Effects of chromate and chromate conversion coatings on corrosion of aluminum alloy 2024-T3

Various effects of chromate conversion coatings (CCCs) and chromate in solu tion on the corrosion of AA2024-T3 and pure Al are studied in this work. Ra man spectroscopy was used to investigate the nature of chromate in CCCs thr ough a comparison with the spectra of known standards and artificial Cr(III )/Cr(VI) mixed oxides. Chromate was shown to be released from CCCs and to m igrate to and protect a nearby, uncoated area in the artificial scratch cel l. However, experiments investigating the effect of chromate in solution on anodic dissolution kinetics under potentiostatic control indicated that la rge chromate concentrations were needed to have an effect. (C) 2001 Elsevie r Science B.V. All rights reserved.