Kabushiki Kaisha Riken

Nissan Motor Company Limited

Nippon Itf, Inc

Masaki Moronuki

Katsuhiro Tsuji

Takuma Sekiya

Yuji Shima

Masayuki Sato

Yuuichi Murayama

Junya Takahashi

Takashi Matsui

Yutaka Mabuchi

Takahiro Hamada

Tomoyuki Koike

Yoshiharu Utsumi

Akira Kunimoto

Hisanori Ohara

Akio Shinohara

Hiroyuki Izumi

Keiji Honda

Minoru Kawanishi

Ryo Wakabayashi

Takayuki Sato

The present invention provides a piston ring having excellent abrasion resistance to an aluminum alloy cylinder or cylinder liner formed of a mating material and is therefore capable of decreasing abrasion of the mating material. An exemplary piston ring has a hard carbon coating formed on an outer peripheral surface, and the hard carbon coating contains 0.5 atom % or more to less than 5 atom % of tungsten (W).

Piston ring

A combination of a cylinderof an internal combustion engine and a piston ringfor sliding an inner periphery of the cylinder, wherein at least a sliding face of the cylinder is composed of an aluminum alloy including 8 mass % to 22 mass % of Si and at least one or more particles selected from the group consisting of Si, AlOand SiOparticles each having a diameter of 3 &#x3bc;m or more, and at least an outer periphery of the piston ring is coated with a hard carbon coatingcomposed only of hydrogen and carbon.

Combination of cylinder and piston ring

Provided is a sliding member capable of achieving excellent wear resistance and high coating adhesion under harsh sliding conditions without subjecting a base member to nitriding treatment. The sliding member includes a base member made of a steel material and a hard coating that is formed on the base member and having a surface serving at least as a sliding surface. The hard coating has a Young's modulus having a distribution to increase first in a depth direction directed from an interface between the hard coating and the base member to the surface, to become maximum at a predetermined depth, and then to decrease in the depth direction directed from the interface to the surface.

Sliding member and piston ring

To provide a combination of a cylinder made of a hypereutectic Al&#x2014;Si alloy and a hard-carbon-coated piston ring both exhibiting excellent wear resistance, the piston ring is provided with a laminate coating at least on an outer peripheral sliding surface thereof; the laminate coating comprising a metal layer, a metal-containing, hard carbon layer, and a metal-free, hard carbon layer in this order from the substrate side; the laminate coating having Martens' hardness (indentation hardness) HMs of 5-13 GPa, indentation modulus E of 70-200 GPa, and a deformation ratio Rpe of 0.45 or less, which is expressed by a ratio (Wp/We) of plastic deformation energy Wp to elastic deformation energy We; and a ratio (Tmf/Tm) of the thickness Tmf of the metal-free, hard carbon layer to the thickness Tm of the metal-containing, hard carbon layer being 2-8.

To provide a high-thermal-conductivity piston ring having excellent scuffing resistance and wear resistance, which can be used in a high-heat-load environment in engines, a TiN coating as thick as 10-60 &#x3bc;m, in which the texture coefficient of a (220) plane is 1.1-1.8 in X-ray diffraction on the coating surface, larger than those of (111) and (200) planes, is formed under the optimized ion plating conditions on a peripheral surface of the piston ring. Also, to obtain excellent sliding characteristics with low friction without losing excellent thermal conductivity of TiN, a hard amorphous carbon coating is formed on the TiN coating.

A high-thermal-conductivity piston ring having excellent scuffing resistance and wear resistance, which can be used in a high-heat-load environment in engines is provided. Also, to provide a piston ring with low friction for contributing to the improvement of fuel efficiency, a TiN coating as thick as 10-60 &#x3bc;m, in which the texture coefficient of a (111) plane is 1.2-1.65 in X-ray diffraction on the coating surface, with the texture coefficient of a (111) plane&#x3e;the texture coefficient of a (220) plane&#x3e;the texture coefficient of a (200) plane, is formed under the optimized ion plating conditions on a peripheral surface of the piston ring. Further, to obtain excellent sliding characteristics with low friction without losing excellent thermal conductivity of TiN, a hard amorphous carbon coating is formed on the TiN coating.

A sliding member is characterized in that a sliding surface of the sliding member is coated with an amorphous hard carbon film, and a surface of the amorphous hard carbon film has a ten-point mean roughness of equal to or less than 0.7 micrometers and an initial wear height in a range of 0.07 to 0.14 micrometers.

Sliding member

An amorphous hard carbon film comprising a first amorphous carbon layer substantially consists only of carbon formed on a substrate surface and a second amorphous carbon layer substantially consists only of carbon formed on the surface of the first amorphous carbon layer, wherein the transmission electron microscope image of the first amorphous carbon layer is brighter than that of the second amorphous carbon layer when the cross section is observed.

Hard amorphous carbon film

A valve lifter, in which an amorphous hard carbon film is coated at least on the surface that slides against a cam, is characterized in that the surface of a base material (substrate) has an arithmetic mean roughness of Ra 0.01 to 0.03 micrometers, and the maximum length of the scratch on the base surface is made to be equal to or shorter than 250 micrometers.

Valve lifter

An amorphous hard carbon film has low friction coefficient from the beginning of sliding, when the metal oxide is contained in the film. The adhesion of the film to the substrate is also improved due to the low temperature treatment of RF plasma enhanced CVD method. This film can be applied to many sliding members, e.g., a piston ring, a vane of compressor and a plunger of fuel injection pump, used under severe condition.

Growing community of inventors

Kashiwazaki, Japan

Masaki Moronuki