THERMAL-CONDUCTIVITY OF HYBRID SHORT-FIBER COMPOSITES

A combined analytical/experimental study has been undertaken to investigate the effective thermal conductivity of hybrid composite materials. The analysis utilizes the equivalent inclusion approach for steady state heat conduction (Hatta and Taya. 1986), through which the interaction between the various reinforcing phases at finite concentrations is approximated by the Mori-Tanaka (1973) mean field approach. The multiple reinforcing phases of the composite are modeled as ellipsoidal in shape and thus can simulate a wide range of microstructural geometry ranging from thin platelet to continuous fiber reinforcement. The case when one phase of the composite is penny-shaped microcracks is studied in detail. Multiphase composites consisting of a Kerimid matrix and Al2O3 short fibers and Si3N4 whiskers were fabricated and after a careful study of their microstructure. their thermal conductivities were measured. Analytical predictions are shown to be in good agreement with experimental results obtained for the Al2O3/Si3N4/Kerimid short fiber composites.