Fundamentals of Corrosion: Mechanisms, Causes, and Preventative Methods (Corrosion technology)

430 Pages·2009·3.23 MB·English

Fundamentals of
CORROSION
Mechanisms, Causes,
and Preventative Methods
Fundamentals of
CORROSION
Mechanisms, Causes,
and Preventative Methods
Philip A. Schweitzer
Boca Raton London New York
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Library of Congress Cataloging‑in‑Publication Data
Schweitzer, Philip A.
Fundamentals of corrosion : mechanisms, causes, and preventative methods / Philip
A. Schweitzer.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4200-6770-5 (hardcover : alk. paper)
1. Building materials--Corrosion. 2. Corrosion and anti-corrosives. I. Title.
TA418.74.S3847 2010
620.1’1223--dc22 2009028737
Visit the Taylor & Francis Web site at
http://www.taylorandfrancis.com
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Contents
List of Figures ........................................................................................................xv
List of Tables ........................................................................................................ xix
Preface ................................................................................................................. xxiii
1 Introduction .....................................................................................................1
1.1 Economic Losses ...................................................................................1
1.2 Indirect Losses .......................................................................................2
1.2.1 Shutdown ..................................................................................2
1.2.2 Contamination..........................................................................2
1.2.3 Loss of Product .........................................................................3
1.2.4 Loss of Effciency .....................................................................3
1.2.5 Environmental Damage ..........................................................3
1.2.6 Overdesign ................................................................................3
1.3 Conservation Losses .............................................................................3
1.4 Nonmetallic Materials ..........................................................................4
1.5 Summary ................................................................................................4
2 Corrosion Mechanisms .................................................................................5
2.1 Cell Potentials ........................................................................................7
2.2 Types of Local Cell Formations ...........................................................8
2.2.1 Dissimilar Electrode Cells ......................................................9
2.2.2 Concentration Cells .................................................................9
2.2.3 Differential Temperature Cells ............................................ 10
2.2.4 Oxygen Concentration Cells ................................................ 11
2.2.5 Metal Ion Concentration Cells ............................................. 11
2.3 Potential–pH Diagrams ...................................................................... 11
2.4 Polarization .......................................................................................... 14
2.4.1 Activation Polarization ......................................................... 15
2.4.2 Concentration Polarization ................................................... 17
2.5 Measuring Polarization ...................................................................... 19
2.5.1 Anodic Polarization ............................................................... 21
2.6 Other Factors Affecting Corrosion ...................................................23
2.7 Corrosion Rate Measurement ............................................................25
2.7.1 Corrosion Rate Expressions ..................................................25
3 Forms of Metallic Corrosion ...................................................................... 27
3.1 General (Uniform) Corrosion ............................................................ 27
3.1.1 Passive Film on Iron ..............................................................28
3.1.2 Passive Film on Nickel .......................................................... 29
3.1.3 Passive Film on Austenitic Stainless Steel .......................... 29
v
vi Contents
3.1.4 Passive Film on Copper......................................................... 29
3.1.5 Passive Film on Aluminum. .................................................30
3.1.6 Passive Film on Titanium .....................................................30
3.1.7 Passive Film on Tantalum. ....................................................30
3.1.8 Uniform Corrosion Rates. .....................................................30
3.1.9 Protective Measures .............................................................. 31
3.2 Intergranular Corrosion. .................................................................... 32
3.2.1 Austenitic Stainless Steels .................................................... 32
3.2.2 Ferritic Stainless Steels. .........................................................35
3.2.3 Other Alloys ...........................................................................35
3.3 Galvanic Corrosion .............................................................................36
3.3.3 Preventive Measures .............................................................38
3.4 Crevice Corrosion ...............................................................................38
3.4.1 Preventive Measures .............................................................40
3.5 Pitting Corrosion. ................................................................................ 41
3.5.1 Preventive Measures .............................................................43
3.6 Erosion Corrosion ...............................................................................44
3.6.1 Preventive Measures .............................................................45
3.7 Stress Corrosion Cracking (SCC). .....................................................46
3.7.1 Preventive Measures ............................................................. 49
3.8 Biological Corrosion............................................................................50
3.8.1 Preventive Measures .............................................................54
3.9 Selective Leaching. .............................................................................. 55
3.9.1 Preventive Measures ............................................................. 57
3.10 Hydrogen Damage. ............................................................................. 57
3.10.1 Sources of Hydrogen ............................................................. 58
3.10.2 Types of Hydrogen Damage. ................................................ 59
3.10.2.1 Hydrogen Embrittlement ...................................... 59
3.10.2.2 Hydrogen Blistering. .............................................. 62
3.10.2.3 Flakes, Fisheyes, and Shatter Cracks. ..................63
3.10.2.4 Hydrogen Attack ....................................................63
3.10.3 Preventive Measures .............................................................65
3.10.3.1 Hydrogen Blistering. ..............................................65
3.10.3.2 Hydrogen Embrittlement ......................................66
3.10.3.3 Hydrogen Attack .................................................... 67
3.11 Liquid Metal Attack. ...........................................................................68
3.11.1 Liquid Metal Embrittlement (LME) .................................... 69
3.11.1.1 Requirements for Embrittlement ......................... 69
3.11.1.2 Factors Infuencing LME ....................................... 71
3.11.1.3 Delayed Failure. ......................................................72
3.11.1.4 Preventive Measures. .............................................72
3.11.2 Corrosion by Liquid Metals .................................................72
3.12 Exfoliation ............................................................................................ 73
3.12.1 Preventive Measures ............................................................. 74
3.13 Corrosion Fatigue ................................................................................ 74
Contents vii
3.13.1 Preventive Measures. ............................................................ 75
3.14 Filiform Corrosion. ............................................................................. 75
3.14.1 Preventive Measures. ............................................................ 76
References ....................................................................................................... 76
4 Atmospheric Corrosion ...............................................................................77
4.1 Atmospheric Types ............................................................................. 78
4.2 Factors Affecting Atmospheric Corrosion....................................... 79
4.2.1 Time of Wetness .....................................................................80
4.2.1.1 Adsorption Layers ..................................................80
4.2.1.2 Phase Layers ............................................................ 81
4.2.2 Composition of Surface Electrolyte .....................................83
4.2.2.1 Oxygen .....................................................................83
4.2.2.2 SO ............................................................................83
x
4.2.2.3 NO ...........................................................................83
x
4.2.2.4 Chlorides .................................................................84
4.2.2.5 CO ............................................................................84
2
4.2.2.6 Concentration of Different Species ......................84
4.2.3 Temperature ............................................................................84
4.2.4 Initial Exposure ......................................................................85
4.2.5 Sheltering ................................................................................85
4.2.6 Wind Velocity .........................................................................86
4.2.7 Nature of Corrosion Products ..............................................86
4.2.8 Pollutants Present .................................................................. 87
4.3 Mechanisms of Atmospheric Corrosion of Metals ........................ 89
4.3.1 Damp Atmospheric Corrosion (Adsorption Layers) ........90
4.3.2 Wet Atmospheric Corrosion (Phase Layers) ...................... 92
4.3.2.1 Dew .......................................................................... 92
4.3.2.2 Rain .......................................................................... 92
4.3.2.3 Fog ............................................................................ 93
4.3.3 Deposit of Pollutants ............................................................. 93
4.4 Corrosion Products ............................................................................. 94
4.5 Specifc Atmospheric Corrodents ..................................................... 96
4.5.1 Sulfur-Containing Compounds ........................................... 97
4.5.2 Nitrogen-Containing Compounds ......................................99
4.5.3 Chlorine-Containing Compounds .................................... 100
4.5.4 Carbon Dioxide (CO ) .......................................................... 101
2
4.5.5 Oxygen (O ) ........................................................................... 101
2
4.5.6 Indoor Atmospheric Compounds ..................................... 101
4.6 Summary ............................................................................................ 101
4.7 Resistance of Specifc Metals and Alloys to Atmospheric
Corrosion ............................................................................................ 102
4.7.1 Carbon Steel .......................................................................... 102
4.7.2 Weathering Steels................................................................. 104
4.7.3 Zinc ........................................................................................ 106
viii Contents
4.7.4 Zinc and Zinc Alloy Coatings on Steel. ............................109
4.7.4.1 Zinc-Aluminum Hot Dip Coatings.................... 111
4.7.4.2 Zinc-Aluminum Thermally Sprayed
Coatings ................................................................. 111
4.7.4.3 Zinc-Iron Alloy Coatings .................................... 112
4.7.4.4 Cast Zinc Alloys ................................................... 112
4.7.5 Copper ................................................................................... 112
4.7.6 Copper Alloys ....................................................................... 114
4.7.6.1 Brasses .................................................................... 114
4.7.6.2 Bronzes .................................................................. 116
4.7.6.3 Copper-Nickel Alloys .......................................... 116
4.7.7 Aluminum Alloys ................................................................ 116
4.7.7.1 Protective Measures ............................................. 120
4.7.7.2 Applications .......................................................... 121
4.7.8 Stainless Steel ....................................................................... 122
4.7.8.1 Austenitic Grades ................................................. 123
4.7.8.2 Ferritic Grades ...................................................... 124
4.7.8.3 Martensitic Grades ............................................... 124
4.7.8.4 Duplex Grades ...................................................... 125
4.7.9 Nickel ..................................................................................... 125
4.7.10 Monel Alloy .......................................................................... 125
4.7.11 Inconel Alloy 600 ................................................................. 125
4.7.12 Inconel Alloy 625, Incoloy Alloy 800, Incoloy
Alloy 825 ................................................................................ 126
4.8 Atmospheric Corrosion of Nonmetals ........................................... 126
4.8.1 Plastics ................................................................................... 126
4.8.1.1 Thermoplastics ..................................................... 127
4.8.1.2 Thermosets ............................................................ 129
4.8.2 Elastomers ............................................................................. 133
4.8.3 Masonry Materials ............................................................... 134
4.8.3.1 Protecting Concrete ............................................. 137
4.8.3.2 Coating Selection .................................................. 139
4.8.3.3 Polymer Concrete ................................................. 140
4.8.3.4 Mortars and Grouts .............................................. 140
4.8.4 Ceramics ................................................................................ 141
4.8.4.1 Forms of Corrosion .............................................. 143
4.8.4.2 Corrosion of Specifc Ceramics .......................... 145
4.8.5 Wood ...................................................................................... 145
4.8.5.1 Plywood ................................................................. 149
4.8.5.2 Reconstituted Wood Products ............................ 150
4.8.5.3 Applied Exterior Wood Finishes ........................ 151
4.8.6 Indoor Atmospheric Corrosion .......................................... 153
References ..................................................................................................... 154
Contents ix
5 Corrosion of Polymer (Plastic) Materia.l.s.. ......................................1..5.7.
5.1 Radiation ............................................................................................ 158
5.2 Permeation ......................................................................................... 159
5.3 Absorption ......................................................................................... 163
5.4 Thermoplasts (Thermoplastic Polymers) ....................................... 166
5.5 Thermoset Polymers ......................................................................... 167
5.6 Environmental Cracking .................................................................. 169
6 Corrosion of Linings .................................................................................. 171
6.1 Liquid Applied Linings .................................................................... 172
6.1.1 Design of the Vessel ............................................................. 172
6.1.2 Lining Selection ................................................................... 176
6.1.3 Lining Application ............................................................... 181
6.1.4 Cure of the Applied Lining ................................................ 182
6.1.5 Causes of Coating Failure ................................................... 182
6.2 Sheet Linings ..................................................................................... 183
6.2.1 Shell Design .......................................................................... 184
6.2.2 Considerations in Liner Selection ...................................... 185
6.2.2.1 Bonded Linings .................................................... 186
6.2.2.2 Unbonded Linings ............................................... 187
6.2.3 Design Considerations ........................................................ 188
6.2.3.1 Permeation ............................................................. 188
6.2.3.2 Absorption............................................................. 190
6.2.4 Inspection of the Lining ...................................................... 191
6.2.5 Causes of Lining Failure ..................................................... 192
6.2.5.1 Liner Selection ...................................................... 192
6.2.5.2 Inadequate Surface Preparation ......................... 192
6.2.5.3 Thermal Stresses .................................................. 192
6.2.5.4 Permeation ............................................................. 192
6.2.5.5 Absorption............................................................. 193
6.2.5.6 Welding Flaws ...................................................... 193
6.2.5.7 Debonding ............................................................. 193
6.2.5.8 Operation ............................................................... 193
6.2.5.9 Environmental Stress Cracking ......................... 193
6.3 Elastomeric Linings .......................................................................... 194
7 Corrosion of Paint ....................................................................................... 197
7.1 Mechanisms of Protection ............................................................... 198
7.2 Composition of Paint ........................................................................200
7.2.1 Binder.....................................................................................200
7.2.2 Pigments ................................................................................ 201
7.2.3 Solvents .................................................................................. 202
7.2.4 Additives ............................................................................... 204
7.2.5 Fillers (Extenders) ................................................................ 206
7.3 Causes of Bond and Coating Failures ............................................ 206