Abstract: Sialon, which is one of promising materials in the field of engineering ceramics, is prepared by mixing a silicon nitride precursor such as amino- or imino-silanes and an alumina precursor such as trialkoxy- or triacyloxy-aluminums or polyaluminoxanes to obtain a sialon precursor, and then heating the sialon precursor at a temperature of not lower than 1000.degree. C. either in an ammonium or inert gas atmosphere or under reduced pressures.

Abstract: A mass of diamond crystals in contact with a mass of eutectiferous silicon-rich alloy and a silicon carbide ceramic substrate are disposed in a container and placed within a pressure transmitting powder medium. Pressure is applied to the powder medium resulting in substantially isostatic pressure being applied to the container and its contents sufficient to dimensionally stabilize the container and its contents. The resulting shaped substantially isostatic system of powder-enveloped container is hot-pressed whereby fluid eutectiferous silicon-rich alloy is produced and infiltrated through the interstices between the diamond crystals and contacts the contacting face of the silicon carbide substrate sufficiently producing, upon cooling, an adherently bonded integral composite.

Abstract: An article of manufacture is provided comprising a substantially transparent high density polycrystalline yttria-base body consisting essentially of yttria and from about 0.01 to 5 wt. % alumina.A method for preparing the transparent yttria doped with alumina is also provided comprising admixing alumina or a precursor thereof with yttria or a precursor thereof, drying the admixed powders, calcining the admixed powders and pressing the calcined powders into a desired shape and thereafter sintering the shaped powder for about 1/4 to six hours at a temperature above the eutectic temperature at a sufficiently low oxygen atmosphere to prevent oxidative contaminants.

Abstract: A hot pressed composite structure, and method of making same are provided, wherein such structure is reinforced in three X, Y, and Z directions and comprises a matrix material, a plurality of straight elongate rigid reinforcing members embedded in the matrix material in spaced parallel relation and each disposed with its elongate dimension parallel to one of the above-mentioned directions, and a plurality of substantially straight elongate rigid reinforcing members embedded in the matrix material each with its elongate dimension disposed substantially along an associated one of the remaining two of the directions.

Abstract: Metal nitride sintered moldings are produced by mixing metal nitride powders with an organosilicon compound or an organosilicon high molecular weight compound as a binder, molding the mixture into a desired shape and heating the formed molding under a non-oxidizing atmosphere to sinter the metal nitride powders.

Abstract: The method of preparing superhard articles consists of placing a mixture of powdered hard-alloy matrix material and diamond grains into a hard-alloy envelope formed from a hard-alloy material, preferably of exactly the same composition as the hard-alloy matrix material of the mixture, with the thickness of the hard-alloy envelope over the entire area thereof exceeding by at least 3-4 times the maximum space between any two adjacent diamond grains within the mixture. The mixture in the envelope is then subjected to sintering in a free condition thereof, without any external mechanical loads being applied thereto.

Abstract: Insulating material, of compacted structure and of low thermal conductivity, is formed of silica-based primary particles; it is obtained by heat treatment of a compound of silane, of which the mean diameter is at most equal to 100 A; the apparent density .rho.a expressed in g/cc is between 6.10.sup.-3 and 2.3.10.sup.-3 d, d being the mean diameter of the primary particles expressed in A; in addition, this apparent density is at most equal to two thirds of the density of the solid material.This material is applicable as a thermal insulator in the field involving low temperatures and high temperatures and in the building sector.

Abstract: Improvements in molded articles from sinterable particulate solids, improvements in method for making such articles, and novel sacrificial binders for use in making such articles are disclosed. The sacrificial binders used in this invention comprise block polymers having the structural formulaAB--AB--.sub..eta. Awherein ".eta." is 0 or a positive integer, "A" is a linear or branched polymer that is glassy or crystalline at room temperature and has its softening point in the range of about 80.degree. C. to about 250.degree. C. and "B" is a polymer different from A that behaves as an elastomer at processing temperatures, a plasticizer which may be oil, wax, or oil and wax, and optionally other components.

Abstract: Uniaxial hot-pressing of ceramic powders to produce monolithic shapes of non-uniform thickness is accomplished by employing a form, preformed to a shape which when properly oriented and uniaxially compressed to final density will deform orderly to assume the final desired shape, and hot-pressing it in a mold against preformed parts having surfaces exactly mating with the surfaces of the preform. Such mold parts have the same compaction ratio as the preform, and a coefficient of thermal expansion substantially equal to that of the preform, and are formed of a powdered composition which is non-reactive with the preform material under hot-pressing conditions. Suitable compositions for the mold part preforms are temporarily bonded mixtures of carbon or graphite powder and a powder material of the preform. The shapes may be slip cast or cold pressed and temporary binders of organic or inorganic material may be employed to give green strength to the parts.

Abstract: A mass of diamond crystals contacting a mass of elemental silicon are confined within a pressure-transmitting medium. The resulting charge assembly is subjected to a pressure of at least 25 kilobars causing application of isostatic pressure to the contacting masses which dimensionally stabilizes them and increases the density of the mass of diamond crystals. The resulting pressure-maintained charge assembly is heated to a temperature sufficient to melt the silicon and at which no significant graphitization of the diamond occurs whereby the silicon is infiltrated through the interstices between the diamond crystals producing, upon cooling, an adherently bonded integral body.

Abstract: The proposed polycrystalline superhard material comprises sintered particles of cubic boron nitride coated over the whole surface thereof with a layer of a crystalline compound of the chemical formula B.sub.x N.sub.y C.sub.z, where x, y and z can assume any value from 0 to 1, said compound binding together the particles of the cubic boron nitride.According to the present invention the proposed material is produced in the following way: particles of cubic boron nitride are placed in a flow of a gas containing carbon for a carbon layer 1-100 A thick to be built up on the whole surface of said particles. Then the particles of cubic boron nitride with the carbon layer built up over the whole surface of the particles are subjected to sintering at a temperature and under a pressure corresponding to the region of thermodynamic stability of cubic boron nitride.The herein-proposed material is highly uniform and features mechanical properties superior to those of the known cubic boron nitride materials.

Abstract: A method of making a polycrystalline Mn containing ferrite body composed of crystallites which have the (111)-crystallographic planes thereof oriented substantially parallel with each other. The method involves providing a manganese compound, forming a body of a mixture made up of the manganese compound and other ferrite constituents, and heating the body made of the mixture into a polycrystalline Mn containing ferrite body of a spinel structure, wherein the manganese compound is in the form of thin platelets which have substantially parallel major surfaces oriented substantially in one direction in the body of the mixture. The ferrite body made thereby is a dense polycrystalline ferrite body having improved resistance to crumbling, improved wear characteristics and suitable physical properties for e.g. magnetic heads.

Abstract: A method for manufacturing metal oxide varistors with an extremely homogeneous dispersion of metal oxides is disclosed. In accordance with one embodiment of the invention, nitrates of zinc and certain metal additives are heated to form a hydrated solution which is further heated to form a dehydrated melt, which is further heated to form an extremely homogeneous dispersion of the metal oxides. Tin and antimony are added as oxides rather than nitrates. This process eliminates the need for ball milling.

Abstract: A method is described for making a shaped silicon carbide-silicon matrix composite. A confined carbon fiber preform is infiltrated with sufficient molten silicon metal at a temperature in the range of from about 1400.degree. C. to about 1800.degree. C. in an inert atmosphere or vacuum.

Abstract: Strengthened and densified ceramic bodies are produced by hot pressing lead itanate powder into a lead titanate ceramic at a pressure from 1000 to 5000 psi and at a temperature from 700 to 1100.degree. C if the atmosphere is reducing or from 700 to 1200.degree. C if the atmosphere is oxidizing and by annealing the lead titanate ceramic at a temperature from 600 to 1100.degree. C in an oxidizing atmosphere for at least four hours.

Abstract: A method of producing improved fused alumina or fused alumina-chromia refractory bodies wherein the binder added to the fused grain powder prior to forming a slurry for molding contains chromium metal and unfused alumina.

Abstract: A composition comprising negatively doped hot pressed particulate silicon carbide, the process for making the composition, an electrical hot surface fuel ignitor manufactured from the composition, a silicon brazed electrical connection for the ignitor and an ignitor circuit containing a dropping resistance.

Abstract: Silicon carbide sintered moldings having a high flexural strength and various excellent properties are produced by mixing SiC powders or SiC fibers with a binder or organosilicon low molecular weight compounds or organosilicon high molecular weight compounds, molding the mixture into a desired shape and heating the molded mixture at a high temperature.

Abstract: Beta-alumina ceramic articles of improved strength and durability particularly for use in sodium sulphur cells are produced by compacting beta-alumina particles or a mixture of powders which react to form beta-alumina, sintering the compacted material in air or oxygen to form an impervious polycrystalline ceramic body and then further densifying the sintered body by subjecting it to the direct isostatic pressing action of a fluid, e.g. a gas at a pressure of at least about 5,000 psi and at a temperature between 1200.degree. C and 1500.degree. C which is above the elastic/plastic transformation, said fluid being inert and non-permeating with respect to said fired body and subsequently cooling the body under pressure to a temperature below the elastic/plastic transformation.

Abstract: In a method for fabricating highly dense, polycrystalline silicon nitride bodies, a mixture of silicon nitride powder and an oxide, hydride or nitride of an element of the lanthanide series in powder form is hot pressed at a temperature ranging from 1600.degree. to 1750.degree. C for a period of 30 to 60 minutes. The method is particularly useful for fabricating structural components, such as stators, blades, airfoils and buckets in high performance gas turbine engines.

Abstract: A method for manufacturing an object of silicon nitride by isostatic pressing of a preformed body of silicon nitride powder utilizing a pressure medium at a temperature sufficiently high to sinter the silicon nitride. The preformed body is subjected to a degassing operation before isostatic pressing. An inner porous layer of a first material and then an outer porous layer of a second material are applied on the preformed powder body. The inner porous layer is transformable, at a temperature below the sintering temperature for silicon nitride, into a pressure medium impermeable layer. The outer porous layer is also transformable into a pressure medium impermeable layer, but at a temperature which is lower than the temperature when the inner porous layer is converted into its pressure medium impermeable form.

Abstract: A dense silicon carbide having improved properties is disclosed which is prepared by the addition of a carbonaceous additive to a boron doped silicon carbide and hot pressing the mixture at a sufficient temperature and pressure whereby a dense substantially nonporous ceramic is formed.

Abstract: Basic fused cast refractory with principal crystal phases of periclase and magnesium-spinel is made by adding nonfused oxidic inorganic grog particles to molten mass of the refractory as it is cast into a mold cavity, thereby resulting in increased modulus of rupture at temperature in the range of about 1340.degree.-1500.degree. C. and avoidance of shell formation. Molten mass has a composition consisting essentially (by weight) of 45-78% MgO, 0-30% Cr.sub.2 O.sub.3, 0-35% Al.sub.2 O.sub.3, 0-17% FeO + Fe.sub.2 O.sub.3, at least 82% MgO + Cr.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + FeO + Fe.sub.2 O.sub.3, 1-8% SiO.sub.2, 0-2% CaO + BaO + SrO.sub.2, 0-10% TiO.sub.2 and 0-3% fluorine. Nonfused particles have a loss on ignition at 1000.degree. C. of less than about 0.5% by weight and an aggregate SiO.sub.2 content at least about equal to the SiO.sub.2 content of the molten mass forming the cast refractory. Grog particles are of a size (e.g., within the range of particles passing about 25 mm.

Abstract: A method of making a ceramic turbine wheel which includes making a ceramic ring, and providing a ceramic disc within the ring by supporting the external periphery of the ring and hot pressing a ceramic powder within the ring. Ceramic blades are then sintered to the external surface of the ring using a layer of metallic silicon between each blade and the ring. The ring and blades are produced by a reaction-sintering process.

Abstract: Fine-grained polygonized halide bodies are formed having comparable optical properties to a single crystal halide body. Heat and force are applied to a single crystal halide to recrystallize or polygonize the halide. The body is then annealed to suppress room temperature grain growth.

Abstract: A hot-pressed beta-alumina composition is provided which consists essentially of M.sub.2 O.nAl.sub.2 O.sub.3, wherein n is a positive integer between about 3 and about 12 and M is selected from Na and K. The new beta-alumina composition features a flexural strength of at least about 45,000 psi as measured by ACMA Test No. 2, and high transmissability to light. Methods for preparing the above-described beta-alumina composition are also provided.

Abstract: Ultra-high pressure generation by using a new pressure transmitting medium consisting essentially of powder of an inorganic material having high hardness and cleavage.

Abstract: Disclosure is made of a high-density, high-strength silicon carbide ceramic material that is produced using a silicon carbide powder containing boron or boron-containing compound as a densification additive by the utilization of boron in the sintering atmosphere.

Abstract: A process for producing flexible graphite material comprises incorporating expanded graphite material with boric acid, compression molding the resulting mixture and, if desired, heating the resulting molding while under compression. This invention also relates to the flexible graphite material produced by the process.

Abstract: Boron nitride-boron nitride composite bodies may be produced by combining pure boron nitride fibers with partially nitrided fibers consisting essentially of B, N, O, and H, and hot pressing the composite at elevated temperatures and pressure. The partially nitrided material serves as a source of matrix material for the boron nitride fibers, and when fiber orientation is properly controlled, bodies of extremely high strength may be obtained. Densities in excess of 1.5 g./cc. may be obtained, in a one-step process which overcomes difficulties inherent in multiple-step nitriding and re-nitriding processes.

Abstract: Abrasive grits are prepared from molten oxide melt by pouring molten abrasive composition between plurality of spaced plates, made of heat resistant material such as graphite or metal to protect surface of molten abrasive from atmosphere and achieve rapid cooling. Abrasive is then comminuted by known methods to the desired grit sizes.

Abstract: Oriented strontium ferrites which yield superior ceramic permanent magnets are produced by the four-step process ofA. preparing small particles of agglomerated less than 0.1 micron grains of ferric oxide and strontium oxide,B. maintaining the particles of agglomerated oxides at temperatures of from about 800.degree. C to 1100.degree. C for up to about 24 hours to cause the oxides to react (ferritize) and form less than 0.5 micron diameter crystallites of strontium ferrite,C. sintering the crystallites into a solid body either by maintaining them at from 1100.degree. C to 1300.degree. C for not more than two hours, or preferably by maintaining them at from 800.degree. C to 1300.degree. C while applying pressure, andD. hot forging the body by applying pressures of up to about 30,000 psi at temperatures of from 800.degree. C to 1300.degree. C.

Abstract: Microscopic fibers are mixed with a metal powder to provide a nonuniform mixture with randomly oriented fibers having metal particles adhered thereto. This mixture is extruded at room temperature at least three times, and is then placed in a die cavity and subjected to a first pressure at room temperature. While adding no additional pressure, the die cavity is heated to bring the mixture to a temperature above the solidus of the metal powder, and the volume of the die cavity is decreased to at least the theoretical volume necessary to receive the mixture if the mixture included no voids. The die cavity is then cooled and the resultant billet ejected therefrom.

Abstract: Abrasive granules are produced from alumina or an alumina-zirconia mixture by melting the oxide material and rapidly cooling the melt. To control the solidification velocity, the melt is cast into a molten chloride of Na, Ca, Ba, Mg or mixtures thereof to cool the oxide material melt, the chloride is separated from the cooled and solidified oxide material, and thereafter abrasive granules are produced from the solidified oxide material.

Abstract: A method of making an electrooptical system including a transparent ferroelectric ceramic element which possesses memory in that a birefringence corresponding to an applied electric field remains after the field is removed. The electrooptical element is hot-pressed from a family of materials which comprises solid solution of the ternary system, lead magnesium niobate-lead titanate-lead zirconate, and the hot-pressed material may additionally contain a small amount of lanthanum oxide (La.sub.2 O.sub.3).

Abstract: Reinforced thermoplastic polymer composite sheets are formable into smooth, shaped objects in a rapid stamping process in a cool mold when pre-heated outside of the mold. The characterizing constituents of the composite sheet are: (1) thermoplastic resin, (2) relatively short reinforcing fibers, (3) relatively long or continuous glass fiber, and (4) a particulate loading agent. This four-component system, laminated together, produces sheets having excellent formability, mechanical properties, uniformity and in particular surface smoothness not heretofore obtainable, and are simple to fabricate continuously.

Abstract: Scintillation phosphors, infrared and ultraviolet transmitting shaped articles of unrestricted length and arbitrary cross section are formed by multiple extrusion of a relatively small single crystal, melt-grown macrocrystal ingot, or, re-extrusion of a relatively small, fully dense polycrystalline parent mass at a temperature below its melting point and under sufficient pressure to form a fully dense, homogeneous polycrystalline mass. A re-extrudate of a first extrudate is wider in cross section than the parent single crystal, or the first extrudate, yet the scintillation, infrared and ultraviolet transmission properties of the polycrystalline re-extrudate are essentially the same or better than those of the parent single crystal or polycrystalline first extrudate.A polycrystalline re-extrudate is disclosed which is optically the same as, but structurally different from a single crystal or first extrudate. It is both optically and structurally different from a hot-pressed or extruded powder.

Abstract: A method for densifying to near theoretical density a shaped body of compacted powdered particles, particularly of a refractory material, by preforming a shaped body of compacted particles of a powdered material characterized by voids, enclosing the shaped body within a loose mass of a pressure-transmitting powder disposed within a confining mold, applying a unidirectional pressure to the pressure-transmitting powder within the mold in order to compress the shaped body more compactly while heating the body to at least the densification temperature of the body, preferably in a controlled atmosphere, the temperature and/or pressure being increased incrementally up to the densification temperature of the refractory material, whereby substantially all voids within the compacted shaped body are collapsed.

Abstract: A pressure sintering process for the fabrication of ultrafine grained cercs having improved strength and enhanced transparency comprising the cold compressing of a ceramic oxide powder having a cubic crystal structure, removing undesired gases, raising to a temperature at which full density of the compact can be obtained in isothermal increments of about 50.degree. under elevated pressures while maintaining the temperature at each incremental increase for a period of about 50-60 minutes, and recovering the product.

Abstract: The invention pertains to a process for agglomerating compressible powders, particles or fibres of mineral substances, said process comprising the steps of placing at least one layer of a steam and gas pervious product on a layer of said compressible substances in which the water content is such that, after vaporization, a sufficient amount of water is still present to ensure the desired chemical reaction, then subjecting the layers to the simultaneous action of pressure and heating.

Abstract: There is provided a method of producing a ceramic represented by the general formula of ABO.sub.3, wherein A includes Pb and at least one element selected from the group consisting of Ba and Sr and B is either of Zr or both of Zr and Ti, by hot-pressing a complex oxide obtained by calcining the mixture of the oxides of A and B characterized by that a solid solution of the oxides of Ba and/or Sr and the oxide of the element constituting B, such as BaTiO.sub.3, SrZrO.sub.3 or (Ba, Sr)ZrO.sub.3, is used as the starting oxides of Ba and/or Sr, and that the starting material contains PbO in an amount of 3 - 20 mol% in excess of that calculated for the objective composition of the final product. Ceramics produced by the method of the present invention have ferroelectric properties and are optically transparent.

Abstract: A method of repairing an injured portion of a refractory furnace-lining characterized by cutting off the injured portion of said lining through the furnace shell using a specific supersonic flame jet cutter; inserting a rigid refractory lining block having a shape which is similar to that of the through-cut hole of the furnace body; and welding the surrounding periphery of the inserted block to the contact surface of said through-cut hole using the above-mentioned supersonic flame jet cutter as a welder, followed by repairing the outside cut-off shell portion of the furnace body.

Abstract: A method for the production of high density compacts of calcium hexaboride omprising the gradual heating of stoichiometric quantities of calcium oxide and boron powder to a temperature of approximately 1500.degree. C and maintaining that temperature for a period of about 30 minutes to produce calcium hexaboride, applying a pressure of about 5500 psi, and maintaining both temperatures and pressures for about 90 minutes.

Abstract: A hot-pressed optical body is disclosed which is free from absorption bands due to carbon dioxide, water, hydroxyl ion and acid fluorides in the ultraviolet, visible and near-infrared wavelength regions. Typically, the optical body is formed from a powder of an alkaline earth metal fluoride, alkali metal fluoride, or rare earth metal fluoride. One or more absorption bands due to a single impurity may be reduced or eliminated, or bands due to plural impurities may be reduced or eliminated sequentially, or simultaneously. The optical body is made by flowing a reactive, reducing gas, optionally, in combination with hydrogen fluoride gas, directly into the die cavity containing a pressable powder, and either hot-pressing or extruding the powder.

Abstract: The subject rotor comprises a disklike body having hub and rim sections joined by a web section. The body is cast, molded or otherwise suitably formed of powdered silicon (and a binder, if necessary, to make it retain its shape until finally treated) which is reaction bonded to convert the silicon particles into a unitary mass. During the casting, molding or other forming step, one or more reinforcing rings of hot pressed silicon nitride or other suitable ceramic are embedded in the body. The ceramic selected must be one which will unite with the silicon during the reaction bonding operation to make a unitary mass. The reinforcing ring or rings are located in regions exposed to unusual stress in the use of the rotor to achieve the required strength.

Abstract: For hydrostatically hot pressing bodies of borides, carbides or nitrides of titanium, zirconium or chromium from a powder having an excess of boron, carbon or nitrogen, the power is enclosed in a sealed container of a material which forms compounds with boron, carbon or nitrogen which have a melting point at least equal to that of the material of the container. Container materials may be for example metals from Group IVb of the Periodic System, particularly titanium and zirconium or their alloys in the case of titanium or chromium compounds and zirconium or zirconium base alloys in the case of zirconium compounds. This allows pressing at temperatures of up to 1700.degree.-1800.degree. C, which is high enough to cause bonding between the powder grains.

Abstract: This invention relates to slurry compositions which are adapted for the formation of ceramic articles. The compositions comprise ceramic particulate matter blended with an aqueous dispersion of an internally plasticized thermosetting resin. These compositions are formed into green (unfired) ceramic tapes which can be ultimately used for electronic purposes wherever fired rigid ceramic bodies are required. The use of these compositions overcomes many of the prior disadvantages relating to dimensional stability, flexibility, atmospheric stability and compatibility with a wide variety of conventional metallizing pastes.

Abstract: A ceramic material includes at least 90% of a single phase silicon aluminum oxynitrite having the general formula:--Si.sub.6.sub.-z Al.sub.z N.sub.8.sub.-z O.sub.z --where z is greater than 0 and less than or equal to 5.One method of producing the ceramic material involves sintering a mixture including not more than 75% by weight of high active surface area alumina powder of particle size less than 10 microns and silicon nitride powder of particle size less than 20 microns.In another method of producing the ceramic material, a mixture of silicon and alumina powders of particle size less than 20 microns is nitrided at a temperature between 1250.degree. C and 1600.degree. C. The proportions of silicon and alumina in the mixture being nitrided are such that the atomic ratio of silicon to aluminium is not less than 1:3.

Abstract: A process for preparing ferrite materials exhibiting an excellent combination of physical and magnetic properties is disclosed. In this process a ferrite powder is formed and subsequently sintered while exerting a mechanical pressure of about 5 to about 500 kg. per square centimeter on the ferrite. The oxygen content of the ferrite is maintained substantially stoichiometric throughout the process by controlling the oxygen content of the ambient atmosphere. Temperatures in the range of about 1100.degree. to about 1400.degree. C during sintering are disclosed. New ferromagnetic ferrite compacts which can be prepared by this process are characterized by an oxygen content which is substantially stoichiometric and a porosity no greater than about 0.4%.

Abstract: A method of producing hot pressed products, especially products of complex shapes, wherein the material from which the component is formed is hot pressed between a plurality of die parts of which at least one is of substantially uniform density and substantially compressible. This enables the shape of the die part to conform exactly or nearly so to the shape of the body being sintered throughout hot pressing, thereby resulting in obtainment of products of complex shapes.