Conversion Coatings for Magnesium and its Alloys

Preface
Acknowledgement
Contents
Editors and Contributors
Part I: Chemical (Inorganic and Organic) Conversion Coatings
Chapter 1: Chemical Conversion Coatings: Fundamentals and Recent Advances
1.1 Introduction
1.2 Conversion Coatings
1.3 Chemical Conversion Coatings
1.4 Major Types of Chemical Conversion Coatings
1.4.1 Chromate Conversion Coatings
1.4.2 Phosphate Conversion Coatings
1.4.3 Rare-Earth Conversion Coatings
1.4.4 Fluoride Conversion Coatings
1.4.5 Carbonate Conversion Coatings
1.4.6 Layered Double Hydroxide Conversion Coatings
1.4.7 Phytic Acid Conversion Coatings
1.5 Comparison and Applications
1.6 Conclusions and Perspectives
References
Chapter 2: Inorganic Conversion Coatings: Composition, Mechanism, and Paint Adhesion
2.1 Introduction
2.2 Phases of Inorganic Conversion Coatings
2.2.1 Crystalline
2.2.2 Non-crystalline
2.3 Solution Composition of Inorganic Conversion Coating Systems
2.3.1 Alkaline
2.3.2 Acidic
2.3.3 Non-aqueous
2.4 Deposition Mechanism
2.4.1 Reduction-Type
2.4.2 Oxidation-Type
2.4.3 Inclusions and Second Phases Effect
2.5 Paint Adhesion on Different Conversion Coatings
2.5.1 Process Requirements of Different Paints
2.5.2 Factors to Paint Adhesion
2.5.2.1 Morphology and Defects: Mechanical Locking
2.5.2.2 Coating Composition: Surface Bonding
2.5.2.3 Corrosion Behavior: Interface Compatibility
2.6 Conclusions and Perspectives
References
Chapter 3: Chromium-Based Conversion Coatings
3.1 Introduction
3.2 Toxicity of Cr(VI) and Cr(III) Species
3.3 Chromate Conversion Coatings (CCC)
3.3.1 Components of CCC Solutions
3.3.2 Color Control of CCC
3.3.3 Formation Process and Structure of CCC
3.4 Trivalent Chromium (TCP) Conversion Coatings
3.4.1 Component of TCP Solution
3.4.2 Formation Mechanism of TCP
3.5 Self-repairing Performances of CCC and TCP
3.6 Chromate Conversion Coatings for Mg and Its Alloys
3.7 Conclusions and Perspectives
References
Chapter 4: Phosphate Conversion Coatings
4.1 Introduction
4.2 Importance of Phosphate Conversion Coatings
4.3 Zinc Phosphate Conversion Coating
4.3.1 Bath Composition and Additives
4.3.2 Mechanism of Formation
4.3.3 Effect of Concentration of Zn2+ Ions and Bath pH
4.3.4 Effect of Temperature
4.3.5 Role of Accelerators and Special Additives
4.3.6 Mechanism of Corrosion
4.4 Calcium-Modified Zinc Phosphate Conversion Coating
4.5 Calcium Phosphate Conversion Coating
4.6 Magnesium Phosphate Conversion Coating
4.7 Manganese Phosphate Conversion Coating
4.8 Strontium Phosphate Conversion Coating
4.9 Lanthanum Phosphate Conversion Coating
4.10 Comparison of Different Types of Phosphate Conversion Coatings
4.11 Influence of Microstructure and Grain Size of the Mg Alloy on Phosphating
4.12 Effect of Pretreatment and Pre-activation on the Formation of Phosphate Coating
4.12.1 Sandblasting, Grinding and Polishing as Pretreatments
4.12.2 Laser Shock Peening as a Pretreatment
4.12.3 Laser Surface Texturing as a Pretreatment
4.12.4 Pre-activation of Mg Alloy Before Phosphating
4.13 Phosphate Conversion Coating as a Part of Multilayered and Composite Coatings
4.14 Conclusions and Perspectives
References
Chapter 5: Permanganate, Molybdate and Vanadate Conversion Coatings
5.1 Introduction
5.2 Permanganate Conversion Coatings (PCCs)
5.2.1 Preparation Processes and Mechanisms
5.2.2 Protective Performance
5.3 Molybdate Conversion Coatings (MCCs)
5.3.1 Preparative Strategies
5.3.2 Optimisation of Molybdate Coatings for High Corrosion Resistance
5.4 Vanadate Conversion Coatings (VCCs)
5.4.1 Preparation Methods
5.4.2 Corrosion Resistance Performance
5.5 Conclusions and Perspectives
References
Chapter 6: Fluoride Conversion Coatings
6.1 Introduction
6.2 Fluoride Conversion Coatings
6.3 Mechanism of Formation
6.4 Ease of Formation: Pure Mg vs Mg Alloys
6.5 Formation of Fluoride Conversion Coating by Mg(OH)2-Mediated Method
6.6 Formation of Fluoride Conversion Coating on Mg/Mg Alloys Prepared by Powder Metallurgy Route
6.7 Characteristic Properties of Fluoride Conversion Coatings
6.7.1 Colour
6.7.2 Thickness
6.7.3 Surface Morphology
6.7.4 Elemental Composition and Chemical Nature
6.7.5 Phase Content
6.7.6 Nature of Functional Groups
6.7.7 Surface Roughness
6.7.8 Contact Angle
6.8 Corrosion Resistance of Fluoride Conversion Coatings
6.9 Hemolysis Ratio of Fluoride Conversion Coatings
6.10 Cytotoxicity of Fluoride Conversion Coatings
6.11 Cell Growth on Fluoride Conversion Coatings
6.12 Fluoride Conversion Coating as a Pretreatment as well as a Part of Multi-layer and Composite Coatings
6.13 Conclusions and Perspectives
References
Chapter 7: Carbonate Conversion Coatings
7.1 Introduction
7.2 Rationale Behind the Choice of Carbonate Conversion Coating
7.3 Carbonate Conversion Coating on Pure Mg and Mg-4Zn Alloy
7.3.1 Morphological Features
7.3.2 Thickness and Elemental Composition
7.3.3 Nature of Functional Groups
7.3.4 Phase Content
7.3.5 Mechanism of Formation of Carbonate Conversion Coating on Mg
7.3.6 Corrosion Behaviour and Bioactivity
7.4 Carbonate Conversion Coatings on AZ31 and AZ61 Mg Alloys
7.4.1 Morphological Features
7.4.2 Chemical Composition
7.4.3 Phase Content and Nature of Functional Groups
7.4.4 Corrosion Behaviour
7.5 Conclusions and Perspectives
References
Chapter 8: Rare-Earth Conversion Coatings
8.1 Introduction
8.2 RE Conversion Coatings
8.3 RE-Based Composite Conversion Coatings
8.3.1 With Inorganic Co-conversion Agents
8.3.2 With Organic Co-conversion Agents
8.4 Conclusions and Perspectives
References
Chapter 9: Zirconium- and Titanium-Based Conversion Coatings
9.1 Introduction
9.2 Deposition Mechanisms
9.3 Design and Evaluation of a ZrCC/TiCC
9.4 Major Determining Parameters
9.4.1 Conversion Bath Parameters
9.4.2 Alloy Surface Characteristics
9.5 Conclusions and Perspectives
References
Chapter 10: Layered Double Hydroxide Coatings
10.1 Introduction
10.2 Preparation Methods of LDHs
10.2.1 Preparation of LDH Powder
10.2.1.1 Coprecipitation
10.2.1.2 Hydrothermal Synthesis
10.2.1.3 Ion Exchange
10.2.1.4 Roasting Reduction
10.2.1.5 Urea Synthesis
10.2.2 Preparation of LDH Film
10.2.2.1 In Situ Growth
10.2.2.2 Spin Coating
10.2.2.3 Electrodeposition
10.2.2.4 Steam Coating
10.2.2.5 Peel-Off Assembly
10.3 Growth Mechanisms
10.3.1 Coprecipitation
10.3.2 Hydrothermal Synthesis
10.3.3 Urea Synthesis
10.3.4 In Situ Growth
10.3.5 Electrodeposition
10.3.6 Steam Coating
10.4 LDH Coatings in Different Applications
10.4.1 Sealing Films Based on LDHs
10.4.1.1 Anticorrosion Coating Based on LDHs
10.4.1.2 Superhydrophobic Coating Based on LDHs
Superhydrophobic Coating
Slippery Liquid-Infused Porous Surface (SLIPS)
10.4.1.3 Self-Healing Coating Based on LDHs
10.4.1.4 Epoxy Coatings Based on LDHs
10.4.2 LDHs-Based Sealing Technology on Anodized Coatings
10.4.2.1 Anodic Oxide Technology
10.4.2.2 Micro-arc Oxidation Technology
10.4.3 Composite Coatings Based on LDHs-MXenes
10.5 Mechanism of Action of Different Types of LDHs
10.5.1 Anticorrosion Coatings
10.5.2 Superhydrophobic and Slippery Liquid-Infused Porous Surfaces
10.5.3 Self-Healing Coatings
10.5.4 Epoxy Coatings
10.5.5 Anodic Oxide Technology
10.5.6 Micro-arc Oxidation Technology
10.6 Conclusions and Perspectives
References
Chapter 11: Phytic Acid Conversion Coatings
11.1 Introduction
11.2 PA Conversion Coatings
11.3 PA-Based Composite Conversion Coatings
11.3.1 Hydroxyapatite
11.3.2 Bioactive Glass
11.3.3 Ceria, Titania
11.3.4 Mg2+ and Ca2+
11.3.5 Micro-arc Oxidation (MAO)
11.4 Conclusions and Perspectives
References
Chapter 12: Tannic and Gallic Acid Conversion Coatings
12.1 Introduction
12.2 Tannic and Gallic Acid Derivates
12.3 Tannic and Gallic Acid Conversion Coatings on Mg and Its Alloys
12.3.1 Tannic Acid-Based Conversion Coatings
12.3.2 Gallic Acid-Based Conversion Coatings
12.3.3 Composite Polyphenol Conversion Coatings for Desired Biological Function
12.4 Conclusions and Perspectives
References
Chapter 13: Hydroxy Benzene/Phenolic Acids and Carboxylic/Fatty Acid Conversion Coatings
13.1 Introduction
13.2 Conversion Coatings Containing Phenol Units
13.2.1 Polydopamine
13.2.2 Catechol and Catechol Derivatives
13.2.3 Tannic and Gallic Acids
13.2.4 Vanillic Acid
13.2.5 Comparison and Discussion
13.3 Carboxylic and Fatty Acid Conversion Coatings
13.3.1 Comparison and Discussion
13.4 Conclusions and Perspectives
References
Part II: Advanced Approaches and Coatings
Chapter 14: Self-Healing Chromate-Free Conversion Coatings
14.1 Introduction
14.2 Conversion Coatings
14.3 Self-Healing Conversion Coatings
14.3.1 Cerium-Based Conversion Coatings
14.3.2 Vanadium-Based Conversion Coatings
14.3.3 Silane-Based Conversion Coatings
14.3.4 Phosphate-Based Conversion Coatings
14.3.5 Phytic Acid-Based Conversion Coatings
14.3.6 Layered Double Hydroxide-Based Conversion Coatings
14.4 Conclusions and Perspectives
References
Chapter 15: Self-Healing Mechanisms in Chemical Conversion Coatings
15.1 Introduction
15.2 Key Concept of Self-Healing Anticorrosive Coatings
15.2.1 Bioinspired Self-Healing Corrosion Protection System
15.2.2 Chemical Conversion Coatings for Self-Healing Application
15.3 Inorganic Compound-Based Self-Healing Conversion Coatings
15.4 Organic Compound-Based Self-Healing Conversion Coatings
15.4.1 Organic Acid-Based Conversion Coatings
15.4.2 Commercial Inhibitor-Based Conversion Coatings
15.5 Polymers in the Application of Self-Healing Conversion Coatings
15.6 Combination of Micro/Nanocapsule Encapsulating Inhibitors with Conversion Coatings
15.7 Layer-by-Layer Approach for Self-Healing Conversion Coatings
15.7.1 LbL-Based Preparation Technology in Self-Healing Coating
15.7.2 Self-Healing Coating Composed of Layered Structure
15.8 Conclusions and Perspectives
References
Chapter 16: Ionic Liquid-Assisted Conversion Coatings
16.1 Introduction
16.2 Ionic Liquids
16.3 Ionic Liquid-Assisted Conversion Coatings
16.3.1 Ionic Liquids with Phosphonium Cation
16.3.1.1 Tri(hexyl)tetradecyl-phosphonium Bis(trifluoromethanesulfonyl)amide
16.3.1.2 Tri(hexyl)tetradecyl-phosphonium Bis(2,4,4-trimethylpentyl)phosphinate
16.3.1.3 Tri(hexyl)tetradecyl-phosphonium Diphenyl Phosphate
16.3.1.4 Tributyl(methyl)-phosphonium Diphenyl Phosphate
16.3.1.5 ILs with Triphenylphosphonium Derived Cations
16.3.2 Ionic Liquids with Imidazolium Cation
16.3.2.1 1-Butyl-3-methyl-imidazolium Cation
16.3.2.2 1,3-Dimethyl-imidazolium and 1-Ethyl-3-methyl-imidazolium Cations
16.3.3 Ionic Liquids with Ammonium Cation
16.3.4 Ionic Liquids with Pyrazole Cation
16.3.5 Deep Eutectic Solvents
16.3.5.1 Choline Chloride-Urea DES
16.3.5.2 Choline Chloride-Ethylene Glycol DES
16.3.5.3 Lithium Chloride-Urea DES
16.4 Conclusions and Perspectives
References
Chapter 17: Chitosan-Based Conversion Coatings
17.1 Introduction
17.2 Functionality of Chitosan
17.3 Chitosan Coating Systems
17.4 Chitosan-Based Conversion Coatings
17.5 Conclusions and Perspectives
References
Chapter 18: Superhydrophobic Surfaces by Conversion Coatings
18.1 Introduction
18.2 Chemical Conversion Coatings
18.2.1 One-Step Processing
18.2.1.1 Hydrothermal
18.2.1.2 Solution Immersion
18.2.2 Two-Step/Multistep Processing
18.2.2.1 Hydrothermal
18.2.2.2 Solution Immersion
18.3 Electrochemical Conversion Coating
18.3.1 Electrochemical Anodic Oxidation
18.3.2 Micro-arc Oxidation
18.4 Conclusions and Perspectives
References
Part III: Electrochemical Conversion Coatings
Chapter 19: Electrochemical Anodization of Mg Alloys: Fundamentals and State-of-the-Art Progress
19.1 Introduction
19.2 Basic Property of Electrochemical Anodization
19.3 Preparation Process and Key Parameters
19.3.1 Preparation Process
19.3.2 Key Parameters in Coating Preparation
19.4 Practical Application and Service Performance
19.4.1 Service Conditions of Anodizing Coating
19.4.2 Corrosion Protection Performance
19.5 Commercial Anodization Processes for Mg Alloys
19.5.1 DOW 17
19.5.2 HAE
19.5.3 Tagnite
19.5.4 Anomag
19.5.5 Keronite
19.5.6 Magoxid Coat
19.5.7 Recent Developments in Anodization
19.5.7.1 Using Nonaqueous Electrolytes and Additives
19.5.7.2 Biologically Degradable Modifications
19.5.7.3 Hydrophobic Functionalization
19.5.7.4 New Routes to Be Environment-Friendly
19.5.7.5 Self-Healing Modifications
19.6 Challenges and Deficiencies
19.7 Conclusions and Perspectives
References
Chapter 20: Plasma Electrolytic Oxidation upon Mg Alloys: Fundamentals, State-of-the-Art Progress and Challenges
20.1 Introduction
20.2 Principles of PEO
20.3 Key Variables of PEO Processes to Coating Quality
20.3.1 Electrical Parameters
20.3.2 Soft Sparking
20.3.3 Gas Evolution
20.3.4 Chemistry of Electrolyte
20.3.5 Additives in PEO Bath
20.3.6 Substrate Composition
20.4 Challenges and Opportunities of PEO Coatings upon Mg Alloys
20.5 Conclusions and Perspectives
References
Chapter 21: Recent Approaches for Enhancing Corrosion Resistance of PEO/MAO-Coated Mg and Its Alloys
21.1 Introduction
21.2 Base Material
21.3 Coating Methods
21.4 Coating Electrolyte
21.5 Particles Addition
21.6 Coating Posttreatment
21.7 Testing Techniques
21.8 Conclusions and Perspectives
References
Chapter 22: MAO-Based Composite Coatings
22.1 Introduction
22.2 Corrosion-Resistant MAO Coatings
22.2.1 Electrolyte Additives
22.2.2 Organic Coatings
22.2.3 Superhydrophobic Treatment
22.2.4 Steam Treatment
22.2.5 Atomic Layer Deposition
22.3 Wear-Resistant MAO Coatings
22.3.1 Electrolyte Additives
22.3.2 Organic Coatings
22.4 Conductive MAO Coatings
22.4.1 Electroless Nickel
22.4.2 Conductive Polymer Coatings
22.5 Biocompatible MAO Coatings
22.5.1 MAO/HA
22.5.2 MAO/Mg(OH)2
22.5.3 MAO/LDH
22.5.4 MAO/CS
22.5.5 MAO/PLA
22.6 Influencing Factors
22.6.1 Porosity
22.6.2 Intermetallic Compounds
22.6.3 Protein
22.7 Formation Mechanisms of MAO/MAO Composite Coatings
22.8 Conclusions and Perspectives
References
Chapter 23: Biomedical-Grade Electrochemical Conversion Coatings
23.1 Introduction
23.2 Anodic Oxidation Coatings for Biomedical Applications
23.3 Plasma Electrolytic Oxidation (PEO)/Micro-arc Oxidation (MAO) Coatings for Biomedical Applications
23.3.1 Single PEO/MAO Coating
23.3.2 Particles-Containing PEO/MAO Coating
23.3.2.1 Oxide Particles
23.3.2.2 Nonmetallic Particles
23.3.2.3 Metallic Particles
23.3.3 PEO/MAO Composite Coatings
23.3.3.1 Calcium Phosphate Sealing Layer
23.3.3.2 Organic Sealing Layer
23.3.3.3 Other Types of Sealing Layer
23.4 The Role of Electrochemical Conversion Coatings on Mg in Biomedical Applications
23.5 Conclusions and Perspectives
References
Chapter 24: Sealing Treatments for Electrochemical Conversion Coatings
24.1 Introduction
24.2 Sealing Treatments
24.2.1 Chemical Conversion Coatings
24.2.1.1 Stannate Treatment
24.2.1.2 Rare Earth-Based Treatment
24.2.1.3 Phosphate-Based Sealing
24.2.1.4 Calcium-Based Sealing
24.2.1.5 SAM-Based
24.2.1.6 Layered Double Hydroxides (LDHs)-Based
24.2.2 Electrodeposition
24.2.2.1 Zinc Oxide Post-treatment
24.2.2.2 Hydroxyapatite Post-treatment
24.2.3 Chemical-Free Steam Method
24.2.4 Polymer Sealant Method
24.2.5 Irradiated Zirconium Oxide Method
24.3 Conclusions and Perspectives
References
Chapter 25: Pre-treatments of Mg Alloys for Anodic Oxide Coatings
25.1 Introduction
25.2 Different Anodic Oxidation Behaviors of Mg Alloys
25.3 Effect of Pre-treatments
25.3.1 Chemical Pre-treatments
25.3.1.1 Pre-treatment Using HF Solution
25.3.1.2 Pre-treatment in Different Acidic Solutions
25.3.1.3 Pre-treatment in Neutral and Alkaline Solutions
25.3.2 Mechanical Pre-treatments
25.3.3 Other Pre-treatments
25.4 Conclusions and Perspectives
References
Index