SRB对X70管线钢在近中性pH溶液中腐蚀行为的影响

Effect of SRB on Corrosion Behavior of X70 Pipeline Steel in Near-neutral p H Solution

采用电化学阻抗、动电位极化及微观观察法,对比了有、无硫酸盐还原菌（SRB）的情况下X70管线钢在近中性pH溶液（NS4）中的腐蚀行为,研究了SRB生长周期对X70钢腐蚀行为的影响。结果表明：X70钢在无菌溶液中腐蚀速率随时间增加呈单一增大的趋势。SRB在NS4溶液中的生长周期分为对数繁殖期（1~3 d）,稳定生长期（4~7 d）和衰亡期（7~14 d）3个阶段。SRB对X70钢在NS4溶液中腐蚀速率的影响与其在溶液中生长规律有关：当SRB处于对数繁殖期和稳定期时,X70钢表面覆盖一层致密的生物膜,对钢起到了保护作用,此时X70钢的腐蚀速率比无菌条件下低;当SRB进入衰亡期,X70钢腐蚀的程度比无菌介质中严重,钢表面腐蚀产物逐渐增多,生物膜出现破裂,腐蚀速率增大。

The corrosion behavior of X70 pipeline steel in a near-neutral p H solution NS4 with and without sulfate-reducing bacteria（SRB） respectively was studied by means of electrochemical impedance spectroscopy（EIS）, potentiodynamic polarization and microscopic observation. The results showed that the corrosion rate of X70 steel increased with time in NS4 solution without SRB;The growth process of the SRB in the solution NS4 can be divided into three phases： logarithmic phase（1~3 d）, stable growth phase（4~7 d） and death phase（7~14 d）. The influence of SRB on the corrosion rate of X70 pipeline steel in the solution NS4 with SRB was related to the growth process of SRB. A compact biological film could form on the steel surface in the stage of logarithmic phase and stable growth phase, which was conducive to enhancing the protectiveness of corrosion products on the steel and therewith the corrosion rate of X70 steel in the NS4 with SRB was lower than that without SRB. While the corrosion of X70 steel in the NS4 with SRB in the death phase was more serious than that without SRB, while the scale of corrosion products became thicker gradually, then the biological film broken and therewith the corrosion rate increased.