Preparation And Properties Of High Resistivity Of Rare Earth Permanent Magnet

In recent years, the rare earth permanent magnets ware widely used in electric motors, generators and other fields. Because of the resistivity of the rare earth permanent magnetic materials is very small, so it can cause eddy current when it work in the induction electromotive. With the eddy current the flux and efficiency will loss. So effective methods for reducing eddy current loss is to improve the electrical resistivity of material. The most direct way to improve the electrical resistivity of the material is increasing the resistivity of the grain boundary. In this paper the high electrical resistivity rare earth permanent magnet ware produced by addition of calcium fluoride. Analysis the impact on the properties and microstructure of the rare earth permanent magnet with the addition of calcium fluoride.The high electrical resistance sintered Sm-Co permanent magnet ware prepared by addition of calcium fluoride. With the research of the effect of the properties and microstructure with the addition of calcium fluoride, it is find that because of the magnet was oxidized during the preparation, so the properties of the magnet was declined seriously. It is not fit to produce by addition of calcium fluoride.This paper study the properties and microstructure of the high electrical resistance sintered Nd-Fe-B permanent magnet prepared by addition of calcium fluoride. The electrical resistivity of the sintered composite Nd-Fe-B magnet increased with the increase of the addition of calcium fluoride while the magnetic properties and density decreased. Magnetic and electric properties of the sintered magnet prepared by mixed calcium fluoride powder are only related to the addition amount of calcium fluoride, it has no relationship with the particle size, but the calcium fluoride is easy dispersing with small size in sinter process. The high electrical resistance sinter Nd-Fe-B magnet has electrical resistivity of1.4mΩ·cm and relatively high magnetic performance of Br=12.17KGs, Hcj=11.93KOe and (BH)max=35.77MGOe.A study of the properties and microstructure of the high electrical resistance hot die-upset Nd-Fe-B permanent magnet prepared by addition of calcium fluoride was performed. Experimental results show that the The electrical resistivity of the hot die-upset composite Nd-Fe-B magnet increased with the increase of the addition of calcium fluoride while the magnetic properties and density decreased. The calcium fluoride distribution perpendicular to the direction of pressure in the high electrical resistance hot die-upset Nd-Fe-B permanent magnet, which is help to improve the resistance of the magnet. The best magnetic properties were obtained when the addition of calcium fluoride is10wt%, the electrical resistivity is1.6mΩ·cm with magnetic performance of Br=8.39KGs, Hcj=6.28KOe and (BH)max=13.7MGOe.