通过电化学阻抗谱、环阳极极化、扫描电镜和x射线能谱等方法研究了铁还原细菌Shewanella algae对316L不锈钢腐蚀行为的影响。电化学结果表明,Shewanella algae使不锈钢的腐蚀电位发生负移;在含该细菌的介质中,不锈钢表面的阻抗值先增大后减小,在第4d达到最大,是初始阻抗值的260倍;不锈钢在无菌介质中的滞后环面积和特征电位区间(击穿电位与保护电位之差)小于其在有菌介质中的滞后环面积和特征电位区间,说明Shewanella algae对不锈钢点蚀的发生与发展起到抑制作用。观察到不锈钢表面为生物膜所覆盖,生物膜及代谢产物改变了不锈钢表面的元素组成和化学性质。从微生物膜氧消耗和电活性生物膜的角度,初步提出了Shewanella algae的腐蚀抑制机理。
Microbiologically influenced corrosion of 316L stainless steel (316LSS) by iron-reducing bacteria (IRB) Shewanella algae was investigated by means of open circuit potential (OCP) measurement, electrochemical impedance spectroscopy (EIS) and cyclic anodic polarization curves, and scanning electron microscopy and energy dispersive X-ray spectroscopy for character- ization of corrosion products. The results showed that after immersion in the IRB containing solu- tion the free corrosion potential of 316LSS shifted negatively; the polarization resistance of 316LSS increased firstly, and then decreased; the presence of IRB reduced the hysteresis loop area of the cyclic anodic polarization curves and also the characteristic potential range of 316LSS, which indicated that IRB inhibited the initiation and propagation of pitting corrosion of 316LSS. The presence of IRB might be beneficial to the formation of biofilms on the surface of 316LSS exposed to in the solution, and therewith the chemical composition and property of the 316LSS surface might be changed by biofllms and metabolites, whilst which resulted in a stronger corrosion inhibition to the 316LSS immersed in the IRB containing solution.