铜合金在模拟深海低温条件下的电偶腐蚀行为研究

目的研究管路铜合金在模拟深海低温条件下的电偶腐蚀行为。方法对舰船常用的管路材料B10合金与管路泵阀材料镍铝青铜偶接后的电偶电位和电偶电流进行监测,对其电偶腐蚀速率和系数进行计算,评价电偶腐蚀敏感性。最后,结合动电位极化曲线的测量探讨温度对偶对阴阳极铜合金腐蚀行为的影响。结果 B10合金为偶合阴极,受到保护,而镍铝青铜为偶合阳极,加速腐蚀。在深海低温条件下,偶对的电偶腐蚀效应和腐蚀速率均较低,表现出轻度电偶腐蚀敏感性。结论温度的降低一方面会减缓B10合金Cu2O钝化膜中Ni的占位,降低膜层电位,同时减缓镍铝青铜的脱Al腐蚀,从而缩小了两者自腐蚀电位的差异,降低电偶腐蚀效应;另一方面,温度的降低会减缓阳离子向溶液本体中的迁移,造成腐蚀产物在电极表面的积累,抑制阳极溶解过程,也会大幅降低氧的扩散速率,造成阴极反应阻力的增大,降低电偶腐蚀速率。

Study on Galvanic Corrosion Behavior of Copper Alloys in Simulated Deep Sea Low-temperature Environment

Objective To study the behavior of galvanic corrosion in simulated deep sea low-temperature environment of the copper alloys. Methods The galvanic potential and galvanic current of the seawater pipe material B10 alloy commonly used in the ships and the pump valve material nickel-aluminum bronze were monitored, and their galvanic corrosion rate and coefficient were calculated, to evaluate their sensitivity to galvanic corrosion. Finally, the influence of temperature on the galvanic corrosion behavior of the copper alloys was discussed in combination with potentiodynamic polarization measurements. Results As the result of coupling, B10 alloy acting as the coupled cathode was prevented from corrosion, while nickel aluminum bronze became the sacrificial anode with accelerated corrosion. Meanwhile, both the galvanic corrosion effect and the galvanic corrosion rate of the coupled copper alloys were low at the low temperature of the simulated deep sea environment, showing insignificant galvanic corrosion sensitivity. Conclusion On one hand, the decrease of seawater temperature could resist the occupation of cation vacancies or the replacement of Cu ions of Cu2O film formed on B10 alloy by Ni ions, and reduce the film potential, meanwhile, it could slow down the Al-removing corrosion of nickel-aluminum bronze, and subsequently reduce the difference of null-circuit potentials of the pair, leading to the attenuation of galvanic corrosion effect. On the other hand, lower temperature could also slow down the migration of cations to the solution matrix, resulting in accumulation of corrosion products on the surface of the electrodes and inhibition of anodic dissolution, besides, it could greatly decrease the diffusion rate of oxygen, resulting in increased reaction resistance and decreased galvanic corrosion rate.