7B04铝合金和30CrMnSiA钢短期腐蚀的电化学行为研究

摘要

Objective To study electrochemical performance of 7B04 Aluminum alloy and 30CrMnSiA alloy steel samples. Methods The electrochemical test, scanning electron microscopy (SEM), corrosion pit depth test were adopted to analyze and test whether 7B04 Aluminum alloy and 30CrMnSiA alloy steel samples were immersed in natural seawater or not, to obtain micro-morphology and corrosion pit depth and electrochemical performance with or without rust on the surface. Results The self-corrosion current of 7B04 aluminum alloy and 30CrMnSiA steel increased with the increase of NaCl concentration. Because of obvious potential difference between them, galvanic corrosion occurred after contacting. The galvanic current was related to the ratio of the cathode to anode area and the concentration of NaCl. Increase of the cathode to anode area ratio or NaCl concentration would lead to intensifying of galvanic effect. After short immersion in seawater, the rust layer on the surface of 7B04 aluminum alloy did not inhibit the corrosion, but increased the self–corrosion. However, the galvanic effect was weakened in deed. Conclusion Coastal equipment in use process should be avoided to work under the aluminum alloy in the rust layer.%目的 研究7B04铝合金和30CrMnSiA合金钢试样的电化学性能.方法 采用电化学实验、扫描电子显微镜(SEM)、腐蚀坑深度测试分别对7B04铝合金和30CrMnSiA合金钢试样在是否经过天然海水浸泡的情况下进行测试分析,得到微观腐蚀形貌和腐蚀坑深度以及试样表面不带锈和带锈时的电化学性能.结果随着NaCl浓度增大,7B04铝合金和30CrMnSiA钢的自腐蚀电流变大,两者之间存在明显的电位差,接触后会发生电偶腐蚀.电偶电流与阴阳极面积比和NaCl浓度有关,阴阳极面积比增大或NaCl浓度升高均会导致电偶效应增强.经过海水短期浸泡后,7B04铝合金表面的锈层不仅没有起到抑制腐蚀的作用,反而使自腐蚀加重,但电偶效应确实有所减弱.结论 沿海设备在使用过程中应竭力避免铝合金在锈层下工作.