温度对工业纯钛与低合金钢电偶腐蚀行为的影响

Influence of Temperature on Galvanic Corrosion of Commercially Pure Titanium/Low Alloying Steel in Seawater

采用多通道零电阻电流计(DL-1)与极化曲线等电化学手段研究了工业纯钛TA2与低合金钢921A在不同温度海水中电偶腐蚀行为规律,采用扫描电镜(SEM)观察表面形貌并利用X射线衍射仪(XRD)分析腐蚀产物组分。结果表明,TA2与921A偶接时有显著的电偶腐蚀现象,其中921A为阳极,发生Fe的溶解,TA2为阴极,发生溶解氧的还原;偶对的腐蚀控制步骤为阴极氧还原反应的氧扩散步骤;温度升高加剧电偶腐蚀,阳极的腐蚀电流密度与温度之间呈指数递增趋势。

The galvanic corrosion in seawater for the couple of commercially pure titanium （TA2） and low alloying steel （921 A） was studied under open circuit conditions by using potentiodynamic polarization measurements and a multi-pass zero-resistance ammeter （DL-1）, and then the effect of elevated temperature was examined. The surface morphology of the tested samples was character- ized by means of scanning electron microscopy （SEM with EDX） and X-ray diffraction （XRD）. Re- suits show that 921A acts as the anode and TA2 acts as the cathodes in galvanic couple. Galvanic corrosion process involves a higher rate of anodic dissolution for 921A and dissolved oxygen reduc- tion reaction on cathodes. The strength of the galvanic coupling effect is typically controlled by the oxidation rate of 921A. The galvanic corrosion of TA2/921A increased with the increasing tempera- ture. The galvanic current density is estimated to exponentially increase with increasing tempera- ture.