Abstract: Compound preforms are provided having a first region, including a porous ceramic and a second region including a porous or solid ceramic in which the two regions differ in composition. The compound preform is infiltrated with a liquid metal which is then solidified to form a metal matrix composite.

Abstract: The specification and drawings describe and show an embodiment of and method of forming a liquid flow through heat exchanger structure cast in a metal matrix composite. The composite comprises a preform reinforcement material infiltrated with molten metal. The composite reinforcement material is injection molded around the heat exchanger structure allowing for intimate contact between the composite and structure. The composite formed has a specific coefficient of thermal expansion to match active heat-generating device(s) mounted thereon. The present invention allows for enhanced thermal and mechanical properties by eliminating voids or gaps at the composite to heat exchanger structure interface, these voids or gaps being present in prior art fabrication methods or induced by usage due to thermal cycling of prior art composites.

Abstract: Removal of classified particles from the classifier apparatus is simplified by the addition of a polymeric dispersant in the slurry, added in an amount substantially in excess of that needed to disperse the particles.

Abstract: Metallization, applied by the thick film screening technique, utilized herein has glass-ceramic bonding agents designed to promote adhesion yet maintain the desired electrical properties and post-processing characteristics.

Abstract: A process for forming articles from inorganic sinterable particulates includes providing a well-dispersed, low pressure injectable slurry, freeze-forming the slurry into a desired geometry, and drying the piece so formed by a predominantly sublimative process, to produce a green article that can be conventionally sintered. The vehicle has a volume change on freezing of not more than .+-.10% by volume; to further control the volume change on freezing, an emulsion derived from different vehicles can be tailored. The slurries preferably have a solids content of at least about 35 v/o, a viscosity of preferably not more than about 1000 cP at 100 s.sup.-1, and are preferably injectable at not more than about 1000 psi, usually at less than 100 psi.

Abstract: Dense, flaw free, complex, 3-dimensional, metal or refractory shapes are formed by preparing a low viscosity, pourable aqueous-based suspension. The aqueous suspension preferably contains ceramic or metal particulates, water, and a compatible mixture of additives for performing dispersant, cryoprotectant, and strength enhancing functions. The low viscosity slip is cast or injection molded at low pressure into a complex mold, frozen, demolded, and freeze dried without the formation of a continuous liquid phase. The green part is subsequently sintered by conventional techniques to achieve a dense part.

Abstract: A solution containing polymerizable monomers and volatile solvents can be used to disperse ceramic particles along with ceramic whiskers and remain pourable even with high solids. Using this dispersion, a high solids ceramic article can be molded, polymerized in situ and fired with a good binder burnout.

Abstract: Whisker reinforced composites having improved strength and toughness are prepared by a process including densification by essentially pressureless sintering. There is no need to hot press or hot isostatic press to achieve a density of 99+% of theoretical for 10 vol. % whiskers and 93+% for 20 vol. % whiskers. The composites are derived from the desired volume fraction of whiskers, a sintering aid preferably submicron in average size range, and a major portion of a pressureless sinterable matrix material having an average particle size of not more than about 0.5 micron. Yttria-alumina composites are sintered at less than about 1800.degree. C. and for less than about two hours to avoid surface degradation.

Abstract: A refractory article and a process for making the same are provided. The article is derived from dissociated zircon and zirconia (99:1 to 80:20, weight basis). These components are formed into a slip, which can be conventionally processed to provide a sintered article. The resulting article can be subsequently heat treated to react any resulting glass phase with the zirconia present; further, the heat treated article can be subsequently redensified. These refractories are well-suited for such applications as tundish nozzle inserts and sliding gate valves.

Abstract: Dense vias may be made with a metallizing composition containing tungsten, alumina, and either nickel or palladium. Further, an infiltration process ensures that vias in ceramic substrates are heremetic. Infiltrating materials, including metals and alloys, are applied to co-fired substrates and the composite is fired. The process may be repeated if necessary. Alternatively, the via holes may be bore-coated prior to infiltrating.

Abstract: A tungsten paste suitable for co-sintering with 98+% alumina substrate can be produced by adding selected compositions of glass to the paste. Circuit packages produced in accordance with the present invention exhibit superior thermal conductivity, low shrinkage variability, and smoother and more homogeneous surface finish. A preferred embodiment of the invention utilizes a substrate comprising narrow size range alumina powder, thus yielding lower sintering temperature and further improvements in shrinkage variability and surface finish.

Abstract: Suspensions of ceramic or metallic colloidal particles having a high volume fraction (greater than about 55 vol. %) solid particles are provided in a pourable form. The pourable suspension includes at least about 55 vol. % ceramic or metallic colloidal particles, an aqueous vehicle, and an acrylic acid-based polymeric polyelectrolytic dispersant. Such suspensions can be prepared by mixing the colloidal particles in a staged order of addition and under a high shear rate with the other components. The suspensions are suitable for making ceramic or metallic articles, and can exhibit a low viscosity.

Abstract: This invention relates to glass-ceramic packages for integrated circuits containing multi-layer, interconnected thick film wiring patterns obtained by co-sintering a glass-ceramic composite and copper, silver, palladium or gold based conductors at temperatures not exceeding about 1000.degree. C. The dielectric systems disclosed herein contains composites of borosilicate glasses and crystalline fillers which are fabricated by either mixing glass frit and the filler or by a sol-gel coating process.

Abstract: Commercial wide size distribution powders are size classified into precise size fractions by means of a controlled, semi-continuous, multi-stage centrifugal classification system. The system has utility for a wide range of colloidal materials. The throughput of the semi-continuous process is higher than that of batch processes, and the semi-continuous process produces narrow size ranges and optimum yields.