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利用高压釜,研究了6.5%Cr钢在80℃和0.8 MPa CO_2条件下的腐蚀行为.利用SEM和EDS研究了腐蚀产物膜表面和截面微观形貌以及Cr在腐蚀产物膜中的富集状况.利用高温高压电化学测试研究了线性极化电阻和电化学阻抗谱(EIS)随腐蚀时间的变化.结合溶液离子浓度测试,探讨了腐蚀产物膜生长机制.结果表明,6.5%Cr钢腐蚀速率为0.72 mm/a,腐蚀产物膜中存在Cr的富集,Cr/Fe之比超过了5∶1.不同腐蚀时间下,溶液中Cr3+含量都很低,说明Cr很少进入溶液.
The corrosion behavior of 6.5% Cr steel at 80 ℃ and 0.8 MPa CO 2 was studied by autoclave.The surface and cross-section morphology of the corrosion products and the enrichment of Cr in the corrosion products were studied by SEM and EDS. The change of linear polarization resistance and electrochemical impedance spectroscopy (EIS) with etching time were studied by high temperature and high pressure electrochemical test.The mechanism of film growth of corrosion products was discussed in combination with solution ion concentration test.The results showed that the corrosion rate of 6.5% Cr steel Is 0.72 mm / a, Cr enrichment is present in the corrosion product film, and the Cr / Fe ratio exceeds 5: 1. The Cr3 + content of the solution is very low at different etching times, indicating that Cr rarely enters the solution.