铜离子及电位对5083铝合金阴极保护行为的影响

Influences of Copper Ions and Potential on Cathodic Protection Behaviors of Aluminum Alloy 5083

目前有关船体防污涂料中的铜离子及阴极保护电位对铝合金船体的腐蚀电化学研究不够深入。通过极化试验、电化学阻抗谱(EIS)测试及外加恒电位阴极保护试验,并结合腐蚀形貌观察,研究了5083铝合金在有无Cu^(2+)的3.5%NaCl溶液中的极化及腐蚀特性,并结合不同电位下的阴极保护行为,探讨了其阴极保护电位范围。结果表明:防污剂中的Cu^(2+)沉积在铝合金基体表面会造成防腐蚀性能下降,降低铝合金舰船的阴极保护效果,应该避免Cu^(2+)的渗入;阴极保护电位过正,保护效果不佳,会造成铝合金表面发生点蚀,但若阴极保护电位过负,表面会发生析氢腐蚀,因此其合理的阴极保护电位范围为-1.00^-1.10 V(vs SCE)。

The corrosion behavior of aluminum alloy 5083 was studied in 3.5 % NaCl solutions with and without copper ions by dynamic polariza- tion technique, EIS technique, and immersion corrosion test, combined with corrosion morphology observation. The protection potential was also discussed by comparing the cathodic protection behaviors at different potentials. Results showed that copper ions in the antifouling agent deposited on the surface of aluminum alloy and caused the decrease of corrosion resistance of aluminum alloy 5083, so the infiltration of copper ions should be avoided. If cathodic potential was too noble, pitting corrosion would occur; if the cathodic potential was too negative, corrosion with hydrogen evolution would take place. So, the reasonable range of the protection potential should be from -1.00 V to -1.10 V（ vs SCE）.