Production of ultrastructural ceramics

A process for the production of polymeric nitride ceramic precursors from organometallic precursors comprising conducting a polymerizing reaction under conditions subjecting said organometallic precursors to supercritical pressure and supercritical temperature.

A process for the production of polymeric silicon nitride ceramic precursors comprising reacting a silane reagent with a nitrogen-containing material under conditions of supercritical pressure and supercritical temperature.

In the method for making polymeric silicon nitride ceramic precursors which comprises reacting an alkylhalosilane with ammonia wherein the improvement comprises subjecting said alkylhalosilane and ammonia to conditions of supercritical pressure and supercritical temperature.

A process for the production of ceramic polymer precursors useful for making nitrides, oxynitrides and carbonitrides comprising reacting a compound chosen from the group consisting RnSiCl.sub.4-n, RnSiH.sub.2, AlOCl, and boehmite wherein R is an aliphatic saturated or unsaturated residue containing one to 20 carbon atoms in the presence of a reactant chosen from the group consisting of nitrogen, ammonia, hydrazine, primary and secondary amines, hydrogen and mixtures thereof and where n is 1, 2, or 3, said process being conducted under conditions of supercritical pressure and supercritical temperature.

A process for the production of ceramic polymer precursors useful of making carbide ceramics which comprises reacting, under conditions of supercritical pressure and supercritical temperature, a compound chosen from the group consisting of organometallics, organic salts, hydrides and mixtures thereof in the presence of a hydrocarbon chosen from the group consisting of methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, as well as a hydrocarbon containing 1 to 20 carbon atoms.