Sumitomo Electric Industries, Limited

Japan Fine Ceramics Center

Japan Atomic Energy Research Institute

Japan Atomic Energy Institute

Masaya Miyake

Akira Yamakawa

Kenji Matsunuma

Takao Nishioka

Matsuo Higuchi

Akio Hara

Hitoyuki Sakanoue

Osamu Komura

Hisao Takeuchi

Koichi Sogabe

Akira Sasame

Takaharu Yamamoto

Minol Nakano

Yoshishige Takano

Takehisa Yamamoto

Tetsuya Katayama

Norio Yasuoka

Kouhei Shimoda

Takao Maeda

Naoji Fujimori

Shuji Yazu

Hirohiko Nakata

Akira Kuibira

Kaoru Murabe

Tetsuya Abe

Chihiro Kawai

Yoshio Murakami

Yoshihiko Doi

Kouichi Sogabe

Hiroshi Nomura

Yasuhisa Yushio

Tsuyoshi Asai

Masaaki Honda

Kiyoshi Uchida

Mitsuo Kodama

Yukio Shimokawa

Takashi Matsuura

Kohei Shimoda

Masaaki Tobioka

Eiji Kamijo

Seiji Hiroki

Koji Watari

Jin-Joo Matsui

Yasuhiro Saito

Hitoshi Akazawa

Tomoyuki Awatsu

Tatsuji Matsui

Kouiti Sogabe

Kozo Ishizaki

Kouichi Sogahe

Noriyuki Ayano

Akira Hara

A slide member has a sliding surface made of ceramic and a has surface roughness of not more than 1.0 .mu.m in center line average roughness Ra. The ceramics includes a silicon nitride sintered body which contains crystal grains having a linear density of at least 35 per 30 .mu.m in length with a boundary phase volume ratio of not more than 15 volume %, and which contains pores of not more than 20 .mu.m in maximum diameter in a content of not more than 3%. In a method of manufacturing the slide member, it is possible to ensure smoothness of the sliding surface by grinding the sliding surface and thereafter heating the ceramic in an either an inert gas or atmospheric air. A slide member that can be used under severe sliding conditions of high-speed sliding or the like and that has excellent wear resistance is obtained. Even if the slide member is used for to a sliding part of a compressor or the like which employs a fluorocarbon containing no chlorine as a cooling medium, it is possible to prevent the occurrence of seizure and abnormal wear on the sliding surface.

Slide member and method of manufacturing the same

Composite bearing structure

Discloses a silicon nitride based sintered body composed only of uniform, fine crystal grains, and improved in both strength and fracture toughness in the middle and low temperature ranges. A crystalline silicon nitride powder composed of crystal grains whose longer-axis diameter is not more than 200 nm or an amorphous silicon nitride powder is used as material powder. The silicon nitride powder is sintered at a temperature of 1200.degree. C. to 1400.degree. C. or sintered with a product of sintering temperature (.degree. C.) and sintering time (sec) below 600000 (.degree. C..multidot.sec) at a temperature of 1400.degree. C. to 1900.degree. C. Thus, a silicon nitride based sintered body in which the longer-axis diameter of silicon nitride and/or sialon crystals is not more than 200 nm is obtained.

Silicon nitride based sintered body

A vacuum vessel is provided in which the majority of a vessel wall including an annular wall portion (1) and a plate-wall portion (2) is formed of ceramic material such as silicon nitride, for example. To bond the plural wall members together, bonding faces having a surface flatness of not more than 1 .mu.m are prepared thereon, and then a ceramic powder bonding substance with an average particle diameter of not more than 1 .mu.m is interposed between adjacent bonding faces and subjected to heating. Because the generation of gas, such as hydrogen, from the wall of the ceramic vessel is reduced, extremely high vacuum can be generated and maintained in the interior of the vacuum vessel. Also, because the wall of the vacuum vessel has a high permeability with respect to a magnetic field and an electric field, the vacuum vessel can be used as a vessel in a particle accelerator that allows the high precision control of charged particles therein by means of an electromagnetic field.

Method of manufacturing a ceramics-type vacuum vessel

A silicon nitride composite sintered which comprises crystal grains of silicon nitride and/or sialon having an average minor axis length of 0.05 to 3 .mu.m and an aspect ratio of 10 or less and foreign particles dispersed in the crystal grains and/or the grain boundary phase, said particles having a thermal expansion coefficient of 5.times.10.sup.-6 /.degree.C. or more and an average particle size of 1 to 500 nm. The sintered body is produced by wet mixing silicon nitride powder, at least two sintering aids selected from among Y.sub.2 O.sub.3, Al.sub.2 O.sub.3, AlN and MgO and at least one compound selected from among the oxides, nitrides, carbides and silicides of the elements, excluding Si and C, of the groups IIa, IIIa, IVa, Va, VIa, IIb, IIIb and IVb of the Periodic Table to form a molding; and heat treating under the specified conditions. The sintered body can also be obtained by coating the surfaces of silicon nitride crystal grains with an organometallic compound convertible to the above foreign particles, heat treating and sintering with the sintering aid.

Silicon nitride composite sintered body and process for producing the

Quadrupole electrode and process for producing the same

Described are sintered silicon nitride bodies useful as materials for parts required to have strength, especially excellent impact strength for items such as automobile parts and machine parts. The sintered Si.sub.3 N.sub.4 bodies contain 80-98 wt. % of silicon nitride and have a porosity not higher than 3% and an shock compressive elasticity limit of at least 15 GPa.

Sintered silicon nitride bodies suitable for use as high impact materials

A high-strength silicon nitride sintered body having a flexural strength of 100 kg/mm.sup.2 or higher and a process for producing the same are disclosed, the sintered body comprising not less than 90% by weight of a single crystalline phase of silicon aluminum oxynitride (Si.sub.6-z Al.sub.2 O.sub.z N.sub.8-z, wherein z is a number of from 0 to 4.2) having an average longer diameter of not more than 5 .mu.m and an aspect ratio of not less than 5, the crystal phase constituting a network structure in the sintered body, the balance being a crystalline or amorphous (glassy) phase comprising one or more of oxides or oxynitrides of a rare earth metal, a group 3A metal, a group 2A metal or Si, and the process comprising mixing silicon nitride powder, an organic metal salt as a first sintering aid, and at least one of a metal oxide, a metal nitride, and a metal oxynitride as a second sintering aid, either separately or as a mixture of two or more thereof, with a solvent and a surface active agent, subjecting the mixture or mixtures to ultrasonic dispersion, mixing the mixtures together followed by drying to obtain a mixed powder, molding the mixed powder, and sintering the molded article at a temperature of from 1,600.degree. C. to 2,200.degree. C. in a non-oxidative atmosphere.

High strength silicon nitride sintered body and process for producing

A ceramics composite material containing crystallized glass as the matrix and fibers or whiskers of ceramics as a reinforcement material, is obtained by melting original glass to form crystallized glass, compounding the same with fibers or whiskers of oxide ceramics and thereafter crystallizing the original glass. This ceramics composite material does not form any voids and can easily contain at least 50 volume percent of the reinforcement material, whereby a good mechanical strength and fracture toughness are achieved. In the compounding step, the content of the reinforcement can be further increased by forcing out any excess part of the original glass from the reinforcement material by applying pressure to a substance obtained by mixing the original glass with the reinforcement. Further, the ceramics composite material can be efficiently formed into a desired configuration by heating because the original glass flows viscously.

Ceramics composite material and method of producing the same

A heat conductive aluminum nitride sintered body contains 100 parts by weight of aluminum nitride, at least 0.005 parts by weight and not more than 0.5 parts by weight of carbon, at least 0.01 parts by weight and not more than 15 parts by weight of a rare earth aluminum oxide in terms of the simple substance of a rare earth element, and at least 0.01 parts by weight and not more than 15 parts by weight of at least one element selected from a group of compounds containing elements belonging to the groups IVB, VB and VIB of the periodic table in terms of the simple substance of the element. Such a sintered body has a heat conductivity of at least 100 W/m.multidot.K. and not more than 270 W/m.multidot.K. at room temperature.

Heat conductive colored aluminum nitride sintered body

A heat conductive aluminum nitride sintered body contains 100 parts by weight of aluminum nitride, at least 0.005 parts by weight and not more than 0.5 parts by weight of carbon, at least 0.01 parts by weight and not more than 15 parts by weight of a rare earth aluminum oxide in terms of the simple substance of a rare earth element, and at least 0.01 parts by weight and not more than 15 parts by weight of at least one element selected from a group of compounds containing elements belonging to the groups IVB, VB and VIB of the periodic table in terms of the simple substance of the element. Heat conductivity of the aluminum nitride sintered body is at least 100 W/m.multidot.K and not more than 270 W/m.multidot.K at the ordinary temperature. According to a method of preparing such an aluminum nitride sintered body, at least 0.01 parts by weight and not more than 5 parts by weight of carbon, at least 0.01 parts by weight and not more than 15 parts by weight of an oxide of a rare earth element, and at least 0.01 parts by weight and not more than 15 parts by weight of an oxide, a carbide or a nitride of an element belonging to the group IVB, VB or VIB of the periodic table are added to 100 parts by weight of aluminum nitride. A compact of this mixture is fired in a nonoxidizing atmosphere under a temperature of at least 1500.degree. C. and not more than 2100.degree. C.

Heat conductive colored aluminum nitride sintered body and method of

The present invention provides a sintered body of aluminum nitride comprising (i) aluminum nitride as a main component and (ii) at least one component selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Co, Ni, Nd, Ho, Ti and compounds thereof in the total amounts of not greater than 1.0 wt. % and not less than 0.01 wt. % in terms of elements on the basis of sintered body, the sintered body being colored and having a thermal conductivity of at least 150 W/mK. The sintered body is useful for the preparation of circuit boards having printed circuits thereon and highly heat-releasing ceramic packages for semiconductive devices.

Sintered body of aluminum nitride

A composite bearing structure can withstand high speed rotation has first, second and third bearing components. The first bearing component supports a radial impact force applied to a rotator during rotation, and is made of an inner ring (1) and an outer ring (2) of silicon nitride ceramic sintered bodies. The second bearing component supports an axial load applied to the rotator while maintaining a required clearance between itself and the rotator and is made of two permanent magnets (12, 13) positioned thrustdirectionally opposite to each other. The third bearing component maintains a radial rotational accuracy of the rotator, and is made of a radial dynamic pressure producing groove (5) provided on a cylindrical surface of the inner ring (1).

The present invention relates to a silicon nitride sintered body [wherein the composition of Si.sub.3 N.sub.4 -first aid (Y.sub.2 O.sub.3 +MgO)-second aid (at least one of Al.sub.2 O.sub.3 and AlN)] falls within a range defined by lines joining points A, B, C and D in FIG. 1, the crystal phase of the sintered body contains both .alpha.-Si.sub.3 N.sub.4 and .beta.'-sialon, and the relative density is 98% or more. This sintered body is produced by subjecting a green compact of the above-described source to primary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 96% or more, and the precipitation ratio of the .alpha.-Si.sub.3 N.sub.4 crystal phases to the .beta.'-sialon crystal phase in the sintered body is in the range of from 40:60 to 80:20; and then subjecting the primary sintered body to secondary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 98% or more. The sintered body has superior strength properties, especially at ordinary temperatures, and can be produced with a high productivity in a high yield at a low cost.

Silicon nitride sintered body and process for producing the same

Growing community of inventors

Hyogo, Japan

Masaya Miyake