Cu-7Ni-7Al合金在人工海水中的腐蚀特征

Corrosion characteristics of Cu-7Ni-7Al alloy in artificial seawater

通过静态全浸试验、扫描电镜(SEM)和电化学测试探讨了Cu-7Ni-7Al合金在人工海水中腐蚀性能。结果表明:在人工海水中,Cu-7Ni-7Al合金的腐蚀速率随浸泡时间的延长而降低,在浸泡144 h前迅速下降,由24 h时的0.0782 g·m^(-2)·h^(-1)降到144 h时的0.0253 g·m^(-2)·h^(-1),在144 h后趋向平稳;合金表面膜的紧密性和厚度逐渐增加,表明合金的耐蚀性能得到改善,但是也存在裂纹和点蚀;电荷转移电阻R_(ct)随着浸泡时间的延长而增加,由3.03×10~4Ω·cm^2增加至9.78×10^(4 )Ω·cm^2;在整个浸泡阶段,自腐蚀电位受表面膜状态影响而波动不明显,电流密度随浸泡时间延长而逐渐降低,在144 h前下降较快,由0 h时的20.13μA/cm^2降到144 h时的6.42μA/cm^2,在144 h后趋向稳定,于240 h达到最小,为5.81μA/cm^2。

The corrosion properties of Cu-7 Ni-7 Al alloy in artificial seawater were investigated by static immersion test, scanning electron microscopy(SEM) and electrochemical test. The results show that the corrosion rate of the Cu-7 Ni-7 Al alloy decreases with the increase of immersion time in artificial seawater and decreases rapidly in the first 144 h, from 0.0782 g·m^-2·h^-1after immersion for 24 h to 0.0253 g·m^-2·h^-1 after immersion for 144 h, and tends to be stable after 144 h. The compactness and thickness of the film on the surface of the alloy increase gradually, which indicates that the corrosion resistance of the alloy is improved, but there are also cracks and pitting. With the increase of immersion time, the charge transfer resistance(Rct) of the alloy increases from 3.03×104 Ω·cm^2 to 9.78×104 Ω·cm^2. During the whole immersion stage, the self-corrosion potential fluctuates little attributed to the surface film state, and the current density of the alloy decreases gradually with the increase of immersion time, and decreases more quickly in the first stage, from 20.13 μA/cm^2 after immersion for 0 h to 6.42 μA/cm^2 after immersion for 144 h, and tends to be stable after 144 h, and reaches its minimum after 240 h, which is 5.81 μA/cm^2.