A silicon nitride powder for sintering which, despite of its fine powdery form, shows a very small increase in the oxygen concentration with time and features excellent storage stability. The silicon nitride powder for sintering has a specific surface area of 5 to 30 m.sup.2/g, and is characterized by having a hydrophobicity (M value) of 30 or more and an increase in the oxygen concentration of 0.30% by mass or less after left to stand in the air of a humidity of 90% and 20° C. for 48 hours. The silicon nitride powder for sintering can be obtained by dry-pulverizing aggregated masses of the silicon nitride in an inert atmosphere in the presence of a silane coupling agent.

The present application discloses a ceramic preform, a method of making a ceramic preform and a metal matrix composite comprising a ceramic preform. In one exemplary embodiment, the ceramic preform comprises a ceramic compound compressed into the shape of a cylinder by rotational compression molding. The cylinder has an inner surface and an outer surface. A first liner may be attached to the inner surface of the cylinder and a second liner may attached to the outer surface of the cylinder. The metal matrix composite of the present application may be formed as a brake drum or a brake disc.

A general procedure applied to a variety of sol-gel precursors and solvent systems for preparing and controlling homogeneous dispersions of very small particles within each other. Fine homogenous dispersions processed at elevated temperatures and controlled atmospheres make a ceramic powder to be consolidated into a component by standard commercial means: sinter, hot press, hot isostatic pressing (HIP), hot/cold extrusion, spark plasma sinter (SPS), etc.

The present invention relates to a mesoporous silica/ceria-silica composite and a method for preparing a mesoporous composite and, more specifically, to a mesoporous silica/ceria-silica composite which is composed of mesoporous silica having a hexagonal or cubic structure and ceria having a hexagonal structure provided on a surface and pores of the mesoporous silica, the oxidation state of the ceria being Ce.sup.4+ and Ce.sup.3+.

A method of depositing silicon carbide on a preform to form a ceramic matrix composite comprises placing the preform into a reaction vessel, removing air from the reaction vessel and backfilling the reaction vessel with an inert gas to an operating pressure. The reaction vessel and the preform are heated to an operating temperature. A carrier gas and precursor materials are heated to a preheat temperature outside of the reaction vessel. The carrier gas and the precursor materials are introduced to the reaction vessel in a specified ratio. Off gasses, the precursor materials that are unspent, and the carrier gas are removed from the reaction vessel to maintain the specified ratio of the precursor materials in the reaction vessel.

A method for forming an ultra-high temperature (UHT) composite structure includes dispensing a polymeric precursor with a spinneret biased at a first DC voltage; forming a plurality of nanofibers from the polymeric precursor; receiving the plurality of nanofibers with a collector biased at a second DC voltage different than the first DC voltage; and changing a direction of movement of the plurality of nanofibers between the spinneret and the collector with a plurality of magnets having a magnetic field by adjusting the magnetic field.

The present invention discloses a method for uniformly coating metal nanoparticles without a carbon impurity on an oxide ceramic powder surface, which includes the steps of putting grinded and mixed a metal organic material and oxide ceramic powder into a rotational reaction chamber, then bubbling oxidizing gas under a rotational and heating condition to oxidize the metal organic material into a metal oxide, and finally bubbling reducing gas to reduce the metal oxide into nanoparticles in a metallic state, so as to implement the uniform coating of the nanoparticles in the metallic state, and avoid coarsening and growing problems of nanoparticles led by a long-term coating reaction under a high temperature. The present invention has a simple method and a short preparation period, and the metal nanoparticles prepared are uniformly dispersed and have wide application prospects in multiple fields like catalytic materials and conductive ceramics.

An ink of the formula: 60-80% by weight BaTiO.sub.3 particles coated with SiO.sub.2; 5-50% by weight high dielectric constant glass; 0.1-5% by weight surfactant; 5-25% by weight solvent; and 5-25% weight organic vehicle. Also a method of manufacturing a capacitor comprising the steps of: heating particles of BaTiO.sub.3 for a special heating cycle, under a mixture of 70-96% by volume N.sub.2 and 4-30% by volume H.sub.2 gas; depositing a film of SiO.sub.2 over the particles; mechanically separating the particles; incorporating them into the above described ink formulation; depositing the ink on a substrate; and heating at 850-900° C. for less than 5 minutes and allowing the ink and substrate to cool to ambient in N.sub.2 atmosphere. Also a dielectric made by: heating particles of BaTiO.sub.3 for a special heating cycle, under a mixture of 70-96% by volume N.sub.2 and 4-30% by volume H.sub.2 gas; depositing a film of SiO.sub.2 over the particles; mechanically separating the particles; forming them into a layer; and heating at 850-900° C. for less than 5 minutes and allowing the layer to cool to ambient in N.sub.2 atmosphere.

A method of forming a porous sol gel, including a dried porous sol gel, is provided comprising forming a sol gel from a sol gel-forming composition comprising a silane solution and a catalyst solution; and non-supercritically drying the sol gel to provide a dried porous sol gel having no springback. The dried porous sol gel can include dried macroporous or mesoporous sol gels or dried hybrid aerogels. The materials may contain open or filled pores. Such materials are useful as thermal insulators.

A W.sub.18O.sub.49 peak is confirmed by X-ray diffraction analysis of a sputtering surface and a cross section orthogonal to the sputtering surface, a ratio I.sub.S(103)/I.sub.S(010) of a diffraction intensity I.sub.S(103) of a (103) plane to a diffraction intensity I.sub.S(010) of a (010) plane of W.sub.18O.sub.49 of the sputtering surface is 0.38 or less, a ratio I.sub.C(103)/I.sub.C(010) of a diffraction intensity I.sub.C(103) of the (103) plane to a diffraction intensity I.sub.C(010) of the (010) plane of W.sub.18O.sub.49 of the cross section is 0.55 or more, and an area ratio of W.sub.18O.sub.49 phase of a surface parallel to the sputtering surface is 37% or more.