交流电和微生物共同作用下Q235钢的腐蚀行为

CORROSION BEHAVIOR OF Q235 STEEL UNDER THE INTERACTION OF ALTERNATING CURRENT AND MICROORGANISMS

采用微生物分析方法研究了交流电(均方根电流密度50 A/m^2,频率50 Hz)对土壤浸出液中硫酸盐还原菌(sulfate reducing bacteria,SRB)的生理影响;通过开路电位、动电位极化曲线、电化学阻抗谱等方法研究了交流电和微生物共同作用对Q235钢的电化学行为的影响;利用SEM观测了试样表面腐蚀产物和腐蚀微观形貌.结果表明,均方根电流密度为50A/m^2,频率为50 Hz的正弦交流电对SRB的生理未造成很大影响,但交流电的交变电场降低了微生物膜的吸附性,促进了微生物膜的脱附.实验前期,活性生物膜抑制金属腐蚀,实验后期,微生物代谢产物促进金属腐蚀.金属在交流电作用下,由于整流效应、交变电场作用以及点蚀的自催化效应等,腐蚀速率加快,腐蚀产物疏松.

With the rapid development of electricity and transport industry, more and more buried pipelines are parallel or cross to the high voltage transmission line and the electrified railway. In this work, microbiological analysis method was used to investigate the effect of alternating current （AC） on the physiology of sulfate reducing bacteria （SRB）. Electrochemical methods, including open circuit potential, potentiondynamic polarization curves and electrochemical impedance spectroscopy （EIS） on Q235 steel samples, were performed in soil leaching solu- tion to study the electrochemical behavior with the presence or absence of AC and SRB. The corrosion morphology was observed by scanning electron microscopy （SEM）. The results indicate that the AC which current density is 50 A/m^2 and frequency is 50 Hz has only a small impact on the growth of SRB, but its alternating electric field can re- duce the adsorption and promote the desorption of the biofilm. During the initial experiment, the active biofilm can inhibit the corrosion of Q235 steel due to the electronegativity and the physical barrier, but the microbial metabo- lites would promote the corrosion during the later experiment without active biofilm. AC can improve the corro- sion rate and lead the corrosion products loose because of the rectifying effect, the alternating electric field and the self catalytic effect of pitting corrosion.