2009 Volume 40 Issue 5 Pages 1303-1308
The specific corrosion mechanism and its prevention method for decorative Cr plating in the presence of highly concnetrated calcium chloride is studied. It is investigated by lavoratory test and market monitoring that Cr plating, whose Cr ratio is 98%, is easily attacked in such corrosive environment. It loses the passivation film by chloride ion and the electropotnetial of Cr shifts to base. Therefore the relationship of galvanic cell between Cr and underlying Ni is switched, and after that the anodic dissolution of Cr is occurred. In addition to the above study, the prevention method aganist such specific corrosion is suggested. Cr-C plating, whose Cr ratio is 60-80%, is investigated by AES and XRD. It contains metalloid element(s) into the film which contribute(s) to organize amorphous. It consists of Cr-C clusters which are coated by oxide phases. Thus, the potnetial shift which causes Cr dissolution is prevented consequently.
