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US 7,255,084 B2Granted
Piston with a skirt having a low coefficient of friction
AssigneeSorevi S.A.
InventorsJérémy Savale, Marc Hervé, François Vérinaud
Life of this patent
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Abstract
A piston for an internal combustion motor has a skirt with a surface, which is at least partially polished and thereafter coated with a coating having a hardness of greater than 8 GPa and having a coefficient of friction of less than 0.20. The piston has an increased performance, a longer lifetime and a reduced friction.
Claims15
A piston for an internal combustion motor, comprising:
- a) a skirt having a surface;
- b) the surface being at least partially polished and thereafter coated with a coating, the coating having a hardness of greater than 8 GPa, the hardness being an indentation modulus as measured by an indenter, and having a coefficient of friction of less than 0.20, the coefficient of friction being as measured in a ball on disk test according to ASTM G99;
- c) the surface of the skirt having a flat surface morphology and having at least partially a ten-point mean roughness Rz of less than 1.0;
- d) the surface of the skirt having at least partially an arithmetical mean roughness Ra of less than 0.15;
- e) the coating being selected from the group consisting of diamond-like carbon coatings, diamond-like nanocomposite coatings, wolfram carbide coatings, and a combination thereof;
- f) an intermediate tie layer being present between the polished surface and the coating;
- and
- g) the intermediate tie layer being selected from a group consisting of diamond-like nanocomposite coatings, doped diamond-like coatings, doped diamond-like nanocomposite coatings, TiN coatings, Ti (C,N) coatings, SiN coatings, CrN coatings, wolfram carbide coatings, and a combination thereof.
5 more elements
A method of treating a piston of an internal combustion motor, the piston having a skirt, the method comprising the following steps:
- a) polishing at least partially the surface of said skirt;
- b) coating the at least partially polished surface with a coating having a hardness of greater than 8 GPa, the hardness being an indentation modulus as measured by an indenter, and having a coefficient of friction of less than 0.20, and the coefficient of friction being as measured in a ball on disk test according to ASTM G99;
- c) providing an intermediate tie layer between the polished surface and the coating;
- and
- d) selecting the intermediate tie layer from a group consisting essentially of diamond-like nanocomposite coatings, doped diamond-like coatings, doped diamond-like nanocomposite coatings, TiN coatings, Ti (C,N) coatings, SiN coatings, CrN coatings, wolfram carbide coatings, and a combination thereof.
2 more elements
A piston for an internal combustion motor, comprising:
- a) a skirt having a surface;
- b) the surface being at least partially polished and thereafter coated with a coating, the coating having a hardness of greater than 8 GPa, the hardness being an indentation modulus as measured by an indenter, and having a coefficient of friction of less than 0.20, the coefficient of friction being as measured in a ball on disk test according to ASTM G99;
- c) an intermediate tie layer being present between the polished surface and the coating;
- and
- d) the intermediate tie layer being selected from a group consisting essentially of diamond-like nanocomposite coatings, doped diamond-like coatings, doped diamond-like nanocomposite coatings, TiN coatings, Ti (C,N) coatings, SiN coatings, CrN coatings, wolfram carbide coatings, and a combination thereof.
2 more elements
Dependencies are inferred from the claim text.