Microstructure and corrosion resistance of Zn-Al/T8 superhydrophobic composite coating on sintered NdFeB magnet
(School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China)
Abstract: In order to improve the corrosion resistance, the Zn-Al/T8 (2-perfluorooctane ethyl acrylate) super- hydrophobic composite coating was prepared on the sintered NdFeB magnet by spin coating method coupled with plasma-enhanced chemical vapor deposition. The results show that the Zn-Al coating is mainly composed of lamellar Zn and Al phases with the thickness of approximately 28 μm. The contact angle of the Zn-Al/T8 coating reaches 151.78° with the rolling angle of 5.13°, indicating that the Zn-Al/T8 coating can provide a superhydrophobic surface. The Zn-Al and Zn-Al/T8 coatings have no significant effect on the magnetic properties of the NdFeB magnets. The Zn-Al coating improves the corrosion resistance of the NdFeB by sacrificing the anode, while the Zn-Al/T8 coating further enhances the corrosion resistance through the superhydrophobic surface. The Zn-Al/T8 composite coating has better salt spray resistance than Zn-Al coating. The Zn-Al/T8 superhydrophobic composite coating is a promising candidate for protecting the sintered NdFeB magnets.
Key words: microstructure; corrosion resistance; sintered NdFeB magnet; Zn-Al coating; superhydrophobic surface; spin coating method; plasma-enhanced chemical vapor deposition