阳极钝化电位对黄铜表面钝化膜半导体性能的影响

目的研究黄铜在不同阳极钝化电位下形成的钝化膜的半导体性能。方法通过动电位极化曲线获取黄铜在硼酸盐缓冲溶液中的维钝电位区间,并选取3个钝化电位值对黄铜进行钝化处理,采用电化学阻抗谱和Mott-Schottky半导体理论研究阳极钝化电位对钝化膜半导体性能的影响,并进一步利用PDM模型进行点缺陷扩散系数的计算。结果黄铜在硼酸盐缓冲溶液中有明显的钝化区间,不同钝化电位对应的Mott-Schottky直线斜率均为负值,且点缺陷扩散系数均为10-14数量级。随着阳极钝化电位的正移,钝化膜的阻抗值不断增加,受主密度降低,平带电位变小,空间电荷层厚度增加。结论黄铜在不同钝化电位下形成的钝化膜均表现出p型半导体的特性,膜中载流子以空穴为主,随着阳极钝化电位的正移,钝化膜的导电性能变差,耐蚀性能增强,对基体的保护作用更好。

Semi-conducting Property of Passive Film Formed on Brass under Different Passivation Potential

Objective To investigate the semi-conducting property of passive films formed on brass under different passivation potential. Methods The passivation range of brass in borate buffer solution was obtained by potentiodynamic polarization curves, and three passivation potentials were chosen. The electrochemical impedance spectroscopy and Mott-Schottky theory were used,and the diffusion coefficient of passive film was calculated using PDM. Results The brass showed obvious passivation state in borate buffer solution. The Mott-Schottky plots were linear with a negative slop. With the passivation potential moving towards positive, the film impedance increased, the acceptor density and the flat potential decreased, the space charge layer thickness increased, and the order of magnitude of point defect diffusion coefficient was 10^-14. Conclusion Under different passivation potential, the passive films on the brass surface showed the property of p-type semiconductor, the majority of the carriers in the passive film were holes. With the passivation potential moving towards positive, the conductivity of the film decreased and the corrosion resistance was improved, resulting in better protection.