The Effect Of Optimizing Process On The Performance Of Sintered NdFeB Magnets

Based on the sintered Nd Fe B production equipments and technology skilled application control, combining with the oxygen content analyzer, SEM, XRD and EDS analysis and other advanced equipments. Related Questions of preparation process to high performance sintered Nd Fe B magnets have been researched. These related Questions include sintering process on magnetic properties, Nd-rich grain boundary phase optimization, improve the degree of orientation, increased remanence, oxygen content on the magnetic properties.Eventually, N52 sintered Nd Fe B magnets prepared stablely by taking hypoxia process route and lower costs with reducing rare earth content. The main conclusions of the article as follows:(1) With the sintering temperature changed from 1045℃ to 1087℃, the density of the magnet increased, the coercive force essentially unchanged, the maximum value of the remanence and energy product appeared at 1080℃.(2) At low temperature sintering process, with sintering temperature reduced from 1060℃ to 1030℃, its coercivity increased by about 39KA/m, magnetic remanence and energy product are also improved to some extent.The sintered magnets with low-temperature significantly reduced grain size, optimized uniform Nd-rich phase at the grain boundaries, the magnet microstructure greatly improved; Nd-rich phase is more evenly distributed with cycling sintered magnets, main phase grain boundaries present clear, continuous network grain boundary phase; with the phase structure of Nd-rich phase changing, the interface wettability of Nd2Fe14 B main phase and Nd-rich phase also changed, the magnet coercivity improved by the above reasons.(3) The oxygen content gradually increased from 511.3 ppm to 1242.4 ppm for Nd29.5FebalTM0.1B0.95 low rare earth content of sintered Nd Fe B magnets. With the increasing of the oxygen content, the density of the magnet is maintain constant, the coercive force was gradually decreasing. Sintered magnets may cause uneven shrinkage with surface oxide of magnet.(4)By adding a lubricant and increasing the number of orientation of magnets, the degree of orientation and remanence significantly improved, remanence increased with the increasing of orientation. C magnet with a high remanence of 1.462 T by adding 3ml/1kg water-based lubricantand and increasing an alignment pulses. The magnets coercivity improved by 2.01 KOe as-sintered comparing to annealed.