General Atomics, Inc.

Quantum Group Inc.

Kuo-Chun Chen

Khodabakhsh S Mazdiyasni

Paul W Trester

High-temperature-stable, fiber-reinforced beryllium metal matrix composite materials are fabricated using coating, infiltration and hot-pressing procedures. High-temperature-stable fibers of metal oxides, carbon or silicon carbide are coated with reaction barrier coatings which prevent chemical reactions from occurring at the interface with the surrounding metallic beryllium matrix at temperatures up to close to the melting point of beryllium. Coatings such as yttria, YAG and mixtures of yttria and YAG or of yttria and beryllia are employed exterior of metal oxide fibers, such as alumina or alumina-silica fibers. Suitable reaction barrier coatings are also employed over carbon fibers (or silicon carbide fibers) which preferably include an interior coating of elemental silicon upon the exterior surface of the carbon fibers. Oxide coatings are preferably applied by immersion in a liquid bath containing a suitable coating solution, preferably an alcohol solvent alkoxide sol-gel.

Stable fiber interfaces for beryllium matrix composites

A method for making rare earth metal oxide ceramic precursor composition comprising reacting a rare earth metal alkoxide with a complexing agent to give a mixture of complexing agent/alkoxide rare earth metal complexes is disclosed. The mixture is hydrolyzed and the precursor composition is isolated. Solubility of the precursor composition in non-polar or polar solvents is affected by the selection of complexing agent amongst other factors. At least partial dissolution of the precursor composition in a solvent gives a preceramic liquid which upon evaporation of the solvent and heating gives a rare earth metal oxide ceramic. Utility of the preceramic liquid include the formation of rare earth metal oxide fibers, thin films, coatings, foams, powders, cast or molded objects or it may be used as a ceramic adhesive.

Method for making rare earth metal oxide ceramic precursor compounds and

Ceramic yttrium aluminate fibers are produced by processes that result in the formation of a microcrystalline ceramic oxide structure. In one process, a stoichiometric amount of a yttrium alkoxide is mixed with an aluminum alkoxide to produce a homogeneous mixture in an alcohol solvent. Following the addition of an alkoxide precursor of ZrO.sub.2 or of HfO.sub.2, the optional addition of an alkoxide precursor of MgO, and the subsequent addition of an organic acid, hydrolytic condensation to produce a suitable sol is accomplished by adding water. A slight excess of yttrium alkoxide can be used instead of the MgO precursor. The viscosity of the sol is adjusted to form a tractable gel that is spun into fibers which, after curing and firing, are shown to be microcrystalline in form, the resulting fibers having a submicron average grain size. Strength and stability result from the presence of solid particles of partially stabilized zirconia or hafnia at the grain boundaries and the triple points. The fibers exhibit good tensile strength at high temperatures and can be employed to make ceramic composites having excellent resistance to high-temperature creep.

Crystalline yttrium aluminate and process for making

Method for in-situ prevention of stable barium carbonate formation in

A method of making high T.sub.c 1-2-3 superconductors having perovskite structure using solution techniques is disclosed. The process uses two solvent systems to form a resinous preceramic material having a controlled viscosity for facilitating its formation into superconducting articles such as fibers, wires, ribbons, films and the like. The process yields a pre-ceramic which is flexible and which has sufficient structural integrity to withstand normal handling.

Method for preparing rare earth-barium-cuprate pre-ceramic resins and

A method of making high T.sub.c 1-2-3 superconductors having perovskite structure using solution techniques is disclosed. The process uses two solvent system to form a resinous pre-ceramic material having a controlled viscosity for facilitating its formation into superconducting articles such as fibers, wires, ribbons, films and the like. The process yields a pre-ceramic which is flexible and which has sufficient structural integrity to withstand normal handling.

Growing community of inventors

Carlsbad, CA, United States of America

Kuo-Chun Chen