SUS 430ステンレス鋼の定電位パルス法による着色皮膜の形成

抄録

A colored surface film can be formed on SUS 430 stainless steel in 0.5∼10kmol m^-3 H₂SO₄ from 298K to 353K using the potential-pulse method. It was showed that the rate of formation of the colored film increased as sulphuric acid concentrations or solution temperature increased. The pulse potential range for getting a fine color film on SUS 430 was 0∼0.95V (vs. SCE), and the pulse time was 10s^∼3-0.2s. The rate of formation of the film decreased as the pulse time decreased from 10^-3s, and no color film was formed at pulse times≥0.5s. The surface film tended to be nonadherent at anodic pulse potentials above 1.0V. This can be explained by considering that the film be dissolved into solution at the more anodic potential. AES analysis showed that the film formed was Cr-rich and Fe-deficient comparing with the matrix. It is suggested that Cr₂O₇^2- ions were formed at the anodic pulse-time, and Cr oxide was deposited by reduction of Cr₂O₇^2- at the cathodic pulse-time.