"微波弧光效应"下异质界面与绝缘膜的演变机理及其对铁硅软磁铁芯电－磁性能的影响

It is very difficult to produce high silicon electrical steel sheet by conventional hot rolling and cold rolling process. In this project, Fe(Si)/SiO2 core-shell heterostructure composite powders will be obtained by in-situ chemical depositing SiO2 film on the surface of spherical Fe(Si) alloy particles, and the interparticle insulated Fe(Si) soft cores will be prepared using microwave activation hot pressing process. The as-prepared Fe(Si) soft cores have many advantages such as free rolling, high density, interparticle insulation, high magnetic conductivity, low core loss and so on. Our research will be focused on the following contents: The microstructure control and formation mechanism of heterojunction interface and nano SiO2 film in Fe(Si)/SiO2 core-shell heterostructure composite powders; the evolution rule and densification mechanism of heterojunction interface and nano SiO2 film under “microwave arcing effect”; and their effect on the electric and magnetic properties of Fe(Si) soft cores. In this project, the interparticle insulated Fe(Si) soft cores will be built, and the thickness and uniformity of insulation film will be controlled in the nanometer range. The eddy currents are limited in micro-sized zones surrounded by nano-insulation film, and the effective radius of eddy currents will be decreased. The balance of iron loss and magnetic conductivity will be built. The rolling puzzles of high silicon electrical steel sheet can be overcome. This project provides a new way to prepare Fe(Si) soft cores with high magnetic conductivity and low core loss. It can also lay the foundation for developing new and small soft cores and their applications in high energy density electric-magnetic switching equipments within the frequency range of 400Hz ~10KHz.

针对高硅电工钢轧制困难的瓶颈，本项目采用化学原位沉积法在球形Fe(Si)合金颗粒表面包覆纳米SiO2膜，随后采用微波活化热压烧结技术制备免轧制、高致密、高导磁、低损耗、颗粒间绝缘的Fe(Si)软磁铁芯。研究Fe(Si)/SiO2核壳结构粉末内异质界面与SiO2绝缘膜的形成机理与结构控制方法；异质界面与SiO2绝缘膜在“微波弧光效应”下的演变规律与致密化机理，及其对Fe(Si)软磁铁芯电-磁性能的影响。项目试图通过构建颗粒间绝缘的Fe(Si)软磁铁芯，在纳米范围内控制颗粒间绝缘膜的厚度与均匀性，将涡流限制在绝缘膜包覆的微小区域内，降低涡流的有效半径，寻求Fe(Si)软磁铁芯导磁性能与涡流损耗之间的平衡，同时可避开高硅电工钢难以轧制的难题。这为丰富高导磁和低损耗铁芯的结构控制手段提供了新的途径，也可为开发适用于400Hz~10KHz频率范围高能量密度电-磁转换装备的小/微型软磁铁芯奠定基础。

针对高硅电工钢铁芯难以轧制的瓶颈，同时为满足高能量密度电-磁转换装置的高频化发展，本项目研究以Fe(Si)基软磁铁芯为主要研究对象，采用化学原位沉积、流态化气相沉积、原位自氧化和机械球磨等工艺实现Fe(Si)合金颗粒表面绝缘，随后采用等离子体活化烧结技术实现铁硅软磁铁芯的高致密成型，使其具有高磁感、高导磁和低损耗等特性。研究表明，化学气相沉积过程中适量的氨水含量（0.02 ml/g）和TEOS浓度（0.135 mol/l）对SiO2绝缘膜的均匀性和厚度具有良好作用。流态化气相沉积结合等离子体活化烧结制备的Fe(Si)软磁铁芯具有高致密度、高磁感（179.4 emg/g）、高导磁（3 kHz下187）和低损耗（P1/10=6.5 W/kg）等优势，并且其损耗明显低于日本JFE公司生产的Fe-6.5wt%Si高硅电工钢铁芯的损耗（P1/10=12.7 W/kg）。原位自氧化法制备的Fe(Si)合金粉末表面氧化层均匀性优良，导致软磁铁芯的电阻率高达248.6 μΩ·m，饱和磁化强度高达181.9 emu/g, 50 kHz下的磁损耗低至7.8 W/kg，仅为纯铁硅软磁铁芯的的3.89%。基于原创性“高温扩散-原位置换”原理制备的软磁铁芯具有优良的软磁性能和超低的高频低损耗。本项目探明了软磁铁芯中多元化异质界面形成机理和绝缘膜的结构控制方法，为丰富高磁感、高导磁、低损耗的Fe(Si)软磁铁芯的制备提供了新的途径，同时也为开发新型Fe/FeSi/FeSiAl基软磁铁芯及其应用奠定了基础，制备的软磁铁芯在400Hz~10 kHz频率范围应用的三维电机、逆变器电源用变压器、音频变压器等小型高能量密度电磁转换装备和10kHz~100 kHz频率范围应用的光伏逆变器用逆变电感、PFC电感、滤波电感等微型高频电感元件方面具有较好的应用前景。

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