海洋污损生物附着不锈钢缝隙微环境特征及其局部腐蚀破坏规律与机理

Marine engineering practice and seawater exposure tests have confirmed that crevice corrosion is a severe local corrosion for stainless steels and its initial attack is easier than pitting corrosion. Moreover, biofouling is almost inevitable in the actual seawater environment, which exacerbates the complexity of crevice corrosion. This project first through actual seawater exposure test and in-situ corrosive micro-environmental monitoring, to identify the chemical composition, ion distribution and migration process of solution in the localized corrosive micro-environment of crevices in seawater, and investigate the composition and distribution of microbial community in micro-environment of crevice under macro organism attachment. According to the simulated crevice corrosion experimental results and the electrochemical measurement, we will be able to clarify the occurrence and development of crevice corrosion of typical stainless steels and their electrochemical mechanism under the influence of marine communities attached biofouling. The morphology and microstructure of biofilm and passive films formed on the surface of stainless steels will then be characterized using HR-TEM, SEM, XRD, XPS, RAMAN,etc. Based on the experimental results, the composition and distribution of biofilm, the development and breakdown of the passive films and the localized corrosion failure process of the typical stainless steels in micro crevice corrosive environment will be well understood in micro/nano-scale. Through the comprehensive research in this proposal, it is expected to establish new theoretical models of marine crevice corrosion, which will provide theoretical foundation for crevice corrosion evaluation of metal materials in marine environment and guidance for protection design of crevice corrosion based on marine fouling control.

不锈钢等钝性金属的缝隙腐蚀是比点蚀更易发生且破坏性极大的局部腐蚀，实际海水环境中由于生物污损影响，更加剧了缝隙腐蚀的复杂性，迄今对其微腐蚀环境特征及腐蚀行为缺乏了解。本项目基于微电极实海原位微环境监测分析，通过研究海洋污损生物附着缝隙微腐蚀环境溶液化学和微生物群落特征；建立室内模拟缝隙腐蚀和电化学测试研究方法，系统研究典型海洋微生物在缝隙内外附着状态及生命活动代谢过程对不锈钢缝隙局部腐蚀发生、发展规律及电化学行为的影响；结合金属表面污损生物膜、钝化膜微观结构以及局部腐蚀发展形态观察表征，从微纳米尺度上全面阐释不锈钢在污损生物附着缝隙微环境下活化/钝化过程及局部腐蚀萌生位置、发展演化微观机制。通过深入探究强腐蚀性离子和海洋微生物膜共同影响下，不锈钢缝隙局部腐蚀发生、发展的主控机制，发展建立海洋缝隙腐蚀理论模型，为海洋金属材料缝隙腐蚀评价和基于污损控制的缝隙腐蚀防护设计提供依据。

金属的缝隙腐蚀是海洋工程实践中导致突发性事故的主要腐蚀破坏形式之一，由于腐蚀过程具有影响因素复杂、隐蔽性强、监测困难等特点，一直是海洋腐蚀研究的难点。本课题通过实海暴露试验和室内模拟加速腐蚀研究，发展建立了海洋污损生物附着缝隙微环境特征与缝隙腐蚀研究方法，对典型海洋工程用不锈钢在海洋环境下的缝隙腐蚀行为及机理开展了系统研究。. 通过在我国典型海域海水环境中长达4年的实海暴露试验，系统获得了316L、2205和2507三种典型不锈钢的缝隙腐蚀数据，阐明了不同材料和缝隙构型的腐蚀行为，揭示了藤壶、贻贝等大型污损生物对海洋缝隙腐蚀的影响规律；通过实海环境因素监测，查明了在实际海洋环境下不锈钢缝隙微环境溶液介质化学组成、微生物群落分布特征和规律，为研究缝隙腐蚀提供了基本环境参数依据。. 通过室内模拟缝隙环境腐蚀试验研究，系统揭示了pH值、溶解氧和典型微生物等因素对不锈钢缝隙腐蚀的影响；发现硫酸盐还原菌等微生物在缝隙内外的生长主要受营养碳源和pH值的协同控制；用模拟缝隙闭塞微环境中的阵列微电极技术结合宏观电极体系，通过腐蚀电位、极化曲线、交流阻抗等电化学测试，系统研究了缝隙微环境化学因素、微生物因素共同作用下，不锈钢缝隙腐蚀电化学过程及机制，阐明了不锈钢在模拟缝隙环境中的成膜特性、钝化膜组成及钝化-活化行为及机理。. 本课题通过实海浅海、深海暴露试验和室内模拟试验研究，系统获取了海洋缝隙腐蚀数据，阐明了海洋环境典型不锈钢缝隙腐蚀的主控机制、行为规律以及微环境演化特征，为我国海洋工程材料腐蚀评价和与防护提供了基础数据和理论依据。本课题共发表SCI论文18篇,培养博士研究生1名，硕士研究生4名。