710 3価クロムめっき浴における電極反応の調査(OS7-(3),OS7 オーガナイズドセッション《精密/微細加工と評価》)

Our laboratory has been developing a chromium plating bath using trivalent chromium as one of the alternative process. It is, however, difficult to comprehend complex behavior of reaction occurring at the electrodes of the plating bath. So, the purpose of this study is to elucidate the reactions and the change of bath composition during the electro deposition. The authors surveyed the composition of gases generated from the various types of bathes by the electrode reaction with gas chromatography, and evaluated the ratio of electric current used for the gas generation. It became obvious that the ratio greatly depends on the bath composition, especially the ratio becomes very low in the trivalent chromium bath. We have concluded that the lower current efficiency is owing to the reaction that Cl_2 generated at the anode dissolves in the bath again as hypochlorous acid.