Corrosion Inhibition of Al and Al Alloys by Hexavalent Cr Compounds - A Mechanistic Overview

摘要

Hexavalent chromium oxo-anions provide excellent corrosion inhibition in numerous applications. They are particularly applicable for passivating light metals and alloys. Unfortunately, hexavalent chromium poses an environmental hazard. Replacement of hexavalent chromium with environmentally benign inhibitors requires a complete understanding of the mechanism by which hexavalent chromium compounds inhibit corrosion. This review considers hexavalent chromate inhibition in terms of the history of chromate conversion coatings, chemistry of hexavalent chromium oxo-anions, hypothesized mechanism of inhibition, and proposed alternatives.