材料期刊网

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 process of crevice corrosion of 2Cr13 stainless steel freely exposed in 3.5% NaCl solution has been examined by means of mieroelectrode technique and ellipsometry.Experimental results show that there are three stages in crevice corrosion of stainless steels,the incubation period,the development period and the stablization period.The decrease of pH values and the increase of Cl~- concentration within a crevice can promote the dissolution of the passive film and accelerate crevice corrosion.In transition from the incubation period to the development period,there exists a critcal crevice solution(CCS),under the effect of which the alloys passive film breaks down.In the present work, experimental results indicated that the composition of the CCS was about 1.2 N C1~- with pH 3.5. In the incubation period,the passive film thickness within a crevice gradually decreases with time until the permanent breakdown of the passive film,Then, the development period of crevice corrosion ensues. Results also show that mieroelectrode technique and ellipsometry can be applied to in-situ measurement of the process in crevice corrosion of stainless steels.