2205双相不锈钢在淡化海水中的点蚀行为

摘要

Objective To study pitting corrosion behaviors of 2205 duplex stainless steel in level 1 reverse osmosis desalina-tion seawater, natural seawater and concentrated seawater.Methods Open circuit potential, alternating-current impedance, anode polarization curve and electrochemical frequency modulation (EFM) were used to study pitting corrosion behaviors of 2205 duplex stainless steel in different water (level 1 reverse osmosis desalination seawater, natural seawater and 1.6 times concen-trated seawater) at different temperature (60~90℃).Results The EOCP of 2205 duplex stainless steel changed to negative with the temperature increasing in level 1 reverse osmosis desalination seawater. In level 1 reverse osmosis desalination seawater at 80℃, the trend of pitting corrosion was found in the 1st day, and stable pitting occurred in the 28th day. The turbulent current of stainless steel was within 2 μA/cm2 at the beginning, it was near 12 μA/cm2 in the 41th day and the fluctuation amplitude was bigger.Conclusion The stability of passive film and the anti-corrosion of 2205 duplex stainless steel decrease with temperature increasing. In passive state, the corrosion ability is more severe in level 1 reverse osmosis desalination seawater than in artificial seawater. The sensibility to pitting corrosion increases with the increase of Cl–concentration.%目的 研究2205双相不锈钢在一级反渗透(RO)淡化海水、海水及浓缩海水中的点蚀行为.方法 运用开路电位、交流阻抗、阳极极化曲线和电化学频率调制技术研究2205双相不锈钢在不同温度(60~90℃)及不同海水(一级反渗透淡化海水、天然海水、1.6倍浓缩海水)中的点蚀行为.结果 2205双相不锈钢在一级RO淡化海水中,随温度升高,自腐蚀电位逐渐负移.在80℃的一级RO淡化海水中,在浸泡1 d时即有发生点蚀的倾向,在第28 d时已经发生了稳态蚀点.浸泡初期不锈钢的扰动电流为2μA/cm2之内,浸泡41 d的扰动电流接近12μA/cm2,且其值波动幅度更大.结论 随着温度的升高钝化膜稳定性降低,2205不锈钢耐蚀性降低.钝化状态下,其在一级RO淡化海水中比在海水中腐蚀严重,点蚀敏感性随Cl–浓度的升高而增加.