雾化喷涂沉积对晶界扩散Nd-Fe-B磁性能和微观结构的影响  

Influence of Spray Coating Deposition on Magnetic Properties and Microstructure of Grain Boundary Diffusion Nd-Fe-B Magnets

作　　者：刁树林 罗阳 彭海军[1,2,3] 林笑 董义[4] 伊海波 吴树杰 张帅 于敦波 Diao Shulin;Luo Yang;Peng Haijun;Lin Xiao;Dong Yi;Yi Haibo;Wu Shujie;Zhang Shuai;Yu Dunbo(National Engineering Research Center for Rare Earth Materials,GRINM Group Co.,Ltd,Beijing 100088,China;GRIREM Advanced Materials Co.,Ltd,Beijing 100088,China;General Research Institute for Nonferrous Metals,Beijing 100088,China;Baotou Tianhe Magnetics Technology Co.,Ltd,Baotou 014010,China)

机构地区：[1]有研科技集团有限公司稀土材料国家工程研究中心,北京100088 [2]有研稀土新材料股份有限公司,北京100088 [3]北京有色金属研究总院,北京100088 [4]包头天和磁材科技股份有限公司,内蒙古包头014010

出　　处：《稀有金属材料与工程》2022年第10期3638-3645,共8页Rare Metal Materials and Engineering

基　　金：Beijing Youth Top-notch Team Support Project of China (2018000021223TD10);Hebei Province Fund for Transformation of Major Science and Technology Achievements of China (19041029Z);Hebei Province International Science and Technology Cooperation Base Construction Project of China(20591002D)。

摘　　要：提出了一种新的雾化喷涂沉积(SCD)方法,在Nd-Fe-B磁体表面均匀沉积TbF_(3)粉末,同时通过晶界扩散过程(GBDP)将Tb元素引入到磁体中。用这种方法(SCD+GBDP)处理厚度达5 mm的钕铁硼磁体。研究了TbF_(3)涂层增重比、扩散时间和扩散温度对烧结磁体组织和磁性能的影响。样品扩散温度和时间为940℃和10 h,退火温度和时间为480℃和5 h。TbF_(3)增重比(w)从0%增加到0.8%时,磁体的矫顽力从1201 kA/m提高到1930 kA/m,剩磁下降约0.01 T。研究发现,随着TbF_(3)增重比的增加,磁体的矫顽力先增大后减小。SEM结果表明,在Nd_(2)Fe_(14)B晶粒边界区域,Tb取代Nd形成(Nd,Tb)_(2)Fe_(14)B核壳相。晶界相和核壳相中较高的磁晶各向异性对矫顽力的增强有积极的促进作用。核壳相的分布和浓度对矫顽力有密切的影响。当TbF_(3)增重比大于2.4%时,靠近磁体表面区域的晶界扩散明显增强。元素的SEM图像显示,进入磁体的Tb越多,晶核内的Tb浓度就越高。此外,大量Nd-F/Nd-O-F相的形成导致晶界相不像w=0.8%时的样品那样连续,这可能是导致矫顽力下降的主要原因。A novel method of spray coating deposition(SCD)was proposed to deposit TbF_(3) powder solution uniformly onto the surface of Nd-Fe-B magnets,and then the Tb element was introduced into the magnets through the grain boundary diffusion process(GBDP).Nd-Fe-B magnets with thickness up to 5 mm were treated with this method(SCD+GBDP).The effects of mass gain ratio(w)of TbF_(3) coatings,diffusion time and the diffusion temperature on the microstructure and magnetic properties of the sintered magnets were investigated.The samples were diffused at 940°C for 10 h and then annealed at 480°C for 5 h.Results show that when the TbF_(3) mass gain ratio increases from 0%to 0.8%,the coercivity of the magnets increases from 1201 to 1930 kA/m and the remanence is only decreased by 0.01 T.With increasing the mass gain ratio of TbF_(3),the coercivity of the magnets increases firstly and then decreases obviously.SEM results show that the(Nd,Tb)_(2)Fe_(14)B core-shell phases can be formed by Tb which replaces the Nd in the boundary region among Nd_(2)Fe_(14)B grains.The improved decoupling effect by the continuous grain boundary phase and the higher magnetocrystalline anisotropy of the core-shell phase plays a positive role in the coercivity enhancement.The distribution and concentration of core-shell phase have a close influence on the coercivity.When the TbF_(3) mass gain ratio is more than 2.4%,the grain boundary diffusion is obviously enhanced in the region close to the magnet surface.The SEM image of the element shows that the more Tb enters the inside of the grain,the higher the Tb concentration in the core than in the shell.Furthermore,the formation of a large amount of Nd-F/Nd-O-F phase causes the grain boundary phase not being as continuous as that of the sample with w=0.8%,which may be the main reason for the decrease in coercivity.

关 键 词：烧结钕铁硼磁体 雾化喷涂 晶界扩散 磁性能 

分 类 号：TG178[金属学及工艺—金属表面处理]