光电化学方法研究不锈钢钝化膜的局部破坏

STUDY ON LOCALIZED BREAKDOWN OF PASSIVE FILMS ON STAINLESS STEELS BY PHOTOELECTROCHEMICAL METHOD

建立了评价钝化膜稳定性的光电化学方法——电位台阶光电流测量和恒电位光电流响应测量。研究了铁素体高铬不锈钢25Cr和奥氏体不锈钢AISl304,316L,321在0.1mol/LNaCI溶液中钝化膜的局部破坏及十二烷基苯磺酸钠和癸胺对AISI304不锈钢孔蚀的抑制作用。结果表明:钝化膜破坏后光电流增加;电位台阶光电流测量得出光电流开始突增的电位值与钝化膜的击穿电位对应,钝化膜破坏后光电流i_(ph)随电极电位增加值△E_b的变化规律可以反映钝化膜破坏的本质;缓蚀剂的加入改变了AISI304不锈钢i_(ph)随△E_b的变化关系。

In this paper the photoelectrochemical methods for evaluating the stability of passive film were established. The localized breakdown of the films formed on ferritic stainless steel 25Cr and austenitic stainless steel AISI 304, 316L and 321 in 0.1 mol/L NaCl was investigated. The inhibition action of decy1 amine and sodium dodecylbenzene sulfonate on the pitting resistance of 304 SS was also studied.The results indicate that the photocurrent i_(ph)increases when the passive film is breakdown. The potential under which the photocurrent increases rapidly is found to correspond to that of the breakdown potential E_(b.) It seems that the relationship between i_(ph)and △E_bmay be indicative of the destruction of the passive films on stainless steels. The addition of inhibitors changes this relationship.