采用电化学技术包括开路电位、电化学阻抗谱、动电位极化、循环极化、表面表征技术、包括扫描电镜和能谱分析研究了316L不锈钢在天然海水中微生物膜影响的初期腐蚀行为。研究表明,海洋微生物在不锈钢表面发生附着形成生物膜。在天然海水中不锈钢的开路电位正移约450mV,而在灭菌海水中不锈钢的开路电位基本保持不变。电化学阻抗和极化实验结果指出,海洋微生物膜使不锈钢阻抗增加,点蚀电位升高,生物膜抑制了不锈钢的腐蚀发生。这种抑制作用经历了一个先变大后减小的过程。天然海水中,海洋生物膜的附着和其代谢产物作用使不锈钢的耐蚀性能得到提高,这一耐蚀性能的提高与生物膜影响的阳极抑制作用有关。
The microbiologically influenced corrosion behaviors of marine microorganism on 316L SS were studied by the immersion experiments in the nature seawater using the open circuit potential(Eocp),electrochemical impedance spectroscopy(EIS),potentiodynamic anodic and cyclic polarization curves,scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) methods.It was observed that marine biofilm was formed by microorganisms on the surface of stainless steel.It was confirmed that E(ocp) of 316L SS in nature seawater shifted in noble direction nearly 450 mV.However,in sterile seawater,E(ocp) was stable in experimental period.The presence of marine biofilms on the stainless steel played a role in inhibiting the initial corrosion according to the decrease in corrosion current densities obtained from the polarization curves,the increase of the polarization resistance(Rρ) obtained from EIS and the increase of the pitting cor rosion potential from the potentiodynamic polarization by the comparison test of 316L SS immersed in nature seawater and sterile seawater.It was suggested that marine biofilm and its metabolites improved the superficial anticorrosive properties of 316L SS by inhibiting the anodic dissolution behavior of stainless steel.