Asea Aktiebolag

Asea Ab

Abb Cerama Ab

Volvo Aero Corporation

Asea Cerama Ab

Asea As

Hans Larker

Jan Nilsson

Jan Adlerborn

Bertil Mattsson

Ragnar Tegman

Robert Lundberg

Sven-Erik Isaksson

Lars Pejryd

Leif Hermansson

Jan Alderborn

Method for manufacturing composites

An object is manufactured from a powdered ceramic material while using isostatic pressing. The powdered material is thereby supplied with a temporary organic binder and is formed into a preformed powder body (10). A major part of the binder is removed from the preformed powder body by driving off under heating, whereas a minor part of the binder, required for keeping the powder body together, is retained in the powder body. The powder body is provided with a gas-permeable embedding material (14) of glass, the retained minor part of the binder then being removed by additional driving off under heating and preferably by also treating the powder body with the surrounding gas-permeable embedding material with an oxidizing gas. The gas-permeable embedding material is then made gas-impermeable by heating and the preformed powder body, freed from binder, with the surrounding gas-impermeable embedding material is subjected to isostatic pressing.

Method of manufacturing an object of a powdered ceramic material

An object is manufactured of a powdered material by isostatic pressing of a body (10), preformed from the powdered material, whereby the preformed body is surrounded by a casing (16) which at least for the main part is transferred to molten phase, before the isostatic pressing is carried out while sintering the powder. As material in the casing there is used glass or a material forming glass when being heated and containing 48-52 percent by weight B.sub.2 O.sub.3, 46-50 percent by weight SiO.sub.2 and 1.5-2.5 percent by weight Al.sub.2 O.sub.3. It can be removed from the finished object by water or water vapor and has a low coefficient of thermal expansion at temperatures below the melting temperature of the glass. To counteract the penetration of molten glass from the casing into the preformed body, a barrier layer (18) may be arranged on the preformed body inside the casing. (FIG. 3)

Method of manufacturing an object of a powdered material by isostatic

When manufacturing an object of powdered material by isostatic pressing of a body (10), preformed from the powdered material, with a gaseous pressure medium, the preformed body is provided with a casing (19) of glass which is made gas-impermeable by heating before carrying out the isostatic pressing. Inside the glass casing there is arranged on the preformed body a barrier layer (11) which counteracts the penetration of melted glass from the enclosure in the preformed body. The barrier layer is built up of at least two layers, of which one layer (12) at least substantially consists of powdered boron nitride and one layer (13) of a mixture of powdered boron nitride and a powdered material with the ability, upon contact with glass from the casing in melted form, to make a layer containing boron nitride tighter.

Method of manufacturing an object of powdered material by isostatic

In the manufacture of an article of ceramic material, for example a bladed turbine wheel of silicon nitride, there is first formed a plurality of article parts, at least one of which is a shaped powder body formed from powder of ceramic material mixed with a plasticizer, after which the plasticizer is driven off by a suitable heating operation. The article parts are then assembled together into a configuration conforming to that of the article to be manufactured, and the assembled article parts are surrounded with a gas-impermeable layer, for example a layer of glass. Finally, the assembled parts are isostatically pressed at elevated temperature to form the assembled article parts into a dense, homogeneous article.

Method of manufacturing articles of ceramic material

An object is manufactured from a powdered material by isostatic pressing of a body, preformed from the powdered material, with a pressure medium, whereby the preformed body, in which at least the surface layer consists of a ceramic material in the form of a nitride, is surrounded by a casing which is rendered impenetrable to the pressure medium, before the isostatic pressing is carried out and the powder sintered. As the material in the casing there is used boron oxide or a glass containing boron oxide or a material forming glass while being heated, in which the content of boron oxide is sufficiently high for the glass--or the glass formed during heating--to be removable by water. The preformed body surrounded by the casing is subjected to a heat treatment for the formation of boron nitride on the surface of the preformed body, before the isostatic pressing is carried out. The casing is removed from the finished product by means of water or water vapor.

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.

Method for manufacturing an object of silicon nitride

Spent fuel rods from a nuclear reactor are enclosed in a body of copper, the fuel rods being embedded in copper powder in a copper container provided with a copper lid. The container with its contents and lid are then subjected to isostatic compression at a pressure and temperature sufficient to form a coherent dense mass unit of the powder, the container and the lid which embeds the fuel rods. The container can be enclosed in a sealed gas-tight capsule prior to the isostatic compression. A preliminary isostatic compression may be conducted at a lower temperature to effect creep deformation of the container, the lid and the powder.

Method of preparing spent nuclear fuel rods for long-term storage

An object of ceramic or metallic material is manufactured by isostatic pressing of a body preformed from a powder of the metallic or ceramic material, the preformed body (10) then being embedded in glass, for example in a mass of glass particles (16) in a vessel (15) which is resistant to the temperature at which the sintering of the metallic or ceramic material is carried out, the material embedding the preformed body being transferred to a melt having a surface limited by the walls of the vessel, below which surface the preformed body is located, and a pressure necessary for the isostatic pressing of the preformed body then being applied on the melt by a gaseous pressure medium.

Method of manufacturing an object of metallic or ceramic material

Bodies of silicon nitride are produced by enclosing a silicon nitride powder in a gas-tight glass casing and subjecting the casing to isostatic pressure using gas as a pressure medium at a temperature of at least 1600.degree. C. and a pressure of at least 100 MPa. The casing is a glass having a high softening point. The casing is evacuated and sealed before compressing. The product may be pre-formed by isostatic compacting at a pressure of at least 100 MPa at a temperature considerably below the sintering temperature. The casing is cooled at a rate of at most 1000.degree. C. per hour and at a pressure of not over 10 MPa.

Method of manufacturing bodies of silicon nitride

A container for enclosing particulate or piece-formed radioactive material which is to be converted into a solid body by isostatic pressing at a high temperature and a high pressure. The container may have a corrugated sheath and suitably a plane lid and a plane bottom. The corrugation makes possible axial compression of the container prior to the pressing. The container may also have a cylindrical sheath and bellows projecting into the sheath and joining the sheath of the container to a lid and a bottom. The bellows make it possible to insert the lid and the bottom by gas pressure, so that the material present in the container is axially compressed.

Container for enclosing radioactive waste and a method for treating

Composite material comprising a matrix of an alloy of about 64 percent by weight iron and about 36 percent by weight nickel or of a different alloy containing iron and nickel having a coefficient of thermal expansion of at the most 3.10.sup.-6 K.sup.-1 within the temperature range 20.degree. C. to 100.degree. C. and veins of copper, distributed in one direction through the matrix, with the copper and the alloy metallurgically bonded to each other through a boundary layer containing copper and the alloy having a thickness of at the most 5 .mu.m.

Composite material

A shaped body is formed by cold-pressing a powdered material into a desired shape and then providing thereon a surface layer of a material having a lower melting point than the powder of the shaped body. The shaped body is then placed in a furnace connectable to vacuum equipment, wherein the pressure is first lowered to a value lower than atmospheric pressure and then the temperature is increased so that the material of the surface layer melts. Thereafter the body is isostatically hot-pressed under the direct influence of an inert, gaseous pressure medium, the powder particles being thus bound together to high density by pressure sintering.

Method of manufacturing a sintered powder body

Disclosed is an improved method for manufacturing an object of silicon nitride. In the method, a body preformed from silicon nitride powder and enclosed in a casing of glass is isostatically pressed with a gaseous pressure medium in a pressure vessel at a temperature required for sintering of silicon nitride. After pressing and sintering are completed, the pressure and the temperature in the pressure vessel are adjusted such that the temperature maintains the glass in a plastic state and the pressure in the pressure vessel is below the partial pressure of nitrogen gas for silicon nitride at that temperature so that the glass casing is blown up around the body and the body is freed from or can easily be freed from the glass casing.

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Robertsfors, Sweden

Hans Larker