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本文应用扫描微参比电极联机测量系统对18-8型不锈钢在含Cl~-介质中点腐蚀发生的早期过程进行研究。结果表明,在点腐蚀发生的早期阶段,可用特征电位E_r表征表面钝化膜的局部破坏和微点腐蚀的发生,E_r电位与传统的E_P电位不同,E_r电位通常比E_p,电位更负100-400mV,E_r电位值与钝化膜的表面状态直接有关,且随介质Cl~-浓度的增加和pH的降低而负移。在E_r电位附近,微点腐蚀开始发生,但一般不能稳定发展,电位越接近于E_p,则已发生的微点腐蚀越容易扩展为宏观点腐蚀,由此,作者提出“不稳定微点腐蚀”的新概念,并对不锈钢点腐蚀发生的早期过程机理加以讨论。
In this paper, the on-line scanning system of micro reference electrode was used to study the early process of 18-8 stainless steel mid-point corrosion in Cl ~ - medium. The results show that in the early stage of pitting corrosion, the characteristic potential E_r can be used to characterize the local damage and micro-corrosion of the surface passivation film. The E_r potential is different from the traditional E_P potential, and the E_r potential is usually more negative than E_p, 400mV, E_r potential value is directly related to the surface state of passivation film, and with the medium Cl ~ - concentration increases and negative pH shift. In the vicinity of the E_r potential, micro-point corrosion begins to occur, but generally can not be stable development, the potential closer to the E_p, then the occurrence of micro-point corrosion more likely to expand macro-point corrosion, thus, the author proposed “unstable micro-point corrosion” The new concept of stainless steel corrosion and point to the early course of the mechanism to be discussed.