溶液中氧化亚铁硫杆菌对球墨铸铁的腐蚀行为影响研究

Effect of Thiobacillus Ferrooxidans on Corrosion Behavior of Ductile Iron in Solution

采用失重腐蚀实验和电化学方法,结合腐蚀形貌分析与产物物相分析研究了氧化亚铁硫杆菌(T.f)对球墨铸铁腐蚀行为的影响。研究结果表明:T.f在9K培养基中0~47 h处于生长停滞期,47 h~159 h为指数生长期,159 h~202 h为稳定生长期,202 h后进入衰亡期,符合细菌生长规律;相对于无菌体系,铸铁在有菌体系中的失重腐蚀速率显著增大,同一时间内,浸泡铸铁挂片的有菌溶液pH值最高,浸泡铸铁挂片的无菌溶液pH值次之,细菌培养基的pH值最小。T.f的存在使铸铁表面覆盖物状态不断发生变化,导致其双电层电容发生较大波动。经同样的浸泡时间,铸铁在T.f体系中腐蚀后的表面腐蚀坑数量更多,腐蚀坑直径更大;T.f体系和无菌体系的腐蚀产物均为黄钾铁矾,说明T.f的存在仅是加速了溶液中铸铁的腐蚀过程。

The influence of thiobacillus ferrooxidans(T.f)on the corrosion behavior of nodular cast iron is studied by weightless corrosion experiment and electrochemical method combining with corrosion morphology analysis and product phase analysis.The results show that the growth of T.f in 9 K medium is stagnant for 0 h~47 h,exponential growth for 47 h~159 h,stable growth for 159 h~202 h,and decay after 202 h,in line with the law of bacterial growth.Comparing with the aseptic system,the weightless corrosion rate of cast iron in the bacteriological system increase significantly.At the same time,the pH value of the bacterial solution soak in cast iron is the highest,the p H value of the sterile solution soak in cast iron is the second,and the pH value of the bacterial culture medium is the lowest.The presence of T.f makes the surface cover of cast iron change constantly,which causes the double layer capacitance to fluctuate greatly.After the same soaking time,the surface corrosion pits of cast iron corrode in T.f system are more and the diameter of corrosion pits is larger.The corrosion products of both T.f system and aseptic system are jarosite,indicating that T.f only accelerate the corrosion process of cast iron in solution.