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

Onoda²,

Sakamoto³

et al. 2005

MSF

Self Cite

The centrifugal method was successfully applied to fabricate functionally graded materials with different profiles of gradient in permittivity (i.e., ε-FGMs) from an alumina/epoxy mixture. Gradient of the number density, packing fraction, and size of the dispersed alumina fillers was confirmed. Non-spherical and spherical alumina fillers were employed to fabricate ε-FGMs, where, conditions of the centrifugal process for both fillers were quite differentiated from each other. The gradient of filler dispersion was intentionally regulated by changing not only conditions of the centrifugal process, but also the size distribution and shape of fillers.

Section: Introductionmentioning

confidence: 99%

Fabrication of Permittivity Graded Epoxy Resin with Non-Uniform Dispersion of Alumina Fillers by a Centrifugal Procedure

Onoda²,

Sakamoto³

et al. 2005

MSF

Self Cite

“…The authors are using a centrifugal method to fabricate functionally graded materials with large size from alumina-particles/epoxy-resin mixtures (1) . During the centrifugal process, drag force is one of the major forces experienced by the particles, and hence, it dominates the movement of the particles.…”

Section: Introductionmentioning

confidence: 99%

“…During the centrifugal process, drag force is one of the major forces experienced by the particles, and hence, it dominates the movement of the particles. It directly depends on the coefficiency of viscosity of the mixture, η, and consequently, precise information of η is indispensable for both the fabrication and simulation process (1) (2) . To evaluate effects of the amount and size of particles involved in the mixture on η, η of unimodal and bimodal alumina/epoxy mixtures were measured under various conditions.…”

Section: Introductionmentioning

confidence: 99%

Viscosity of Unimodal and Bimodal Alumina/Epoxy Mixtures

Sulistio

Tsuru³

et al. 2005

IEEJ Trans. FM

Self Cite

Experimental results on characteristics of viscosity η of unimodal and bimodal alumina/epoxy mixtures are shown and discussed based on theoretical consideration. Spherical alumina particles with nominal diameters of 35µm and 80µm, both of which had narrow dispersion of diameter distribution, were used as fine and coarse particles, respectively. η of the unimodal mixture increases remarkably with a volume packing fraction of particle ν p , and that Brinkman equation can be applied to estimate η from ν p . On the other hand, η of the bimodal mixture depends not only on ν p , but also on the ratio of coarse particles to fine ones. For larger ν p , η of the bimodal mixture becomes smaller than that of the unimodal mixture. It is shown that an approximation procedure of η yields reasonable estimation for smaller ν p , and underestimation for larger ν p .

Improved method to simulate gradient in alumina packing fraction in alumina/epoxy composite fabricated by a centrifugal method

IEEJ Transactions Elec Engng

Sugahara

Tsuru

et al. 2006

A centrifugal method was used to fabricate large‐scale functionally graded materials (FGMs) from solid‐particles/viscous‐matrix mixtures at room temperature. The conventional simulation procedure of the centrifugal process was improved by considering the dependency of the viscosity η of the mixture on the packing fraction νp of particle, the effects of arbitrary shape of the actual fillers on η, the statistical dispersion of the diameters of the actual fillers, and the formation and growth of the fully packed layer (FPL) near the FGM bottom. The new simulation method was applied to three centrifugal processes employed for experimental FGM fabrications from alumina/epoxy mixtures. The numerical profiles of νp are in good agreement with the experimental ones regardless of the shapes of fillers and 'ponding viscosity of the solutions without fillers, the total amount of fillers loaded, and the centrifugal conditions. The saturating nature of νp near the far end of the FGM column is also simulated with reasonable precision. Finally, the manner in which the particles exert varying influences on the gradient of νp is demonstrated: the particles exhibit different movements depending on their size. On the basis of these results, the effectiveness of the new simulation method proposed is confirmed for the modeling of similar processes involved in the fabrication of FGMs from solid‐particles/viscous‐matrix mixtures by the centrifugal method. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.