锈层对X80管线钢在鹰潭土壤模拟溶液中腐蚀行为的影响

Effect of Rust Layer on Corrosion Behavior of X80 Pipeline Steel in Yingtan Soil Simulated Solution

将X80钢在鹰潭土壤模拟溶液中浸泡一周使其表面生成锈层,采用扫描电镜观察了锈层的微观形貌,采用极化曲线和电化学阻抗谱研究X80裸钢和带锈X80钢在模拟溶液中的电化学行为。SEM观察表明,锈层较均匀地覆盖在试样表面,但疏松多孔易脱落。电化学试验分析表明,与X80裸钢相比,带锈X80钢在模拟溶液中的自腐蚀电流密度增大,电极反应时电荷转移电阻明显减小。这主要是因为缺陷较多的锈层增大了X80钢腐蚀时电极反应的真实面积,因而短期形成的锈层对X80钢并未起到保护作用,反而促进了腐蚀的发生。

A rust layer was obtained by X80 steel immersed in Yingtan soil simulated solution for 7 days, the surface morphology of the rust was analyzed by SEM, and the electrochemical behaviors of X80 bare steel and X80 steel with rust layer were investigated by polarization curves and EIS. The SEM results show that the rust layer was formed uniformly on the surface, however, it was loose and porous. Electrochemical experiments show that the free corrosion current density of X80 steel with rust was higher than that of X80 bare steel, and the charge transfer resistance of the former was lower than that of the latter. It was due to the increase of the real electrode area for the electrode reaction of XS0 steel resulted from porous rust. Therefore, the short-term rust on the X80 steel could not protect the X80 steel from corroding.