Study On The Effects Of Methanococcus Maripaludis On Corrosion Behavior Of EH40 And E690 Steel In Seawater

With the application of technologies such as gene sequencing in recent years,relevant studies have shown that methanogenic archaea dominate the microbial community in certain anaerobic corrosive environments,and the anaerobic corrosion performance of methanogenic archaea in the environment has proven to be not weaker than sulfate-reducing bacteria(SRB).These findings make methanogenic archaea one of the hotspots in the field of anaerobic microbial corrosion in recent years.However,at present,there is little research on the corrosion of microorganisms related to methanogenic archaea,and there are no targeted anti-corrosion measures.Therefore,it is of great significance to study the mechanism of carbon steel corrosion caused by methanogenic archaea.In this paper.Methanococcus maripaludis(M.maripaludis),a common hydrotrophic methanogenic archaea in the ocean,was selected as the research strain.First,the growth and metabolism of M.maripaludis under different typical energy sources were studied,and then through corrosion weightlessness experiments and electrochemical behavior analysis and surface analysis and other research methods explored the effect of M.maripaludis on the corrosion behavior of EH40 and E690 steel in seawater,and proposed the corresponding corrosion mechanism.The main conclusions of this study are as follows(1)The research results of different typical energy sources(sodium acetate,H2)on the growth and metabolism of M maripaludis in seawater show that the production of CH4 is positively correlated with the activity of M.maripaludis.When sodium acetate is used as the only energy source,M maripaludis metabolizes sodium acetate as a substrate to produce CH4 and CO2.CO2 dissolves in the medium and causes acidification of the medium.At the same time,the activity of M maripaludis is low due to lack of nutrients;When H2 is used as the only energy source and CO2 provides the carbon source,M maripaludis uses H2/CO2 as a substrate to generate CH4 for normal metabolic growth and high activity.At the same time,M.maripaludis metabolizes CO2 and causes the culture medium to alkalize(2)The research results of the influence of M.maripaludis on the corrosion behavior of EH40 steel in seawater show that M.maripaludis has a double effect on the corrosion process of EH40 steel.5 days before immersion,M maripaludis promoted rapid film formation on the steel surface,and the film was protective and prevented the corrosion process from proceeding.After 5 days of immersion,the presence of M.maripaludis accelerates the corrosion of steel,Cl-erosion and microbial corrosion destroy the protective properties of the film.The corrosion feature is localized corrosion.The corrosion mechanism is M.maripaludis non-uniformly distributed microbial membranes to induce pitting corrosion and metabolic acceleration of anodic and cathodic depolarization processes to promote corrosion(3)The research results of the influence of M.maripaludis on the corrosion behavior of E690 steel in seawater show that M maripaludis has a double effect on the corrosion process of E690 steel.The corrosion of steel was inhibited and promoted before and after 5 days of immersion.The corrosion mechanism and corrosion characteristics were the same as those of EH40 steel,but M.maripaludis caused different behaviors of carbon steel with different compositions.After immersion for 5 days,the charge transfer resistance Rct in E690 steel increases with time when M.maripaludis is present,and there is a "suppression" phenomenon that is not found in EH40 steel when M maripaludis accelerates the corrosion of E690 steel.In addition,the center of the pitting pit caused by M.maripaludis corrosion of E690 steel has an uncorroded characteristic "round table" area.