温度对厌氧环境中硫酸盐还原菌所致铜镍合金腐蚀行为的影响

Effect of Temperature on Corrosion Behavior of Copper-nickel Alloys by Sulphate-reducing Bacteria in Anaerobic Environment

目的 探究环境因素(温度)在微生物腐蚀(Microbiologically Influenced Corrosion,MIC)过程中的影响以及细菌最适宜的温度条件,初步探索铜合金的MIC机理,为微生物的腐蚀与防护提供依据。方法利用生物学分析、表面分析以及电化学手段,研究不同温度(25、37、45℃)条件下培养基中硫酸盐还原菌(Sulfate-reducing Bacteria,SRB)的生长状况和铜镍合金表面的腐蚀状态,进而对微生物体系中的MIC行为进行分析。结果从生物学分析来看,培养周期内SRB细胞的数量先迅速增加,之后又逐渐减少。温度为37℃时,检测出的SRB细胞数和培养基中生成的H_(2)S最多。从表面分析来看,铜镍合金表面生成不致密的生物膜,在生物膜下面检测出点蚀坑,且点蚀密度小。温度为37℃时,生物膜覆盖的区域最大,且该温度下检测到最大的平均点蚀坑深度,约9.3μm。从电化学分析来看,在各种温度下,浸泡在生物介质中的试样的开路电位(OCP)大致向正方向移动,R_(p)曲线呈现先上升后下降的趋势,温度为37℃,试样检测出的R_(p)值最小。结论温度能够影响SRB所导致的铜镍合金的MIC行为,且温度为37℃时,SRB的生长状态最好,铜镍合金的腐蚀最严重。SRB所导致的铜镍合金腐蚀的腐蚀机制可能是EET-MIC和M-MIC同时存在,且与铜镍含量的差异相关。

This paper aims to investigate the influence of environmental factors(temperature)in the process of microbio¬logically influenced corrosion(MIC),the optimum temperature conditions for bacteria and a preliminary exploration of the MIC mechanism of copper alloys to provide a basis for microbial corrosion and protection.The growth of sulphate-reducing bacteria(SRB)and the corrosion state of copper-nickel surfaces in the medium at different temperatures(25℃,37℃and 45℃)were investigated by means of biological analysis,surface analysis and electrochemical testing techniques.Results revealed that the number of SRB cells first increased rapidly during the incubation period and then decreased gradually.The highest number of SRB cells detected and the highest amount of H_(2)S generated in the culture medium were found at 37℃.An undense biofilm was generated on the surface of the copper-nickel alloy and pitting pits were detected beneath the biofilm with a small pitting density.The area covered by the biofilm was greatest at 37℃ and the greatest average pitting pit depth,approximately 9.3μm,was detected at this temperature.At all temperatures,the OCP of specimens immersed in biological media moved in a generally positive direction,with the linear polarization resistance(R_(p))curve showing a tendency to rise and then fall.At 37℃,R_(p) values detected for specimens were the smallest.The conclusions are drawn from the analysis of the results.Temperature is able to influence the MIC behaviour of copper-nickel alloys caused by SRB.The best growth of SRB and the most severe corrosion of copper-nickel alloys occurs at 37℃.The corrosion mechanism of copper-nickel alloys caused by SRB may be both EET-MIC and M-MIC,which may be related to the difference in copper-nickel content.