【作者】 段继周；

【导师】 侯保荣；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋化学， 2003， 博士

【摘要】 随着人们对海洋的广泛开发和利用，海洋环境下金属构筑物的微生物腐蚀已引起了人们广泛的关注。本文研究了海水和海泥环境中硫酸盐还原菌（SRB）影响的海洋用钢的微生物腐蚀行为, 探讨了SRB腐蚀的作用机制，并研究了海泥环境中SRB对阴极保护电位的影响。考虑包括SRB在内的腐蚀环境因子，使用模糊聚类分析技术对区域性海洋沉积物腐蚀性进行了划分。从我国渤海海域的海泥中成功富集培养出SRB。荧光显微镜观察发现，在接种SRB的修正的Postgate’s C培养基中，SRB在316L SS表面附着发展并形成生物膜。生物膜的形成改变了不锈钢的电化学阻抗谱（EIS）特征。在接近自然腐蚀电位（Ecorr）附近，出现了显著的阳极电流峰值，电流峰值是硫化物氧化的结果。在SRB的厌氧环境中，由于硫化铁作为阴极去极化剂加速了阴极去极化反应，从而使阳极溶解增加，导致其钝性降低。在SRB介质中长期浸泡后的XPS分析显示，表层钝化膜中的Cr/Fe比增加，钝化膜中出现了少量的Mo和S。在该环境介质中Cr的增加和Mo的出现，初步认为是一种钝化膜的保护性自修复过程。在含有活性SRB的海泥环境中，弱极化曲线和显示，低合金钢的腐蚀速度先降低，后增加。根据EIS变化特征，提出了低合金钢在海泥中的腐蚀过程。初期是厌氧条件下的氢去极化，生成氧化物产物层；然后在SRB代谢产生的H2S作用下，发生氧化物到硫化物的转变。初期硫化物生成，腐蚀速度变化不大，后期随着硫化物的增加，不再具有保护性，而使腐蚀速度加快。根据其后期腐蚀速度变化和阻抗谱特征，有可能生物有机硫化物的存在加快了其腐蚀速度。在SRB存在下，最佳阴极保护电位移向更负的值，-1030 mV（相对铜/硫酸铜电极，CSE）甚至更低的电位是需要的。在-1030 mVCSE保护电位下，保护电流密度约为11mA/m2。生成的硫化铁产物的不稳定保护作用，导致保护电位的降低。考虑包括SRB在内的腐蚀环境因子，使用模糊聚类分析技术对区域性海洋沉积物腐蚀性进行了划分，并据此绘出腐蚀图谱。与因子打分法相比较，较好的反映了实际情况更多还原

【Abstract】 Microbiologically influenced corrosion (MIC) has been given severe attention in marine environment concerned of all kinds of structure constructions, such as pipeline, platform for petroleum, etc. In the paper, sulfate-reducing bacteria (SRB) influenced corrosion was studied in seawater and seamud environments, concerned of stainless steel and low alloyed steels, respectively. The influence of SRB on cathodic protection (CP) was also conducted in seamud. Given corrosion factors including SRB, the corrosiveness of regional marine sediment was classified based on the fuzzy clustering analysis technology (FCA).SRB was cultured and enriched originated seamud from Bohai gulf using medicated Postgate’s C medium. Biofilm containing SRB was observed on the surface of 316L SS by fluorescence microscopy in medicated Postgate’s C medium inoculated SRB. The changes of Electrochemical impedance spectra (EIS) could be ascribed to the SRB biofilm and the metabolism activities. SRB biofilm and proliferation resulted the debasement of passivity of stainless steel. The distinct anodic current peak was observed in the seawater containing SRB. It was presumed that it was the result of electrochemical oxidation of sulfide.In anaerobic environment containing SRB, iron sulfide as depolarization reagent accelerated the depolarization of cathodic reaction, resulting the increase of anodic dissolution. The result of X-ray photoelectron spectra (XPS) indicated, after exposure to SRB, the ratio of Cr/Fe had an increase, Mo and S were detected in the surface layer of passive film. Organic molybdenum sulphide (Mo(V)-Cysteine) was found in passive film. The increase of Cr and the appearance of Mo were thought an auto-repair behaviour.In seamud containing active SRB, the corrosion rate of low-alloyed steels decreased firstly and then increased. According to EIS and surface analysis, the corrosion process of steels in seamud containing active SRB was presented. In the first stage, anaerobic hydrogen depolarization is predominant and produced iron oxide corrosion product layer; in the second stage, due to bio-produced hydrogen sulphide, iron oxide was biomineralized and translated iron sulphide. The iron oxide and initial iron sulphide had a certain extent protect properties, so the corrosion rate decreased and kept stable. Subsequently, the crystal structure and type of iron sulphide changed gradually, there existed crannies in corrosion products, resulting the increase of corrosion rate. According to the characteristics of the EIS change, it is an alternative mechanism that bioorganic sulphide accelerated the corrosion.The optimal CP potential shifted to negative direction in seamud containing active SRB, -1030 mV (vs. saturated Cu/CuSO4 electrode, CSE ) or lower potential was needed.Accordingly, the CP current density was about 11 mA/m2. Given corrosion factors including SRB, the corrosiveness of regional marine sediment was classified based on FCA. The corrosion rate were predicted by FCA. The chart of corrosiviness was plotted. Compared to the factors analysis, FCA can give better results更多还原