具有阴极电泳涂层AM50镁合金与钢接触电偶腐蚀

Galvanic Corrosion of AM50 Magnesium Alloy with Cathodic Electrophoretic Coating and Q235 Steel

研究了AM50裸镁合金及在裸镁合金上进行阴极电泳处理、硅烷预处理再阴极电泳处理3种不同样件与Q235钢螺栓连接在5%NaCl水溶液中浸泡的腐蚀规律,仔细观察对比3种不同表面状态的镁合金在不同时间浸泡后的表面腐蚀情况,测定各自的腐蚀速率,对腐蚀后的区域进行微观分析,并用腐蚀模型对其腐蚀的行为规律进行了解释。结果表明:镁合金可以通过阴极电泳处理获得耐蚀防护涂层,硅烷预处理可以进一步提高电泳膜层与基体的附着力,从而大大提高镁合金与钢螺栓接触的耐电偶腐蚀性;AM50镁合金与Q235钢螺栓接触电偶腐蚀的影响区面积不随腐蚀时间的延长而增大,其电偶腐蚀速度沿纵深方向(与螺栓接触方向)比横向的均匀腐蚀速度快。

The corrosion behavior has been studied on the three different coupled samples dipped in 5%NaCl solution. The coupled samples are Q235 steel with AM50 alloys, one without any coating, the other with cathodic E and cathodic electrophoretic coating on magnesium alloy. The surface morphologies of magnesium alloys with three different surface conditions have been observed in detail after dipped. The corrosion rates have been measured and the microstructure has been examined after ending the corrosion dip. The phenomena and law of galvanic corrosion have been explained by corrosion model. The results show that the cathodic electrophoretic coating could postpone the galvanic corrosion of magnesium alloy with steel effective and pre-silane treatment with much better protection. The affection area of galvanic corrosion did not increase with the dipping time. The corrosion developed more quickly along the coupled area than along the surface extending.