富铈液相合金添加的再生烧结钕铁硼磁体研究

Recycling of Waste Sintered NdFeB Magnets by Adding Ce-rich Alloys

采用废旧的烧结钕铁硼电机磁钢作为研究对象（牌号33H）,研究富铈液相合金添加量对再生烧结钕铁硼磁体的磁性能和微结构的影响。研究结果表明,在相同的烧结温度下,当未添加液相时,再生磁体密度很低;进一步提高烧结温度,磁体密度略有提高,但是磁体容易氧化、甚至开裂。随着液相合金的添加,再生磁体的密度不断提高,磁性能相应地明显改善,这说明液相合金具有明显的助烧结作用。但是当液相合金的添加量超过8%（质量分数）时,再生磁体的矫顽力降低,这可能因为过多的富铈液相添加使磁体中的富稀土相团聚,磁体微观结构变差。当液相合金添加量为5%,烧结温度为1080℃时,再生烧结钕铁硼磁体的磁性能最佳：剩磁Br达到11.67 k Gs,内秉矫顽力Hcj达到18.94 k Oe,磁能积（BH）max为33.1 MGOe。再生磁体的性能与原废旧磁钢相当,甚至略有提高,再生磁体具有优异的退磁曲线方形度（Hk/Hcj=0.972）。

The waste Nde Fe B sintered magnets（ grade 33 H） were recycled to manufacture anisotropic sintered magnets by adding Ce-rich alloys. The influences of additive amounts of Ce-rich alloys on the microstructures and the magnetic properties of the recycled sintered magnets were investigated. It shows that the recycled sintered Nd-Fe-B magnet without Ce-rich alloy addition,has rather lower density; the density of the magnet is slightly raised with increased sintering temperature,but the recycled magnet is prone to oxidation,even cracking. For the recycled sintered magnets with Ce-rich alloy addition,the densities of the magnets are upgraded with increasing amounts of Ce-rich alloy,as well as the magnetic properties are obviously improved. It suggests that the Ce-rich alloy plays an important role of sintering-aid in the densification of the recycled magnet.However,the coercivities of the recycled magnets are decreased,when the additive amounts of Ce-rich alloy are over 8 wt.%.That is probably because an excessive Ce-rich alloy addition can cause RE-rich phase aggregation at the triple grain boundary junctions,and deteriorate the microstructure of the recycled magnets. The recycled magnet exhibits the optimal magnetic properties： remanence（ Br） of 11. 67 k Gs,coercivity（ Hci） of 18. 94 k Oe,and maximum energy product [（ BH） max] of33. 1 MGOe,respectively,with 5 wt.% Ce-rich alloy adding,sintered at 1080 ℃. The magnetic properties of the recycled magnets are comparative to those of the waste magnets. The recycled magnets have higher coercivity and perfect squareness of demagnetization curve（ Hk/Hcj= 0. 972）.