Technical status of Cr (VI) alternative deposits

For replacing heavy-pollution hexavalent chromium electroplating to implement cleaner production and protect ecological enviroment, trivalent chromium electroplating process and chromium alternative process were developed. Trivalent chromium plating and chromium alternative process and their characteristics were described, and research trend of trivalent chromium plating was presented as well. Hard chromium deposit is the hardest in all metal deposit with hardness as high as 800～(1 000) HV. Composite deposit was a main alternative to hard chromium layer today, and its research status was summarized. The reasons for which the thickness of chromium layer becomes no more increase after a certain time of hard chromium plating in trivalent chromium solutions were analyzed.