Thermodynamics of Oxidation: Free Energy–Temperature Diagram 218

11.4 Protective and Nonprotective Scales 218

11.5 Wagner Theory of Oxidation 223

11.6 Oxide Properties and Oxidation 224

11.7 Galvanic Effects and Electrolysis of Oxides 227

11.8 Hot Ash Corrosion 229

11.9 Hot Corrosion 229

11.10 Oxidation of Copper 230

11.11 Oxidation of Iron and Iron Alloys 232

11.12 Life Test for Oxidation-Resistant Wires 233

11.13 Oxidation-Resistant Alloys 234

12 STRAY-CURRENT CORROSION 241

12.1 Introduction 241

12.2 Sources of Stray Currents 242

12.3 Quantitative Damage by Stray Currents 244

12.4 Detection of Stray Currents 245

12.5 Soil-Resistivity Measurement 246

12.6 Means for Reducing Stray-Current Corrosion 246

13 CATHODIC PROTECTION 251

13.1 Introduction 251

13.2 Brief History 252

13.3 How Applied 253

13.4 Combined Use with Coatings 255

13.5 Magnitude of Current Required 257

13.6 Anode Materials and Backfi ll 258

13.7 Criteria of Protection 260

13.8 Economics of Cathodic Protection 263

13.9 Anodic Protection 263

14 METALLIC COATINGS 269

14.1 Methods of Application 269

14.2 Classification of Coatings 271

14.3 Specific Metal Coatings 272

15 INORGANIC COATINGS 285

15.1 Vitreous Enamels 285

15.2 Portland Cement Coatings 286

15.3 Chemical Conversion Coatings 286

16 ORGANIC COATINGS 289

16.1 Introduction 289

16.2 Paints 289

16.3 Requirements for Corrosion Protection 291

16.4 Metal Surface Preparation 293

16.5 Applying Paint Coatings 295

16.6 Filiform Corrosion 296

16.7 Plastic Linings 299

17 INHIBITORS AND PASSIVATORS 303

17.1 Introduction 303

17.2 Passivators 304

17.3 Pickling Inhibitors 310

17.4 Slushing Compounds 313

17.5 Vapor-Phase Inhibitors 313

18 TREATMENT OF WATER AND STEAM SYSTEMS 317

18.1 Deaeration and Deactivation 317

18.2 Hot- and Cold-Water Treatment 321

18.3 Boiler-Water Treatment 323

19 ALLOYING FOR CORROSION RESISTANCE; STAINLESS STEELS 333

19.1 Introduction 333

19.2 Stainless Steels 335

20 COPPER AND COPPER ALLOYS 367

20.1 Copper 367

20.2 Copper Alloys 371

21 ALUMINUM AND ALUMINUM ALLOYS 383

21.1 Aluminum 383

21.2 Aluminum Alloys 393

22 MAGNESIUM AND MAGNESIUM ALLOYS 399

22.1 Introduction 399

22.2 Magnesium 399

22.3 Magnesium Alloys 400

22.4 Summary 404

23 NICKEL AND NICKEL ALLOYS 407

23.1 Introduction 407

23.2 Nickel 408

23.3 Nickel Alloys 411

24 COBALT AND COBALT ALLOYS 419

24.1 Introduction 419

24.2 Cobalt Alloys 420

25 TITANIUM 425

25.1 Titanium 425

25.2 Titanium Alloys 427

25.3 Pitting and Crevice Corrosion 429

25.4 Intergranular Corrosion and Stress-Corrosion Cracking 430

26 ZIRCONIUM 435

26.1 Introduction 435

26.2 Zirconium Alloys 436

26.3 Behavior in Hot Water and Steam 437

27 TANTALUM 441

27.1 Introduction 441

27.2 Corrosion Behavior 441

28 LEAD 445

28.1 Introduction 445

28.2 Corrosion Behavior of Lead and Lead Alloys 446

28.3 Summary 448

29 APPENDIX 451

29.1 Activity and Activity Coeffi cients of Strong Electrolytes 451

29.2 Derivation of Stern–Geary Equation for Calculating Corrosion Rates from Polarization Data Obtained at Low Current Densities 456

29.3 Derivation of Equation Expressing the Saturation Index of a Natural Water 461

29.4 Derivation of Potential Change along a Cathodically Protected Pipeline 467

29.5 Derivation of the Equation for Potential Drop along the Soil Surface Created by Current Entering or Leaving a Buried Pipe 469

29.6 Derivation of the Equation for Determining Resistivity of Soil by Four-Electrode Method 470

29.7 Derivation of the Equation Expressing Weight Loss by Fretting Corrosion 471

29.8 Conversion Factors 474

29.9 Standard Potentials 476

29.10 Notation and Abbreviations 476

References 478

Index 479