Fabrication of Functionally Graded Epoxy Resin with Alumina Fillers and its Simulation by Using a Centrifugal Method

抄録

Functionally graded materials that had gradient profiles of permittivity (i. e., ε-FGMs) were fabricated from an alumina/epoxy mixture by a centrifugal method. Gradient distribution of both the packing fraction and size of the dispersed alumina fillers was confirmed by SEM images. Furthermore, a new numerical method to simulate the fabrication process was proposed based on the movement of solid particles dispersed in the viscous liquid under the centrifugal operation. In the simulation, both the cumulative probability of the practical filler diameter and the existence and growth of the fully-packed layer were taken in account. Permittivity profiles in ε-FGM was calculated and compared with the experimental ones, resulting in reasonable agreement between them. Therefore, it is concluded that the simulation method proposed can be applied to model the similar process of fabricating FGMs by the centrifugal method. The gradient of the fillers is intentionally regulated not only by changing in both the velocity and/or duration of the centrifugal operation, but also by changing in the distribution of filler size. In particular, existence of fillers with various sizes is indispensable to attain and control the centrifugal process because the fillers, depending on their sizes, play different roles in determining the profiles of packing fraction and resultant permittivity.