Kabushiki Kaisha Kobe Seiko Sho

Kabushiki Kaisha Kobe Sekio Sho

Hiroshi Okada

Takao Fujikawa

Tsuneo Tatsuno

Yoshihiko Sakashita

Masato Moritoki

Katsuhiro Uehara

Takao Kawanaka

Katuhiko Honma

Seiichiro Ohmoto

Kazuya Suzuki

Katsuhiko Honma

A high-pressure container 1 as a furnace casing is equipped with insulating cylinder 2 of an inverted glass shape, and heater elements 18 individually mounted on heater mounting plates 16 arranged in parallel to section vertically the space for arranging the heater elements 18 at a given interval in the insulating cylinder 2. For the procedures of single crystal growth by heating in a high-pressure gas atmosphere, the insulating cylinder 2 and the heater mounting plates 16 can suppress the effects of spontaneous convection of a high-pressure gas and the effects of the radiation heat from an adjacent heater element, as less as possible, so that the temperature controllability of each heating zone can be improved whereby the vertical temperature distribution in the furnace can be controlled appropriately. Also, a heater element 18 of a larger aperture size can be maintained at a stably supported state, whereby a single crystal of a larger dimension can be grown.

Vertical furnace for the growth of single crystals

Apparatus for preparing compound single crystals

Method of forming a single crystal of ZnSe. A charge of material is loaded in a container. The charge of material is melted to create a melt of material. A single crystal is grown from the melt of material. Then, the grown crystal is brought out of contact with the wall surface of the container. The temperature of the crystal is varied across its phase transition temperature range while establishing a temperature gradient from one end of the grown crystal to the other end. This method is carried out, using a crystal grower comprising the container and an elevation member. The container is disposed inside a high-pressure vessel. The container tapers off downward and is provided with a hole extending from its lower end. The elevation member is inserted into the hole from below to push the grown crystal in a crucible upward. The container is composed of plural separable parts. After the growth of the crystal, the assembled parts are moved substantially horizontally outwardly so that the parts are separated from each other.

Method for growing single crystal

The specification describes a method for producing high density sintered silicon nitride (Si.sub.3 N.sub.4) having a relative density of at least 98%. In a first step, silicon nitride powder is compacted into a desired shape. It is then pre-sintered in a second step, generally, under normal pressure to obtain a presintered body having a relative density of at least 92%. In a third step, the presintered body is subjected to a hot isostatic pressing (HIP) in an inert gas atmosphere of 1500.degree.-2100.degree. C. and of nitrogen gas partial pressure of at least 500 atm. Since the presintering does not require any capsule, it is possible to produce high density sintered Si.sub.3 N.sub.4 of complex configurations. As a sintering aid, Y.sub.2 O.sub.3 --Al.sub.2 O.sub.3 --MgO system sintering aid is particularly effective. To improve the strength of sintered Si.sub.3 N.sub.4, it is effective to add a heat treatment step after the HIP and maintain the temperature of the sintered Si.sub.3 N.sub.4 above 500.degree. C. for a while. Between the second and third steps, the temperature of the presintered body is preferably maintained above 500.degree. C. These temperature controls are effective not only to improve the strength of sintered Si.sub.3 N.sub.4 but also to save the thermal energy and to shorten the production cycle.

Method for producing high density sintered silicon nitride(Si.sub.3 N.sub.4

The specification describes a method for producing high density sintered silicon nitride(Si.sub.3 N.sub.4) having a relative density of at least 98%. In a first step, silicon nitride powder is compacted into a desired shape. It is then presintered in a second step, generally, under normal pressure to obtain a presintered body having a relative density of at least 92%. In a third step, the presintered body is subjected to a hot isostatic pressing(HIP) in an inert gas atmosphere of 1500-2100.degree. C. and of nitrogen gas partial pressure of at least 500 atm. Since the presintering does not require any capsule, it is possible to produce high density sintered Si.sub.3 N.sub.4 of complex configurations. As a sintering aid, Y.sub.2 O.sub.3 -Al.sub.2 O.sub.3 -MgO system sintering aid is particularly effective. To improve the strength of sintered Si.sub.3 N.sub.4, it is effective to add a heat treatment step after the HIP and maintain the temperature of the sintered Si.sub.3 N.sub.4 above 500.degree. C. for a while. Between the second and third steps, the temperature of the presintered body is preferably maintained above 500.degree. C. These temperature controls are effective not only to improve the strength of sintered Si.sub.3 N.sub.4 but also to save the thermal energy and to shorten the production cycle.

Method for producing high density sintered silicon nitride (SI.sub.3 N.sub.

The specification describes a method for producing high density sintered silicon nitride(Si.sub.3 N.sub.4) having a relative density of at least 98%. In a first step, silicon nitride powder is compacted into a desired shape. It is then presintered in a second step, generally, under normal pressure to obtain a presintered body having a relative density of at least 92%. In a third step, the presintered body is subjected to a hot isostatic pressing(HIP) in an inert gas atmosphere of 1500-2100.degree. C. and of nitrogen gas partial pressure of at least 500 atm. Since the presintering does not require any capsule, it is possible to produce high density sintered Si.sub.3 N.sub.4 of complex configurations. As a sintering aid, Y.sub.2 O.sub.3 --Al.sub.2 O.sub.3 --MgO system sintering aid is particularly effective. To improve the strength of sintered Si.sub.3 N.sub.4, it is effective to add a heat treatment step after the HIP and maintain the temperature of the sintered Si.sub.3 N.sub.4, above 500.degree. C. for a while. Between the second and third steps, the temperature of the presintered body is preferably maintained above 500.degree. C. These temperature controls are effective not only to improve the strength of sintered Si.sub.3 N.sub.4 but also to save the thermal energy and to shorten the production cycle.

Method for producing high density sintered silicon nitride (Si.sub.3 N.sub.

A method for producing a high strength sintered silicon carbide, the method comprising: molding a mixture of silicon carbide powder and a sintering aid into a green compact of a predetermined shape: preliminarily sintering the green compact to obtain a preliminarily sintered compact having a relative density higher than 80%; charging the preliminarily sintered compact in a HIP equipment without using a capsule; and subject the preliminarily sintered compact to a HIP treatment in a high-temperature and high-pressure N.sub.2 gas atmosphere maintaining a pressure higher than 500 atms and a temperature in the range of 1400.degree.-2300.degree. C.

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Kobe, Japan

Hiroshi Okada