リン酸－硫酸系電解液を用いた払拭法によるSUS304ステンレス鋼の電解研磨条件の検討

―添加剤，電解電圧と払拭速度の表面形態への影響―

抄録

Electrolyte additives, applied voltage, and wiping speed were investigated to elucidate the optimum conditions for electropolishing of stainless steel（SUS304）using a wiping method with an electrolyte-solution-impregnated felt wiper cathode. Adding a viscosity improver and a surfactant to the electrolyte solution（mixed acid of 98% sulfuric acid and 85% phosphoric acid（1 : 3, v/v））reduced the evolution of pits on the electropolished SUS304 surfaces caused by the wiping method, but it reduced the polishing rate. Conditions of higher applied voltage and lower wiping speed led to an increased polishing rate and decreased pit evolution on the SUS304 surface. Electropolishing by the wiping method using the electrolyte containing the viscosity improver and 8 V of applied voltage and 10 mm s^－1 wiping speed produced extremely smooth and high-gloss surfaces. Analysis by glow discharge optical emission spectroscopy revealed that the depth profile of the surface composition had a Cr-rich layer formed on the electropolished SUS304 surface by the wiping method. The pitting potential of SUS304 surface shifted to a more positive value after electropolishing using the wiping method. That value was comparable to that obtained after conventional electropolishing.