氧化钛绝缘层的水解制备及其对磁粉芯的影响

Hydrolytic synthesis of titanium oxide insulation layer and its effect on powder core

优化绝缘工艺对研制高性能磁粉芯至关重要。采用钛酸四丁酯水解工艺在气雾化铁硅铝磁粉表面成功包覆了一层均匀致密的氧化钛绝缘层,并系统探究了水用量对绝缘效果的影响,分析了不同氧化钛绝缘层对所制得粉芯电磁性能的影响规律。结果表明,随着水用量从磁粉质量的10%增加到40%,磁粉表面绝缘层先均匀致密,后增厚疏松。较高的水用量可加快水解缩聚反应,但过高水用量易导致水解过快,不利于绝缘层的均匀结晶生长。均匀致密的绝缘层可在保证相对较高的粉芯密度的前提下,提高粉芯电阻率,从而有效抑制高频涡流、增强磁导率频率稳定性。水用量为磁粉质量的20%时制得的粉芯样品综合性能最优,其有效磁导率可达82,电阻率高达1022.35 kΩ·cm,在100 kHz,50 mT下的磁损耗仅为77.63 mW/cm^(3)。

Optimizing insulation technique plays a vital role in developing high performance magnetic powder core.Uniform dense titanium dioxide insulation layer was successfully coated on atomized Fe-Si-Al powder through hydrolysis of tetrabutyl titanate and the effect of water content on insulation quality was systematically investigated.The influences of titanium oxide insulation layer on electromagnetic properties of corresponding powder cores were also discussed.The results show that when the mass of water is increased from 10%to 40%of Fe-Si-Al powder,the insulation layer on particle surface first grows thicker and then becomes loose.High water content favors quick hydrolysis and condensation,while too large volumes of water leads to excessively high hydrolysis rate,which is adverse to the uniform growth and crystallization of titanium dioxide insulation layer.It is proven that uniform and dense insulation layer would contribute to the increase of resistivity under the premise of high density of powder core,which is conducive to the suppression of eddy current and frequency stability of permeability.When the mass of water is 20%of Fe-Si-Al powder,the prepared corresponding powder core has the optimal overall performance,the permeability is as high as 82,the resistivity is up to 1022.35 kΩ·cm and the core loss is as low as 77.63 mW/cm3(at 100 kHz and 50 mT).