NdFeB永磁体表面磁控溅射铝防护镀层性能研究

目的研究一种NdFeB永磁体表面腐蚀防护技术。方法采用磁控溅射技术,在烧结NdFeB永磁体表面沉积一层纯铝防护薄膜,然后对纯铝薄膜进行阿洛丁化学转化复合处理,表征膜层的表面和截面形貌,并研究结构及耐腐蚀性能。结果沉积的Al中间层和Al薄膜均结构致密,膜/基界面平整,膜层的自腐蚀电流密度为3.5×10-6A/cm2,说明纯Al薄膜能够对NdFeB永磁体提供有效的防护。阿洛丁化学转化可使铝薄膜表面更加致密,自腐蚀电流密度低至7.9×10-7A/cm2,进一步提高了纯铝薄膜的防护性能。结论 NdFeB永磁体表面磁控溅射镀铝是一种有效且环保的防护技术,可用于替代不环保的电镀防护。

Corrosion Resistance of Aluminum Film on NdFeB Permanent Magnets by Magnetron Sputtering

Objective To study a kind of technology that can be used to protect the NdFeB permanent magnets. Methods Aluminum film was deposited by magnetic sputtering on NdFeB permanent magnets. Surface and cross-section images of aluminum film were observed by a scanning electron microscope ( SEM) . The corrosion properties of samples were investigated and compared by potentiodynamic polarization and neutral salt spry test. Results The results indicated that the corrosion current density of NdFeB specimen coated with pure Al film was approximately 3. 5 X10^-6A / cm²,for the sample coated with Al film and Anoding chemical conversion film,the corrosion current density was 7. 9 X10^-7A / cm² , which was about 2 orders of magnitude lower than that of the bare NdFeB magnet. The results showed that the pure Al film could provide good protection for the NdFeB substrate,and the Anoding chemical conversion could make the Al film much denser. Conclusion The aluminum coating prepared by magnetic sputtering could effectively protect the NdFeB magnets, and it is a good substitute for the current electroplating technology.