Abstract: The present invention relates to a novel process for making a macrocomposite body. Specifically, a metal matrix composite body is first formed and thereafter, a ceramic body or a ceramic matrix composite body is caused to form from at least one surface of the already formed metal matrix composite body. The ceramic or ceramic composite body can be formed by, for example, changing from spontaneous infiltration conditions which permit a molten matrix metal to infiltrate a filler material or preform to conditions which favor the growth of a ceramic oxidation reaction product from the matrix metal (e.g., the matrix metal serves the dual role of a matrix metal and a parent metal for growth of oxidation reaction product). The growth of oxidation reaction product can occur from one or more surfaces of a metal matrix composite body and can be controlled to result in any desired shape.

Abstract: This invention relates generally to a novel method for forming a self-supporting body. Specifically, the formed self-supporting body has a higher volume percent of metallic constituent relative to a body formed by similar techniques. A first porous self-supporting body is formed by reactively infiltrating a molten parent metal into a bed or mass containing a boron donor material and a carbon donor material (e.g., boron carbide) and/or a boron donor material and a nitrogen material (e.g., boron nitride) and, optionally, one or more inert fillers. Additionally, powdered parent metal may be admixed with a mass to be reactively infiltrated to form additional porosity therein. The porous self-supporting body which is formed by the reactive infiltration process according to this invention should contain at least some interconnected porosity which is capable of being filled in a subsequent step with additional metal, thus increasing the volume percent of parent metal in the body at the expense of porosity.

Abstract: A method of producing a self-supporting ceramic composite body having therein at least one cavity which inversely replicates the geometry of a positive mold of parent metal. The method includes embedding the mold of parent metal within a conformable bed of filler to provide therein a cavity shaped and filled by the mold. The assembly is heated to melt the parent metal mold, e.g., an aluminum parent metal mold, and contacted with an oxidant to oxidize the molten parent metal to form a polycrystalline material which grows through the surrounding bed of filler, the molten metal being drawn through the growing polycrystalline material to be oxidized at the interface between the oxidant and previously formed oxidation reaction product whereby the cavity formerly filled by the mold of parent metal is eventually evacuated of the metal. There remains behind a cavity whose shape inversely replicates the original shape of the mold.

Abstract: A ceramic forming paper sheet is prepared by dispersing in water a ceramic-forming powder, a thermoplastic pulp and wood pulp, flocculating the dispersion by adding a cationic wet strength resin and an anionic polymer, dewatering the flocculated dispersion to form a sheet, and wet pressing and drying the sheet. The sheets can be stacked, and pressed or thermoformed, followed by firing to consolidate the sheets to a ceramic.

Abstract: The present invention relates to a novel process for forming metal matrix composite bodies. Specifically, a metal which typically would not exhibit spontaneous infiltration properties under a given set of processing conditions can be induced to infiltrate a filler material or preform when combined or contacted with a matrix metal which does exhibit spontaneous infiltration properties. Stated more particularly, when an infiltration enhancer and/or an infiltration enhancer precursor and/or an infiltrating atmosphere are in communication with a filler material or a preform, at least at some point during the process, and a metal which, under the process conditions, ordinarily would not exhibit spontaneous infiltration, is combined with (e.g., alloyed, mixed with and/or exposed to) a matrix metal which does exhibit spontaneous infiltration behavior under the same processing conditions, the combination of metals will spontaneously infiltrate the filler material or preform.

Abstract: A net shaped ceramic-reinforced aluminum matrix composite is provided by forming a permeable mass of ceramic material with a defined surface boundary having a barrier, and contacting a molten aluminum-magnesium alloy with the permeable mass of ceramic material in the presence of a gas comprising from about 10 to 100% nitrogen, by volume, balance nonoxidizing gas, e.g. hydrogen or argon. Under these conditions, the molten alloy spontaneously infiltrates the ceramic mass under normal atmospheric pressures until it reaches the barrier. A solid body of the alloy can be placed adjacent to a permeable bedding of ceramic material having a barrier, and brought to the molten state, preferably to at least about 700.degree. C., in order to form the net shape aluminum matrix composite by spontaneous infiltration. In addition to magnesium, auxiliary alloying elements may be employed with aluminum. The resulting composite products may contain a discontinuous aluminum nitride phase in the aluminum matrix.

Abstract: The present invention relates to methods for producing self-supporting ceramic and ceramic composite bodies having a protective surface region on at least a portion of the surface of the formed bodies, and bodies produced thereby. The protective surface region is formed upon reaction of at least two components of the ceramic or ceramic composite body.

Abstract: An uncrosslinked polysilazane containing chemically bound peroxide groups is prepared by reacting a polysilazane and a hydroperoxide at a temperature below the decomposition temperature of the hydroperoxide. A thermoset polymer is formed by heating an uncrosslinked, peroxide-substituted silazane that is also substituted by alkenyl or alkynyl groups at temperatures sufficiently high to decompose the chemically bound peroxide groups to yield a free radical, thereby initiating crosslinking. The crosslinked polysilazanes can be pyrolyzed to form ceramic articles.

Abstract: An aluminum-nitrogen polymer is prepared by reacting an organic nitrile with a dialkylaluminum hydride to form an organoaluminum imine, and heating the imine to a temperature of 50.degree. to 200.degree. C. for at least 2 hours. The polymeric product can be subjected to an additional heat treatment to form a more highly cross-linked polymer. After either heat treatment the polymeric product can be further reacted with a primary amine or ammonia. The organoaluminum imine as well as the aminated or non-aminated polymers can be pyrolyzed to form an aluminum nitride-containing ceramic.

Abstract: The present invention relates to the formation of a metal matrix composite body by a spontaneous infiltration technique. Particularly, an infiltration enhancer and/or infiltration enhancer precursor can be positioned at least partially between or at an interface between a matrix metal and a filler material (or preform) which is to be infiltrated by molten matrix metal. Moreover, at least at some point during the process, an infiltrating atmosphere may be in communication with the filler material or preform and/or matrix metal.

Abstract: This invention provides a process for manufacturing aluminum-nitrogen polymers (i.e., polymers having a backbone of alternating aluminum and nitrogen atoms) in which portions of the polymer have an organic substituent on each aluminum and nitrogen atom. The novel polymers so produced are useful for making green shapes pyrolyzable to AlN articles suitable for high performance applications. The process generally comprises reacting an organic nitrile having the formula R.sup.1 CN with a trialkylaluminum compound having the formula R.sup.2 R.sup.3 R.sup.4 Al, and optionally heating the reaction product, to form an organoaluminum imine, and heating the organoaluminum imine to a temperature of at least 300.degree. C. and less than 600.degree. C. for at least two hours to form an aluminum-nitrogen polymer. The polymer or the imine can be pyrolyzed to form an aluminum nitride ceramic article. In the foregoing formulae, R.sup.

Abstract: Ceramic foams in which the open cells are connected by a three-dimensional, substantially continuous ceramic matrix formed of interconnected hollow ligaments, are made from an open-cell, reticulated precursor metal, i.e. a metal foam. The precursor metal first is treated so as to allow a support coating to form thereon, and thereafter the coated precursor is heated above the melting point of the metal in the presence of an oxidant to form an oxidation reaction product.

Abstract: This invention relates generally to a novel directed metal oxidation process which is utilized to produce self-supporting bodies. In some of the more specific aspects of the invention, a parent metal (e.g., a parent metal vapor) is induced to react with at least one solid oxidant-containing material to result in the directed growth of a reaction product which is formed from a reaction between the parent metal and the solid oxidant-containing material. The inventive process can be utilized to form bodies having substantially homogeneous compositions, graded compositions, and macrocomposite bodies.

Abstract: A sintered silicon nitride ceramic product that has high strength at both ambient and elevated temperatures, good oxidation resistance at high temperatures and retention of strength after exposure to oxidizing conditions contains 1 to 80 wt. % Mo.sub.5 Si.sub.3.

Abstract: This invention relates generally to a novel method of manufacturing a composite body, such as a ZrB.sub.2 --ZrC--Zr (optional) composite body, by utilizing a post-treatment process and to the novel products made thereby. More particularly, the invention relates to a method of modifying a composite body comprising one or more boron-containing compounds (e.g., a boride or a boride and a carbide) which has been made by the reactive infiltration of a molten parent metal into a bed or mass containing boron carbide, and optionally one or more inert fillers, to form the body.

Abstract: A block copolymer is prepared by reacting an aluminumnitrogen polymer and a silazane polymer at a temperature not greater than 400.degree. C. Block copolymers containing alkenyl or alkynyl groups can be crosslinked by supplying energy to generate free radicals, An AlN/SiC-containing ceramic is formed by pyrolyzing the crosslinked block copolymer in a nonoxidizing atmosphere.

Abstract: In the present invention, there is described a setup for producing a self-supporting ceramic body or ceramic composite by the oxidation of a parent metal to form a polycrystalline ceramic material comprising the oxidation reaction product of said parent metal with an oxidant, including a vapor-phase oxidant, and optionally one or more metallic constituents dispersed throughout the polycrystalline ceramic material. The setup is used with a method which comprises the steps of providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body, and heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal. At that temperature, the molten metal is reacted with the oxidant, thus forming the oxidation reaction product.

Abstract: This invention relates generally to a novel method for removing metal from a formed self-supporting body. A self-supporting body is made by reactively infiltrating a molten parent metal into a bed or mass containing a boron donor material and a carbon donor material (e.g., boron carbide) and/or a boron donor material and a nitrogen donor material (e.g., boron nitride) and, optionally, one or more inert fillers. Once the self-supporting body is formed, it is then subjected to appropriate conditions which causes metallic constituent contained in the self-supporting body to be at least partially removed.

Abstract: This invention broadly relates to methods for producing self-supporting silicon carbide and silicon carbide composite bodies. More particularly, this invention relates to silicon carbide and silicon carbide composites, grown by the oxidation reaction of a silicon metal with a gas comprising at least one gas selected from the group consisting of fluorinated hydrocarbon gases, chlorohydrocarbon gases, and chlorofluorocarbon gases.

Abstract: Organometallic ceramic precursor binders are used to fabricate shaped bodies by different techniques. Exemplary shape making techniques which utilize hardenable, liquid, organometallic, ceramic precursor binders include the fabrication of negatives of parts to be made (e.g., sand molds and sand cores for metalcasting, etc.), as well as utilizing ceramic precursor binders to make shapes directly (e.g., brake shoes, brake pads, clutch parts, grinding wheels, polymer concrete, refractory patches and liners, etc.). A preferred embodiment of the invention involves the fabrication of preforms used in the formation of composite articles.