Effect Of Inorganic Insulating Material Doping On The Structure And Properties Of Hot-pressed Nd Fe B Magnets

In the service process of rotating power equipment such as high-power permanent magnet motor,hot-deformation NdFeB magnet will produce eddy current loss during service due to its low resistivity and poor thermal stability,which will reduce the performance of the motor.Therefore,in order to solve a series of problems of hot deformed NdFeB magnet in motor service,the core technology is to improve the resistivity of NdFeB magnet as a rotor,so as to reduce eddy current loss.In this thesis,by choosing different inorganic insulation powder(two kinds of nitride,a fluoride)doped,preparation of hot-pressing thermal deformation NdFeB magnets,probe into its compactness of hot-pressing magnet respectively,and the influence of magnet magnetic resistivity and thermal deformation,and use the 3D simulation technology to simulate the process of NdFeB compact thermal deformation,through the analysis on flow stress and damage coefficient,By exploring the uniformity change rule of NdFeB magnet,the resistivity of the heat-deformed permanent magnet was improved and it had good magnetic properties.The main experimental contents and conclusions are as follows:(1)Deform 3D software was used to simulate the influence of different heating temperatures on the failure coefficient and stress distribution of thermal deformation NdFeB magnet,and experimental optimization was carried out according to the simulation results.The simulation results show that when the heating temperature is850?,the flow stress distribution inside the magnet is the best,the stress concentration is easy to occur around the surface of the magnet,and the damage risk of the contact part between the side of the magnet and the workpiece is high,which should be avoided.(2)The density of hot-pressed NdFeB magnet decreases with the increase of nitrogen doping.However,when w(Zr N)is 1%,the density of the magnet is 1.01 relative to that of the undoped magnet because the Zr N particle content is small and can fill the internal pores of the magnet.Nitrogen doping can cause the magnetic properties of thermally deformed NdFeB decreased significantly,among which Al N powder doping is more serious.The core magnetic properties of thermally deformed NdFeB magnets are the best,and the magnetic properties gradually decrease along the radial direction.Moreover,nitrogen doping can also aggravate the magnetic inhomogeneity of different regions of thermally deformed NdFeB magnets.The resistivity of the magnets is improved,the range of improvement is 8.7%-52.%,which is small.(3)With the addition of SmF3,although the magnetic properties decreased,the decreasing trend was relatively gentle.Due to the relatively stable chemical properties of fluoride itself,the XRD patterns do not show other alloy phases,and the resistivity of the sample is also significantly improved.When the doping w(Sm F3)is 1%,the resistivity of the magnet is 850??·cm,which is more than two times higher than that.At the same time,it has good anisotropy,which is in line with the experimental expectations.Both high resistivity and good magnetic properties.