微胞软磁复合材料软磁特性的有限元模拟

发布时间：2018-11-03 08:23

【摘要】：随着科技的进步,无论是电力电子器件、信息技术产业还是军事国防工业,都对软磁材料提出了更高的要求。本课题组制备出的具有微胞结构的软磁复合材料,以软磁铁氧体作为的绝缘包覆层,利用等离子放电烧结技术实现的高、低熔点不同相的致密烧结,在提高软磁材料电阻率的同时,兼顾到磁导率和饱和磁感应强度,是解决软磁材料高磁能密度与高电阻率矛盾的可行办法。本文对微胞软磁复合材料的制备工艺进行改良,制备出了微胞尺寸一致,包覆层均匀的微胞软磁复合材料,样品电阻率有了明显的提高。针对微胞软磁复合材料的特殊结构,构建微胞软磁复合材料的模拟模型。以有限个微胞实现对无穷多个微胞堆垛时单个微胞电磁场分布情况的近似求解,使得对具有复杂形状周期性堆垛的软磁复合材料进行模拟计算成为可能。在模拟计算过程中,改了变金属粉体粒径、金属粉体与包覆层磁导率、包覆层电阻率和样品宏观电阻率,计算出不同条件下样品的等效磁导率、胞间涡流损耗、胞内涡流损耗,定量分析出了以上各个因素的变化对制备出的微胞软磁复合材料性能的影响。模拟计算的结果表明：采用高磁导率的绝缘包覆材料是提高具有微胞结构的软磁复合材料等效磁导率的最主要手段。在软磁性绝缘包覆的前提下,提高金属粉体的磁导率,降低包覆层的体积分数可以进一步提高样品的等效磁导率。微胞软磁复合材料的可以分为胞间涡流损耗和胞内涡流损耗两个部分,胞间涡流损耗与频率的平方成正比,与宏观电阻率成反比；胞内涡流损耗与粒径的平方、频率的平方成正比,与颗粒的电阻率成反比。当样品宏观电阻率达到一定水平后,其涡流损耗逐渐以胞内损耗为主,需要采用更高电阻率、更小粒径的金属粉体以进一步降低总涡流损耗。本文建立了微胞软磁复合材料软磁特性的有限元模拟模型,定量说明了微胞软磁复合材料采用软磁性绝缘包覆对于提高样品磁导率的重要性,为今后原材料的选择和样品的性能改进指明了方向。通过数值计算获得材料的软磁性能,从而减少和简化微胞软磁复合材料研究过程中的实验工作,降低研发成本,缩短研发周期,为进一步深入的研究做好了铺垫,并开辟了全新的视角。
[Abstract]:With the development of science and technology, both power electronic devices, information technology industry and military defense industry have put forward higher requirements for soft magnetic materials. The soft magnetic composites with microcellular structure were prepared by our research group. The soft magnetic ferrite was used as the insulating coating. The dense sintering of different phases with high and low melting points was realized by using plasma discharge sintering technology. It is a feasible method to solve the contradiction between high magnetic energy density and high resistivity of soft magnetic material by increasing the resistivity of soft magnetic material and taking into account the permeability and saturation magnetic induction intensity at the same time. In this paper, the preparation process of microcellular soft magnetic composites was improved, and the microcellular soft magnetic composites with uniform microcell size and uniform coating layer were prepared, and the resistivity of the samples was improved obviously. According to the special structure of microcellular soft magnetic composites, the simulation model of microcellular soft magnetic composites was constructed. A finite number of microcells are used to approximate the electromagnetic field distribution of a single microcell when infinite cells are stacked, which makes it possible to simulate and calculate the soft magnetic composites with complex shape periodic stacking. In the process of simulation and calculation, the particle size, permeability, resistivity of coating layer and macroscopic resistivity of samples were changed to calculate the equivalent permeability, intercellular eddy current loss and intracellular eddy current loss of samples under different conditions. The effects of the above factors on the properties of the microcellular soft magnetic composites were quantitatively analyzed. The simulation results show that the insulation coating material with high permeability is the most important means to increase the effective permeability of the soft magnetic composite with microcellular structure. Under the premise of soft magnetic insulation coating, the effective permeability of the sample can be further improved by increasing the permeability of the metal powder and reducing the volume fraction of the coating layer. The microcellular soft magnetic composites can be divided into two parts: intercellular eddy current loss and intracellular eddy current loss. The intercellular eddy current loss is proportional to the square of the frequency and inversely proportional to the macroscopic resistivity. The eddy current loss is proportional to the square of particle size, the square of frequency and the resistivity of particle. When the macroscopic resistivity of the sample reaches a certain level, the eddy current loss of the sample is gradually dominated by the intracellular loss, and the metal powder with higher resistivity and smaller particle size is needed to further reduce the total eddy current loss. In this paper, the finite element simulation model of soft magnetic properties of microcellular soft magnetic composites is established, and the importance of using soft magnetic insulation coating to improve the permeability of microcellular soft magnetic composites is quantitatively explained. It points out the direction for the selection of raw materials and the improvement of the performance of the samples in the future. Through numerical calculation, the soft magnetic properties of the materials are obtained, thus reducing and simplifying the experimental work in the research process of microcellular soft magnetic composites, reducing the research and development costs, shortening the research and development cycle, paving the way for further in-depth research. And opened up a new perspective.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

【参考文献】