Abstract: The present invention comprises an adhesive composition and a method of using the composition to join non-oxide, silicon-based ceramic parts. The composition is a non-aqueous paste comprising high levels of non-oxide powders, silicon carbide or silicon nitride powder blended with a mixture of polymeric precursors to silicon carbide and zirconium boride. The resulting blend of the present invention is capable of decomposing on heating (in an inert or reducing atmosphere) into Si-based ceramic phases. The powder is fully suspended and dispersed in the polymer such that pockets of dry powder are not present. Although the polymer penetrates between particles and wets the surfaces to be joined, it does not prevent some contact between particles and the surface. Because the paste contains only low levels of volatile solvents and it converts into Si-based ceramics upon pyrolysis, it provides strong chemical bonding to Si-based ceramics.

Abstract: The application discloses and claims an oxidation resistant, continuous-fiber-reinforced ceramic composition, durable at temperatures above 1000° C., and capable of taking on any arbitrary near net shape formed without machining and tooling. The composition of the invention comprises a fine grained ceramic matrix which in turn comprises a mixture of a ZrB2 phase and a SiC phase with the matrix being reinforced with SiC or C or an oxide fiber, resulting in a fine grained ZrB2—SiC matrix with domain sizes ?0.5 ?m. The ZrB2 phase of the invention is capable of forming small microcrystalline domains ?0.5 ?m upon heat treatment. The composition the invention also comprises a fiber reinforced composite with a high degree of filling and densification of its preform resulting in a composition containing a low level of porosity and high fiber volume fraction.