The Effect On Composition And Performance Parameters And The Formation Mechanism Of NiZn Ferrites Powders By Combustion Synthesis

This paper reviewed the structure, unique properties, applications and preparation methods of NiZn ferrite powders. A brief introduction of the mechanism of coal combustion, key technologies and research status of combustion synthesis NiZn ferrites was given. And the contents and significance of this research were discussed. Theoretical analyses of Fe-ZnO-NiO-Fe2O3-NaClO4system were performed in terms of combustion synthesis Nio.4Zno.6Fe2O4ferrite powder. The influence of the quantity of reactants, NaCl diluent content, the iron content and NaC104content on the phase composition, microphotography and the magnetic properties of samples were studied individual and discussed the influence mechanism. The main-points are summarized as follows.Calculated the adiabatic temperature of the system of kFe-Zn0-NiO-Fe2O3-NaClO4with different iron content based on thermodynamic principle. The result shows with the increase of iron content in the raw material, the system of adiabatic temperature rise. When the k≥0.5, the adiabatic temperature larger1800K. The ferrite powders were sintered and compared the results of XRD, SEM and hysteresis loop, determine the optimum amount of reactants funally. When the amount of reactants is1500g, the distribution of powder particle size is uniform, the product has the higher saturation magnetization Ms=63.72emu/g and lower coercive force Hc=15.61Oe.Add a certain amount of NaCl diluent to raw materials decreased the particle size of products, and the ZnO, Fe2O3and Fe1-xO impurities were found in samples. The influence of diluent NaCl content on the magnetic properties of the sample was not significant, and the saturation magnetization of product first increased and then decreased gradually, the coercive force were similar.Research the influence of iron content in the system on the properties of ferrite. The results showed that an increase in the iron content results in an increase of combustion temperature and combustion wave velocity.With the increase of k, the particle size of combustion products is gradually increase and distribution is not uniform. After annealing, the crystallinity of the particle increase and crystal defect improved. When k value is0.6, the product has high saturation magnetization and low coercive force.Study the influence of excess oxidant NaClO4on the properties of ferrite. The results show that the excess amount of NaClO4has supreme purity and high crystallinity. Excess of Oxidant has no effect on product particle size and morphology. With the increase of the system of amount of oxidant, the saturation magnetization of product first increased and then decreased gradually and the coercive force values were similar, when the sample with40%excess of NaClO4has the best magnetic properties, the saturation magnetization of Ms=68.80emu/g and the coercive force Hc=16.08Oe.