循环冷却水中2507双相不锈钢微生物腐蚀研究

Microbiological Corrosion Characteristics of 2507 Duplex Stainless Steel in Circulating Cooling Water

目的研究2507双相不锈钢在循环冷却水模拟溶液(添加微生物SRB+IOB)中的腐蚀特征,确定其腐蚀机理。方法模拟某炼油厂循环冷却水溶液,采用SEM,EDS和电化学测试等手段分析2507双相不锈钢在SRB+IOB循环冷却水中浸泡不同时间后的腐蚀产物形貌及其电化学腐蚀情况。结果2507双相不锈钢的腐蚀速率很低,属于轻度腐蚀;在循环冷却水模拟溶液中的阳极极化曲线具有明显的钝化区,且钝化膜具有良好的自修复能力;腐蚀倾向随时间增加先增大后减小,腐蚀速率随时间增加先减小后增大。结论 SRB和IOB及其代谢活动与Cl-协同作用是点蚀的主要原因;2507双相不锈钢具有良好的钝化性和耐微生物腐蚀性能。

Objective To study the corrosion characteristics and determine the corrosion mechanism of 2507 duplex stainless steel in circulating cooling water simulated solution containing SRB＋IOB. Methods The circulating cooling water in a refinery was simulated, and the morphology of corrosion products and the corrosion mechanism of electrochemical of 2507 duplex stainless steel in circulating cooling water simulated solution containing SRB＋IOB were analyzed by SEM, EDS and electrochemical impedance spectroscopy （ EIS） and polarization curves after soaking for different days. Results The corrosion rate of 2507 duplex stainless steel was very low, belonging to mild corrosion. Anodic polarization curves of 2507 duplex stainless steel in circulating cooling wa-ter simulated solution showed significant passivation regions and the passivation film had a good self-healing ability. With increasingcorrosion time, the corrosion tendency first increased and then decreased while the corrosion rate first decreased and then in-creased. Conclusion The main cause for the pitting corrosion was the synergic effect of the surface adsorbed SRB and IOB as well as their metabolic activities with Cl-. 2507 duplex stainless steel had a good passivation performance and resistance to microbiologi-cal corrosion.