碳钢在生物膜和硫化物膜下的电化学腐蚀行为

应用丝束电极技术比较了SRB生物膜以及硫化物膜对Q2 35碳钢腐蚀过程的影响机制 ,采用电位、电流扫描技术测试了生物膜和FeS膜下的碳钢腐蚀不均匀性特征 ,发现由于膜的导电性致使表面电位扫描已不能作为膜下局部腐蚀的判据 .动电位扫描表明无氧近中性溶液中 ,硫化物膜对碳钢具有一定保护作用 .电化学阻抗谱显示 ,硫化物膜电容增加缓慢 ,其极化电阻Rp 随时间呈先增后降的趋势 .与硫化物膜相比 ,生物膜表现出极大的电容 (10 4 ～ 10 5μF/cm2 ) ,且膜电容随时间呈S型增加 ,而极化电阻Rp 则呈指数下降 ,由此可知生物膜加速了腐蚀

Electrochemistry Characteristic of Carbon Steel under Biofilm and Sulfide Film

Wire Beam Electrode (WBE) made of Q235 carbon steel was applied to study the heterogeneous corrosion beneath biofilm formed by Sulfate Reducing Bacteria (SRB) in culture and sulfide film in solution with 1% NaCl and 300 mg/L S2-. The potential,galvanic density mapping,as well as polarization curve and Electrochemical Impedance Spectrum (EIS) were measured to predict the localized corrosion under biofilm and sulfide film.As a result,the mapping showed the potential fluctuation on the WBE surface decreased over time due to the conductivity of the biofilm and sulfide film.Therefore,the potential mapping could not be a criterion of localized corrosion under biofilm.Instead,the current mapping could give a good prediction to the MIC.The sulfide film could inhibit corrosion of carbon steel.However,the biofilm accelerate the corrosion.Polarization resistance Rp increased over time in the Na2S solution if lack of O2.In addition,the biofilm capacity moved up to a very large level (～105 μF/cm2)in shape of Sigmoid with its polarization resistance decreasing exponentially when SRB grew.