Bonded Ndfeb Magnet Design, Preparation, And Special Applications

Bonded NdFeB magnet is studied systematically in the aspect of theoretic analysis, experiments and special application in the article. Several factors are discussed, including the amount of magnet constitutes, the choice of technical parameters, the method of anti-erosion, the pre-design , the preparation and the test of enormous NdFeB magnet.Several formulations are given in the article. They show many relationships, such as the relationship between component ratio and geometrical size of institutes, the relationship between magnet power and the volume percentage of magnet powder. Two expressions about magnetic field value are calculated, which make things convenient for the pre-design of magnetic circuit and the choice of magnet. A effective method of anti-erosion is concluded by comparing all kinds of post-treatment technics.By experiments, many factors that affect magnet performance are discussed in the article, including category and quantum of constitutes, technological conditions, and the way of anti-erosion. Results are as following,Firstly, the physical state of bond has an important effect on magnet densitification. Liquid or half-solid bond is helpful to improve the density of bonded magnet than solid bond does. The magnet performance will not rise linearly as the ratio of bond rises, but gets the maximum when its weight percentage is 3%?%. And the changing of magnet product is similar with the change of the volumepercentage of magnetic powder. In addition, the larger the pressure is, the higher the density and the magnet performance are.Secondly, coupling agent helps to improve the magnetic power and its anti-erosion capacity, which promote the combination of magnet powder and bond. Different coupling agent and different treatment conditions have different impacts on magnet performance. It is the best using titanate coupling agents as pretreatment reagent and dimethylbenzene as solvent.Thirdly, Magnet can get high density under lower pressure easily, usingheating-pressing process. Remarkably, the temperature must be limited between softening point and solidification value, at which the bond can get perfect fluidity and stickiness. Effects of bond content and pressure on magnet product during heating-pressing process are the same with effects during common-pressing process.Fourthly, it is more than 250 hours before magnet is eroded when it is coated with lacquer by way of cathode electrophoresis.Fifthly, it is successful to pre-design special magnet and magnetic circuit before magnet preparation and application, making the best use of theoretical formulations, experimental results and practical demands. All kinds of technical parameters of enormous magnets are gotten by pre-design method before they are produced by heating-pressing process. The uneven degree of magnetic field in circuit is within 5%. It should be said that heating-pressing process is a good way to get even magnet with high density.Lastly, calculating the magnet performance using theoretical formulation, which expresses the relationship of the external magnetic field and remanence of the magnet, can tell the type of unknown magnet. Similarly, incapable magnet can be abandoned in this way. Detailed approaches are given in the article.