Environmental Degradation and Protection

Instructor: Aleksey Yerokhin

Course Summary

This course focuses on the interaction of metallic materials with wet environment, their associated degradation, evaluation, control and protection. The electrochemical nature of corrosion is reviewed form thermodynamics and kinetics points of view. The role of anodic and cathodic reactions in the corrosion process is revealed, leading to an understanding of the mechanisms governing materials degradation in different environments. Phenomenological models of uniform corrosion and common types of localised corrosion are considered. Appropriate methods of corrosion testing, monitoring and control are discussed along with the application of design to minimise/mitigate the corrosion-related damage. Finally the application of coatings for and the effect of surface treatment routes on corrosion prevention at various combinations of materials and environment are addressed.

Course Format

Hours of lectureHours of discussionHours in laboratoryHours of independent studyTotal numbers of hours
2444472

Learning Outcomes

  • Demonstrate an understanding of some basic electrochemical principles of wet corrosion, particularly potential-pH diagrams, the E-log I plot and different forms of polarisation;
  • Demonstrate an understanding of different forms and mechanisms of corrosion and degradation of metals and alloys, and of measures that improve material’s durability and stability;
  • Demonstrate an awareness of different types of corrosion and methods of protection;
  • Demonstrate an appreciation of the implications of design on the corrosion response of a component/structure;
  • Demonstrate an understanding of different methods used to evaluate corrosion mechanisms and kinetics of corrosion process;
  • Demonstrate knowledge of surface coating and treatment processes used for corrosion prevention/control and their respective capabilities.

Course Content

Part I. Fundamentals of corrosion (6 hours)

  • Introduction.
  • Characteristics of Wet Corrosion: Mechanisms Determining Corrosion Rates, Corrosion Prevention Measures, Corrosion Rates
  • Thermodynamics of corrosion: Equilibrium Potentials, Electrode Reactions and Electrode Potentials, Standard Electrode Potentials, Equilibrium Potentials of Reactions with Fe, Pourbaix Diagrams
  • Electrode Kinetics: Anode and cathode potentials, Overvoltage and Exchange Current; Activation polarisation, Concentration Polarisation, Resistance Polarisation, Determination of Corrosion Potential and Corrosion Rates

Part II. Types of corrosion (6 hours)

  • Passivation and Passivity: Reasons and features, Groups of passive layers, Breakdown of passivity, Practical utilisation of passivity
  • Corrosion Types with Different Cathodic Reactions: Corrosion under oxygen reduction, Corrosion under hydrogen evolution, CO2 corrosion, H2S corrosion, Cl2 corrosion
  • Corrosion Types Based on Appearance: Uniform corrosion, Galvanic corrosion, Crevice corrosion, Pitting corrosion

Part III. Corrosion evaluation, testing and prevention (6 hours)

  • Corrosion Testing: Methods, Procedures, Cabinet Testing, Weight Loss Measurements, Electrochemical Testing
  • Corrosion Prevention: Materials Selection; Change of Environment, Design, Cathodic Protection, Anodic Protection

Part IV. Corrosion protection by coatings (6 hours)

  • Metallic Coatings: Noble, Barrier, Sacrificial Coatings
  • Inorganic Coatings: Anodic Oxide Films, Conversion Coatings; Enamels; Other Inorganic Coatings
  • Organic Coatings: Paint Coatings, Sol-gel, Other Forms of Organic Coatings
  • Pre-and Post-treatments

Practical/Laboratory work (4 h) — Determination of corrosion rates

Reading List

Core Texts:

  1. E. Bardal: Corrosion and Protection, Springer, 2004, 368pp
  2. J. C. Scully, The Fundamentals of Corrosion, Pergamon Pr., 226 pp

Secondary Texts:

  1. R Tretheway and J Chamberlain: Corrosion for science and Engineering, Longman 1995
  2. G Wanglen: An Introduction to Corrosion and Protection of Metals, Chapmant Hall, 1985
  3. Shrier: Corrosion, Vol 1 & 2 (2nd/3rd Edition)

Peripheral Reading:

  1. ASM Handbook. V 13, Corrosion, ASM Int.

Grading

Class participation20%
Homework assignments30%
Final exam50%