1Cr18Ni9Ti不锈钢在酸性NaCl溶液中的点蚀电化学特征

Pitting Electrochemical Features of 1Cr18Ni9Ti Stainless Steel in Acidic NaCl Solution

研究结果表明,1Cr18Ni9Ti不锈钢在pH=1的酸性NaCl溶液介质中浸泡最初期,噪声电流曲线无噪声峰,噪声电阻大,电化学阻抗谱为一容抗弧,阻抗模值大,电极表面处于稳定状态。浸泡24h噪声电流曲线出现尖峰波动,但波动峰值只有几个微安,噪声电阻直线下降,阻抗谱高频部分为一容抗弧,低频下出现感抗特征,阻抗模值大幅度下降表面处于点蚀诱导期的亚稳状态。浸泡48h后,噪声电流波动峰值突然增大至100μA,噪声峰也增多,噪声电阻基本稳定,阻抗谱低频下的感抗成分消失,点蚀进入稳定发展阶段。动电位极化曲线与电化学噪声测试结果表明,1Cr18Ni9Ti不锈钢在pH=1的酸性NaCl溶液介质中的耐点蚀性能随浸泡时间延长而降低。

The research results indicated that, when the 1 Cr18Ni9Ti stainless steel just immersed in the acidic NaCl solution, there was not noise pulse in the curve of current noise, the value of noise resistance was large, the impendence module of electrochemical impendence spectroscopy （EIS） was large, which showed that the surface of the 1Crl 8Ni9Ti stainless steel was stable. After 24 hours immersed in the solution, small noise pulse emerged in the curve of current noise, noise resistance decreased, the inductive component emerged in the EIS and the impendence module decreased suddenly, which showed that the pitting was formed and repaired in the passive film of the surface. After 24 hours immersed in the solution, the value of noise pulse increased to 100μA suddenly and the number of noise pulse increase also, the noise resistance stopped charging, and the inductive component disappeared in the EIS, which showed that the pitting emerged in the surface. The result of potential dynamic polarization curves of 1Cr18Ni9Ti stainless steel immersed in acidic NaCl solution after different time, showed that the capability of resistance pitting decreased with the immersion time prolonging.