李鑫,尚东芝,李子墨,姜有文,陈长风.不同阴极极化条件对L245的SRB腐蚀行为影响[J].表面技术,2022,51(7):207-217, 235.
LI Xin,SHANG Dong-zhi,LI Zi-mo,JIANG You-wen,CHEN Chang-feng.SRB Corrosion Behavior of L245 Pipeline Steel with Different Cathode Polarization Potential[J].Surface Technology,2022,51(7):207-217, 235 |
| 不同阴极极化条件对L245的SRB腐蚀行为影响 |
| SRB Corrosion Behavior of L245 Pipeline Steel with Different Cathode Polarization Potential |
| 投稿时间：2022-02-15 |
| DOI：10.16490/j.cnki.issn.1001-3660.2022.07.020 |
| 中文关键词: 阴极极化 SRB微生物膜 聚焦离子束扫描电镜 膜截面 点蚀 |
| 英文关键词:cathode polarization SRB biofilm FIB-SEM cross-section pitting field testing showed that |
| 基金项目: |
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| Author | Institution |
| LI Xin | China University of Petroleum, Beijing 102249, China;China Petroleum Pipeline Bureau, Hebei Langfang 065000, China |
| SHANG Dong-zhi | China University of Petroleum, Beijing 102249, China |
| LI Zi-mo | China University of Petroleum, Beijing 102249, China |
| JIANG You-wen | Pipe China North Pipeline company, Hebei Langfang 065000, China |
| CHEN Chang-feng | China University of Petroleum, Beijing 102249, China |
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| 中文摘要: |
| 目的 通过模拟试验研究SRB环境中不同极化电位下L245管线钢微生物腐蚀(MIC)行为差异，探索极化电位对MIC过程的影响规律和微观机理。方法 采用静态浸泡法研究了施加4种不同极化电位条件下的L245电极试样在SRB环境中浸泡腐蚀7 d过程。利用细菌计数法分析微生物膜中固着细菌数量随极化电位的变化情况，通过开路电位测量、电化学交流阻抗(EIS)技术，分析微生物膜随电位的变化情况。利用扫描电镜(SEM & EDS)和聚焦离子束扫描电镜(FIB–SEM&EDS)分析膜表面和纵截面结构变化和元素成分分布。利用激光共聚焦显微镜(CLSM)对膜下点蚀坑随电位变化情况进行了统计分析。结果 弱阴极极化条件下，–0.75 V(vs. SCE)和–0.875 V(vs. SCE)明显促进了 SRB 的代谢活动，SRB细菌个体在材料表面的吸附和生长得到促进，膜中固着SRB数量大幅增加，细菌个体外围被硫化物和有机物覆盖，膜下点蚀程度随电位负移而加剧。–0.875 V(vs. SCE)条件下表现相对更明显。随着电位负移，膜厚逐渐增大，S、P等代谢活动元素含量随之增高。强阴极极化条件下，–1.05 V(vs. SCE)使SRB代谢活性得到抑制，固着细菌数目明显减少，点蚀现象基本消失。结论 弱阴极极化作用有助于增加SRB腐蚀的倾向，强极化电位则抑制了细菌的代谢活性，减缓了点蚀。揭示了阴极极化电位通过影响膜中SRB代谢活性和数量促使点蚀程度加剧的机理。SRB代谢活性的增强和膜下点蚀的发生是SRB从金属表面直接获取电子而导致的结果。 |
| 英文摘要: |
| The influence of cathode polarization on sulfate-reducing bacteria (SRB) corrosion behavior of pipeline steel has gained great attention from corrosion industry. The difference of microbial corrosion behavior of L245 pipeline steel with different cathodic polarization potentials in SRB containing environment was studied by simulation experiment, and the influence rule and microscopic pitting mechanism of the microbiologically influenced corrosion (MIC) process with polarization potential were explored. Laboratory tests were conducted to elucidate the cathodic reactions and MIC process by different potentiostatic cathodic polarization (OCP, –0.75 V, –0.875 V, –1.05 V) of L245 steel specimens for 7 days. MPN method were used to analyse sessile SRB quantity variation and its metabolism in biofilm, electrochemical measurements method such as open circuit potentiometry and electrochemical impedance spectroscopy (EIS) were applied to analyse the development and changes of morphology and composition of the corrosion product film. In order to investigate the surface and inner composition and structural changes, corrosion products film were cross-sectioned and detected by scanning electron microscope (SEM) and focused ion beam-scanning electron microscope (FIB-SEM&EDS) respectively. Laser scanning confocal microscope (CLSM) were used to analysis the difference of pitting behavior happening under the biofilm with different polarization potentials. This study focuses on MIC process, biofilm development and pitting corrosion caused by an SRB consortium with different CPs using FIB-SEM. Several concluding findings are listed as below:Proliferation of SRB bacteria was not inhibited in the presence of cathodic polarization and corrosion continued in the localized regions under biofilm. With the mild cathode polarization, applying –0.75 V and –0.875 V significantly could promote the SRB metabolic activity, strengthen the adsorption and growth of SRB on the surface of the electrode, greatly increased the number of sessile SRB in biofilm, so the pitting degree was aggravated accordingly, The result at ‒0.875 V was the more significant. Sessile SRB cells, in the corrosion product film formed at mild polarization potentials, were covered with sulfide and organic substance. With the potentials changing from OCP to ‒0.875 V, the thickness of biofilm gradually increased, and the content of bacterial metabolite elements such as S, P also increased. With the condition of strong cathode polarization ‒1.05 V, the upper layer of the corrosion product film was enriched with C, O, Ca elements, which mean that mineralization has occurred. The metabolic activity of SRB was inhibited and the number of sessile SRB cells decreased significantly, so the pitting phenomenon disappeared accordingly. The strong polarization potential inhibited the metabolic activity of bacteria and prevented pitting corrosion happening.The mild cathodic polarization ocould increase the MIC tendency of SRB, while the strong polarization potential inhibited the metabolic activity of bacteria and prevented the pitting corrosion occurring. The mechanism that the pitting degree was aggravated by the effect of cathode polarization potential on the metabolic activity and quantity of sessile SRB in biofilm was revealed. The enhancement of metabolic activity of SRB underneath the biofilm are the results of SRB's direct acquisition of electrons from the metal surface, H+ from microbial activities of SRB cells in biofilm accumulated underneath the biofilm and led to pitting corrosion. |
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