Preparation of nanocomposite permanent magnetic materials and the effective anisotropy and coercivity of

Title: Preparation of nanocomposite permanent magnetic materials and the effective anisotropy and coercivity ofAuthor: Guo JiajunDegree-granting unit: Hebei Normal University,Keywords: nanocomposite permanent materials;; laser crystallization process;; magnetic properties;; effective anisotropy;; coercivitySummary:

Permanent magnet material is a kind of mechanical energy and electromagnetic energy to achieve mutual conversion of magnetic materials, magnetic materials,Magnetic lifter  energy conversion as function of various physical and magnetic effects, making it a computer, network information, household appliances, telecommunications, transportation , aerospace and many other areas of the core high-tech devices. Nanocomposite permanent materials is a new type of rare earth permanent magnet materials, from soft and hard magnetic phase-phase compound in the nanometer size range is made, is expected to develop a new generation of rare earth permanent magnet materials.

The current experimentally prepared nanocomposite permanent magnetic materials and energy product greater difference between the theoretical expected value, because the nanocomposite permanent materials, while having a high remanence, coercivity decreased but too much, limiting the improvement of energy product . How to maintain a high remanence, while the maximum increase in coercivity materials for enhancing the magnetic properties of nanocomposite permanent key. In this paper, experimental and theoretical aspects of nanocomposite magnets have been studied, the main research contents and results are as follows:

1 on the R & D experiment of the laser crystallization unit, laser crystallization process of the preparation of nano-composite magnetic materials have been studied and prepared Nd3.7Pr3.4Dy0.9Fe86B5Nb1 samples. Crystallization of amorphous thin with the best experimental parameters are: pulse frequency of 15Hz, laser energy 700mJ, heat 1 minute. The best magnetic properties of the sample is: Hcj = 6.6 kOe,, Br = 1.23T, Mr / Ms = 0.78, (BH) max = 18.5 MGOe. Studies have shown that: the use of laser crystallization fabricated nanocomposite permanent materials with low power consumption, high efficiency advantages, can be completed within a short time crystallization process, crystallization processing time and processing power exactly crystallized adjustable. Overcome the traditional heat treatment process is not easy to control the crystallization process defects.

2 In theory, the Nd2Fe14B / α-Fe as an example, consider the coupling between grains of different states, were investigated by phase-grain size on the soft and hard magnetic phase and nanocomposite permanent materials effective anisotropy and the coercivity of the impact study: soft and hard magnetic exchange coupling between the grains of soft magnetic grains increase the effective anisotropy and coercivity, and the corresponding weakening of the hard http://www.999magnet.com/products/131-magnetic-lifter  magnetic grains to the effective sex and the coercivity. Nanocomposite permanent materials, effective anisotropy and coercivity are hard magnetic phase with the increase of volume fraction, grain size decreases with the decrease, when the grain size less than 20nm, the coercivity dramatically reduced. Therefore, experiments were prepared in order to ensure the nanocomposite permanent materials with high coercivity, grain size should be maintained at about 20nm.Degree Year: 2010