Abstract: There is disclosed a method for eliminating an organic dispersion medium from a molded product obtained by plasticizing-molding or casting-molding of metallic and/or ceramic powders wherein the elimination is by extraction by liquid carbon dioxide at a temperature not lower than -30.degree. C. and not higher than -31.1.degree. C. The method prevents nonuniform volumetric decrease of the molded product to be otherwise caused by the extraction of the organic dispersion medium, while also making it possible to completely eliminate the organic dispersion medium without causing residual strain or deformation in the molded product.

Abstract: A ceramic material comprising a double phase complex sialon sintered body of .beta.'-type sialon and O'-type sialon being composed of the four elements of Si,Al,O and N and having a ratio of .beta.'-type sailon/O'-type sialon of 7/1 to 3/5 by weight ratio.The .beta.'-phase-O'-phase complex sailon has a dense structure and is excellent in high strength and high oxidation-resistance.

Abstract: In a process for producing a sintered body using a gas-impermeable membrane formed by softening of a powder layer provided on the surface of a porous body, a metal polymer selected from polysilanes, polycarbosilanes, polysilazanes and hydrolyzates of metal alkoxides is added as a binder to the powder layer. According to the process of the invention, the gas-impermeable membrane is formed with high reliability, and high density sintered bodies can be obtained in a simple process.

Abstract: A ceramic sintered body comprising TiB.sub.2 as the principal component, 0.5 to 30 wt. % of SiC and 2 to 40 wt. % of ZrO.sub.2. In some cases ZrO.sub.2 includes stabilizers for tetragonal crystal, such as Y.sub.2 O.sub.3, MgO or CeO.sub.2. The sintered body has a dense structure where TiB.sub.2, ZrO.sub.2 and SiC uniformly disperse. ZrO.sub.2 is located at the grain boundary of TiB.sub.2, and inhibits the grain growth of TiB.sub.2 as well as improves the strength of the sintered body by binding it to TiB.sub.2 strongly. SiC is located not only at the grain boundary but also on the inside of both grains. Since the contract of SiC during cooling process of the sintered body is less than TiB.sub.2 and ZrO.sub.2, compressive stress is produced in SiC and around thereof. The sintered body is remarkably strengthened by the residual compressive stress, and simultaneously, the high fracture toughness is also achieved.

Abstract: Method for manufacturing a sintered body with high density comprises: turning first powder into a first slurry by dispersing the first powder in a first dispersion medium composed mainly of substances capable of being extracted by supercritical fluid and forming a compact which contains the first dispersion medium, by casting the first slurry; turning second powder into a second slurry by dispersing the second powder in a second dispersion medium composed mainly of substances capable of being extracted by supercritical fluid, and forming a film layer by coating the surface of the compact with the second slurry; extracting and removing the substances contained in the compact and the substances contained in the film layer by means of the supercritical fluid; turning the film layer on the surface of the compact into an impermeable film layer to gas by heating the compact, from which the substances have been extracted and removed; and applying a hot isostatic pressing process to the compact, the film layer on the

Abstract: The invention is concerned with the method of compression molding a metallic or ceramic powders. The method includes the step of maintaining a negative pressure within a first mold of noncompactable powders for intimately contacting on its inner surface a pouch-like member of thin-walled resilient material for producing a second mold, and the step of compactly charging starting powders into the second mold and exhausting air from and sealing the second mold, taking out a pre-molded body of the metallis or ceramic powders together with the second mold and the step of processing the pre-molded body by a cold or hot isostatic press.

Abstract: A method for refining powders comprising the steps of: (a) adding polytetrafluoroethylene powders to non-oxide ceramic powders to form a mixture by mixing; and (b) heating the mixture in non-oxidizing atmosphere to convert oxides existing on the surface of the non-oxide ceramic powders into gaseous fluorides, and removing gaseous fluorides. The fluororesin is a polytetrafluoroethylene resin. The heating temperature in the non-oxidizing atmosphere is 500.degree. C. to 1300.degree. C.

Abstract: An apparatus for manufacturing a sintered body with high density comprises: a table having an object to be processed laid thereon; a pressure vessel accommodating a heat element heating the object around and a heat-insulating mantle surrounding the heat element; supply device for supplying to the pressure vessel an extractant which extracts a binder or a dispersion medium contained in the object, exhaust device for exhausting the extractant and an extracted substance from the pressure vessel; pressure device for raising a pressure in the pressure vessel, and vacuum means for evacuating the pressure vessel. The apparatus enables carrying out the three steps of drying or degreasing, sintering and hot isostatic pressing of the object once put in the pressure vessel without handling the object outside the vessel. The object is formed as a compact in the preprocess in advance of being put in the apparatus.

Abstract: A method is provided for manufacturing a sintered body comprising the steps of: heating a membrane of an inorganic polysilazane in liquid formed on the surface of a porous body to oxidize a surface portion of the layer into an oxide layer and still pyrolyzing the remaining of the inorganic polysilazane, the inorganic polysilazane having the formula of (--SiH.sub.2 NH--)n where n represents the degree of polymerization; softening the oxide layer to make it impermeable; and sintering the porous body with the oxide layer having impermeability at high pressure and at high temperature n of degree of polymerization ranges 6 to 25. The layer is of 0.5 to 2.0 mm in thickness.

Abstract: A method for molding powders which comprises introducing a thin-wall resilient mold inside a ventilative mold support, reducing the outside pressure of the ventilative mold support to less than the atmospheric pressure (760 Torr), putting a thin-wall resilient mold exactly close to the inside wall of the ventilative mold support, supplying powder material into the thin-wall resilient mold, exhausting air existing in the voids formed in the powder material, and taking the ventilative mold support apart to apply cold isostatic press treatment to the thin-wall resilient mold. The shape of the thin-wall resilient mold is similar to the shape of the ventilative mold support.

Abstract: A method for eliminating a dispersion medium from a molded product obtained by plasticizing-molding or casting-molding one or more of metallic and ceramic powders, wherein the elimination process is carried out in a supercritical liquid carbon dioxide atmosphere without heating to higher temperatures.

Abstract: A method of sintering compacts of metals, ceramics and the like in powder form. At least the surface portion of the compact is sintered in a plasma atmosphere having a pressure of 10 Torr or less thereby eliminating the open voids and then the compact is subjected to a hot isostatic press process.

Abstract: A tetrafluoroethylene-type fluoroplastic powder is added and mixed with a metal powder and the mixture is shaped. The compact is heated in a nonoxidizing atmosphere and the oxides on the surface of the metal particles are converted and removed as gaseous fluorides. Alternatively, after the oxides are converted to solid or liquid fluorides, the fluorides are reduced by hydrogen and then they are removed as gaseous reaction products. Thereafter, the compact is sintered.

Abstract: A method and an apparatus for continuously manufacturing non-fired pellets, which comprise: continuously supplying green pellets containing a carbonating binder into a vertical type reactor to continuously pass the green pellets sequentially through a predrying zone, a carbonating zone and a drying zone in the vertical type reactor; blowing a predrying gas having a relative humidity of up to 70% and a temperature of from 40.degree. to 250.degree. C. into the predrying zone to predry the green pellets therein until the water content of the green pellets in the predyring zone falls within the range of from 1 to 7 wt. %; blowing a carbonating gas comprising carbon dioxide gas of from 5 to 95 vol. % and saturated steam of from 5 to 95 vol. % and having a temperature of from 30.degree. to 98.degree. C. into the carbonating zone to carbonate the carbonating binder contained in the green pellets therein; and blowing a drying gas at a temperature of from 100.degree. to 300.degree. C.

Abstract: A method of compression molding powders of metals, ceramics and the like. A thin rubber bag is adhered to the inside of a cavity formed within a permeable mold support so as to define a mold therein and the bag is packed with a raw material powder. The powder in the bag is evacuated to a degree of vacuum to compactly compress it and the rubber bag is sealed. In this condition, the compressed powder is removed from the support and compression molded to a higher degree of denseness by the CIP process. The inflation adhesion of the rubber bag to the inside of the support cavity is effected by reducing the pressure outside the permeable support.

Abstract: A method for distilling shale oil from oil shale, which comprises: supplying an oil shale together with a granular heat medium heated to a prescribed temperature in a heating furnace to a distiling furnace, where a gas containing a gaseous shale oil, hydrogen and carbon monoxide is separated by vaporization from said oil shale through heat exchange with said granular heat medium; separating the liquid shale oil from said gas, separating said granular heat medium from the waste oil shale after separation of said gas; and then, feeding back said granular heat medium into said heating furnace to reheat said heat medium again to said prescribed temperature and to use said heat medium in recycle. In said method, said granular heat medium comprises manganese oxides and iron oxides. The heat of said granular heat medium is replenished with the heat produced by exothermic reaction of said hydrogen and said carbon monoxide contained in said gas with Mn.sub.2 O.sub.

Abstract: A method for recovering and utilizing heat of coke-oven gas, which comprises: through heat exchange with a high-temperature coke-oven gas generated from a coke oven battery and containing vaporized coal tar, vaporized low boiling point substances and dust, drying and preheating a blended raw material coal fine to be charged into coking ovens of said coke oven battery, and, on the other hand, causing most of said coal tar contained in said coke-oven gas to condense and deposit onto the particle surfaces of said coal fine during the process of said heat exchange, thereby recovering and utilizing sensible heat and condensation heat of said coke-oven gas and substances contained therein, and at the same time, eliminating most of the contained coal tar from said coke-oven gas.

Abstract: There is provided a method of blast furnace operation utilizing selective recycling of peripheral gas stream wherein the number of outlet ports for peripheral gas stream and the position of the gas outlet ports relative to the inlet ports for reducing gas are optimalized and the content of nitrogen in the recycling gas and the content of nitrogen in the reducing gas to be injected are controlled within the respective predetermined ranges.