烧结NdFeB磁体表面沉积Ni膜及其耐腐蚀性

为改善烧结钕铁硼(NdFeB)磁体的耐腐蚀性能,在磁体表面用磁控溅射方法制备了Ni薄膜。利用扫描电子显微镜(SEM)观察了Ni薄膜的组织形貌,利用电化学测试、中性盐雾试验(NSS)测试了镀膜样品的耐腐蚀性能,研究了溅射功率和负偏压对Ni薄膜组织结构、电化学性能和中性盐雾环境下耐腐蚀性能的影响。结果表明:Ni薄膜的厚度和致密性是影响其耐腐蚀性能的关键因素;随溅射功率增大,Ni薄膜厚度增大,但晶粒尺寸变大、致密性降低,耐腐蚀性能先升高后降低;加负偏压后,Ni薄膜厚度有所减小,但膜层表面更加光滑、组织更加致密均匀,因此镀膜样品耐腐蚀性能有所提高;在溅射功率为100~120 W、负偏压为150 V条件下制备的磁控溅射镀Ni样品具有最好的耐腐蚀性能。

Deposition of Ni Films on Sintered NdFeB Magnets and Its Corrosion Resistance

In order to improve the corrosion resistance of sintered NdFeB magnet,Ni film was deposited on the surface of magnets by magnetron sputtering.The surface morphology of Ni coating was characterized by scanning electron microscopy (SEM),and the corrosion resistance was investigated by electrochemical tests and neutral salt spray (NSS) test.Furthermore,the influences of sputtering power and negative bias on the surface morphology,electrochemical performance and corrosion resistance in neutral salt spray of Ni coating were studied.Results showed that the thickness and density of Ni coating were the key factors for the corrosion resistance.When the sputtering power increased,the thickness of Ni film increased,but the grain size also increased and the density decreased,leading to that the corrosion resistance increased firstly and then decreased.When the negative bias was applied,the Ni film becane smoother and more compact.Therefore,the corrosion resistance of film was improved.When deposited with a power of 100-120 W and a negative bias of 150 V,the magnet with Ni coating could achieve the optimal corrosion resistance.