Abstract: Shaped articles of polycrystalline aluminum nitride are disclosed having a tensile strength of at least about 100 Kpsi. The shaped articles are preferably fibers. Composites of polycrystalline AlN fibers in a matrix of organic or inorganic polymer, metal, glass or ceramic are also disclosed herein. The process for the preparation of polycrystalline aluminum nitride fibers is covered.

Abstract: Methods are described for preparing aluminum nitride of controllable morphology for ceramic and heat conduction applications. The methods comprise forming spherical particles or flakes of an intermediate, RAlNH, followed by heating the spheres or flakes of RAlNH at elevated temperatures to produce high purity aluminum nitride of corresponding morphology. Spheres of RAlNH are formed by (i) freezing a suspension of RAlNH in a liquid medium and thawing, by (ii) aging the suspension, or by (iii) dissolving RAlNH in a liquid medium and precipitating it. Flakes are formed by freezing a suspension of RAlNH in a liquid medium and removing frozen medium from the frozen suspension.

Abstract: Shaped articles of polycrystalline AlN and AlN-containing composites; the AlN articles having thermal conductivities of at least about 70 W/mK (watts/meter .degree.K); the AlN component effecting good thermal conductivity in the composited articles.

Abstract: There is disclosed an improved process for preparing a superconducting composition having the formula MBa.sub.2 Cu.sub.3 O.sub.x wherein M is selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tn, Yb and Lu; x is from about 6.5 to about 7.0; said composition having a superconducting transition temperature of about 90.degree. K.; said process consisting essentially of preparing a precursor solution, drying the solution to obtain a solid material, and heating and cooling the solid material under specified conditions to obtain the desired product. In another embodiment, a shaped superconducting MBa.sub.2 Cu.sub.3 O.sub.x article is prepared by impregnating an article of cellulose material with the precursor solution, drying the impregnated article, and heating and cooling the impregnated article under prescribed conditions to obtain the desired product.

Abstract: A method of producing coatings of boron nitride on substrates by the application of solutions containing boron compounds.

Abstract: Dense highly pure fibers of silicon carbide are made by incorporating silicon carbide particles into a polymeric silicon carbide precursor, spinning and sintering.

Abstract: Methods are described for preparing aluminum nitride of controllable morphology for ceramic and heat conduction applications. The methods comprise forming spherical particles or flakes of an intermediate, RA1NH, followed by heating the spheres or flakes of RA1NH at elevated temperatures to produce high purity aluminum nitride of corresponding morphology. Spheres of RA1NH are formed by (i) freezing a suspension of RA1NH in a liquid medium and thawing, by (ii) aging the suspension, or by (iii) dissolving RA1NH in a liquid medium and precipitating it. Flakes are formed by freezing a suspension of RAINH in a liquid medium and removing frozen medium from the frozen suspension.

Abstract: There is disclosed an improved process for preparing a superconducting composition having the formula MBa.sub.2 Cu.sub.3 O.sub.x wherein M is selected from the group consisting of Y, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Lu; x is from about 6.5 to about 7.0; said composition having a superconducting transition temperature of about 90 K; said process consisting essentially of preparing a precursor solution, drying the solution of obtain a solid material, and heating and cooling the solid material under specified conditions to obtain the desired product. In another embodiment, a shaped superconducting MBa.sub.2 Cu.sub.3 O.sub.x article is prepared by impregnating an article of cellulose material with the precursor solution, drying the impregnated article, and heating and cooling the impregnated article under prescribed conditions to obtain the desired product.

Abstract: Aluminum nitride fibers or films are made by carbothermal nitridation of precursor fibers or films which contain a source of alumina and a source of carbon. Improved articles are obtained by providing a stoichiometric excess of carbon, by stabilizing the precursor prior to carbonization and nitridation, by removing excess carbon after nitridation and introducing a sintering aid to promote densification of the final structure.

Abstract: Method for making a ceramic mixture of boron and aluminum nitrides in the ratio of about 0.2 to 20 g atoms of aluminum per g atom of boron, and method for making shaped articles of the ceramic and of the intermediate from which the ceramic is prepared, comprising the steps (i) reacting a boron nitrogen compound with an organoaluminum compound in a suitable solvent to form a shapeable intermediate, and (ii) heating the intermediate at temperatures and under conditions to effect formation of the mixed nitrides.

Abstract: Aluminum nitride structures are made by pyrolyzing the condensation products of certain organo-aluminum compounds with certain aromatic diamines, triamines or tetraamines.

Abstract: Cross-linked organosilazane polymers which are useful as ceramic precursors and film casting are disclosed.

Abstract: Oxidative stabilization of pitch fiber is accelerated in an oxidizing atmosphere wherein the oxidizing gas is at a pressure of at least about two atmospheres.