Methods for making ceramic matrix composites using precursor polymers to refractory metal carbides and metal borides

The present invention relates to the formation of ceramic matrix composites using precursor polymers which, upon pyrolysis or other energetic treatment, decompose to yield substantially pure refractory metal carbides and/or refractory metal borides. The present invention provides a method for making a ceramic matrix composite comprising forming an infiltrated fiber reinforcement by infiltrating a plurality of plies of a fibrous material with a precursor polymer which decomposes to a substantially pure product selected from the group consisting of a refractory metal carbide and a refractory metal boride, and exposing the infiltrated fiber reinforcement to conditions effective to cure the precursor polymer and to decompose the precursor polymer to said substantially pure product.