Study on the Corrosion Resistance Enhancement of NdFeB Magnets by ZnO-ZnAl Composite Coatings

钕铁硼(NdFeB)永磁材料凭借其优异的磁性能在电子、汽车、能源等领域获得了广泛应用。然而，该材料存在一个显著缺陷，即易受环境因素影响而发生腐蚀，这限制了其使用的长期稳定性。为了有效提升NdFeB磁体的耐腐蚀性能，科研人员开发了多种涂层体系，如金属镀层、陶瓷涂层和有机涂层等。本文针对烧结NdFeB磁体，采用刷涂法制备Zn层、Al层、ZnAl复合涂层，进一步地在ZnAl涂层体系中引入纳米氧化锌(ZnO)颗粒进行改性处理。重点关注了各类涂层的微观组织形貌，深入探讨其抗腐蚀性能、稳定性及磁性能方面的作用机制。此外，本文通过电化学测试、中性盐雾试验等手段，系统评估了上述涂层的防护效果。研究结果表明，ZnO-ZnAl复合涂层在提高磁体耐腐蚀性方面具有优异表现，能够有效延长NdFeB磁体的使用寿命。NdFeB permanent magnets have been widely used in electronics, automotive, and energy industries due to their excellent magnetic properties. However, a significant drawback of NdFeB magnets is that they are easily affected by environmental factors. Which limits the long-term stability in use. In order to effectively improve the corrosion resistance of NdFeB magnets, various coating systems have been developed, such as metallic coatings, ceramic coatings, and organic coatings. In this paper, Zn coating, Al coating and ZnAl composite coating are prepared by brush coating on sintered NdFeB magnets. Furthermore, Nano-ZnO particles are further introduced into the ZnAl coating system for modification. We focused on the microstructure morphology of various coatings, and deeply explored the mechanism in terms of corrosion resistance, stability, and magnetic properties. Furthermore, electrochemical tests and neutral salt spray (NSS) tests were conducted to systematically evaluate the protective performance of the coatings. The results demonstrated that the ZnO-ZnAl composite coating exhibited superior corrosion resistance, significantly extending the service life of NdFeB magnets.