烧结NdFeB表面Zn-Al涂层制备及耐腐蚀机理研究

Preparation and Corrosion Resistance of Zn-Al Coating on Sintered NdFeB Permanent Magnet

在烧结钕铁硼永磁试样表面制备了无铬锌铝烧结涂层,并确定了工艺参数。利用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、Fourier变换红外光谱(FTIR)、热重分析和差热综合热分析仪(TGDTA)对涂层的形貌、组成和形成机理进行了观察和研究。讨论了涂层耐腐蚀机制及其对磁体磁性能的影响。结果表明:Zn-Al涂层均匀地涂覆于NdFeB磁体表面,涂层厚度约为27μm,耐中性盐雾实验能力高达1000 h以上,对NdFeB基体起到阴极保护作用和物理屏蔽功能。

A Cr-free Zn-Al coating was prepared via a two-step process,namely spraying Zn-Al paste and subsequently baking,on the surface of sintered Nd-Fe-B permanent magnet,and which was further examined by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis,and differential thermal comprehensive thermal analyzer(TG-DTA)in terms of its morphology,composition,and formation mechanism of the coating.The corrosion behavior of the coated Nd-Fe-B magnet was studied via immersion testing in 3.5%NaCl solution,and neutral salt spray testing.The results show that Zn-Al coating is uniformly coated on the surface of the NdFeB magnet,the coating thickness is about27μm,while,its corrosion resistance to neutral salt spray testing is higher than 1000 h;In other word,the Cr-free Zn-Al coating can provide excellent cathodic protection and physical barrier for NdFeB permanent magnet.