材料期刊网

采用电化学实验及SEM和EDS分析技术,研究了B10合金分别在无菌和接种了远青弧菌、硫酸盐还原菌(SRB)以及二者混合菌种的海水中的腐蚀行为.结果表明,不同海洋微生物条件下B10合金的腐蚀行为及机制有所不同.远青弧菌通过阻滞氧去极化阴极过程在一定程度上抑制B10合金腐蚀;SRB则通过氢去极化使阳极溶解加速,而生成的粗大颗粒状腐蚀产物Cu2S对基体的保护性不佳,促进了B10合金的腐蚀;而在混合菌种条件下,B10合金腐蚀的阴极过程与仅接种SRB时相似,但阳极溶解形成的腐蚀产物比后者细小且致密均匀,使其阳极极化显著增大,阻滞了试样的进一步腐蚀,其腐蚀电流密度介于2种单一菌种之间.因此在工程实践中,根据实验室单一菌种条件下材料的腐蚀行为来估计和预测在实际微生物环境中材料的腐蚀行为时宜慎重.

With increasing attention paid to the security issues of onshore engineering structure,corrosion researches of copper alloy were focused on the influence of single bacteria,especially the anaerobic sulfate-reducing bacteria (SRB).However,a part of documents indicated that comprehensive influence of natural bacteria on the copper alloy does exist,and whether the influence of single bacteria could represent the real impact of natural complex bacteria is remaining unclear.Under this consideration,electrochemical measurements,incorporated with surface morphology and composition analysis,were employed to investigate the corrosion behavior of B 10 alloy in seawater which was inoculated into Vibrio azureus,SRB and their mixed strains,respectively,in this work.The results showed that these marine micro-organisms could affect the corrosion process of B 10 alloy in relatively different ways.Compared with the sterile condition,Vibrio azureus could inhabit the corrosion of B 10 alloy to some extent by blocking cathodic oxygen reducing process,while SRB could significantly promote its corrosion by accelerating anodic dissolution of B 10 alloy via hydrogen depolarization and forming loose and bulky corrosion products without complete protection.In the mixed microbial medium,SRB multiply rapidly in the local anaerobic environment created by the biological membrane of Vibrio azureus,their interacting changed the corrosive micro-environment on the surface of B10 alloy.The smaller and complicated corrosion products formed in the seawater containing mixed strains obviously performed better than that produced in the medium containing SRB only,giving rise to a significant increase in anodic polarization; at the same time,similar cathodic process was still occurred in the mixed culture.As a result,the corrosion current density of B10 alloy fell in between those detected in two single microbial media.For the practice engineering applications,therefore,the conclusions drawn from single microbe medium should be cautiously and carefully adopted as the criterion to evaluate corrosion behavior of B10 alloy in actual microbial environment.