Abstract: A process for producing agglomerates from dust (especially electrostatic precipitator dust) collected from a process involving the thermal conversion of a material containing gibbsite to sub-alpha alumina and alpha alumina, and the agglomerates so formed. The process involves binding the dust particles together using water and undercalcined alumina taken from an intermediate stage of the same thermal conversion that originally produces the dust. The added undercalcined alumina is ground, in order to create fresh surfaces, to a median particle size of less than 30 microns and a specific surface area of about 130 to 300 m.sup.2 /g. About 1-4 parts by weight of the dust are mixed with every part by weight of the ground undercalcined alumina. A special procedure is employed for mixing the solids and water which makes use of intensive mixing.

Abstract: The present invention relates to a catalytic converter including a nonwoven mat comprising shot-free, high strength, magnesium aluminosilicate glass fiber.

Abstract: This invention relates generally to a novel method of preparing self-supporting bodies, and to novel products made thereby. In its more specific aspects, this invention relates to a method of producing self-supporting bodies comprising one or more boron-containing compounds, e.g., a boride or a boride and a carbide, by reactive infiltration of a molten parent metal actinide into (1) a bed or mass containing boron carbide and, optionally, (2) at least one of a boron donor material (i.e., a boron-containing material) and a carbon donor material (i.e., a carbon-containing material), (3) a bed or mass comprising a mixture of a boron donor material and a carbon donor material and, optionally, (4) one or more inert fillers in any of the above masses, to form the body.

Abstract: Needlelike single crystal particles of .alpha.- alumina, .theta.-alumina, mullite, sillimanite, etc. are produced by adding a silicon-containing substance to needlelike alumina precursor particles and heating the resultant product of addition.

Abstract: The invention relates to refractory materials which comprise:(A) grains of at least one refractory material whose melting point and thermal decomposition temperature are higher than 1700.degree. C.;(B) a binding matrix which binds these grains together and predominantly consists of aluminum nitride AlN of hexagonal structure and/or of at least one of the polytypes of AlN; and(C) hexagonal boron nitride particles and/or crystalline graphite flakes dispersed in the binding matrix.Applications in iron and steel metallurgy, in particular as plates in a slide closure device.

Abstract: Disclosed are an oxide superconductor, and an optimum process for producing the same. The oxide superconductor comprises a base material phase including an oxide superconducting material, the oxide superconducting material including barium (Ba) at least and being free from grain boundaries, and precipitation phases contained in an amount of 1 to 50% by volume in the base material phase and dotted therein in a manner like islands, the precipitation phases being oxides of a metal selected from the group consisting of silicon (Si), aluminum (Al), zirconium (Zr), magnesium (Mg), titanium (Ti), strontium (Sr), tungsten (W), cobalt (Co) and vanadium (V), and being products of decomposition reaction of the base material phase. In the production process, the constituent materials are treated thermally at a partially melting temperature in order to give the above-described novel structure to the oxide superconductor.

Abstract: Aluminum oxide powders having a high .alpha. proportion, crystallite sizes of approximately 0.1 .mu.m and narrow particle size distribution are prepared from customary Bayer aluminum hydroxide (gibbsite) or from aluminum oxide calcined at a low temperature. The starting material is wet-disagglomerated, mixed with .alpha.-aluminum oxide nuclei, dried and calcined. The calcination produces agglomerates which already have the crystallite size required, and which only need to be disagglomerated to the particle size required. The .alpha.-aluminum oxide powders prepared by such process are particularly suitable as a starting material for the production of high-performance ceramics, for example, of blanking dies.

Abstract: A moulding compound is described which contains an inorganic powder together with a binder system. The binder system contains a thermoplast having a melting temperature greater than 180.degree. C. A process is also described for making a sintered molding from the molding compound, which process includes the steps of injection moulding, removal of the binder by heating, and sintering.

Abstract: A proteinaceous gelatin binder is used to make aqueous green ceramic compositions suitable for forming green ceramic tape by tape casting. Any known ceramic may be used. The tapes may be fired individual or as a laminate to produce sintered ceramic articles.

Abstract: The present invention provides an as-fired, high alumina, low silica, corrosion resistant, refractory product and a method for making said product where the product includes from about 50 wt. % to about 80 wt. % of a bubble alumina, from about 10 wt. % to about 30 wt. % of a fine calcined alumina and from about 5 wt. % to about 20 wt. % of a fine hydrated alumina. The product is characterized by having an alumina content of at least 98 wt. % alumina, a silica content of less than 1 wt. %, a density of from about 80 to about 95 pounds per cubic feet, a porosity of from about 55% to about 65%, a room temperature modulus of rupture of at least 200 psig and a cold crushing strength of from at least 200 psi.

Abstract: There is disclosed an Al.sub.2 O.sub.3 based ceramic which includes 5% to 50% by weight of a hard dispersed phase of at least one compound selected from metal carbide, metal nitride, metal carbonitride, metal oxy-carbide, metal oxy-nitride and metal carbo-oxy-nitride. The compound is represented by M(CNO), wherein M is at least one metal selected from the group consisting of Ti, Zr and Hf. The ceramic optionally contains 1% to 25% by weight of ZrO.sub.2, and balance Al.sub.2 O.sub.3 matrix, which contains an additive dissolved in the Al.sub.2 O.sub.3 grains so as to form solid solution therewith. The additive is contained in an amount of 0.01% to 12% by weight with respect to the Al.sub.2 O.sub.3 matrix and is at least one oxide of an element selected from the group consisting of Y, Mg, Cr, Ni, Co, and rare earth elements. The Al.sub.2 O.sub.3 grains have an average grain size no larger than 1.0 .mu. m while the hard phase constituent has an average grain size no larger than 0.6 .mu. m.

Abstract: The present invention relates to a novel method of manufacturing a composite body, such as a ZrB.sub.2 --ZrC--Zr composite body, by utilizing a post-treatment technique which may improve the oxidation resistance of the composite body. Moreover, the invention relates to novel products made according to the process. The novel process modifies at least a portion of a composite body by exposing said body to a source of second metal.

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: Method for producing mono-crystalline alumina grains comprising fusing alna materials in the presence of halide to induce oxyhalide phase at grain boundaries, cooling and solidifying fused materials and separating oxyhalide phase by means of inorganic acid or alkali before or after crushing, and said alumina materials are composed of either aluminum oxides alone or aluminum oxides and at least one of the metallic oxides selected from the group consisting of chromium oxide, titanium oxide and vanadium oxide.

Abstract: A ceramic composition for forming a ceramic dielectric body having a dielectric constant of less than about 5.5 and a TCE of less than about 3.5 ppm/.degree.C. The composition comprises a mixture of finely divided particles of 20-80 vol. % borosilicate glass and 20-80 vol. % of Al.sub.x B.sub.y O.sub.z wherein x is in the range of 4 to 22, y is in the range of 2 to 5, and z is in the range of 9 to 36. The Al.sub.x B.sub.y O.sub.z inhibits the formation of crystalline forms of silica. The composition can be used with a polymeric binder to produce an unfired green tape which is co-fireable with high conductivity metallurgies such as gold, silver and silver/palladium.

Abstract: A method for producing a self-supporting ceramic composite body which comprises preparing a polycrystalline material as the oxidation reaction product of a parent metal with a vapor-phase oxidant, comminuting the resulting material to a particulate, forming a permeable mass of said particulate as filler, and infiltrating said particulate with an oxidation reaction product of a parent metal with a vapor-phase oxidant, thereby forming said ceramic composite body.

Abstract: Shaped, self-supporting ceramic bodies are produced by preparing a mold by applying a permeable, conformable material to a shape-defining surface of an expendable pattern. The permeable, conformable material, when set or stable, provides a mold with a shaped surface which is defined by, and is therefore substantially congruent to, the shape-defining surface. Upon heating, the material of the expendable pattern combusts or volatilizes and thus establishes the shaped cavity mold. A molten parent metal is then vaporized with a vapor-phase oxidant in such a manner as to form a ceramic body which grows into the mold cavity, and is shaped by it. The ceramic body is recovered from the mold having a shaped surface replicating the shape-defining surface of the expendable pattern.

Abstract: There is disclosed a method for producing a self-supporting ceramic body by oxidation of a molten precursor metal with a vapor-phase oxidant to form an oxidation reaction product and inducing a molten flux comprising said molten precursor metal through said oxidation reaction product. A second metal is incorporated into said molten flux during the oxidation reaction. The resulting ceramic body includes sufficient second metal such that one or more properties of said ceramic body are at least partially affected by the presence and properties of said second metal in the metallic constituent.

Abstract: In a method for producing ceramic body by oxidation of a parent metal having a graded microstructure characterized by a plurality of zones differing from each other in one or more properties by altering the process conditions during formation of said ceramic body such that a zone of the oxidation reaction product formed posterior to said altering has one or more properties different from a zone of the oxidation reaction product formed anterior to said altering.

Abstract: Green bodies suitable for use in manufacturing ceramic articles are provided. The bodies comprise a coherent mass of particles of aluminium oxide free of organic binder and having a fracture stress measured by a biaxial disc flexure test of at least 10 MPa. The particles of aluminium oxide are coated with at least one inorganic oxide or hydrous oxide.The green body can be shaped by drilling, sawing etc. to a desired shape approximating to that of the ceramic article which it is used to produce. Generally such shaping is considerably easier than shaping the finished ceramic article.

Abstract: A granular abrasive material is produced from a dispersion consisting of raw materials containing alumina, compounds containing silica and other additives. The dispersion is ground to a sinterable slip with a grain size of less than 1 micrometer. The slip is dried and may be pressed before being subjected to a multi-stage heating process to produce sintered corundum crystals.

Abstract: Colored corundum composite with a matrix of .alpha.-Al.sub.2 O.sub.3, as formed by sol-gel process ending in sintering and size reduction steps with addition of oxide pigments (or precursors of such oxide pigments, formable to the oxide pigment in sinter heating) added to the sol before full gelation thereof.

Abstract: Green ceramic formulations comprising an atactic polypropylene-containing binder are suitable for tape casting and can be effectively removed during thermal processing in reducing atmospheres. The binder may be removed in substantially dry reducing atmosphere. The tapes may be used for forming ceramic substrates and metallized ceramics such as those used in electronic packaging.

Abstract: This invention is directed to the formation of glass bonded ceramic composite articles, with particular emphasis on forming abrasive products such as grinding wheels. The glasses consist essentially, in weight percent of 15-35% CaO, 35-55% B.sub.2 O.sub.3, and 10-35% SiO.sub.2, with alumina comprising the preferred abrasive particles being bonded into an abrasive product.

Abstract: The properties of silicon carbide whisker reinforced aluminum oxide, at present used for cutting tools when machining nickel based alloys, are in a very complex way related to processing and microstructure. Important parameters that have been recognized include whisker/platelet distribution, diameter, aspect ratio, surface chemistry and surface morphology. One parameter that has not been discussed is the crystal structure of the silicon carbide phase. Silicon carbide exist in a number of different polytypes, the most common with cubic or hexagonal structure. Available commercial silicon carbide contains mixed hexagonal and cubic silicon carbide-phases or single phase cubic. During sintering it is possible to transform cubic to hexagonal phase by special processing. It is shown that the hexagonal to cubic ratio strongly affects the performance in metal cutting operations and especially toughness behavior is related to a high hexagonal to cubic ratio.

Abstract: The invention relates to ceramic composite articles formed by infiltration of a particulate, permeable bed or permeable preform with a polycrystalline matrix produced as a metal-oxidant reaction product. The bed or preform includes a dross material.

Abstract: A refractory mix for forming high strength, low thermal conductivity refractory shapes comprising from about 40 to 75% by weight of at least one dense refractory aggregate, about 10 to 30% by weight of a bonding agent, and about 5 to 25% by weight of hollow ceramic microspheres having a diameter of about 1 to 350 microns.

Abstract: Ceramic binder for forming and processing ceramic ware, comprising a sol-gel of a mixture of highly charged metal hydroxy cations and one or more low charged metal hydroxy cations, which are able to form an aqueous sol.

Abstract: A process for producing composite materials with a metal matrix and with a content of powder reinforcer agent lower than is minimum theoretical compaction value, with said process being based on an infiltration technique, is disclosed, which essentially consists in charging the reinforcer material to a casting mould, and then infiltrating into the same mould the metal matrix in the molten state, with said metal matrix being let cool until it solidifies, and characterized in that the reinforcer agent, consisting of non-metal powders, is blended, before being charged to said casting mould, with a diluting agent having a different compaction degree, constituted by metal fibres and/or ceramic fibres and/or ceramic whiskers and/or metal powders of the same composition as of the matrix.

Abstract: Shaped bodies of transparent, polycrystalline alumina are produced in a green body is formed in a first step using pure, fine-grained alumina wherein, in the given circumstances, the green body is freed from the auxiliary agents used int he production by burning-out in a second step, wherein pretreat is carried out as a subsequent third step, and wherein the compaction to transparent, polycrystalline alumina takes place in a fourth step, in order to render the method more economical, it is suggested that the pretreatment be carried out in such a way as to produce a closed surface on the shaped body and that pressure from all sides at elevated temperature be used to compact the shaped body in the fourth step.

Abstract: Ceramic bodies are bonded together via a layer of an oxidation reaction product of a molten metal, which metal is present in one or both of the ceramic bodies prior to bonding. At least one of the ceramic bodies comprises a ceramic product formed by the oxidation reaction of molten parent metal (e.g., alumina from molten aluminum) and grown as molten metal is transported through, and oxidized on the surface of, its own oxidation product. One or both of the ceramic bodies used in the bonding process contains surface-accessible channels of residual metal, i.e., metal channels which have resulted from molten-metal transport during the ceramic growth process. When the suitably assembled ceramic bodies are heated in the presence of an oxidant at a temperature above the melting point of the residual metal, molten metal at the surface of at least one of the ceramic bodies reacts with the oxidant to form a layer of oxidation reaction product, which may or may not incorporate at least one filler material.

Abstract: Self-supporting bodies are produced by reactive infiltration of a parent metal into a boron donor material and a carbon donor material. The reactive infiltration typically results in a composite comprising a boron-containing compound, a carbon-containing compound and residual metal, if desired. The mass to be infiltrated may contain one or more inert fillers admixed with the boron donor material and carbon donor material. The relative amounts of reactants and process conditions may be altered or controlled to yield a body containing a wide ranging varying volume percentage of ceramic, metal, and porosity.

Abstract: A sintered material, especially usuable as an abrasive, based on .alpha.-aluminum oxide is produced from Al(OH).sub.3 or aluminum oxide calcined at a lower temperature. Aluminum hydroxide resulting in the Bayer process can be used as the Al(OH).sub.3. The sintered material is distinguished by a crystallite size of standard <0.5 .mu.m, high density and great hardness.

Abstract: In the present invention there is provided a method for producing a self-supporting ceramic or ceramic composite body 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 vaporphase oxidant, and optionally one or more metallic constituents dispersed throughout the polylcrystalline ceramic material. The method comprises the steps of providing at least a portion of 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: A process for manufacturing MgO-based .beta."-alumina sintered bodies from a starting powder comprising an MgO-based .beta."-alumina as a main ingredient, through shaping and firing, in which process shaped bodies before firing contain 0.3.about.5 wt. %, preferably 1.about.3 wt. %, of Na aluminate. The resulting sintered bodies are high in density, ionic conductivity and strength and useful for solid electrolytes, for example, of sodium sulfur cells.

Abstract: An electrical resistive material used for making e.g. a heating element for a thermal printing element. It is a Cr--Al--B--Zr--O alloy and is composed of a quaternary alloy and 15 to 25 at % of oxygen, wherein the quaternary alloy is composed of 2 to 25 at % of zirconium and a ternary alloy containing 35 to 55 at % of chromium, 2 to 23 at % of aluminium and 37 to 58 at % of boron.

Abstract: This invention relates to a method for producing a self-supporting ceramic structure comprising an oxidation reaction product of a parent metal and a vapor-phase oxidant characterized by an altered microstructure attributable to the addition of one or more process modifiers relative to substantially the same oxidation reaction product produced without a process modifier.

Abstract: This invention provides an improved alpha alumina-based ceramic and a method to make the same. The improvement consists of the addition of a chromium-based nucleating agent. Particularly useful embodiments of the improved alpha alumina-based ceramic include abrasive particles and fibers.

Abstract: A refractory component for use in contact with molten metal comprising a ceramic matrix which is three-dimensionally interconnected, said matrix comprising an oxidation reaction product of aluminum parent metal, said ceramic matrix containing less than about 0.5% by weight residual parent metal, said ceramic matrix embedding at least one filler material, thereby forming a ceramic composite body, said ceramic composite body having a porosity which is interconnected, said interconnected porosity comprising openings having a mean diameter of less than about 6 microns.

Abstract: Green bodies suitable for use in manufacturing ceramic articles are provided. The bodies comprise a coherent mass of particles of titanium dioxide free of organic binder and having a fracture stress measured by a biaxial disc flexure test of at least 5 MPa. The particles of titanium dioxide are coated with at least one inorganic oxide or hydrous oxide.The green body can be shaped by drilling, sawing etc. to a desired shape approximating to that of the ceramic article which it is used to produce. Generally such shaping is considerably easier than shaping the finished ceramic article.

Abstract: A process is presented for the fabrication of a metal/ceramic composite by a non-vapor phase oxidation of a molten metal by contacting said molten metal at an elevated temperature with a sacrificial ceramic preform. The shape of the preform is retained but the ceramic preform is reduced, oxidizing the molten metal. A preferred sacrificial ceramic preform is silica, but can also be, for example, mullite, titania or zirconia, and the preferred molten metal is aluminum or an aluminum alloy. Thus, for example, is produced from immersing a silica preform into molten aluminum alloy, an Al/Al.sub.2 O.sub.3 composite metal/ceramic article which does not contain silica or silicon and which is extremely tough.

Abstract: A process for the manufacture of grinding elements composed of aluminum oxide, the process including the steps of (a) mixing aluminum oxide with from 0.5 to 2.5 Wt. % of an organic binder based on the aluminum oxide to provide a mixture; (b) granulating the mixture to form a granulate; (c) molding the granulate into molded pieces having grinding element shapes by applying pressure thereto; and (d) firing the molded pieces at a temperature ranging from 1500.degree. C. to 1850.degree. C. in a vertical kiln to produce grinding elements comprised of aluminum oxide.

Abstract: A monolithic refractory with improved resistance to molten aluminum and a method of imparting the resistance by adding 0.2 to 1 wt.% polyvinyl chloride powder to the base mix.

Abstract: A high density, shock resistant ceramic comprising from 1 to about 4 mols of a a dense spinel ceramic matrix having dispersed therein, 1.5 to 1, respectively, of a metal oxide derived from a decomposable salt of said metal and having a thermal expansion characteristic different from said dense spinel ceramic matrix and at the decomposition temperature a volume less than that exhibited by its salt form and a process for preparing same.

Abstract: Several methods are disclosed for the preparation microporous alumina ceramic membranes. For the first time, porous alumina membranes are made which have mean pore sizes less than 100 Angstroms and substantially no pores larger than that size. The methods are based on improved sol-gel techniques.

Abstract: A ceramic sintered body and a method for manufacturing the same in which the body includes a first material having at least one of a precursor and a metastable material of the final sintered body and a second material morphologically related to the first material and added to the first material to affect transformation of said first material into the desired crystalline form of the ceramic sintered body, in which method transformation of a metal oxide compound from one phase to another, where the compound has a high activation energy and is confronted with a high nucleation energy barrier to the transformation, produces the body and includes the steps of making a mixture by bringing a multiplicity of particles of the compound into intimate contact with the multiplicity of nucleation particles having crystallographically related structure to act as nuclei for the transformation and sintering the resulting mixture to transform the compound from one phase to another by nucleation and growth, independently of gro

Abstract: A method of producing self-supporting ceramic a ceramic composite structures comprising (i) a polycrystalline oxidation reaction product formed upon oxidation of a body of molten parent metal with an oxidant, and (ii) interconnected porosity at least partially accessible from one or more surfaces of the ceramic body. A second polycrystalline ceramic or ceramic composite material is incorporated into the porosity of the ceramic or ceramic composite body to modify or contribute to its properties.

Abstract: A process for preparing ceramic powders suitable for pressing into articles comprises the dispersing of a particulate ceramic, preferably of particle size below 1 .mu.m, in water in the presence of ammonia or an alkylamine having a boiling point below that of water and spray - drying the dispersion to give powders. The process is particularly applicable to zirconia and gives rise to fine, free-flowing powders which can be processed into articles of uniform density.

Abstract: A method is provided for producing a self-supporting ceramic body comprising a polycrystalline material comprised of the oxidation reaction product of a parent metal and having therein one or more channels which inversely replicate the geometry of a configured fugative metal. The method includes providing an assembly of the configured fugitive metal and the parent metal, optionally including a bed of permeable filler, and heating the assembly to form a body of molten parent metal. The molten parent metal is oxidized under selected conditions to grow the polycrystalline material to engulf the configured fugitive metal (and to infiltrate the filler, if the filler is present) and to cause the fugitive metal to disperse into the engulfing polycrystalline material thereby leaving behind as the one or more channels the space formerly occupied by the configured fugitive metal.

Abstract: A lightweight oil and gas well proppant made by simultaneously mixing and compacting a mixture of kaolin clay which has been calcined at a temperature low enough to prevent the formation of mullite and crystobalites to an LOI of 12 or less when tested at 1400.degree. C., and amorphous to microcrystalline silica both of which have been milled to an average agglomerated particle size of 7 microns or less to form green pellets, and then drying, screening and sintering the pellets to form proppant pellets having a specific gravity of 2.7 or less, the proppant having a conductivity of at least 3,000 millidarci-feet as measured by the Stim-Lab Technique after 50 hours at 8,000 psi and 275.degree. F. in the presence of deoxygenated aqueous 2% solution of KCl using sandstone shims.