Controllable SiO2 coating layer of FeSiBPNb amorphous powder cores with excellent soft magnetic properties
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Amorphous powder cores based on spherical (Fe0.76Si0.09B0.1P0.05)99Nb1 amorphous powder and their SiO2 layer prepared by in situ coating insulation process were investigated in detail. These cores were characterized by scanning electron microscopy and X-ray diffraction analyses, and the results revealed that the surface layer of the amorphous powder was composed of SiO2 with uniform surface coverage. The thickness of the SiO2 insulating layer could be controlled by adjusting the tetraethyl orthosilicate (TEOS) content. By cold-pressing with epoxy resin under a pressure of 1800 MPa, a ring powder core with an outer diameter of 20.3 mm, inner diameter of 12.7 mm, and height of 5.3 mm was prepared. The FeSiBPNb composite core showed its best properties when the TEOS content was 2 mL/g (the volume of TEOS for each gram of (Fe0.76Si0.09B0.1P0.05)99Nb1 amorphous powder, mL/g), which showed good relative permeability in the high-frequency range of up to 10 MHz and a low core loss of 320 W/kg under the maximum magnetic flux density of 0.1 T and frequency of 100 kHz.
KeywordsSoft magnetic composite Core loss Relative permeability In situ chemical deposition Amorphous powder
The work was with the support from the National Key Research and Development Program of China (Grant No. 2017YFB0903902), National Natural Science Foundation of China (Grant Nos. 51601205, 51671035, 51071034, and 51671206), and Ningbo Municipal Nature Science Foundation (Grant No. 2017A610036).