Kabushiki Kaisha Riken

Ryou Obara

Toshikatsu Hayashi

Katsumi Takiguchi

Kouhei Sugimoto

Yoshinari Watanabe

Yukio Hosotsubo

Provided is a piston ring capable of maintaining an excellent effect of preventing aluminum cohesion in a high output engine over a long period of time. At least one of the upper, lower, and side faces of the piston ring is coated with a silica-based coating in which hard nanoparticles are dispersed. The coating has a Martens hardness of 1,000 to 8,000 N/mm. As the hard nanoparticles, carbon nanoparticles, nanodiamond particles, carbon nanotubes, or carbon nanofibers are used. To the coating, resin particles of a fluorine-based resin or a polyether-based resin may be added.

Piston ring

The piston ring of the present invention comprises a thermal spray coating comprising chromium carbide particles having an average particle size of 5 &#x3bc;m or less, and a matrix metal composed of a Ni&#x2014;Cr alloy or a Ni&#x2014;Cr alloy and Ni at least on an outer peripheral surface, said thermal spray coating having an average pore diameter of 10 &#x3bc;m or less and a porosity of 8% or less by volume. A piston ring having excellent wear resistance, scuffing resistance and peeling resistance with little attackability on a mating member is obtained by forming a homogeneous thermal spray coating having a fine microstructure.

Piston ring and thermal spray coating used therein, and method for manufacturing thereof

A thermal spray coated piston ring having improved initial running-in propery, and having scuffing resistance and wear resistance is provided. The spray coating film () of the piston ring () contains from 2 to 40 mass % of Sn and from 5 to 50 mass % of graphite, and if necessary, P, Sb, Co, Be, Cr, Mn, Si, Cd, Zn, Fe, Ni and/or Pb, the balance essentially consisting of Cu.

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Tokyo, Japan

Ryou Obara