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利用微电极和椭圆偏振仪研究了2Cr13不锈钢在3.5%NaCl 溶液中的缝隙腐蚀历程。实验结果表明,不锈钢的缝隙腐蚀经历了三个阶段一孕育期,发展期和稳定期。缝内 pH 值下降和 Cl~-浓度增加均促进了钝化膜的溶解和加速了缝隙腐蚀。从孕育期向发展期的过渡中,存在着使合金钝化膜破裂的临界缝隙溶液(CCS)。在本试验条件下,其组成大约为 pH=3.5,[Cl~-]:1.2N。在孕育期,缝内钝化膜厚度随时间逐渐减薄,直到钝化膜肢裂,此时,缝隙腐蚀即进入发展期。微电极测试技术和椭圆偏振法可应用于不锈钢缝隙腐蚀过程的原位测试。
The crevice corrosion process of 2Cr13 stainless steel in 3.5% NaCl solution was studied by using microelectrode and ellipsometer. The experimental results show that the crevice corrosion of stainless steel experienced three stages of a period of incubation, development and stability. The decrease of pH and the increase of Cl ~ - in the seams all contributed to the dissolution of the passivation film and accelerated crevice corrosion. From the period of incubation to development, there is a critical gap solution (CCS) that ruptures the passivation film of the alloy. Under the experimental conditions, the composition is about pH = 3.5, [Cl ~ -]: 1.2N. During the gestation period, the thickness of the passive film in the seams gradually decreases with time, until the passive film ruptures. At this moment, crevice corrosion will enter the developmental period. Microelectrode testing technology and ellipsometry can be applied to the stainless steel crevice corrosion in situ testing.