Corrosion Resistance of Aluminum and Magnesium Alloys: Understanding, Performance, and Testing / E. Ghali (2010)

 

 

 

 

Brief Contents

Part One – Electrochemical Fundamentals and Active–Passive Corrosion Behaviors

  1. Fundamentals of Electrochemical Corrosion

  • Overview

A. Thermodynamic Considerations of Corrosion

  • Electrolytic Conductance
    • Faraday Laws
  • Tendency to Corrosion
  • The Electrochemical Interface
    • Electric Double Layer
    • Equivalent Circuit of the Electric Double Layer
  • Nernst Equation
  • Standard Potentials of Electrodes
    • Standard States in Solution
    • Hydrogen Electrode
    • Positive and Negative Signs of Potentials
    • Graphical Presentation

B. Activity and Conductance of the Electrolyte

  • Activity of the Electrolyte
    • Constant and Degree of Dissociation
    • Activity and Concentration
    • Theory of More Concentrated Solutions
    • Electrolytic Conduction
  • Mobility of Ions
    • Law of Additivity of Kohlrausch
    • Ion Transport Number or Index
  • Conductance
  • Potential of Decomposition

C. The Different Types of Electrodes

  • Gas Electrodes
  • Metal–Metal Ion Electrodes
  • Alloyed Electrodes
  • Metal–Insoluble Salt or Oxide Electrodes
    • Metal–Insoluble Salt Electrodes
    • Metal–Insoluble Oxide Electrodes
  • Electrodes of Oxidation–Reduction
  • Selective Ion Electrodes
  • Glass Electrodes
  • Copper Ion-Selective Electrodes

D. Electrochemical and Corrosion Cells

  • Chemical Cells
    • Chemical Cell with Transport
    • Chemical Cell Without Transport
  • Concentration Cells
    • Concentration Cell with Difference of Activity at the Electrode and Electrolyte
    • Junction Potential
  • Solvent Corrosion Cells
    • Cathodic Oxidoreduction Reaction
    • Displacement Cell
    • Complexing Agent Cells
    • Stray Current Corrosion Cell
  • Temperature Differential Cells
  • Overlapping of Different Corrosion Cells

E. Chemical and Electrochemical Corrosion

  • Definition and Description of Corrosion
  • Electrochemical and Chemical Reactions
    • Electrochemical Corrosion
    • Film-Free Chemical Interactions
  • References
  1. Aqueous and High-Temperature Corrosion

  • Overview
  • Atmospheric Media
    • Description
    • Types of Corrosion
    • Atmospheric Contaminants
    • Corrosion Prevention and Protection
  • Aqueous Environments
  • Organic Solvent Properties
  • Underground Media
  • Water Media Properties
    • Water Composition
    • The Oxidizing Power of Solution
    • Scale Formation and Water Indexes
  • Corrosion at High Temperatures
    • Description
    • The Pilling–Bedworth Ratio (PBR)
    • Kinetics of Formation
    • Corrosion Behaviors of Some Alloys at Elevated Temperatures
  • References
  1. Active and Passive Behaviors of Aluminum and Magnesium and Their Alloys

  • Overview
  • Potential–pH Diagrams of Aluminum and Magnesium
    • Construction of Pourbaix Diagrams
    • Predictions of E–pH Diagrams
    • Utility and Limits of Pourbaix Diagrams
  • Active Behavior and Overpotentials
    • Active Behavior and Polarization
    • Overpotentials
  • Passive Behavior
    • The Phenomenon of Passivation
    • Passive Layers and Their Formation
    • Breakdown of Passivity
    • Electrochemical and Physical Techniques for Passive Film Studies
  • Active and Passive Behaviors of Aluminum and Its Alloys
    • The E–pH Diagram of Aluminum
    • Active and Passive Behaviors
    • Pitting Corrosion of Aluminum Alloy 5086
  • Active and Passive Behaviors of Magnesium and Its Alloys
    • E–pH Diagram of Magnesium
    • Passive Mg Layers (Films)
    • Passive Properties and Stability
    • Temperature Influence in Aqueous Media
    • Atmospheric and HighTemperature Oxidation
  • References

Part Two – Performance and Corrosion Forms of Aluminum and Its Alloys

  1. Properties, Use, and Performance of Aluminum and Its Alloys

  • Overview

A. Properties of Aluminum

  • Physical and General Properties of Aluminum
  • Cast Aluminum Alloys
    • Designation of Cast Aluminum Alloys and Ingots
    • Alloying Elements
    • Cast Alloys Series
  • Wrought Aluminum Alloys
    • Designation of Wrought Aluminum Alloys
    • Alloying Elements
    • Wrought Aluminum Alloys Series
    • Description of the Wrought Alloys Series
  • Aluminum Powders and Aluminum Matrix Composites
    • Aluminum Powders
    • Rapid Solidification Processing
    • Aluminum Matrix Composites and P/M- MMCs
    • Al MMC Particles and Formation

B. Use of Aluminum and Aluminum Alloys

  • Use of Cast Aluminum Alloys
    • Standard General Purpose Aluminum Alloys
    • Some Specific Uses
  • Use of Wrought Aluminum Alloys
    • Aerospace Applications
    • Automotive Sheet and Structural Alloys
    • Shipping
    • Building and Construction
    • Packaging
    • Electrical Conductor Alloys

C. Aluminum Performance

  • Resistance of Aluminum Alloys to Atmospheric Corrosion
  • Factors Affecting Atmospheric Corrosion of Aluminum Alloys
  • Water Corrosion
  • Seawater
  • Soil Corrosion
  • Some Aggressive Media: Acid and Alkaline Solutions
  • Acids
  • Alkalis
  • Dry and Aqueous Organic Compounds
  • Gases
  • Mercury
  • Corrosion Performance of Alloys
    • Performance of the Cast Series
    • Performance of the Wrought Series
  • Aluminum High-Temperature Corrosion
  • References
  1. General, Galvanic, and Localized Corrosion of Aluminum and Its Alloys

  • Overview

A. General Corrosion

  • General Considerations
  • Description
  • Mechanisms
  • Prevention
    • Design Considerations
    • Surface Pretreatment
    • Corrosion Control
    • Aluminum Alloys and Resistance to General Corrosion

B. Galvanic Corrosion

  • General Considerations
  • Galvanic Series of Aluminum Alloys
  • Mechanisms
    • Cu–Al Galvanic Cell
    • Mg–Al Galvanic Cell
    • Galvanic Effect of a Coating
  • Deposition Corrosion
  • Stray Current Corrosion
  • Prevention
  • Basic Study of Al–Cu Galvanic Corrosion Cell

C. Localized Corrosion

  • Pitting Corrosion
    • Occurrence and Morphology
    • Kinetics
    • The Pitting Potential
    • Mechanisms
    • Possible Stages of Pitting
    • Prevention of Pitting Corrosion
    • Corrosion Resistance of Aluminum Cathodes
  • Crevice Corrosion
    • General Considerations and Description
    • Poultice Corrosion
    • Mechanisms
    • Water Stains on AA3xxx
  • Filiform Corrosion
    • General Considerations
    • Aluminum Alloys and Filiform Corrosion
    • Kinetics, Mechanism, and Prevention
    • Filiform Occurrence
  • References
  1. Metallurgically and Microbiologically Influenced Corrosion of Aluminum and Its Alloys

  • Overview

A. Metallurgically Influenced Corrosion (METIC)

  • Fundamentals of METIC
    • Influence of Metallurgical and Mechanical Treatments
  • Types of Metallurgically Influenced Corrosion
    • Dealloying (Dealuminification)
    • Intergranular Corrosion
    • Exfoliation
  • Joining and Welding
    • Corrosion Resistance of Brazed, Soldered, and Bonded Joints
    • Welding Fundamentals
    • Welding Influence on Behavior of Aluminum Alloys
    • Frequent Corrosion Types of Welded Aluminum Alloys
    • Corrosion Resistance of Wrought and Cast Al Alloys
  • Metal Matrix Composites for Nuclear Dry Waste Storage

B. Microbiologically Influenced Corrosion: The Basics

  • Microorganisms
    • Bacteria (Prokaryotes)
    • Fungi and Yeast (Eukaryotes)
    • Algae (Eukaryotes)
    • Lichens
  • Natural and Artificial Media
    • Air Media
    • Aqueous Media
    • Soils
  • Anaerobic and Aerobic Bacteria in Action
    • Anaerobic Bacteria
    • Aerobic Bacteria
    • Co-action of Anaerobic and Aerobic Bacteria
  • MIC of Aluminum and Aluminum Alloys
    • Fungi and Bacteria (Space)
    • Geotrichum (Tropical Atmosphere)
    • Cyanobacteria and Algae (Polluted Freshwater)
    • Rod-Shaped Bacteria and Algae (Polluted Seawater)
    • SRB (Industrial and Seawater)
    • Hormoconis resinae (Kerosene)
  • Mechanisms of MIC and Inhibition
    • Corrosion Mechanisms
    • Influence of Biofilms on Passive Behavior of Aluminum
    • Corrosion Inhibition by Microorganisms
  • MIC Prevention and Control
  • References
  1. Mechanically Assisted Corrosion of Aluminum and Its Alloys

  • Overview

A. Erosion Corrosion

  • Impingement with Liquid-Containing Solid Particles
  • Corrosion by Cavitation
  • Water Drop Impingement Corrosion
  • Fretting Corrosion
  • Fretting Fatigue Corrosion
  • Prevention of Erosion Corrosion

B. Corrosion Fatigue

  • General Considerations and Morphology
  • Parameters
    • Environmental Considerations
    • Cyclic Stresses
    • Material Factors
  • Mechanisms of Corrosion Fatigue
  • Corrosion Fatigue of Aluminum Alloys
    • Corrosion Fatigue of AA7017- T651
    • Corrosion Fatigue of AA7075- T6
    • Corrosion Fatigue of Al–Mg–Si Compared to Al–Mg Alloys
    • Modeling of the Propagation of Fatigue Cracks in Aluminum Alloys
  • Prevention of Corrosion Fatigue
  • References
  1. Environmentally Induced Cracking of Aluminum and Its Alloys

  • Overview
  • Introduction and Definition of SCC
  • Key Parameters
    • Stress
    • Environment
  • SCC Parameters of Aluminum Alloys
    • Influence of Stress
    • Role of Environment
  • SCC Mechanisms
    • Overlapping of Cracking Phenomena
    • Significance of the Magnitude of Strain Rates
    • Cracking Initiation and Propagation
  • SCC of Aluminum Alloys
    • SCC Resistance of Aluminum Alloys
    • Influence of Heat Treatments on Corrosion Forms
  • SCC of Welded Aluminum Alloys
    • Galvanic Corrosion and SCC of Welded Assemblies
    • SCC Knife-Line Attack
    • Localized Corrosion and SCC of LBW AA6013
    • Mechanically Influenced Corrosion and SCC of Welds
    • Corrosion Fatigue of Friction Stir Welding White Zone
    • SCC of Friction Stir Welded 7075 and 6056 Alloys
    • SCC of FSW of 7075-T651 and 7050-T451 Alloys
  • Prevention of SCC
    • Design and Stresses
    • Environmental Considerations
    • Metallurgical Considerations
    • Surface Modification
    • Prevention of Hydrogen Damage
  • References

Part Three – Performance and Corrosion Forms of Magnesium and Its Alloys

  1. Properties, Use, and Performance of Magnesium and Its Alloys

  • Overview

A. Properties of Magnesium Alloys

  • Physical and General Properties of Magnesium
  • Properties of Cast Magnesium Alloys
    • Designation of Cast Magnesium Alloys
    • Alloying Elements
    • Cast Magnesium Alloys Series
  • Properties of Wrought Magnesium Alloys
  • Magnesium Powder
  • Magnesium Composites
  • Particles Reinforcing Magnesium Alloy Matrix
    • SiC
    • Mg2Si
    • Nanosized Alumina Particulates

B. Use of Magnesium and Magnesium Alloys

  • Applications of Cast Magnesium Alloys
    • Automotive and Aerospace Applications
    • Application as Refractory Material
    • Other Uses
  • Applications of Wrought Magnesium Alloys

C. Magnesium Performance

  • Resistance of Magnesium Alloys to Atmospheric Corrosion
  • Factors Affecting Atmospheric Corrosion of Magnesium Alloys: Effect of Sulfites and Sulfates
  • Water Corrosion
  • Salt Solutions
  • Acid and Alkaline Solutions
  • Aqueous Organic Compounds
  • Dry Organic Compounds
  • Gases at Ambient Temperature Up to About 100 ⁰C
  • Magnesium High-Temperature Corrosion
  • References
  1. General, Galvanic, and Localized Corrosion of Magnesium and Its Alloys

  • Overview

A. General Corrosion

  • Corrosion Resistance of Passive Magnesium
    • Ecorr and Corrosion Rates in Natural and Aqueous Media
    • Corrosion Rate Methods of Mg–Al Alloys
    • Critical Evaluation of the Passive Properties of Magnesium Alloys
  • The Negative Difference Effect (NDE)
  • Kinetic Studies of General and Pitting Corrosion of Magnesium Alloys
  • Electrochemical Noise Studies
  • Corrosion Prevention

B. Galvanic Corrosion

  • Hydrogen Overpotentials
  • Galvanic Corrosion of Pure and Alloyed Magnesium
    • Cathodic Corrosion of Aluminum
    • Cathodic Damage to Coatings
  • Composite Coat for Molten Magnesium
  • Metal Matrix Composite Galvanic Corrosion
  • Prevention of Galvanic Corrosion
    • Joining Magnesium to Dissimilar Metal Assemblies
    • Joining Magnesium to Nonmetallic Assemblies

C. Localized Corrosion

  • Pitting Corrosion
    • The Pitting Potential Determination
    • Polarization Curves and Pitting Potential of AXJ Alloy
  • Crevice Corrosion
  • Filiform Corrosion
    • Initiation and Kinetics Parameters
    • Mechanism of Proppagation
  • References
  1. Metallurgically and Microbiologically Influenced Corrosion
    of Magnesium and Its Alloys

  • Overview

A. Metallurgically Influenced Corrosion of Magnesium Alloys

  • Casting Alloys and Alloying Elements
    • Casting Alloys
    • Magnesium–Rare Earth, Magnesium–Thorium, and Magnesium–Silver Alloys
    • Alloying Elements and Tolerance Limit
  • Corrosion Influenced By Metallurgical Properties
    • Galvanic Corrosion and Secondary Phases
    • Intergranular Corrosion
    • Exfoliation Corrosion
    • High-Temperature Corrosion and Creep Deformation
    • Microstructure and Corrosion Creep of Magnesium Die-Cast Alloys
    • The OCP, icorr, and Corrosion Creep
    • Corrosion Creep and Aging
    • Corrosion Creep of HighStrength AE42 and MEZ 397
  • Influence of the Microstructure, Different Phases, and Welding
    • Influence of Heat Treatments
    • Effect of Rapid Solidification
    • Influence of the Microstructure of Some Mg Alloys
    • Influence of Joining and Welding
    • Cold Chamber Processes
    • Hot Chamber Processes and Corrosion Resistance of Thin Plates

B. MIC of Magnesium and Magnesium Alloys

  • Rational Degradation
    • Behavior of Sacrificial Magnesium
    • Rational Biocorrosion of Mg and Its Alloys in the Human Body
  • Stress Corrosion Cracking and Implants
  • Approaches to Control Biodegradation
    • Alloying
    • Surface Treatment (Anodizing)
    • Magnesium Implants and Bone Surgery
  • References
  1. Mechanically Assisted Corrosion of Magnesium and Its Alloys

  • Overview
  • Erosion Corrosion and Fretting Fatigue Corrosion
    • Erosion Corrosion
    • Fretting Fatigue Corrosion
  • Corrosion Fatigue of Magnesium Alloys
    • Corrosion Fatigue of Cast Magnesium Alloys
    • Corrosion Fatigue of High-Strength Magnesium Alloys
    • Crack Propagation of Wrought Extruded Alloys
    • Welding and Corrosion Fatigue of AZ31
    • Mechanisms of Corrosion Fatigue: Initiation and Propagation
    • Prevention of Corrosion Fatigue
  • References
  1. Environmentally Induced Corrosion of Magnesium and Its Alloys

  • Overview
  • Use of Magnesium Alloys and Stress-Corrosion Cracking Failures
  • Key Parameters
    • Alloy Composition and Magnesium Impurities
    • Microstructure and Crack Morphology
    • Effect of Stress
    • Effect of the Environment
  • Influence of Other Forms or Types of Corrosion on SCC
    • Effect of General Corrosion
    • Bimetallic or Galvanic Corrosion
    • Pitting and Localized Corrosion
    • Welded Material and SCC
    • Environment-Enhanced Creep and SCC of Mg Alloys
  • Propagation Mechanisms of Corrosion
    • Electrochemical Dissolution Models
    • Hydrogen Embrittlement
  • SCC–HE of Some Magnesium Alloys
  • SCC Prevention
  • References

Part Four – Coating and Testing

  1. Aluminum Coatings: Description and Testing

  • Overview
  • Inhibitors
  • Metallic Coatings
    • Conventional Plating and Electroless Plating of Aluminum
    • Surface Preparation for Thermal Spraying
    • Sacrificial Protection by Aluminum Alloys
    • Aluminum Powder as a Coating
    • Cathodic Protection of Aluminum Alloys
  • Conversion Coating
    • Phosphates and/or Chromates
    • Chromate–Phosphate Treatments
    • Chromate Alternatives
  • Anodization
  • Organic Finishing
    • Thermoplastic Coatings or Liquors
    • Converted Coating During or After Application
    • Coatings Containing Metals More Active than Aluminum
    • Electrodeposited Coatings
  • Corrosion Testing of Coated Metal
    • Electrochemical Testing of Coatings
    • Conventional Testing
    • Corrosion Fatigue of Thermal Spraying of Aluminum as a Coating
    • Environmentally Assisted Cracking of Metallic Sprayed Coatings
  • References
  1. Magnesium Coatings: Description and Testing

  • Overview
  • General Approach and Surface Preparation
  • Metallic and Conversion Coatings
    • Metallic Coatings
    • Chemical Conversion Surface Treatments
  • Anodic Treatments
    • Anodizing Description and Approaches
    • Formation of Anodized Coatings
    • Properties and Chemical Composition
    • Some Industrial and Developing Anodizing Processes
    • Forms of Surface Corrosion: Anodized or with Conversion Treatments
  • Surface Modification
    • Chemical and Physical Vapor Deposition
    • The H-Coat and Magnesium Hydrides
  • Electrochemical Characterization of the Metal–Film Interface
    • OCP and Polarization Studies of the Metal–Oxide Interface
    • Impedance Measurements
  • Organic Finishing and Corrosion Testing of Coated Material
    • Organic Coatings
    • Conventional Corrosion Testing of Coated Metal
  • References

Part Five – Evaluation and Testing

  1. Conventional and Electrochemical Methods of Investigation

  • Overview
  • Corrosion Testing Approaches and Methods of Investigation
    • Testing Approach
    • Categories of Corrosion Testing
    • Testing Duration
    • Testing Modes
    • Removal of Corrosion Products
  • Physical and Mechanical Testing of Corroded Materials
    • Visual and Microscopic Techniques of Testing
    • Nondestructive Evaluation Techniques
    • Mechanical Testing
    • Chemical Analysis
    • Surface Chemical Analysis
    • Published Data of Performance and Corrosion Resistance
  • Electrochemical Polarization Studies
    • Measurements of the Corrosion Potential
    • Potentiodynamic Methods
    • Cyclovoltammetry Techniques and Pitting
    • Potentiostatic, Galvanostatic, and Galvanodynamic Methods
  • The ac Electrochemical Impedance Spectroscopy Technique
    • Introduction
    • EIS Terms and Equivalent Circuits
    • Impedance Plots
  • Electrochemical Noise Measurements
    • Historical and Electrochemical Noise Definition
    • EN Generation and Data Acquisition Systems
    • Analysis of ENM Data
    • Potentiodynamic, Potentiostatic, and Galvanostatic EN Studies
  • Scanning Reference Electrode Technique
  • Microsystems and Wire Beam Electrode
    • Microsystems and Atomic Force Microscopy
    • Wire Beam Electrode
  • References
  1. Evaluation of Corrosion Forms of Aluminum and Its Alloys

  • Overview
  • General Corrosion of Aluminum and Its Alloys
  • Galvanic Corrosion
    • General Considerations
    • Influence of the Composition and Microstructure
    • Electrochemical Testing
  • Localized Corrosion of Aluminum and Its Alloys
    • Pitting Corrosion
    • Crevice Corrosion
    • Filiform Corrosion Testing of Al Alloys
  • Metallurgically Influenced Corrosion
    • Intergranular Corrosion Testing
    • Exfoliation Testing
    • Joining and Testing
  • MIC and Biodegradation Evaluation
  • Mechanically Influenced Corrosion of Aluminum and Its Alloys
    • Erosion Corrosion Testing
    • Corrosion Fatigue Testing
  • Environmentally Influenced Corrosion
    • SCC Testing Procedures of Aluminum Alloys
    • Test Specimens
    • Stressors
    • Fracture Morphology and SCC of Aluminum Alloys
  • References
  1. Evaluation of Corrosion Forms of Magnesium and Its Alloys

  • Overview
  • Testing Solutions
    • Hydroxide Solutions
    • Chloride, Sulfate, and Hydroxide Solutions
    • ASTM D1384-96 Corrosive Water
    • Buffered Solutions
  • General Corrosion Form
    • Immersion Testing and Corrosion Rate
    • Salt Spray Corrosion Test
    • Some Electrochemical Methods of Investigation
  • Galvanic or Bimetallic Corrosion of Magnesium and Its Alloys
  • Localized Corrosion of Magnesium and Its Alloys
    • Open Circuit Potential and Pitting Corrosion Studies
    • Electrochemical Noise Measurements
    • Magnesium SRET Studies
  • Metallurgically Influenced Corrosion of Magnesium and Its Alloys
  • MIC and Biodegradation of Magnesium and Its Alloys
  • Corrosion Fatigue
  • SCC Testing and Evaluation of Magnesium Alloys
    • Static Loading of Smooth Specimens and General Considerations
    • Stresses
    • Solutions and Operational Conditions
    • Constant Extension Rate and Linearly Increasing Stress Tests
    • SCC CERT Versus LIST Techniques
  • References

Part Six – Bibliography, International Units, and Abbreviations

Appendix 1. Corrosion and Prevention Books, Data, and ASTM Standards

  • 1. Some Recommended Books on Corrosion
  • 2. Bibliography of Corrosion Data for Performance of Materials
  • 3. ASTM Standards

Appendix 2. International Units and Some Equations

  • 1. Constants, Conventions, and Key Equations
  • 1.1. Constants
  • 1.2. Conventions
  • 1.3. Key Equations
  • 2. Examples of Reference Electrodes and Metallic and Ionic Reduction Reactions
  • 3. Electrochemical Cells and Their Potentials
  • 4. Standard Electrode Potential of Cations (T¼25 C)
  • 5. The Periodic Table

Appendix 3. Abbreviations and Symbols

Index

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