Fabrication of Permittivity graded materials applied for electric power apparatus

本课题的主要研究成果如下：1。采用离心法制备大规模功能梯度材料（fgm），以氧化铝/环氧树脂为原料制备氧化铝级配环氧树脂。发现球形填料比不规则填料更好，因为球形填料增加了fgm中可达到的最大填充分数，因此，介电常数的变化范围很大。在离心时间、离心速度、氧化铝性能、混合料配比等条件下进行了制备。在此基础上，得到了制备条件与梯度之间的关系。测定了氧化铝填充环氧树脂的热扩散系数与氧化铝填充率的关系。利用该关系式计算了FGM的热电阻率。在此基础上，定量得出了梯度曲线与FGM热电阻率之间的关系。利用自制的FGM柱对未来全固态变电站接头中出现的固体/固体界面进行了建模，并对界面粗糙度、FGM界面组合和均匀界面等不同界面条件下的界面抗雷击电压性能进行了实验研究。实验结果表明，在该界面表面引入FGM会导致耐压升高。然而，表面的粗糙度对这种表面的电性能有很大的影响。开发了一种能够模拟离心过程中颗粒运动的新型仿真程序。在该程序中，精确地模拟了颗粒直径的累积分布，并准确地考虑了阻力对填料分数的依赖关系。实验结果与数值结果的比较表明，对填料分数梯度分布的估计具有合理的精度。最后，验证了仿真代码的有效性。少

Major results obtained from the present research project are as follows :1.An centrifugal method was employed to fabricate large-scaled functionally graded materials (FGMs), and alumina-graded epoxy resin was fabricated from alumina/epoxy mixtures.2.It is found that spherical fillers are preferable than irregular fillers, since the spherical fillers increase the maximum packing fraction attainable in FGMs, and accordingly, attain large range of the variation of dielectric constant.3.The fabrication was conducted under various conditions of centrifugal time and velocity, alumina properties, ratio of the mixture, and so on. Based on results, relationship between the fabrication conditions and the gradient is obtained.4.A coefficient of thermal diffusion of alumina filled epoxy resin was measured as a function of the alumina packing fraction. This relationship was used to calculate the thermal resistivity of FGM. Based on the numerical results, relationship between the profiles of gradien … More t and the thermal resistivity of FGM is quantitatively obtained.5.Solid/solid interface, which will appear in the joints of future all solid substation, was modeled by using the FGM columns fabricated by the authors, and properties of the interface against the lightning impulse voltage was experimentally examined under various interface conditions such as the roughness of the interface, combination of the FGM interface and the uniform interface. Based on the experimental results, it is found that the introduction of FGM on the surface of such interface causes increase of the electrical withstand voltage. However, the roughness of the surface has significant influence on the electrical properties of such surface.6.A novel simulation code, which can simulate movement of particles during the centrifugal process, was developed. In this code, the cumulative distribution of the particle diameters was precisely simulated and the dependency of the drag force on the packing fraction was exactly considered. Comparison between the experimental and numerical results shows that the estimation of profiles of gradient in the packing fraction was conducted with reasonable precision. In the end, the effectiveness of the present simulation code is verified. Less