Polymer impregnation and pyrolysis process development for improving thermal conductivity of SiCp/SiC–PIP matrix fabrication

The polymer impregnation and pyrolysis (PIP) method is optimized to consolidate particulates, and to produce a continuous SiC network to yield high thermal conductivity monoliths from particulates. The process as presently employed, consists of impregnating a polymeric precursor into a cast sample or a pressed pellet, pyrolyzing, and crystallizing at high temperature to a final form. The use of gas pressure in the polymer impregnation step was found essential to improve the density of the matrix, provided that the nature of the gas and the pressure applied were optimized. Thermal conductivity of this matrix indicated that higher crystallization temperatures improve the conductivity by removing impurities and increasing crystallite size. The impregnation process also permits bonding of solids to produce complex engineering shapes if high temperature crystallization is possible.