Agency of Industrial Science and Technology

Director-general of the Agency of Industrial Science and Technology

Oiles Industry Co., Ltd.

Denki Kagaku Kogyo Kabushiki Kaisha

Kazuo Kobayashi

Ichitaro Ogawa

Hisayoshi Yoshida

Tsuyoshi Hagio

Kenji Miyazaki

Wataru Abe

Kazutsugu Kashima

Takashi Tada

Eiji Tani

Hidemasa Honda

Hiroshi Nishikawa

Hidetoshi Ueno

Hiroshi Harada

Shigeru Akiyama

Minoru Shiraishi

Satoshi Arai

Kazushi Kishi

Hiroaki Yasunaga

Takayoshi Yamamoto

Yoichiro Hayashi

Youichirou Hayashi

Seiki Umebayashi

Yasuhiro Matsushita

Tetsuhiko Hasuda

Hagio Tsuyoshi

Shiroh Ohmori

A pressureless sintered body of boron nitride contains more than 95 wt% of boron nitride. The pressureless sintered body hexagonal of boron nitride has a density of not less than 1.10 g/cm.sup.3 and a bending strength of not less than 300 kg/cm.sup.2. A process of producing the pressureless sintered body of boron nitride comprises pulverizing powders of starting feed boron nitride so that a specific surface area of each of the powders is two times or more than that of the starting feed boron nitride powder, molding the thus pulverized powders to obtain a pre-molded body and sintering the pre-molded body at a temperature of not less than 1400.degree. C. under atmospheric pressure and under non-oxidative atmosphere.

Pressureless sintered body of boron nitride

A process for producing a .beta.-sialon.silicon carbide complex includes mixing silicon nitride and silicon carbide with an aluminum alkoxide solution or a soluble aluminum salt solution and using the resulting homogeneous mixture as a starting material in forming a sintered body. The aluminum alkoxide solution or aluminum salt solution penetrates into the surface of each particle of the silicon nitride and silicon carbide, whereby the whole surface of each nitride and carbide particle is covered with aluminum alkoxide solution or aluminum salt solution, and homogeneous mixing is achieved. Therefore, defects such as pores, clusters of large grains, or unsintered parts are eliminated and the strength of the final sintered bodies is improved.

Process for producing high strength .beta.sialon-silicon carbide

Described herein is a method for producing a carbon-ceramic composite material, which is characterized by firing a ground powder mixture of low temperature coke and a ceramic material in a non-oxidizing atmosphere at a temperature higher than 800.degree. C., inclusive, and lower than an inceptive sintering temperature of the ceramic material, prior to shaping and sintering stages.

Method for producing carbon-ceramic composite material

Disclosed herein is a high temperature-resistant and abrasion-resistant sliding member of graphite-metal borides showing a friction coefficient of 0.01 to 0.09 and a specific amount of abrasion of 1.0 to 4.0.times.10.sup.-8 mm.sup.2 /kg under the measuring conditions of a load of 20 kg/cm.sup.2 and a sliding velocity of 5 m/min at an atmosphere temperature of 300.degree. C., a bending strength of 230 to 900 kg.f/cm.sup.2 and a Shore hardness of 28 to 45, produced by sintering (a) 70 to 93% by weight of amorphous carbon powder, (b) 5 to 20% by weight of at least one boride of a metal of IVa group, Va group of VIa group of the periodic table and (c) 2 to 10% by weight of powdery natural graphite, powdery Kish graphite or a mixture thereof.

Sliding member of graphite-metal borides

Disclosed herein is a high temperature-resistant and abrasion-resistant sliding member of graphite-boron carbides showing the friction coefficient of 0.01 to 0.13 and the specific abrasion amount of 10.sup.-7 to 10.sup.-9 mm.sup.2 /kg under the measuring conditions of the load of 20 kg/cm.sup.2 and the sliding velocity of 5 m/min at a temperature of 300.degree. C., the bending strength of 300 to 1600 kg.f/cm.sup.2 and the Shore hardness of from 45 to 60, obtained by mixing and stirring from 65 to 95% by weight of powdery carbon of an average particle size of 10 to 150 .mu.m and from 5 to 35% by weight of powdery boron carbide of an average particle size of 0.5 to 2.5 .mu.m until the powdery boron carbide is uniformly dispersed in the powdery carbon, and sintering the thus formed mixture at a temperature of 2020.degree. C. or more and less than the transition point at which the structure of carbon and boron carbide in the thus formed mixture is remarkably changed, under a pressure of 100-250 kg/cm.sup.2.

Sliding member of graphite-boron carbides

Disclosed herein is a heat resistant vaned stirrer for use in a high temperature atmosphere. To endure stirring operations in high temperature molten metals of 300.degree.-1200.degree. C., the stirrer vanes are formed of a carbon-ceramics composite material which is produced from coke powder blended with 10-50% by volume of ceramics powder and which has a bending strength higher than 200 kg/cm.

Vaned stirrer for use in high temperature atmosphere

The carbonaceous body of the invention is prepared by shaping and sintering uniform powdery mixture composed of a powder of a low-temperature coke, a powder of boron carbide and a powder of silicon carbide in such a proportion that the weight proportion of the boron carbide and the silicon carbide is in the range from 2:98 to 80:20 and the volume proportion of the coke powder and the combination of the boron carbide and silicon carbide is in the range from 50:50 to 95:5. The carbonaceous body thus obtained is highly resistant against air oxidation even at a temperature of 1400.degree. C. in addition to the outstandingly high mechanical strengths in comparison with conventional carbonaceous shaped materials such as artificial graphite.

Silicon carbide-boron carbide carbonaceous body

A process for the production of shaped articles of high density graphite ing excellent mold-releasing property which comprises incorporating amorphous carbon powder such as powdery coke or artificial graphite powder with about 3-20% by weight of boric acid or boron oxide as a sintering-promoting agent, and baking the mixture under a pressure of 150-500 kg/cm.sup.2 without the aid of a binding agent such as pitch. Shaped articles of high density graphite possessing excellent mechanical strength are obtained by this process.

Process for the production of shaped articles of high density graphite

Disclosed are graphitized hollow spheres and a method for the manufacture thereof which comprises coating a spherical core of foamed polystyrene with carbonaceous powder and a binder, heating the coated core under controlled conditions to decompose the spherical core of foamed polystyrene, and further heating the resultant carbonaceous body at a high temperature.

Method for manufacture of graphitized hollow spheres and hollow spheres

Growing community of inventors

Tosu, Japan

Kazuo Kobayashi