| Summary: | 碩士 === 國立臺北科技大學 === 材料及資源工程系研究所 === 100 === Commercial available powder was used as host material in this study. After milling for various durations, the effects of the physical characteristics of the powders on the mechanical properties of the sintered ferrites were evaluated. The best milling parameters were then used throughout this study. Dopants including oxide A , B, C, D were added in Ni-Zn-Cu ferrites in the amount 0 ~ 5 wt% and their effects on the mechanical properties of Ni-Zn-Cu ferrites magnetic characteristics were investigated.
The results show that the particle size of the powder decreased with increasing milling time, and the particle size distribution became narrower. It was found that milling time of 24 h effectively reduced the average particle size down to 0.54 μm. Owing to both the ionic radius of the dopants and their solubility in the ferrite are different, the microstructural evolution of the sintered ferrites emerged to be significantly different and thus heir mechanical properties and magnetic properties as well. Of the dopants added, ferrite with 5.0 wt % oxide A addition registered the highest bending strength of 143 MPa. Too much oxide A addition would lead to abnormal grain growth and result in lower mechanical properties. As magnetic properties concern, ferrite with 1.5wt % oxide D addition reported the highest initial permeability of 587.
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