热处理和粉末形态对Fe-SiO2软磁复合材料磁性能的影响

Effects of Heat Treatment and Powder Morphology on Magnetic Properties of Fe-SiO2 Soft Magnetic Composites

以采用反相微乳液法制备出的二氧化硅为绝缘包覆剂,通过压制和热处理获得铁基软磁复合材料,重点探讨了热处理温度和球磨时间对材料磁性能的影响。结果表明,随着热处理温度的提高,软磁复合材料的最大磁导率、饱和磁感应强度上升,矫顽力下降。经500℃热处理后,在1~50 k Hz频率范围内样品磁导率实部值（μ＇）均超过110,比未退火热处理样品提高了37.5%。当热处理温度超过700℃,样品的μ＇急剧下降、磁损耗显著上升,绝缘层发生破坏。磁损耗分离研究显示,与不规则粉末相比,扁平化粉末不易压制成型但有利于形成完整的Si O2绝缘层,提高材料的电阻率,降低涡流损耗。

Using silica prepared by inverse microemulsion method as insulating coating agent, Fe-based soft magnetic composites were obtained by pressing and heat treatment. The effects of heat treatment temperature and ball milling time on the magnetic properties of the materials were emphatically discussed. The results show that, with the increase of heat treatment temperature, the maximum permeability, saturation magnetic induction strength of soft magnetic composites increase and the coercivity decreases. After heat treatment at 500 ℃, the real part of permeability（μ＇） of the samples is over 110 in the frequency range of 1-50 k Hz, which is 37.5% higher than that of the unannealed samples. When the heat treatment temperature is higher than 700 ℃, the μ＇ of the sample decreases sharply, the magnetic loss increases significantly and the insulation layer is destroyed. The study of magnetic loss separation shows that, the flattened powder is not easy to be compacted but it is helpful to form a complete insulating SiO2 layer to increase the resistivity of the material and reduce the eddy current loss compared with that of the irregular powder.