Abstract: The galvanic corrosion behavior of magnesium alloy and Q235 steel system different Sc/Sa(negative / anode area ratio) in simulated solution of tank bottom water in Daxie oil depot was studied by immersion experiment, electrochemical test and micro morphology observation method. The impact of different Sc/Sa on corrosion rate was found out, which curve and expression were fitted. The results show that, the corrosion rate of magnesium alloy anode increases greatly with the increasing of Sc/Sa, but the increasing of corrosion rate for the negative part is not obvious. Based on the galvanic current image, the galvanic current fluctuates and decreases with time. When Sc/Sa is 1.0 or 2.0, the galvanic current decreases obviously, which does not decrease obviously when Sc/Sa is 0.5. The corrosion rate is calculated by galvanic current. It is demonstrated that the galvanic current, as well as the corrosion degree increases linearly with the increase of Sc/Sa.

Key words: Anodic sacrifice protection, Tank bottom corrosion, Q235 steel, Magnesium alloy

摘要： 利用浸泡实验、电化学测试和微观形貌观测研究大榭油库罐底水模拟溶液下镁合金与Q235钢体系的电偶腐蚀行为，对比研究不同Sc/Sa（阴/阳极面积比）对镁合金/Q235钢电偶腐蚀的影响，探明Sc/Sa与腐蚀速率的关系，并拟合成曲线和表达式。结果表明，当电极阴极面积不变时，随着Sc/Sa的增加，镁合金阳极的腐蚀速率大幅度增加，阴极腐蚀速率虽有增长但并不明显。电偶电流图像中，电偶电流随时间变化出现波动和下降趋势，Sc/Sa为1.0、2.0时电偶电流下降明显，但Sc/Sa为0.5时电偶电流无明显下降。通过电偶电流计算腐蚀速率，发现随着Sc/Sa增大，腐蚀程度加重，腐蚀速率随Sc/Sa的增大呈线性增长。

关键词: 牺牲阳极保护, 罐底腐蚀, Q235钢, 镁合金