纳米涂层/铝合金在不同pH值的海水溶液中的腐蚀行为研究

Corrosion Behavior of Nano-coating/Aluminum Alloy in Seawater Solution with Different pH Values

目的评价纳米涂层/铝合金在不同pH值海水溶液中的腐蚀行为。方法通过测试纳米涂层/铝合金试样在不同pH值海水溶液中的EIS值,分析试样阻抗谱图及Bode谱图的演化规律,建立不同EIS图谱的不同电极阻抗模型,并采用ZView软件解析涂层体系不同时期的电化学阻抗谱,获得涂层电阻的变化趋势,及不同pH值海水浸泡的纳米涂层体系腐蚀失效速度。结果随着浸泡时间的增加及pH值的降低,纳米涂层/铝合金体系腐蚀损伤失效速率在浸泡前期整体趋势增大,但中后期由于腐蚀产物逐渐堵塞了涂层的微孔,腐蚀介质向铝合金表面渗透的速率逐渐减小。结论pH为2.0海水浸泡下的3涂层失效最快,其次是pH为4.0海水浸泡下的2涂层,最后为p H为6.0海水浸泡下的1涂层,该涂层体系应采用等效电路模型C进行拟合。

The paper aims to evaluate the corrosion behavior of nano-coating/aluminum alloy in seawater solution with different pH values.Through testing the EIS value of nano coating/aluminum alloy in sea solution of different pH values,the evolution law of impedance spectra and Bode spectrogram of samples were analyzed to establish different electrode impedance models of different EIS spectra,and the ZView software was used to analyze electrochemical impedance spectroscopy of the coating system in different periods,to obtain the change tendency of the coating resistance and the corrosion failure rate of the nano coating system in sea solution of different pH values.With the increase of immersion time and the decrease of pH value,the corrosion damage failure rate of nano-coating/aluminum alloy system generally increased in the early immersion period;but in the middle and later stages,as corrosion products gradually blocked the coating pores,the penetration rate of corrosion medium to the surface of aluminum alloy gradually decreased.For the nano-coating systems with different pH values,the corrosion failure rate is as follows:coating 1 immersed in seawater of pH 2.0 failed the fastest,followed by coating 2 immersed in seawater of pH 4.0,and finally followed by coating 1 immersed in seawater of pH 6.0.The coating systems should be fitted with equivalent circuit model C.