The Preparation Of Rare Earth Nano-crystalline Composite Permanent Magnet Materials And Computer Model

In this paper, nanocrystalline rare-earth ferrite, Fe₂O₃ precursors and powders have been prepared at a relatively low caleination temperature by a gel-sol technique using citric acid as a fuelrduetant and nitric acid as oxidants. By different methods of heat treatment under different condition, little crystalline grain size, highly scattered nanocrystalline rare-earth ferrite and Fe₂O₃ can be prepared. Utilize the property that SmFeO₃ and Fe₂O₃ can produce coupling of exchanging in a situation that the crystalline grain is smaller than 20nm, hign magnetic properties were developed, including high magnetism energy, coercive force, thus enable magnetic properties to have improvement by a large margin. Simultaneously, the study discussed effects of pH, interior oxygen, the consumption of dispersant and complexing agent, the influence of absolute ethyl alcohol bathing on dispersiveness, crystalline grain size, burn complete situation, sample purity , exchange coupling, etc.By means of heavy analysis instrument (TG-DTG), infrared spectrum, scanning electron microscope (SEM), energy spectrum (ES), chemical analysis of phase state, X-ray diffractometer (XRD) and vibration sample magnetometer (VSM), etc. the loss of weight of powder during combustion process, phase change, conglobation, grain size, crystalline grain distortion situation, maximum magnetic energy and coercive force were get detaily.With uniform design experiment as guidance, various kinds of factors about preparation of sample were considerd in an all-round way. A basic response model was set up through linear return, by optimizational method, optimizational scheme was get. Combine with the result of computer imitation, the best scheme on preparating of sample was get finally.Properties of powder: average grain size of Fe₂O₃ is 11 nanometers, average grain size of Fe₂O₃ /SmFeO₃ is 17 nanometers, maximum magnetic energy is 6500Oe.Preparation conditions of sample: pH=2, nitric acid consumption is 6 millitres, calcinate under 350°C/2h then500°C/lh, mol ratio of complexing agent and metallic elements is 3:1, dispersant agent consumption is 20 millitres.Through computer simulation of the crystal growth course, demagnetization curves of double-phase nanometer brilliant permanent magnetism material get by different tombarthite...