目的 采用悬浮液等离子喷涂技术，在烧结Nd-Fe-B磁体表面制备结构完整、厚度可控、结合力较强的Dy2O3涂层，并通过晶界扩散提高Nd-Fe-B磁体的矫顽力。方法 制备Dy2O3悬浮液，在烧结Nd-Fe-B表面，利用悬浮液等离子喷涂技术制备Dy2O3涂层。利用激光粒度仪测试粉体粒度。采用光学显微镜、扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)对Dy2O3涂层的显微形貌、组织结构和物相组成进行分析。通过涂层附着力自动划痕仪测试涂层的结合力。利用NIM-2000H自动磁性能测量仪对烧结Nd-Fe-B磁体的磁性能进行测试分析。结果 875 ℃的晶界扩散Dy2O3使磁体的矫顽力从1161.19 kA/m增加到1277.74 kA/m，剩磁下降0.01 T。矫顽力得到较高提升，且剩磁略微下降。SEM和EDS分析结果表明，晶界组织形貌的改善和(Nd,Dy)2Fe14B外延层的形成是矫顽力提升的主要原因。结论 证实了悬浮液等离子喷涂-晶界扩散技术能够控制涂层厚度，绿色高效地制备高矫顽力烧结Nd-Fe-B磁体

The suspension plasma spraying technology is used to prepare a Dy2O3 coating with complete structure, controllable thickness and high bonding force on the surface of the sintered Nd-Fe-B magnet, and the coercivity of the Nd-Fe-B magnet is improved by the grain boundary diffusion. The method is to prepare Dy2O3 suspension, and prepare Dy2O3 coating on the surface of sintered Nd-Fe-B by using suspension plasma spraying technology. The particle size of the powder is tested by a laser particle size analyzer. The microscopic morphology, structure and phase composition of the Dy2O3 coating is analyzed by the optical microscope, scanning electron microscope (SEM), energy spectrometer (EDS), and X-ray diffractometer (XRD). The coating adhesion is tested by the coating adhesion automatic scratch tester. The magnetic properties of sintered Nd-Fe-B magnets were tested and analyzed by the NIM-2000H automatic magnetic property measuring instrument. The result is that the grain boundary diffusion Dy2O3 at 875 ℃ increases the coercivity of the magnet from 1161.19 kA/m to 1277.74 kA/m, and the remanence decreases by 0.01 T. The coercivity is improved higher and the remanence decreases slightly. SEM and EDS analysis results show that the improvement of grain boundary structure and the formation of (Nd,Dy)2Fe14B epitaxial layer are the main reasons for the increase in coercivity. It is proved that the suspension plasma spraying-grain boundary diffusion technology is a green and efficient technology for preparing high-coercivity sintered Nd-Fe-B magnets that can control the thickness of the coating.