抄録
A defect associated with the use of a Sargent bath, a widely used chromium plating device, is the substantially lower current efficiency of chromium compared to that of other metals. It has been reported that the use of a formic acid bath leads to the production of amorphous-structured chromium deposits with a higher current efficiency. However, it is difficult to use this process commercially, because of difficulties involved in maintaining the bath. The purpose of this study was to examine in detail the conditions for chromium deposition in a formic acid bath with the objective of developing an optimum plating method with a higher current efficiency and a higher deposition rate. In order to realize a higher deposition rate, the effect of agitating the solution, via the use of a rotating disk electrode (RDE) apparatus, was examined. The findings show that the rate of deposition and current efficiency increased with increasing current density. By rotating the specimen, however, plating with bright surfaces was obtained more easily and under a wide variaty of plating conditions. The appearance of the surface of the deposited chromium was affected by the current density, the aging time of the solution used, and the rotating speed. We conclude that the morphology of the deposited chromium is closely related to the Cr3+ concentration in the proximity of the surface of the specimen.
