Active Protective Coatings (eBook)

Contents 6
Contributors 8
1 Introduction 10
1.1 Introduction 10
1.2 The Problem 12
1.3 What Are Smart Coatings? 14
1.4 Biomimicry 17
1.5 The Structure of the Book 18
References 20
Part IFundamentals 23
2 Fundamentals of Corrosion Kinetics 24
2.1 Introduction 24
2.2 Corrosion Reactions 25
2.3 Activation Controlled Kinetics 28
2.4 Mixed Potential Theory 29
2.5 Mass Transport Controlled Kinetics 32
2.6 Inhibition 35
2.7 Passivity 36
Recommended Reading 39
3 The Atmosphere Conditions and Surface Interactions 40
3.1 Introduction 40
3.2 Factors Controlling the Deposition of Pollutants on the Surface of a Coated Metal 41
3.3 Aerosol Chemistry and Reactions in Moisture Layers 42
3.4 Key Aqueous/Gas Reactions 44
3.4.1 Sulfuric Acid–Ammonia–Water System 44
3.5 Reactions in Marine Aerosols 45
3.6 Aerosol Transportation 46
3.6.1 General Scale of Movement of Gases and Particles 46
3.6.2 Analytical Approach to Gas Transport 47
3.6.3 Aerosol Transport 47
3.6.4 Deposition of Pollutants 48
3.6.4.1 Rain 48
3.6.4.2 Gas and Particle Deposition 48
3.6.4.3 Deposition of Gases onto Wet and Dry Surfaces 50
3.6.4.4 Comparison of Deposition Modes 51
3.6.4.5 Cloud Nucleation and Rain Chemistry 52
3.6.4.6 Role of Rain and Wind in Surface Cleaning 54
3.6.5 Forms of Moisture on Surfaces 54
3.6.5.1 Re-Wetting of Surfaces and Condensation 54
3.6.5.2 Surface Temperature of Plates 55
3.6.5.3 Evaporation and Condensation on a Porous Surface 56
3.6.6 Summary of Environmental Conditions 57
3.7 Relevance of Environmental Conditions to Moisture Ingress and Inhibitor Stability 59
3.8 Damage to Coatings 61
3.9 Summary 61
References 62
4 Corrosion Inhibitors 65
4.1 Classification of Corrosion Inhibitors 65
4.1.1 Definition of Corrosion Inhibitor 65
4.2 Effect of the Inhibitor on Partial Electrochemical Reactions 67
4.2.1 Cathodic Inhibitors 67
4.2.2 Anodic Inhibitors 67
4.2.3 Mixed Inhibitors 68
4.3 Inhibition Mechanisms 70
4.3.1 Inhibitors for Acid Environments 70
4.3.1.1 Adsorption of Inhibitors 70
4.3.1.2 Film Formation 72
4.3.2 Inhibitors for Neutral Environments 74
4.3.2.1 Adsorption of Inhibitors 74
4.3.2.2 Precipitation of Protective Salt Films 76
4.3.2.3 Film Precipitation or Polymerization 78
4.3.2.4 Passivation 78
4.3.2.5 Synergistic Effect of Mixtures of Inhibitors 84
4.3.3 Gas Phase Inhibitors 86
4.3.3.1 Volatile Corrosion Inhibitors 86
4.3.3.2 Migrating Corrosion Inhibitors 87
References 89
5 Formulating Surface Coatings 91
5.1 Introduction 91
5.2 Component Selection: the Composition of Paints 93
5.2.1 Resins 93
5.2.2 Pigments 95
5.2.2.1 White Pigments 95
5.2.2.2 Coloured Pigments 96
5.2.3 Solvents 96
5.2.4 Additives 97
5.2.5 Encapsulated Liquids 97
5.3 Formulation and Production: Disperse Phases 97
5.3.1 Grinding and Dispersing Pigments 98
5.3.1.1 Batch Ball Mills 98
5.3.1.2 Continuous Mills 99
5.3.1.3 Horizontal Bead Mills with ‘Rotating Gap’ 100
5.3.1.4 Immersion Mills 100
5.3.1.5 High Shear Rate Pre-milling 101
5.3.1.6 High Shear Stress Milling 101
5.3.1.7 Testing the End Point 101
5.3.2 Colloidal Stabilization 102
5.3.2.1 Settling/Sedimentation 102
5.3.2.2 Miscibility 102
5.3.2.3 Dispersants 103
5.3.3 Modes of Adsorption of Surfactants and Dispersants at Interfaces 103
5.3.3.1 Acid–Base (Lewis) Interaction’ Adsorption/Chemisorption 104
5.3.3.2 Anionic Surfactants and Dispersants 104
5.3.3.3 Cationic Surfactants 104
5.3.3.4 Steric Enthalpic Stabilizers 104
5.3.3.5 Entropic Stabilizers 105
5.3.3.6 Polymer Resin Dispersancy 105
5.4 Developing a Formulation 105
5.5 Summary 109
References 109
Part IIAdvances in Active Protective Coatings 111
6 Fostering Green Inhibitors for Corrosion Prevention 112
6.1 Introduction 112
6.1.1 Importance of Corrosion Inhibitors 114
6.1.2 New Trends Towards “Green” Inhibitors 114
6.2 Biological Inhibitors 115
6.2.1 Chitosan 115
6.2.2 Aminoacids 118
6.2.3 Other Biological Inhibitors 121
6.2.4 Bacteria and Fungi 122
6.3 Vegetable Inhibitors 123
6.3.1 Extracts of Plants 123
6.3.2 Shells and Seeds 125
6.3.3 Tannins 127
6.4 Pharmaceutical Drugs 128
6.5 Rare-Earth Inhibitors 131
6.5.1 Rare-Earth Cations 131
6.5.2 Rare-Earth Conversion Coatings 132
6.5.3 Rare-Earth Compounds Additives in Coatings 134
6.6 Mixtures and Synergies of New Inhibitors 135
6.7 Future Trends 137
Acknowledgement 138
References 138
7 Active Protective Coatings: Sense and Heal Concepts for Organic Coatings 143
7.1 Introduction 143
7.2 Organic Polymeric Coatings 144
7.3 Sensing Mechanisms Incorporated into Organic Coatings 146
7.3.1 Sensor Systems Based on Colour Response 147
7.3.2 Sensor Systems Based on Non-colour Response 148
7.4 Responsive Mechanisms Incorporated into Organic Coatings 148
7.4.1 Corrosion Triggered Protective Response: Underlying Metal Protection 150
7.4.1.1 Controlled Release by Desorption and Ion Exchange 151
7.4.1.2 Controlled Release by Environmental pH Changes 151
7.4.2 Response Aiming a Closure of the Passive Protective Surface 153
7.4.2.1 Surface Coverage 153
7.4.2.2 Gap Filling 154
7.4.3 Recovery of Other Functionalities 156
7.5 Concluding Remarks 157
Acknowledgments 157
References 157
8 Delivery Systems for Self Healing Protective Coatings 161
8.1 Introduction 161
8.2 Overview of Self Healing Coatings 162
8.2.1 Nanotraps 163
8.2.2 Water Displacing from Defects 164
8.2.3 Self-sealing 165
8.3 Self Healing in Polymer Networks 167
8.4 Coating Systems with Encapsulated Inhibitors 169
8.4.1 Volume of Self Healing Agent Required 171
8.5 Encapsulation Systems 173
8.5.1 Sol-Gel: Transition Metals 173
8.5.2 Sol-Gel: Silicon 175
8.5.3 Emulsification and Sols 176
8.5.4 Inorganic Capsules 177
8.5.4.1 Natural Materials 177
8.5.4.2 Synthetic Materials 178
8.5.4.3 Sheet Materials 182
8.5.5 Exfoliation and Reassembly into Capsules—Pickering Particles 183
8.5.6 Polymer Capsules 184
8.5.7 Hollow Tubes 186
8.5.8 Self Assembly 186
8.5.9 Dendrimers 187
8.5.10 Conductive Polymers 188
8.6 Summarizing Discussion on Triggering Mechanisms 189
8.6.1 Autonomic Triggering 189
8.6.2 External Triggering and Transduction 190
8.7 Practical Considerations 191
8.8 Conclusions 193
References 193
Part IIICharacterisation Techniques—MeasuringSelf Healing or Repair 204
9 Electrochemical Techniques for the Study of Self Healing Coatings 205
9.1 Electrochemistry in the Context of Corrosion 205
9.2 Electrochemical Evaluation of Self-healing/Self-repair Coatings 206
9.3 Conventional Electrochemical Techniques 209
9.3.1 Open Circuit Potential 209
9.3.2 Potentiodynamic Measurements 209
9.3.3 Electrochemical Impedance Spectroscopy (EIS) 212
9.3.4 Odd-Random Phase Multisine Electrochemical Impedance Spectroscopy 218
9.3.5 AC/DC/AC Accelerated Electrochemical Protocol 220
9.4 High-Throughput Screening Techniques 221
9.5 Local Electrochemical Techniques 223
9.5.1 Electrochemical Microcapillary Cell 224
9.5.2 Scanning Vibrating Electrode Technique (SVET) 226
9.5.3 Selective-Ion Electrode Technique (SIET) 229
9.5.4 Scanning Electrochemical Microscope (SECM) 230
9.5.5 Local Electrochemical Impedance Spectroscopy (LEIS) 235
9.6 Conclusions 236
References 237
10 Physico-Chemical Characterisation of Protective Coatings and Self Healing Processes 243
10.1 Introduction 243
10.2 Tomography and Microscopy 245
10.2.1 Tomographical Methods 245
10.2.1.1 Non-destructive Tomographical Methods 246
10.2.1.2 Transmission Electron Microscopy (TEM) 251
10.2.1.3 Destructive Tomographical Methods—Microtomy 252
10.2.1.4 Tomographical Reconstructions 253
10.2.1.5 4-D Tomography 255
10.2.1.6 X-ray K-edge Subtraction Tomography 257
10.2.1.7 Data Constrained Tomography 258
10.2.2 AFM Based Analysis of Surface Topography, Adhesive Properties, and Mechanics 262
10.3 Electron and Nuclear Spectroscopy 266
10.3.1 Electron Spectroscopy 266
10.3.1.1 X-Ray Photoelectron Spectroscopy (XPS) 266
10.3.1.2 Spatially Resolved XPS 271
10.3.1.3 Auger Electron Spectroscopy (AES) 272
10.3.2 Nuclear and Ion Spectroscopy 272
10.4 Optical Spectroscopy 276
10.4.1 Fourier Transform Infrared Reflection-Absorption Spectroscopy (FT-IRRAS) 276
10.4.2 Attenuated Total Reflection Infrared Spectroscopy (ATR-FTIR) and Surface Enhanced ATR-Spectroscopy 280
10.4.3 Surface Enhanced Raman Spectroscopy (SERS) 286
10.5 Concluding Remarks 287
References 288
11 Transport in Protective Coatings 301
11.1 Introduction 301
11.2 Water and Oxygen Transport in Polymers and Coatings 302
11.3 Effect of Coating Constituents on the Transport Properties 305
11.3.1 Effect of Pigmentation 305
11.3.2 Effect of Binder 306
11.3.3 Effect of Additives 307
11.4 Transport in Rebar Reinforced Concrete 307
11.5 Measurement and Monitoring of Transport of Corrosion Inhibitors in Coatings 308
11.6 Summary 311
References 312
Part IVApplications 315
12 Aerospace Coatings 316
12.1 Introduction 316
12.2 Aerospace Market 317
12.3 Corrosion Control in the Aerospace Industry 318
12.3.1 Introduction to the Corrosion Protection Scheme 319
12.3.1.1 Aluminium Alloys Used in Aerospace 320
12.3.1.2 Surface Treatment of Aluminium 320
12.3.1.3 Organic Coatings 323
12.3.2 Types of Corrosion and Failures 323
12.3.3 Corrosion Protection and Design 325
12.4 Introduction into Aerospace Coatings 327
12.4.1 History of Aerospace Coatings 327
12.4.2 Aerospace Coating Systems and Their Requirements 328
12.4.2.1 Exterior Systems 328
12.4.2.2 Structural Coating Systems 329
12.4.2.3 Special Purpose Coating Systems 330
12.4.2.4 Coating System Requirements and Specifications 331
12.4.3 Coating Chemistry 333
12.4.3.1 Coating Technologies 333
12.4.3.2 Aerospace Primer Coating Technologies 335
12.4.3.3 Aerospace Topcoat Technologies 337
12.4.4 Active Corrosion Protection and Leaching 339
12.4.5 Application 341
12.4.5.1 Equipment 341
12.4.5.2 Paint Automation for Exterior and Structural Painting 343
12.4.5.3 Application of an Exterior Paint System 343
12.4.6 Trends in the Aerospace Coatings 343
12.5 Developments Towards a Chromate Free Corrosion Protective Scheme 345
12.5.1 Chromate-Free Pre-treatments 346
12.5.1.1 Chemical Conversion Coatings 346
12.5.1.2 Anodising 347
12.5.1.3 Pre-treatments 348
12.5.2 Developments in Chromate-Free Organic Coatings 349
12.5.2.1 Corrosion Inhibiting Strategies 350
12.5.2.2 Inhibition Through Leaching 350
12.5.2.3 Galvanic Inhibition 351
12.5.2.4 Smart and Self-healing Coating Technologies 353
12.5.2.5 Alternative Coating Techniques 355
12.5.3 New Approaches Towards Chromate Free Coatings Technology 356
12.5.3.1 High-Throughput Experimentation 356
12.5.3.2 Imaging Techniques for Corrosion Evaluation 357
12.6 Remaining Challenges for Chromate Replacement 359
12.7 Summary and Conclusion 361
References 362
13 Automotive Coatings 374
13.1 Introduction 374
13.2 Automotive Paint Application and Materials 375
13.2.1 Pretreatment 375
13.2.2 Electrocoat 377
13.2.3 Primer 378
13.2.4 Basecoat and Clearcoat 379
13.2.5 Compact Paint Processes 381
13.3 Future Technologies Needs 382
13.4 Summary 384
References 385
14 Polymer Coatings for Oilfield Pipelines 386
14.1 Introduction 386
14.2 A Brief History on the Evolution of Pipe Coatings 387
14.3 Materials and Processing 393
14.3.1 Fusion Bonded Epoxy Coatings 393
14.3.2 Three Layer Polyolefin Coatings 395
14.3.2.1 Chemistry of Primer 395
14.3.2.2 Chemistry and Synthesis of Adhesives 396
14.3.2.3 Composition of Topcoat 398
14.3.3 Thermally Insulated Polyolefin Coatings for Deepwater Applications 400
14.3.4 Mill Applied Pipe Coating Manufacture 403
14.3.5 Field Joint Coatings 405
14.4 Performance 407
14.4.1 Industry Standards 407
14.4.2 Common Failure Modes 407
14.4.2.1 Blistering and Disbondment 409
14.4.2.2 Cracking and Wrinkling 410
14.4.2.3 Field Joint Failures 411
14.4.2.4 Testing and Performance Evaluation 411
Adhesion 415
Cathodic Protection Considerations 415
Presence of Holidays 418
14.4.2.5 Long-Term Exposure to Elevated Temperatures 418
14.5 New Developments 419
14.5.1 Toughness and Durability 419
14.5.2 Self-healing Capabilities 420
14.5.3 High Temperature Adhesives 421
14.6 Concluding Remarks 423
Acknowledgements 424
References 424