Abstract: The invention is a process for producing ZnO-based varistors incorporating a metal oxide dopant. In one form, the invention comprises providing a varistor powder mix of colloidal particles of ZnO and metal-oxide dopants including Bi.sub.2 O.sub.3. The mix is hot-pressed to form a compact at temperatures below 850.degree. C. and under conditions effecting reduction of the ZnO to sub-stoichiometric oxide. This promotes densification while restricting liquid formation and grain growth. The compact then is heated under conditions restoring the zinc oxide to stoichiometric composition, thus improving the varistor properties of the compact. The process produces fine-grain varistors characterized by a high actual breakdown voltage and a high average breakdown voltage per individual grain boundary.

Abstract: A method of manufacturing a highly porous refractory material by feeding raw material in discrete particle form into the hot zone of a furnace chamber, the method including the initial step of making a slurry of the raw material and feeding the slurry into a spray drier to produce particles of refractory material with very little fines.

Abstract: A system for manufacturing three-dimensional work pieces, such as interior automobile components, includes several cooperating stations arranged in such a way that a hingeable mold member connected to a hinging frame may cooperate with another mold member or with other tools such as trimming tools, curing tools, cleaning and waxing tools and the like. The hinging frame is engageable by hinging bolts of the same construction located in different work stations. The hingeable mold member is transportable, for example on an endless conveyor, when it is disengaged from the hinging bolts. The number of work pieces produced per unit of time is increased by the cooperation of a forming or shaping station with a trimming station, with a foaming station and several curing stations for the foamed material in a shaped work piece.

Abstract: Disclosed is a method for manufacturing an object of silicon nitride. In the method, a body preformed from silicon nitride is surrounded with a casing which is permeable to gas. Upon heating, the casing is transformed into a layer which is impermeable to a pressure medium which is used during isostatic pressing of the preformed body while a pressure outside the casing is maintained which is at least as high as the pressure of the gas which is present in the pores of the preformed product. After the casing has been made impermeable to the pressure medium and the preformed body has been enclosed therein, the isostatic pressing is carried out while the body is simultaneously sintered.

Abstract: A process for producing a boehmite shaped product comprises slurrying a mixture of a gibbsite powder and at least one powder selected from the group consisting of powders of pseudo-boehmite, amorphous aluminum hydroxide, alumina cement and .rho.-alumina, molding the slurry thereby obtained and subjecting the molded product to hydrothermal treatment.

Abstract: A blank is molded from a powdery mixture of silicon, .alpha.-silicon nitride, and a sintering agent. The blank is nitrided to nitride the silicon content of the blank, and thereafter the blank is subjected to hot isostatic pressing. The silicon content of the original powdery mixture is between 5% and 60% by weight of the mixture, and the sintering agent, which may be an oxide, is present in the original powdery mixture in the range between 0.1% and 10% by weight. The nitriding is carried out in a nitrogen atmosphere at a temperature between 1100.degree. C. and 1600.degree. C. The nitriding may be carried out in two stages, first at a temperature between 1050.degree. C. and 1400.degree. C., and then at a temperature above the melting point of silicon.

Abstract: A method of making a densified silicon nitride/oxynitride composite is disclosed. The method comprises: (a) shaping a substantially homogeneous powder mixture of silicon nitride, 6-18% yttrium silicon oxynitride of the Y.sub.10 Si.sub.6 O.sub.24 N.sub.2 phase in an amount to form a viscous solution with at least a portion of the silicon nitride, and (b) densifying the body by heat fusion, with or without the use of mechanical pressure, to a density and a dimension required for the final product.

Abstract: A method of preparing green ceramic tapes, comprising adding to 100 parts by weight of a fine ceramic powder, 2 to 15 parts by weight, in terms of its resin content, of a binder mixture consisting of an aqueous polyurethane and a water-soluble acrylic resin, the amount of said water-soluble acrylic resin ranging from 10 to 1500 parts by weight per 100 parts by weight of said aqueous polyurethane in said binder mixture, adding a small amount of a dispersing agent to the mixture followed by a sufficient amount of water, kneading the resultant mixture for a time sufficient to prepare an aqueous slip, forming a tape in a known manner from said aqueous, and then drying the green tape obtained.

Abstract: Gypsum board is formed into a continuous sheet by depositing an aqueous slurry of calcium sulfate hemihydrate, including conventional additives, between two paper cover sheets on a moving conveyor. After the slurry has reached the initial stiffening degree of set and before the slurry has reached a final or temperature rise set, and in the preferred form before it has reached a Vicat set, the moving sheet is transversely cut into individual boards by means of a high pressure and velocity fluid cutting jet. Since the cutting may be carried out before the Vicat set is reached, the board line may be operated at an increased velocity, thereby enabling a particular board line materially to increase its production within a given period of time and to use conveying equipment which is shorter in length.

Abstract: Large and thin ceramic plates of, particularly at least 30.times.30 cm in size and not greater than 20 mm especially not greater than 8 mm in thickness and having oriented crystals are produced by a method comprising drawing a green body from an extruder in a curved shape, cutting and spreading the green body in a plate form, rolling the plates in the same direction as that of drawing, subjecting the rolled plates to the treatment with far infrared rays or high-frequency heating before the plates contain a moisture reduced to less than 15% while the plates are transferred in the same direction as that of drawing, drying the plates thus treated while the plates are further transferred in the same direction, and then firing the plates in a kiln. The ceramic plates are large and thin but nevertheless easy to handle.

Abstract: The invention is a shaped article of boron nitride having a density of at least 95% of the theoretical density which consists of polycrystalline hexagonal boron nitride in the form of a homogeneous isotropic microstructure and which has been manufactured from pure boron nitride powder without the concomitant use of sintering aids by isostatic hot-pressing in a vacuum-tight casing at temperatures of from about 1200.degree. to 1500.degree. C. under a pressure of from about 50 to 300 MPa. Boron nitride powders having a free boric oxide content of not more than 1.0% by weight and having a specific surface area of from 5 to 30 m.sup.2 /g are used as starting material. The powders either are filled into prefabricated casings consisting of steel or glass and densified by vibration or are preshaped to form green bodies having pores open to the surface and then placed in prefabricated casings or coated with a material which forms a vacuum-tight casing.

Abstract: A new process for producing an inorganic fiber of superior tensile strength and modulus of elasticity, which comprises spinning a spinning solution in organic solvent of polymetaloxane of good spinnability to form a precursor fiber, calcining said precursor fiber, and wherein said solution contains polymetaloxane comprising 0.1-95 mole % of a structural unit represented by the following general formula [A] and 99.9-5 mole % of the following formula [B]: ##STR1## (wherein, M represents a trivalent or tetravalent metal atom, X.sub.1 represents an organic group which is the same as or different from ##STR2## hydrogen, nitro or halogen, X.sub.2 and X.sub.3 represent an organic group other than ##STR3## Y represents an organic group, nitro or halogen, m represents an integer from 1 to 3.).

Abstract: A polycrystalline translucent alumina sintered body having high in-line transmission, which is suitable for an envelope for a high pressure vapor discharge lamp, is produced by adding to alumina powder having a purity of more than 99.8% MgO or a compound forming MgO in an amount of 0.01-0.1% by weight calculated as MgO, La.sub.2 O.sub.3 or a compound forming La.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as La.sub.2 O.sub.3, and Y.sub.2 O.sub.3 or a compound forming Y.sub.2 O.sub.3 in an amount of 0.001-0.05% by weight calculated as Y.sub.2 O.sub.3, thoroughly mixing the resulting mixture, shaping the mixture into a desired form and firing the shaped article under vacuum or either atmosphere of hydrogen gas or dissociated ammonia gas under oxygen concentration of 10.sup.-15 -10.sup.-25 atm.

Abstract: The method of moldless manufacturing light construction elements comprises a first step of mold-free shaping a blank comprising a first layer of an expandable first clay material and a second layer of a non-expandable second clay material. The blanks are supported at their second layers and conveyed through an oven with radiation heating of the blanks at least from above, so that the first layer progressively expands as the blanks are conveyed through the oven. After cooling, the expanded blank is further processed to assume the required final dimensions.

Abstract: The invention relates to a truss shoring method and an apparatus therefor utilized in the pouring of concrete floors and includes a plurality of unitary members adapted to provide vertically adjustable and horizontally movable primary modular units serving to support poured concrete.

Abstract: High-strength, fine-grain multi-phase substantially crystalline sintered ceramic bodies are produced by a process comprising the steps of cold pressing, followed by sintering at a high temperature, the temperature increase to maximum sintering temperature being accomplished by the use of a heating rate in excess of about 100.degree. C./minute.

Abstract: Semiconductive ceramic materials suitable for use in varistors, consisting essentially of a major proportion of Sr(.sub.1-x)Ca.sub.x TiO.sub.3, where x is from about 0.01 to about 0.50, the balance being at least one of Nb.sub.2 O.sub.5, Ta.sub.2 O.sub.5, WO.sub.3, La.sub.2 O.sub.3, CeO.sub.2, Nd.sub.2 O.sub.3, Y.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Pr.sub.6 O.sub.11 and Dy.sub.2 O.sub.3, and Na.sub.2 O. The ceramic materials may further comprise a minor proportion of at least one of Ag.sub.2 O, CuO, MnO.sub.2 and SiO.sub.2, and/or a minor proportion of Al.sub.2 O.sub.3. For the fabrication of ceramic bodies of the above compositions there are prepared mixtures of the noted ingredients in powdered form in various possible combinations, plus an organic binder. The mixtures are molded under pressure into desired shape. The moldings are first fired in a reductive or neutral atmosphere and then refired in an oxidative atmosphere. Na.sub.2 O can be included in the initial mixtures in the form of Na.sub.

Abstract: A method is disclosed for hot pressing agglomerated materials in a pressing assembly having walls which can be reactive with the material to be pressed under the environmental, temperature, and pressure conditions to be experienced by the material at the interface with the pressing assembly walls. After a plurality of generally flat stackable billets (10-20) of the powdered material are formed and stacked in a pressing assembly (21) in a predetermined aligned order, a barrier wall (30) is interposed between the interface of the billets and pressing assembly along at least a zone (26) in which a temperature of 1600.degree.-1750.degree. C. and a pressure of at least 3000 psi will be experienced at the interface during hot pressing. The billets are then hot pressed to a desirable density and removed, leaving the assembly walls in a substantially unreacted condition.

Abstract: Prefabricated prestressed concrete members are formed on a stressing bed with a number of working stations arranged next to one another along the length of the bed. A frame froms the working stations and the frame is movable over the stressing bed. With a previously poured concrete member in one of the working stations, part of a form is placed in another working station and is filled with concrete. After the form part is completely filled and consolidated, a second form part is placed downwardly on the filled part completing the form. A lifting member on the frame which placed the second form part on the filled part is then moved to the station containing the previously poured member which is still within the form. The form is stripped from the concrete member and the frame is then moved along with the lifting member returning the stripped form to the working station where it is to be filled with concrete.

Abstract: A sintered body of silicon carbide having an outstandingly high density is readily obtained by sintering a shaped form of a powdery blend composed of a silicon carbide powder, an aluminum borate as a sintering aid and a carbonizable organic compound mixed together in a limited proportion.