Nippon Piston Ring Co., Ltd.

Takuya Ozaki

Hiroyuki Sugiura

To provide a piston ring comprising a hard carbon film that is easy to form and exhibits excellent wear resistance. The above-described problem is solved by having a hard carbon filmformed on at least an outer peripheral sliding surfaceof a piston ring base material, wherein the hard carbon filmis a laminated film comprising a plurality of layers, and is configured so as to contain boron within a range of an atomic density of 0.2&#xd7;10atoms/cmto 2.0&#xd7;10atoms/cminclusive. This hard carbon filmmay be configured to have an spcomponent ratio within a range of 40% to 80% inclusive, measured in a TEM-EELS spectrum formed by combining electron energy loss spectroscopy (EELS) with a transmission electron microscope (TEM), and a hydrogen content within a range of 0.1 atom % to 5 atom % inclusive. Further, a total thickness of this hard carbon filmmay be configured to be within a range of 0.5 &#x3bc;m to 20 &#x3bc;m inclusive.

Piston ring

To provide a piston ring comprising a hard carbon film that is easy to form and exhibits excellent adhesion and wear resistance, and a manufacturing method therefor. The above-described problem is solved by means of a piston ring comprising a hard carbon filmformed on at least an outer peripheral sliding surfaceof a piston ring base material, wherein the hard carbon filmis a laminated film comprising a plurality of layers, including an upper layerwith a lamination pitch within a range of 3 nm to 50 nm inclusive, a middle layerwith a lamination pitch less than that of the upper layer, and a lower layerwith a lamination pitch within the same range as that of the upper layerand greater than that of the middle layer. This hard carbon filmmay be configured to have an spcomponent ratio within a range of 35% to 80% inclusive, measured in a TEM-EELS spectrum formed by combining electron energy loss spectroscopy (EELS) with a transmission electron microscope (TEM), and a hydrogen content within a range of 0.1 atom % to 5 atom % inclusive.

Piston ring and manufacturing method therefor

A piston ring having a hard carbon film formed on at least an external peripheral sliding surface of a piston ring base material, the hard carbon film having an spcomponent ratio within a range of 40% to 80% inclusive as measured by a TEM-EELS spectrum which combines electron energy loss spectroscopy (EELS) with a transmission electron microscope (TEM), a hydrogen content being in a range of 0.1 at. % to 5 at. % inclusive, and an amount of macroparticles appearing on the surface being within a range of 0.1% to 10% inclusive by area ratio. The hard carbon film is formed on a hard carbon foundation film formed under low-speed film-forming conditions on the side of the piston ring base material, and the hard carbon foundation film is formed with an arc current value 80% or less of the arc current value during the formation of the hard carbon film.

A piston ring having a hard carbon coating film is provided that can be easily formed in the same batch, does not cause delamination, and is excellent in initial running-in and wear resistance. A hard carbon coating film is formed at least on an outer peripheral sliding surface of a piston ring base and contains substantially no hydrogen, wherein the hard carbon coating film has an spcontent ratio ranging from 40% to 80% measured in a TEM-EELS spectrum where transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) are combined together, and an area ratio of contained macro particles on a surface of the hard carbon coating film ranges from 0.1% to 10.0%.

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Ichinoseki, Japan

Takuya Ozaki