| Summary: | 碩士 === 國立成功大學 === 資源工程學系 === 107 === The effects of FeSiCr alloy powder@SiO2 on the electric and magnetic properties were studied. Fe-Si-Cr alloy powder with an average particle size of 10 μm was coated with nano-sized silica powder to increase the resistivity and DC bias superposition characteristic.
In this study, sodium silicate was used as a precursor to form the amorphous silica on the surface of FeSiCr alloy powder. FeSiCr alloy powder was mixed with sodium silicate solution and then carbon dioxide was injected to form an amorphous silica layer on the surface of the alloy powder. Transmission electron microscope was used to investigate the amorphous silica layer. It shows that the thickness of insulating layer was about 20 nm to 50 nm, and the thickness can be controlled by the amount of sodium silicate. The amorphous silica layer can significantly promote the anti-oxidation, resistivity and DC bias superposition characteristic. The magnetic loss is dominated by the hysteresis loss while the frequency is below 3 MHz. The coercive force increased with increasing the SiO2 content, which led to the increase in total magnetic loss.
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