• Types, definitions, fundamental laws, metrics
• Thermodynamics, Potential-pH Diagrams, Kinetic Stability Diagrams
• Passivity and the Point Defect Model
• General corrosion, Mixed Potential Theory
• Coupled Environment Models for Localized Corrosion
• Pitting Corrosion
• Stress Corrosion Cracking
• Corrosion Fatigue
• Hydrogen Embrittlement
• Damage Function Analysis and the Deterministic Prediction of Damage
• Application of DFA
• Corrosion in the Oil Patch
• The Future

Synopsis

This one-day course will present corrosion science and engineering within a uniform context based upon three great natural laws/postulates: Conservation of Charge CoC), Wagner-Traud Hypothesis (WTH), and the Differential Aeration Hypothesis (DAH). All corrosion phenomena can be interpreted within a framework of these three theoretical concepts. Thus, all general and localized corrosion processes invoke the CoC and the WTH, while localized corrosion phenomena are primarily governed by the CoC and the DAH. The reason why reactive metals such as Fe, Ni, Cr, Al, Mg, Ti, Zr, etc. can be used as structural materials in contact with corrosive environments is because of enhanced kinetic stability due to the phenomenon of passivity, which arises from the formation of a oxide film on the metal surface, which effectively separates the reactive metal from the corrosive environment. The thermodynamics of corrosion will be explored in terms of potential-pH (Pourbaix) diagrams and kinetic aspects are described in terms of Kinetic Stability Diagrams (KSDs). It is shown that passivity is a meta-stable state that owes its continued existence to an appropriate relationship between the rate of formation and the rate of destruction of the barrier oxide layer of the passive film. Localized corrosion is described in terms of the coupled environment models that recognize coupling between processes that occur because of the spatial separation of the local anode and the local cathode. In the case of stress corrosion cracking the coupling current provides a means of examining the processes that occur at the crack tip and, in the case of intergranular stress corrosion cracking in sensitized Type 304 SS in high temperature water it is found that the crack propagates via temporally resolved brittle micro-fracture events of a few micro-meters in dimension; a mechanism which is consistent with hydrogen induced fracture (HIC) and not with the slip-dissolution model. Some attention will be paid to the deterministic prediction of corrosion damage via Damage Function Analysis (DFA), which has been made possible by the development of deterministic models for passivity breakdown, repassivation, and corrosion cavity growth. The application of DFA will be illustrated by reference to the failure of low pressure steam turbines, condensing heat exchangers, and cracking in nuclear power reactors. Finally, the prospects of applying DFA to predict the accumulation of corrosion damage in oil facilities (e.g., pipelines) will be reviewed and some initial work carried out by the author will be reviewed.

The course will require six to eight hours of class time and will be accompanied by written notes and reference to papers in the literature.