海洋大气湿度对LY12铝合金初期腐蚀的影响

INFLUENCE OF MARINE ATMOSPHERE HUMIDITY ON INITIAL CORROSION OF LY12

根据表面带Cl-的LY12铝合金在模拟海洋大气环境中的腐蚀形貌、增重、最大点蚀深度以及腐蚀体系的自腐蚀电位、交流阻抗等变化,分析相对湿度对其初期腐蚀行为的影响.结果表明,表面含1 mg/dm2Cl-的LY12铝合金在大气环境的相对湿度<70%时,几乎不发生腐蚀;在相对湿度>70%时,发生明显点蚀;在相对湿度>90%时,腐蚀较严重.腐蚀增重随相对湿度增大而增大,不同相对湿度条件下的腐蚀增重-时间曲线较好地符合Boltz-man模型.相对湿度为90%左右,倾向于出现最深的蚀坑.LY12铝合金腐蚀形貌的变化几乎不会引起其厚水膜高Cl-自腐蚀体系的电位改变.其厚水膜高Cl-自腐蚀体系的Nyquist图是实部收缩的单一容抗弧.

Series of accelerated corrosion tests were conducted in simulated marine atmosphere to study initial corrosion of LY12 aluminum alloy （ corresponds to USA 2024） at different humidity. The change of corrosion morphology ,weight gain, maximum pitting depth and electrochemical parameters （corrosion potential, AC impedance） were inspected in corrosion course. Results showed that for Cl^- deposition about 1 mg/dm^2 and temperature 25℃, LY12 aluminum alloy did not erode under relative humidity 60%, can develop pitting corrosion in 31 days above relative humidity 70%, erodes seriously not only in weight gain, but also in pit depth above relative humidity 90%. In marine atmosphere, the relationship of LY12 weight gain -time at different humidity fitted model Boltzman. For pitting surface of LY12 at different humidity in marine atmosphere,Nyquist graph was single arc of capacitance resistance and the shape of arc was identical with retractile real part.