稀土元素(La,Ce)对镁合电偶腐蚀的影响

针对镁合金化学和电化学活性较高,与其他金属材料接触时易产生电偶腐蚀的特点,主要研究了其电偶腐蚀特性及环境因素的影响规律.采用电化学方法通过测定电偶电流密度,研究了添加约1%混合稀土RE(45%La,50?)的AZ91合金在NaCl溶液中与A3钢、紫铜偶接时的电偶腐蚀行为,探讨了溶液中氯离子浓度、偶接金属种类以及阴阳极面积比对电偶电流密度JgMg的影响.结果表明:Cl-浓度增大,JgMg变大;阴阳极面积比越大,JgMg也越大;偶接金属A3钢比紫铜更易促进镁合金的腐蚀;稀土La,Ce的添加使电偶腐蚀有效距离变窄.

Effect of Rare Earth ( La, Ce ) on Galvanic Corrosion of AZ91 Magnesium Alloy

The galvanic corrosion behavior of AZ91 magnesium alloy and its dependence on environmental factors were investigated with respect to the high chemical and electrochemical activity of the Mg alloy.Thus the effect of mixed rare earth(45%La,55%Ce,mass fraction) addition by 1% on the corrosion behavior of AZ91 magnesium alloy coupled with A3 steel or copper in NaCl solution was studied.An electrochemical method was used to measure the current density of the Mg alloy coupled with different metals,while the influences of Cl~(-) concentration,the coupled metal,and the cathode to anode surface area ratio(Sc/Sa) on the coupling current density were discussed.The results showed that the coupling current density increased with increasing concentration of Cl~(-) and Sc/Sa.The A3 steel as the coupling metal was more powerful in promoting the corrosion of the AZ91 alloy than the copper,while the introduction of the mixed rare earth contributed to decrease the effective galvanic corrosion range of the Mg alloy.