硫酸盐还原菌的生长过程对X70钢腐蚀行为的影响

摘要

在模拟海水中接种了硫酸盐还原菌(SRB)，测得其生长曲线以及该模拟海水pH和溶解氧浓度随时间的变化曲线；在接种及未接种SRB模拟海水中采用三电极体系测得X70钢的开路电位、极化曲线和电化学阻抗谱，分析了SRB不同生长阶段对其腐蚀行为的影响.结果表明：SRB的生长经历了数量呈指数增长时期(0~5d)，数量达到最大的稳定生长期(6~10d)和数量减少的衰亡期(11~14d)三个阶段；接种SRB模拟海水的pH稳定在6．19~7．18之间，溶解氧浓度随时间的延长呈下降趋势；在接种SRB模拟海水中，随着SRB数量的增多， X70钢的自腐蚀电流密度逐渐增加；在接种SRB模拟海水中试样的表面点蚀坑较为明显，且随时间的延长点蚀坑直径有所增大.%Sulfate reducing bacteria (SRB)were added in simulated sea water,and then the growth curve of SRB,the pH value and dissolved oxygen concentration of the simulated sea water were measured;the open circuit potential,polarization curve and electrochemical impedance spectrum of X70 steel in the simulated sea water with and without SRB were obtained by three-electrode system,and the influence of SRB growth process on the corrosion behavior of X70 steel was also analyzed.The results show that the growth of SRB went through three stages of exponential growth period (0-5 d)with the exponential increase of SRB amount,stable growth period (6-10 d) with the largest SRB amount and decline period (11-14 d)with the decrease of SRB amount.The pH value of the simulated sea water with SRB was between 6.19 and 7.18 and the dissolved oxygen concentration decreased with the extension of time.In the simulated sea water with SRB,the free corrosion current density of X70 steel increased gradually with the SRB amount increasing.The corrosion pits were more obvious on the sample surface in the simulated sea water with SRB and the diameter of corrosion pit increased with the increase of time.