硫化物を起点とする腐食反応の微小電気化学

研究了硫化氢离子(HS-)对316L不锈钢在pH 8.4的硼酸-硼酸盐缓冲溶液中钝化性能的影响。镀有Ag2S的银微电极在不锈钢表面上同时产生了OH-和HS-。在不锈钢恒电位极化过程中，钝化电流密度随表面附近HS-浓度的增加而增大。在HS-存在的极化过程中，不锈钢的恒频阻抗下降，而在HS-稀释后，阻抗保持不变。电化学阻抗谱、莫特-肖特基(M-S)分析和扫描电化学显微镜(SECM)分析表明，在含HS-的溶液中形成了缺陷的n型半导体钝化膜。俄歇电子能谱(AES)表明，在含HS-的溶液中形成的不锈钢钝化膜中的金属阳离子和氧空位增加。钝化膜性能的一系列变化被认为是由于极化过程中HS-在膜表面的吸附所致。

The effect of hydrogen sulfide ions (HS－) on the passivity of type 316L stainless steel was investigated in pH 8.4 boric acid-borate buffer solution. Galvanostatic polarization of a silver microelectrode covered with Ag2S generated both OH－ and HS－ above the stainless steel surface. During potentiostatic polarization of the stainless steel, the passivity-maintaining current density increased with increase in the concentration of HS－ in the vicinity of the surface. The impedance of the stainless steel at a constant frequency decreased during polarization in the presence of HS－, while it was sustained after dilution of HS－. Electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S) analysis and scanning electrochemical microscopy (SECM) showed that a defective and n-type semiconductive passive film was formed in the solution containing HS－. Auger electron spectroscopy (AES) revealed that metal cations and oxygen vacancies in the passive film on the stainless steel increased when it was formed in a HS－-containing solution. The series of changes in passive film properties is thought to be due to adsorption of HS－ on the film surface during the polarization.