Improved wear and corrosion resistance of chromium(III) plating by oxynitrocarburising and steam oxidation

Postsurface treatments, such as oxynitrocarburising and steam oxidation, were applied to amorphous Cr plating on SM45C mild carbon steel obtained from a trivalent (111) chromium bath to improve wear and corrosion properties. Higher wear properties of hardness (HV 1450), wear rate (1.9 x 10(-6) mm(3)/rev) and friction coefficient (0.4) were found for both the oxynitrocarburised and the steam-oxidized Cr platings due to the formation of chromium carbide, Cr7C3, during the treatments. Excellent corrosion resistance was also observed for the posttreated Cr platings due to the crack healing effect as a result of the formation of iron oxides (Fe3O4, Fe2O3) and/or nitride (Fe4N), suggesting that these treatments are highly effective in enhancing wear and corrosion resistance of the chromium platings. (C) 2004 Elsevier B.V. All rights reserved.