Hitachi, Ltd.

Hitachi Koki Co., Ltd.

Masahisa Sobue

Yoshiyuki Yasutomi

Nobuyuki Yamashita

Tadahiko Miyoshi

Hiroshi Nagase

Kiyohiko Tanno

Akio Chiba

Shoji Arimoto

Fumio Jooraku

Kazuo Tahara

Toshiyuki Kajiwara

Tomoaki Kimura

Keiichi Kuniya

Mitsuo Nihei

Kousuke Nakamura

Junji Sakai

Shun Suzuki

Hideki Kita

Kimihiko Akahori

Toshimi Sasaki

Sensuke Okada

Nobuyuki Koganezawa

Toshimi Abukawa

Toshiaki Arato

Seiji Watahiki

Toshiaki Narisawa

Shin'ichi Sakamoto

The invention provides a conductor comprising a reaction-sintered body of a conductive nitride produced from a powder of at least one metal selected from Ti, Zr, V, Nb, Ta, Cr, Ce, Co, Mn, Hf, W, Mo, Fe, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Lu, Th and Ni, and a process for producing such conductor by heating a molding containing a metal powder in a nitriding gaseous atmosphere containing no CO gas.

Conductive material and process for preparing the same

Disclosed is a ceramic composite which comprises particles of at least one inorganic compound selected from the group consisting of a carbide, a nitride, an oxide, a boride, a silicide and an oxy-nitride and particles and whiskers of Si.sub.3 N.sub.4, Si.sub.2 N.sub.2 O or SiO.sub.2. This ceramic composite is small in volume change on sintering, and provides heat resistance. In addition, the composite can absorb thermal shock by its voids. It can be used in association with ceramic heaters, current collectors, commutators for starter motors and alternators, and in other areas.

Process for producing ceramic compositions

Ceramic composite and process for production thereof

A commutator has a central support supporting a plurality of conductive segments separated by a plurality of insulative segments. In addition to providing an insulative function between the conductive segments, the dielectric constant, the area, and the thickness of the insulative segments are chosen so that they provide a capacitive effect, which capacitive effect suppresses current peaks during operation of the commutator. Preferably, the dielectric constant is greater than 10. The central support may include a metal shaft and an insulating ring, which insulating ring is preferably of material with a lower dielectric constant thereby to suppress-shorting between the shaft and the conductive segments. It is particularly advantageous if the conductive and insulative segments are of ceramics material since this provides good wear resistance. In further alternatives, capacitors are formed between the conductive segments by rings or other bodies of insulative materials of a suitably high dielectric constant.

Commutator

A casting method for manufacturing various types of ceramics products having an intricate configuration and a partly diversified wall thickness, such as compressor scroll blade and a screw rotor, by casting a slurry including ceramics, etc. in a mold, includes an arrangement wherein the mold is partly or entirely formed of a flexible gel material which can be melted by heating at a temperature lower than the boiling point of the dispersion medium, whereby the stresses generated when molding the product can be mitigated. Thus, the molding of a product having a high level of dimensional accuracy can be carried out with ease.

Slip casting method

Ceramics material are not resistant to tensile force, though they are resistant to compression force. Therefore, ceramics materials, when used as the material of a commutator of an electric rotary machine, tends to be cracked and broken due to tensile stress generated in the inner peripheral portion of the commutator when the latter is press-fitted on the rotor shaft of the machine. The invention is aimed at obviating the above-described problem, so as to make it possible to produce a sliding current collector of an electric rotary machine from a ceramics material. To this end, according to the invention, an annular gap is formed between the inner peripheral surface of the ceramics commutator and the other peripheral surface of the rotary shaft and the gap is filled with a resin such as a thermosetting resin which is then thermally set to form a resin layer by which the commutator is bonded to the rotor shaft. The resin layer effectively absorbs any tensile stress which may otherwise be caused in the inner peripheral portion of the commutator due to, for example, thermal expansion of the rotor shaft. It is thus possible to securely fix the commutator to the rotor shaft without risk of cracking or damaging of the commutator.

Sliding current collector made of ceramics

The present invention is a composite ceramic structure having a porosity of 5 to 40% by volume comprising particles selected from the group consisting of grains and whiskers of at least one inorganic compound AB, where B is oxygen, nitrogen or carbon and A is any metal so the difference in electronegativity between A and B is less than 1.7; or particles selected from the group consisting of grains and whiskers of an inorganic compound, where there is a difference of 1.7 and higher between the components, and having layers of the inorganic compound AB formed on the surfaces of the particles. The particles are bonded together by silicon nitride particles having an average particle size of less than 0.2 micron. The composite ceramic structure is produced by sintering a shape composed of particles of AB or composed of particles having layers of AB formed on the surfaces of the particles in a gaseous atmosphere containing silicon and nitrogen to grow silicon nitride particles on the surfaces of the shaped inorganic particles.

High strength composite ceramic structure and process for producing the

The present invention relates to an inorganically insulated heater having a long life for use in air flow sensors, cathode ray tube cathode heaters etc., wherein the distribution of inorganic insulating particles of the whole insulating layer is made uniform and thereby the development of cracks and the like in the insulating layer is reduced and breaking of wire and dielectric breakdown occur with difficulty even at high temperatures and under strong vibrations.

Inorganically insulated heater, and cathode ray tube and air flow sensor

A roller for rolling mill comprising an entirely non-metallic sintered body composed principally of at least one material selected from silicon carbide, silicon nitride, sialon, alumina and zirconia and having a relative density which is at least 96% of the theoretical density, the roller having an initial crown in the range of -300 .mu.m to +300 .mu.m, is provided. This roller for rolling mill has a high hardness and high wear resistance and can be used as a work roll.

Rollers for rolling mills

A roller for rolling mill comprising an entirely non-metallic sintered body composed principally of at least one material selected from silicon carbide, silicon nitride, sialon, alumina and zirconia and having a relative density which is at least 96% of the theoretical density of the sintered body, the roller having an initial crown in the range of -300 .mu.m to +300 .mu.m, is provided. This roller for rolling mill has a high hardness and high wear resistance and can be used as a work roll.

Growing community of inventors

Mito, Japan

Masahisa Sobue