| The demands for performance of magnetic materials, especially the most application of MnZn, are increasingly high, along with the miniaturization lightweight and thin trend of electronic equipments. MnZn ferrite was focused on, in order to satisfy the rapid development of electronic and information materials. In this paper, the precursor powders of MnZn ferrite were synthesized by chemical co-precipitation. The influence of the sintering schedule, formulation and additives was researched particularly. Steel pickling waste liquor and dissolved solution of casting zinc slag was used as raw materials. The MnZn ferrite was synthesized by chemical co-precipitation. Then the preparation and performance were researched.The optimization of preparation technology was defined according to our results of chemical co-precipitation in the past few years. The effects of reaction time and feeding mode on properties, included the distribution of particle size, morphology and magnetic property, was discussed in this paper. The particle size of the precursor increased with the extension of the reaction time, but the growth rate of precursor particle size increased less and less. After56h, the reaction system nearly reached dynamic balance, and the D50was about4u m. The final particles were ball and several hundreds nanometers. The robust and flake particles generated previously gradually disappeared. Through the magnetic hysteresis loop of precursors, the reaction time had less influence on the coercive force, while greater influence on the saturation magnetization. Results of feeding modes showed that the procurers with small and uniform particle size distribution were prepared by three feeding ways. However precursors by concurrent feeding way showed the largerest saturation magnetization.The MnZn ferrite powders were formed after the precursor was calcined at450℃for4hours. The influence of sintering process on the magnetic properties was researched by the samples prepared by MnZn ferrite powders. The sintering process included heating rate, holding time and nitrogen rate during cooling process. It was necessary for the samples with the best magnetic properties to satisfy the following sintering process. The heating rate was1℃/min among950℃to1350℃, the holding time was3.5hours and the nitrogen rate during cooling process was2L/min. The samples were investigated by HP4291A impedance analyzer. It showed that initial permeability, relative loss factor at0.1MHz and cut-off frequence of samples were Ui≈2640, tan δ/μ≈1.17×10-5and f≈4MHz.Utilizing optimized preparation and sintering processed, MnZn ferrite powder was prepared by chemical co-precipitation using steel pickling waste liquor and dissolved solution of casting zinc slag as raw materials. The main cause of performance deterioration of powders was the impurity ions, such as Ca2+.Al3+. In order to improve the performance of powders, the impurity ions of the raw materials must be got rid of. In steel pickling waste liquor, Ca2+ions could be wiped out by fluorination method, while non-ionic polyacrylamide flocculant (PAM)In the end, the influence of formula and additives on the performance was studied. The sample had minimum relative loss factor at0.3MHz when the mole ratio of Fe:Mn:Zn was69:24:7. The effects of different additives on the performance of MnZn ferrite was analysed by the orthogonal experiments.Appropriate doping could significantly improve electric and magnetic performance of MnZn ferrite. |
