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从渤海油田分离嗜热硫酸盐还原菌(SRB),用电化学测试技术研究其胞外高聚物(EPS)活性对13Cr不锈钢点蚀敏感性的影响.结果表明:低质量分数EPS在电极表面形成吸附层一定程度上抑制腐蚀,使得自腐蚀电位正移,但高质量分数EPS使不锈钢的耐蚀性降低;介质中少量Ca2+对EPS活性的促进作用使得EPS对Fe2+的吸附作用加强,促进不锈钢的阳极溶解;但过量Ca2+与Fe2+竞争,减少了EPS和Fe2+的结合,一定程度上抑制腐蚀;Mg2+更易与EPS作用导致EPS活性降低,低质量分数时即可抑制腐蚀;EPS和Ca2+络合的阈值为0.001 mol/L,和Mg2+络合的阈值为0.000 1 mol/L,大于此质量分数的Ca2+和Mg2+会抑制EPS的活性,减少EPS与腐蚀产生的Fe2+络合的机会,从而降低不锈钢腐蚀的敏感性.
Thermophilic sulfate-reducing bacteria (SRB) were isolated from Bohai Oilfield and the effect of extracellular polymer (EPS) activity on the pitting sensitivity of 13Cr stainless steel was studied by electrochemical test. The results showed that the low quality fraction EPS The formation of adsorption layer to a certain extent, inhibit corrosion, making the self-corrosion potential is positive, but the high quality fractional EPS stainless steel corrosion resistance decreased; a small amount of Ca2 + medium on the EPS activity of the role of EPS makes the adsorption of Fe2 + to enhance the promotion of stainless steel However, excessive Ca2 + competed with Fe2 +, reduced the combination of EPS and Fe2 +, and inhibited the corrosion to a certain extent. Mg2 + was more easily reduced with EPS and decreased the activity of EPS, and inhibited the corrosion with low mass fraction. EPS and Ca2 + The threshold value is 0.001 mol / L, and the threshold value of complexing with Mg2 + is 0.000 1 mol / L. The contents of Ca2 + and Mg2 + above this concentration can inhibit the activity of EPS and reduce the chances of EPS complexing with Fe2 + from corrosion and thus reduce the corrosion of stainless steel Sensitivity.