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: A lightweight armor system may comprise multiple reinforcement materials layered within a single metal matrix casting. These reinforcement materials may comprise ceramics, metals, or other composites with microstructures that may be porous, dense, fibrous or particulate. Various geometries of flat plates, and combinations of reinforcement materials may be utilized. These reinforcement materials are infiltrated with liquid metal, the liquid metal solidifies within the material layers of open porosity forming a dense hermetic metal matrix composite armor in the desired product shape geometry. The metal infiltration process allows for metal to penetrate throughout the overall structure extending from one layer to the next, thereby binding the layers together and integrating the structure.

Abstract: A lightweight armor system may comprise multiple reinforcement materials layered within a single metal matrix casting. These reinforcement materials may comprise ceramics, metals, or other composites with microstructures that may be porous, dense, fibrous or particulate. Various geometries of flat plates, and combinations of reinforcement materials may be utilized. These reinforcement materials are infiltrated with liquid metal, the liquid metal solidifies within the material layers of open porosity forming a dense hermetic metal matrix composite armor in the desired product shape geometry. The metal infiltration process allows for metal to penetrate throughout the overall structure extending from one layer to the next, thereby binding the layers together and integrating the structure.

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 an active heat-generating device 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: 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: 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 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 metal vias in pure alumina substrates are derived from a metallization composition having 80-97% refractory metal, 2-15% alumina, 0.05-5% sintering aid, and 0-5% bonding additive; it has been found that for alumina contents greater than about 12%, a bonding additive is not required. The same compositions, absent the sintering aid, can be used to form bimetallic vias; these vias include a porous metal network where the pores are infiltrated with another metal, for example, porous tungsten infiltrated with copper.

Abstract: An improved method and system are provided for centrifugally separating a suspended colloidal phase. The method in accordance with a preferred embodiment of the invention involves filling a spinning centrifuge bowl with a fluid medium distinct from the suspension, so that a static zone of liquid forms in the bowl, and then introducing the suspension into the bowl in a feed location concentrically inside of the static zone.

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: Slurries or suspensions for forming sintered ceramic or metallic articles are described as having a high volume fraction of sinterable particles, at least 55% by volume. while the slurries maintain a pourable viscosity, such as not more that 2000 cPs at 100 s.sup.-1 ; the slurries can be dilatant and/or pseudoplastic. The slurries are prepared by using specific families of dispersants; namely acrylic acid-based polymeric polyelectrolytes, polyethylene imine-based polyelectrolytes, and coupling agents from the subfamilies of oxy-silane esters and phosphate esters. Fabrication of the compositions includes milling under high energy and the addition of at least a portion of the particles in a step-wise manner.

Abstract: Bonding additives for refractory metallization compositions allow for circuit traces having good resistivities and adhesion values in excess of 6 kpsi, generally between about 10 and 20 kpsi. The inks are provided in formulations devoid of a glass component, and are suitable for co-sintering circuit traces and vias with 96% alumina substrates, and especially for 99% alumina substrates. Suitable bonding additives are the oxides of molybdenum, tungsten, niobium, manganese, yttrium, and titanium, or mixtures of such oxides.

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: 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: A highly loaded, uniform ceramic composite can be made by first preparing a highly loaded suspension. Due to the particle-particle interactions of a highly concentrated system, virtually any dopant can be added, including other suspensions, fibers, and whiskers. The process is particularly useful for making composites of materials which coagulate when mixed at low concentration.

Abstract: Glass-ceramic packages for integrated circuits containing multi-layer, interconnected thick film wiring patterns are obtained by co-sintering a glass-ceramic composite and copper, silver, palladium, gold, based conductors at temperatures not exceeding about 1000.degree. C. The dielectric systems include 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. The package is fabricated using a tape specifically designed for clean binder burnout in a reducing atmosphere at low temperatures and also for superior mechanical and thermal properties. 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.