CORROSION AND SURFACE CHEMISTRY OF METALS

CORROSION AND SURFACE CHEMISTRY OF METALS......Page 2
PREFACE......Page 4
TABLE OF CONTENTS......Page 7
TABLE OF CONTENTS......Page 0
1.1.1 Overview of the phenomena......Page 9
1.1.2 The economic importance of the corrosion......Page 10
1.2.1 Corrosion reactions......Page 11
Partial reactions......Page 12
1.2.2 Faraday’s Law......Page 13
1.2.3 Corrosion rate......Page 15
Influence of corrosion products......Page 16
1.3.1 Uniform and localized corrosion......Page 17
1.3.2 Different types of corrosion damage and their origin......Page 19
References......Page 21
2.1.1 Basic concepts......Page 22
Convention (II)......Page 23
2.1.2 Standard free energy of reaction......Page 24
Ellingham diagrams......Page 25
2.1.3 Activity of electrolytes......Page 27
2.2.1 Standard potential of a cell reaction......Page 29
Formalism for representing electrochemical cells......Page 30
Electrode reaction......Page 31
Standard hydrogen electrode......Page 32
2.2.3 Variation of the standard potential as a function of temperature and pressure......Page 33
2.2.4 Nernst equation......Page 36
A comment about the sign......Page 37
Theoretical voltage of an electrochemical cell......Page 38
Displacement reactions......Page 39
2.3.2 Protection potential......Page 40
Disproportionation reactions......Page 42
Corrosion by metal ions having more than one oxidation state......Page 43
Equilibrium between dissolved species in contact with an inert electrode......Page 44
2.3.4 Corrosion in the presence of complexing agents......Page 45
Complexation constant......Page 46
2.3.5 Pourbaix diagrams......Page 47
The potential–pH diagram of aluminum......Page 48
Stability domain of water......Page 49
Potential–pH diagram of iron......Page 50
Hydrogen electrode......Page 51
Calomel electrode......Page 52
Other reference electrodes......Page 53
2.4.1 Electrochemical potential......Page 54
2.4.2 Single–electrolyte electrochemical cells......Page 55
Example of a liquid junction cell: The Daniell cell......Page 57
Junction potential......Page 58
Concentration cells......Page 59
2.5.1 Reversible potential and the Fermi level......Page 61
2.5.2 Relation between electrochemical and physical potential scales......Page 63
References......Page 65
3.1.1 Surface energy......Page 66
Energy of grain boundaries......Page 67
Surface tension......Page 68
Young-Laplace Equation......Page 69
Kelvin equation......Page 71
3.1.3 Gibbs equation......Page 72
3.2.1 Heat of adsorption......Page 73
Chemical adsorption or chemisorption......Page 74
3.2.2 Adsorption isotherms......Page 75
Langmuir isotherm......Page 76
Other adsorption isotherms......Page 77
Adsorption rate......Page 78
Experimental determination of the heat of adsorption......Page 79
3.3.1 Surface analysis methods......Page 80
Energy of XPS bands......Page 82
Identification of XPS bands......Page 83
Electron escape depth......Page 84
Quantitative analysis......Page 85
Chemical shift......Page 86
3.3.3 Auger Electron Spectroscopy......Page 87
Energy of Auger peaks......Page 89
Quantitative analysis......Page 90
Chemical Imaging......Page 91
3.3.4 Ion scattering spectroscopy......Page 92
Static and dynamic modes......Page 94
3.4.1 Atomic structure and topography of metal surfaces......Page 96
Surface structure and topography at the atomic scale......Page 97
Structural characterization of surfaces at the atomic scale......Page 99
Characterization of surface topography at the microscopic scale......Page 103
3.5.1 Electric double layer......Page 105
Charge distribution at the metal-electrolyte interface......Page 106
Electric analog to the double layer......Page 107
Helmholtz model......Page 108
Gouy-Chapman Model......Page 109
Stern Model......Page 111
Electrocapillary curve and potential of zero charge......Page 114
Capacity measurements......Page 115
Basic concepts......Page 116
Space-charge layer......Page 118
Mott-Schottky equation......Page 119
Influence of the electrolyte......Page 120
3.5.4 Chemical equilibria at the oxide-electrolyte interface......Page 122
General bibliography......Page 124
References......Page 125
4.1.1 Single and mixed electrodes......Page 126
4.1.2 Polarization curves......Page 127
Galvanostatic mode......Page 128
Influence of the ohmic drop in the electrolyte......Page 130
Cathodic partial reactions......Page 131
4.2.1 Butler-Volmer equation of a single electrode......Page 132
Exchange current density......Page 135
Tafel coefficients......Page 136
Tafel lines......Page 137
Value of the exchange current density and of the Tafel coefficients......Page 139
4.2.2 Butler-Volmer equation of a mixed electrode......Page 140
Generalization......Page 143
Immersion tests......Page 144
Extrapolation of Tafel lines......Page 145
Determination of polarization resistance......Page 147
Effect of ohmic drop......Page 148
Flux of minor ionic species......Page 149
Limiting current density......Page 151
Concentration overpotential......Page 152
Reactions under mixed control......Page 154
4.3.2 Convective transport......Page 156
Dimensionless correlations......Page 157
Rotating disk electrode......Page 159
Electrode reactions under mixed control......Page 161
Free convection......Page 163
Horizontal electrodes......Page 164
Convection induced by gas bubbles......Page 165
Transport equations......Page 166
Mobility......Page 167
Conductivity......Page 168
Transport number......Page 169
Flux at the electrodes......Page 170
Corrosion by oxygen......Page 172
Corrosion of iron in neutral, aerated media......Page 174
Corrosion in weakly acidic environments......Page 176
Maximum rate of dissolution......Page 178
Corrosion rate......Page 181
References......Page 183
5.1.1 Standard rate constant of an electrode reaction......Page 185
Dissolution of copper......Page 187
Dissolution of iron......Page 189
Volmer-Heyrovsky Mechanism......Page 192
Volmer-Tafel mechanism......Page 194
Exchange-current density of the hydrogen electrode......Page 195
5.1.4 Determination of reaction order......Page 196
Example: anodic dissolution of zinc......Page 197
5.2.1 Overview of electrochemical non-steady-state methods......Page 198
5.2.2 Potential step method......Page 199
Mass transport......Page 203
Double layer capacity......Page 206
5.2.4 Voltammetry......Page 207
Single sweep voltammetry......Page 208
Non-steady-state mass transport regime......Page 209
Cyclic voltammetry......Page 210
Electrode response to a sinusoidal perturbation of the potential......Page 212
Experimental determination of the electrochemical impedance......Page 215
Impedance of the passive elements......Page 216
Impedance of an electrical circuit......Page 218
Equivalent circuit of an electrochemical system......Page 219
Faradaic impedance......Page 222
Warburg Impedance......Page 223
Nernst impedance......Page 225
Randles equivalent circuit......Page 226
Application of impedance measurements in corrosion......Page 228
References......Page 230
6.1.1 Active and passive metals......Page 232
Definitions......Page 234
Anodic passivation and spontaneous passivation......Page 235
Passivation potential......Page 237
Passivation current density......Page 239
Experimental study of passive films......Page 245
Structure of passive films......Page 247
Chemical composition of passive films......Page 248
Passive films on iron-chromium alloys......Page 249
6.2.2 Growth of anodic oxide films......Page 251
High field conduction......Page 252
Galvanostatic growth of oxide films......Page 254
Potentiostatic growth of oxide films......Page 256
Influence of film dissolution......Page 257
Interface controlled film growth......Page 258
Oxidation of water......Page 259
Reduction of oxygen......Page 260
Electron transfer by tunneling......Page 261
Electron transfer between a semiconducting oxide and the electrolyte......Page 262
Gerischer diagrams......Page 266
6.3.1 Anodic dissolution in the transpassive potential region......Page 267
Uniform transpassive dissolution by film oxidation......Page 268
Localized dissolution by pitting......Page 269
High-rate transpassive dissolution......Page 270
Depassivation due to anion penetration......Page 272
Depassivation at defects......Page 273
Film dissolution promoted by anion adsorption......Page 274
General bibliography......Page 277
References......Page 278
7.1.1 Origin and properties of corrosion cells......Page 280
Ohmic control......Page 283
7.1.2 Galvanic corrosion......Page 284
Galvanic series......Page 286
Corrosion rate......Page 288
Displacement reactions......Page 289
7.1.3 Aeration cells......Page 290
Effect of the local pH at the metal surface......Page 293
7.2.1 Effect of microstructure on local dissolution rate......Page 296
Crystalline attack......Page 297
Corrosion behavior of amorphous alloys......Page 298
Multiphase alloys......Page 300
7.2.2 Dealloying......Page 302
Polarization behavior of binary single-phase alloys......Page 303
Subcritical potential region......Page 304
Selectivity at overcritical potentials......Page 307
Selective dissolution in the overcritical potential region......Page 308
7.2.3 Intergranular corrosion......Page 310
Intergranular corrosion of austenitic stainless steel......Page 311
Intergranular corrosion tests......Page 313
Intergranular corrosion near welds......Page 314
Intergranular corrosion of ferritic stainless steels......Page 315
Intergranular corrosion of aluminum alloys......Page 316
7.3.1 Phenomenological Aspects......Page 317
Critical pitting potential......Page 318
Pitting corrosion tests......Page 319
Influence of alloy composition......Page 320
Influence of inclusions......Page 321
Influence of electrolyte composition......Page 323
7.3.3 Metastable pits......Page 325
Growth under ohmic control......Page 329
Mass-transport controlled growth......Page 330
General Bibliography......Page 332
References......Page 333
8.1.1 Reaction of metals with oxygen......Page 335
8.1.2 Experimental study of low-temperature oxidation......Page 336
Island formation......Page 338
Film growth......Page 339
Growth limited by electron tunneling......Page 340
Growth limited by high-field ionic conduction......Page 342
Other models......Page 344
Contribution of anions......Page 345
Influence of the oxide structure......Page 346
Humidity......Page 347
Time of wetness......Page 349
SO2 concentration......Page 350
Chloride concentration......Page 352
Classification of atmospheres according to their corrosivity......Page 353
Constituents of rust......Page 354
Phases of trivalent iron......Page 355
Reaction of a humid iron surface with oxygen......Page 356
Reactions in the presence of rust......Page 358
Instantaneous rate of partial reactions......Page 359
Effect of sulfates......Page 361
Importance of surface cleaning......Page 362
Weathering steel......Page 363
8.3 ATMOSPHERIC CORROSION OF NON-FERROUS METALS......Page 364
Atmospheric corrosion of zinc......Page 365
Atmospheric corrosion of aluminum......Page 366
General Bibliography......Page 367
References......Page 368
9.1.1 High-temperature versus low-temperature corrosion......Page 369
Reaction with oxygen......Page 370
Reaction with sulfur compounds......Page 371
Reaction with hydrogen......Page 372
9.1.3 Experimental study of high-temperature corrosion......Page 374
Parabolic growth law......Page 375
Crystal structure......Page 376
Melting temperature......Page 377
Thermal expansion coefficient......Page 378
Concentration of point defects in stoichiometric oxides......Page 379
Concentration of point defects in non-stoichiometric oxides......Page 380
9.2.2 Wagner’s theory of oxidation......Page 382
Growth of the n-type oxides M1+xO......Page 384
Growth of p-type oxides M1-xO......Page 386
Influence of the oxide bond energy......Page 387
Diffusion at grain boundaries......Page 388
Formation of multiple layers......Page 389
Cracking and spalling......Page 391
9.3.1 Oxidation mechanisms......Page 392
Selective internal oxidation......Page 393
Simultaneous oxidation with formation of partially miscible oxides......Page 394
Simultaneous oxidation with formation of completely miscible oxides......Page 395
Rate limited by oxygen diffusion......Page 396
Rate limited by the diffusion of metal A......Page 398
Transition criterion......Page 400
Miscible oxides......Page 401
Compound oxides......Page 402
9.3.4 Multi-component alloys......Page 404
Coatings......Page 405
Equilibria in the system M-S2......Page 406
Equilibria in the system M-SO2-O2......Page 407
9.4.2 Sulfidation......Page 409
9.4.3 Hot corrosion......Page 410
Solubility of oxides in molten sulfate......Page 412
Mechanism of hot corrosion of nickel......Page 413
Protection methods......Page 415
References......Page 416
Wear due to sliding and rolling between solids......Page 418
Friction coefficient......Page 420
Formation and breaking of adhesive junctions......Page 422
Material displacement by plowing......Page 424
Contact temperature......Page 425
Transient temperature at asperity contacts......Page 426
10.2.3 Friction in lubricated contacts......Page 427
Stribeck curve......Page 428
Surface chemical reactions of oil additives......Page 429
Friction in water lubricated systems......Page 430
10.3.1 Experimental methods......Page 431
Wear rate......Page 432
Adhesive wear......Page 433
Abrasive wear......Page 435
Delamination wear......Page 437
Oxidative wear......Page 439
Wear maps......Page 441
Passive film damage due to rubbing......Page 442
Modeling wear accelerated corrosion......Page 444
Third body effects......Page 446
10.4.1 Flow accelerated corrosion......Page 447
Critical flow velocity......Page 448
Influence of surface roughness......Page 451
Erosion due to impingement of particles entrained by a gas......Page 452
Erosion corrosion of passive metals......Page 454
Erosion corrosion in turbulent pipe flow......Page 455
Origins of degradation by cavitation......Page 456
Experimental study of cavitation corrosion......Page 458
Interpretation of the results......Page 459
Mechanisms of cavitation corrosion......Page 460
References......Page 462
11.1 INTRODUCTION......Page 464
Intergranular and transgranular cracking......Page 465
11.2.1 Overview of test methods......Page 468
11.2.2 Static tests with non-precracked specimens......Page 469
Principle of the method......Page 472
Geometry of test specimens......Page 474
Variation of the stress intensity during crack growth......Page 475
Influence of the plasticity......Page 476
11.2.4 Slow strain rate testing......Page 477
Thermodynamic solubility......Page 480
Chemical state of dissolved hydrogen......Page 481
Influence of defects on the solubility of hydrogen......Page 482
Superficial damage by hydride formation......Page 483
Hydrogen blistering......Page 484
Spontaneous cracking induced by hydrogen......Page 485
Hydrogen induced stress cracking......Page 486
11.3.3 Reaction steps in hydrogen induced stress cracking......Page 488
Adsorption......Page 489
Dissolution of hydrogen into metal......Page 490
Diffusion of hydrogen inside the metal......Page 492
Reaction mechanism of hydrogen at the crack tip......Page 493
Austenitic stainless steel......Page 494
Aluminum alloys......Page 496
Carbon steels......Page 497
11.4.2 Electrochemical considerations......Page 498
Role of surface films......Page 499
Influence of the temperature......Page 500
Crack propagation......Page 501
Crack propagation by anodic dissolution......Page 502
Propagation by successive brittle fracture......Page 504
Corrosion fatigue testing with non-precracked specimens......Page 505
Factors affecting the results obtained with non-precracked specimens......Page 506
Corrosion fatigue testing with precracked specimens......Page 507
Comparison of corrosion fatigue with stress corrosion cracking......Page 508
Crack propagation......Page 510
11.5.3 Overview of environment induced cracking phenomena......Page 512
References......Page 513
12.1.1 Introduction......Page 515
Stress concentration......Page 516
Crevices......Page 517
Sources of information......Page 518
Corrosion resistance of alloys......Page 519
Stainless steel......Page 520
Nickel alloys......Page 522
Copper Alloys......Page 523
Aluminum alloys......Page 524
Titanium alloys......Page 525
Protection mechanisms......Page 526
Fabrication of metal coatings......Page 527
Conversion coatings......Page 530
Contact coatings......Page 533
Classification of organic coatings......Page 534
Main components of paints......Page 535
Barrier effect......Page 537
Inhibition of corrosion reactions......Page 538
Galvanic effect......Page 539
Blister formation......Page 540
Accelerated exposure tests......Page 541
Electrochemical methods......Page 542
Scanning Kelvin Probe......Page 543
Scanning acoustic microscopy......Page 545
12.3.1 Classification of corrosion inhibitors......Page 546
Fields of application......Page 547
Effect on partial electrochemical reactions......Page 548
Molecular structure of adsorption type inhibitors......Page 550
Influence of the electron density......Page 551
Influence of the concentration......Page 553
12.3.3 Inhibitors for neutral environments......Page 555
Inhibition by precipitation film......Page 558
Inhibitors for cooling-water circuits......Page 559
Inhibition by adsorption......Page 556
Inhibition by passivation......Page 557
Biofilms......Page 560
Corrosion of steel in the presence of sulfate reducing bacteria......Page 561
Effect of aerobic bacteria on the pitting corrosion of stainless steel......Page 562
Biocides......Page 563
Protection potential......Page 565
Protection current......Page 566
Technological aspects of cathodic protection......Page 567
12.4.2 Electrochemical protection by passivation......Page 568
Protection by cathodic polarization into the passive region......Page 569
Importance of potential control......Page 570
12.4.3 Electrochemical systems under ohmic control......Page 571
Ohmic resistance between two plane parallel plate electrodes......Page 572
Ohmic resistance between concentric cylinder electrodes......Page 573
Ohmic resistance between concentric spherical electrodes......Page 574
Ohmic resistance to a disk electrode......Page 575
Factors affecting the potential and current distributions on electrodes......Page 576
Current distribution in a cell of trapezoidal geometry......Page 578
Potential variation on a cathodically protected pipeline......Page 579
Spacing of anodes and current requirements......Page 582
Design considerations of electrochemical protection systems......Page 583
References......Page 584
Numerical values for 25 °C......Page 586
A.2 PERIODIC TABLE OF THE ELEMENTS......Page 588
2.1......Page 589
2.7......Page 590
2.13......Page 591
3.2......Page 592
3.9......Page 593
4.3......Page 594
4.6......Page 595
4.11......Page 596
4.16......Page 597
5.4......Page 598
5.5......Page 599
6.2......Page 600
6.7......Page 601
7.2......Page 602
7.6......Page 603
8.1......Page 604
8.5......Page 605
9.3......Page 606
10.4......Page 607
11.2......Page 608
12.2......Page 609
12.7......Page 610
12.8......Page 611
A.4 LIST OF SYMBOLS......Page 612
Superscripts......Page 615