The electrochemical anode-cathode-electrolyte mechanism behind every corrosion cell, the distinct forms it takes — uniform, galvanic, pitting, crevice, and stress corrosion cracking — and the coating, material-selection, and cathodic-protection methods used to prevent it.
Corrosion is an electrochemical reaction, not generic chemical wear, and every corrosion cell — no matter which of its many forms it takes — depends on the same four ingredients acting together: an anode, a cathode, an electrolyte, and a metallic path between them. This module works through that mechanism first, then through the specific forms it produces in practice: predictable, measurable uniform corrosion; galvanic corrosion between dissimilar metals; the far more dangerous localized attack of pitting and crevice corrosion; and stress corrosion cracking, which requires a susceptible alloy, a specific environment, and sustained tensile stress all at once.
By the end of this module you should be able to explain why removing any one of a corrosion cell's four ingredients is the organizing idea behind coatings, material selection, and cathodic protection alike — and why a sacrificial zinc coating keeps protecting steel even after it is scratched. Module 13's failure analysis content returns to corrosion as one of the most common root causes an investigator has to rule in or out.