Study On The Design Of Composition And Preparation Of High Performance Sintered NdFeB Magnet

As the new generation of performanent magnetic materials with highest magnetic properties,NdFeB permanent magnet has been applied in many kinds fields in morden science and technology ,such as computer ,communications,aerospace ,transportviechdes and office automation etc.Although energy product of the NdFeB magnets has achieved as high as 414kJ/m3(52 MGOe)for the world leading level produced in industrial scale in present.There still exists some backward in magnetic properties comsistency and stabilily for the majority product of domestic entderprise due to outdated production equipment and process ,These reasons cause the poor marketing into some fields of high performance requirement.Based on this situation and HEYE SPECIAL STEEL.CO.,LTD.,The design of composition and process for high performance of NdFeB mgnets has been studied in this work,According to the theory of composition design for high magnetic energy product and the actual losses of some alloy elements in magnet-making, thecomposition of test materials has been calculated .Considering the microstructure to get the high permanent magnetic properties, The sheet ingot+HD+Jet Mill process for sintering powder has been chosen. The geometric characteristics and size distribution have been analysed and compared with that of traditional mechanical preparation. It is show that that the powder processed by HD+Jet Mill has been characterised by small size ,high uniformity distribution round in geometrically and high proportion of single-crystal powder .The experiments of sintering for two kinds of powder under different temperatures has shown that not exceeding 1% for Dy content and 1% for Nb content .The addition of Nb enhance the coercivity of magnets,but lead to the decrease of the remanane.This problem can be solved by Dy addition so that the good magnetic properties can be achieved.Through this work ,the process parameter and composition has been optimized on this basis,the expected mircrostructure of sintering magnet can characterised.At present ,The industrial production of N45 magnets in HEYE SPECIAL STEEL.CO.,LTD.stable.