【摘要】 以再生水管常用QT500-7球墨铸铁为研究对象，通过浸泡腐蚀试验和电化学腐蚀试验系统研究了再生水中的硫酸盐还原菌（SRB）和铁细菌（IOB）对其腐蚀行为的影响，并通过第一性原理计算从原子尺度揭示微生物腐蚀的微观机理。结果表明：在IOB/SRB共存再生水环境中浸泡288 h后，球墨铸铁的平均腐蚀速率达0.201 mm·a^-1，较在无菌再生水环境中提高约35.8%。微生物显著加速球墨铸铁的腐蚀进程，且在腐蚀前期（72～144 h）微生物的促进作用尤为显著。在IOB/SRB共存再生水环境中浸泡腐蚀后，表面腐蚀产物除了Fe₂O₃外，还存在FeS；腐蚀288 h后表面存在大量裂缝和孔洞，其中的石墨数量与未腐蚀球墨铸铁相比降低65.6%，降低程度大于在无菌再生水环境中的。在含微生物再生水溶液的电化学腐蚀液中或者经微生物环境预腐蚀后，球墨铸铁均表现出强的腐蚀倾向，在IOB/SRB共存再生水环境中预腐蚀288 h后的球墨铸铁在IOB/SRB共存再生水溶液中表现出最高的电化学腐蚀活性，其自腐蚀电位最低，为–1 201.7 mV，较未腐蚀球墨铸铁负移28.7%，自腐蚀电流密度高达1.811 3×10^-4 A·cm^-2。SRB代谢产物硫的存在使氧在Fe（110）表面的吸附能从–3.789 eV降至–7.504 eV，在热力学上更有利于铁的初始氧化腐蚀。更多还原

【Abstract】 Taking QT500-7 ductile iron,commonly used in reclaimed water pipes,as the research object,the effects of sulfate-reducing bacteria（SRB） and iron bacteria（IOB） in the reclaimed water on the corrosion behavior of the ductile iron were systematically investigated through immersion corrosion tests and electrochemical corrosion tests. The firstprinciples calculation was employed to reveal the microscopic mechanism of microbiological corrosion at the atomic scale.The results show that after immersion in the reclaimed water with coexisting IOB and SRB for 288 h,the average corrosion rate of ductile iron reached 0.201 mm·a^-1,which was approximately 35.8% higher than that in the sterile reclaimed water.Microorganisms significantly accelerated the corrosion process of ductile iron,and their promoting effect was particularly pronounced during the early stage of corrosion（72-144 h）. After immersion corrosion in the reclaimed water with coexisting IOB and SRB,in addition to Fe₂O₃,FeS was also present among the surface corrosion products. After corrosion for 288 h,a large number of cracks and holes appeared on the surface,and the amount of graphites in the ductile iron decreased by 65.6% compared to that of uncorroded ductile iron,which was a greater reduction than that observed in the sterile reclaimed water environment. Ductile iron exhibited a strong corrosion tendency either in the electrochemical corrosion solution of the reclaimed water solution containing microorganisms or after being pre-corroded in the microbial environment. Among all samples,the ductile iron pre-corroded in the reclaimed water with coexisting IOB and SRB for288 h showed the highest electrochemical corrosion activity when tested in the same reclaimed water solution with coexisting IOB and SRB. Its free-corrosion potential reached a minimum value of –1 201.7 mV,which was 28.7% more negative than that of uncorroded ductile iron,and the free-corrosion current density was as high as 1.811 3×10^-4 A·cm^-2.The presence of sulfur,a metabolite of SRB,reduced the adsorption energy of oxygen on the Fe（110） surface from –3.789 eV to –7.504 eV,thermodynamically favoring the initial oxidative corrosion of iron.更多还原