Effects Of The Powder Size And Preparation Process On The Performance Of Sintered NdFeB

As a type of important functional material, sintered NdFeB permanent magnetic materials have outstanding magnetic properties, but its strength and toughness are poor which not only make it hard to machining, but also limit the applications. Withthe vehement market competition and low sale price, sintered NdFeB permanent magnetic materials have been given a lot of attention with the question of improving manufacture techniques to enhance production efficiency and reduce production cost.The initial hydrogen blasting powders of different particle size were prepared, then they were prepared to the sintering NdFeB magnets samples in the subsequent process of the same conditions. Samples were tested of the bending strength and fracture toughness, and research the influence of different powder particle size on the mechanical properties of magnets. Through the observation of magnetic characteristics of macro-and micro-fracture, analyzed the fracture mode and the fracture mechanism of sintering NdFeB permanent magnet materials.The results showed that with the initial powder particle size decreases, the mechanical properties of sintered magnets gradually improved.The key proeess parmaeters of manufacturing sintered NdFeB magnets:such as double-sided water-cooled copper mold ingot process, hydrogen decrepitation proeess, jet-milling proeess, orientation and pressing proeess, sintering and annealing process are investigated in this article.Getting the optimum process of the composition of (PrNd) 30.5 Dy0.5 Al0.2 Cu0.1Nd0.45 B1.05 Fe67.2 magnet:double-sided water-cooled copper mold ingot, dehydrogenation process is 580℃×9.5h,the average particle size of the jet-milling powder is 3.7μm, adding anti-oxidants, sintering and tempering process for the sintering temperature 1080℃,sintering time 3h, first tempering temperature of 900℃, tempering time 2h, second tempering temperature of 490℃tempering time 2h.