Nissan Motor Company Limited

Yusuke Okamoto

Makoto Kano

Yoshiteru Yasuda

Yutaka Mabuchi

Takahiro Hamada

Naoto Hirosaki

Yoshio Akimune

Takafumi Ueno

Takuro Yamaguchi

Jean Michel Martin

Saihei Kano

A gear comprised of a tooth surface and a hard carbon film formed on at least a part of the tooth surface. When the gear is used in lubricant including a specific component, a friction of a tooth surface of the gear is largely decreased, and therefore the gear performs an excellent power transmission efficiency. Further, when the gear is employed in a planetary gear mechanism or speed reducing mechanism which has a plurality of meshing portions of gears, the power transmission efficiency of the mechanism is also improved.

Gear

A low-friction sliding member such as a piston, a piston ring, a piston skirt section and a cylinder liner section of an internal combustion engine. The low-friction sliding member includes a base material having a surface. A hard carbon thin film is formed at at least a part of the surface of the base material. Here, a tribo-film having at least one functional group selected from the group consisting of ether linkage, oxido and hydroxyl group is formed on the hard carbon thin film when the hard carbon thin film is in slidable contact with an opposite member in presence of an organic oxygen-containing compound.

Low-friction sliding member and low-friction sliding mechanism using same

A sliding structure for an automotive engine includes a sliding member with a sliding portion and a lubricant applied to the sliding portion so that the sliding portion can make sliding contact with a counterpart member via the lubricant. The sliding member is either of a piston ring, a piston pin, a cam lobe, a cam journal, a plain bearing, a rotary vane and a timing chain. The sliding portion has a base made of a steel or aluminum material and a hard carbon film formed on the base to coat the sliding portion. The hard carbon film has a thickness of 0.3 to 2.0 &#x3bc;m, a Knoop hardness of 1500 to 4500 kg/mm, a surface roughness Ry (&#x3bc;m) satisfying the following equation: Ry&#x3c;{(0.75&#x2212;Hk/8000)&#xd7;h+0.07/0.8}, where h is the thickness (&#x3bc;m) of the film; and Hk is the Knoop hardness (kg/mm) of the film.

Sliding structure for automotive engine

The invention relates to a sintered composite of silicon carbide and silicon nitride. The sintered composite includes a polycrystalline matrix and polycrystalline aggregates dispersed in the matrix. The matrix includes silicon carbide grains, first silicon-nitride grains and a first sintering aid thereof. Each of the aggregates includes second silicon-nitride grains and a second sintering aid thereof. The aggregates have an average diameter within a range from 10 .mu.m to 50 .mu.m. This average diameter is defined as a diameter of a circle having an area which is the same as the average area of the aggregates on a two-dimensional section of the sintered composite. The sintered composite is light in weight and superior in strength and fracture toughness at high temperature as well as at room temperature.

Sintered composite of silicon carbide and silicon nitride

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Kanagawa, Japan

Yusuke Okamoto