Metal treatment – Stock – Carburized or nitrided
Reexamination Certificate
1999-06-14
2001-11-13
Sheehan, John (Department: 1742)
Metal treatment
Stock
Carburized or nitrided
C148S530000, C148S537000, C428S660000, C428S457000, C428S908800
Reexamination Certificate
active
06315840
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sliding member, particularly, having superior wear resistance, superior scuffing resistance, and a superior property not to increase an amount of wear on an opponent material (hereinafter referred as an opponent attacking property), for example used as a sliding member of an internal-combustion engine.
There have been applied conventional surface treatments such as hard chromium plating and nitriding for surfaces processing for the purpose of improving wear resistance, on a sliding surface of a piston ring as a sliding member for an internal-combustion engine in order to improve durability.
In recent years, since piston rings have been subjected to the increasingly harsh operating environments due to higher engine outputs and lightening of an internal-combustion engine, piston rings which are processed with the conventional surface treatments can not be satisfied a function such as wear resistance sufficiently,
For that reason, it is demanded that a sliding member such as a piston ring has a film or is applied a surface treatment, which have a superior quality such as superior wear resistance, superior scuffing resistance, and a superior opponent attacking property.
To respond to these problems, some internal-combustion engines or parts thereof are coated with a hard film such as a film of chromium nitride (CrN) or titanium nitride (TiN) which is prepared through use of a physical vapor deposition (PVD) method, in order to improved wear resistance. These films, however, have a problem such that the films make an amount of wear of a cylinder liner as an opponent material increase on occasion, although the wear resistance thereof is improved.
SUMMARY OF THE INVENTION
An object of the present invention from the above-described point, is to soluble a problem of conventional surface treatments and to provide a sliding member which is coated a film having superior wear resistance, superior scuffing resistance and a superior opponent attacking property.
This object can be achieved according to the present invention by providing a sliding member coated by an alloy film of chrome (Cr) - boron (B) - nitrogen (N) on the outer surface thereof. In this case, it is preferable that the Cr—B—N alloy film is formed through use of a physical vapor deposition, particularly ion plating, vacuum deposition, or sputtering. Further, it is preferable that the boron (B) content is within the range of 0.05-20 wt.%. According to the present invention, since the Cr—B—N alloy film formed on the outer surface of the sliding member has superior wear resistance, superior scuffing resistance and a superior opponent attacking property, it is possible to provide the sliding member which satisfies demand characteristics even when the sliding member are subjected to the harsh operating environments.
Further, it is preferable that nitriding layer is formed on a whole surface or at least an outer surface of the sliding member, and the Cr—B—N alloy film is covered on the nitriding layer. According to the present invention, since the hard nitriding layer is formed on the surface of the sliding member, the sliding member becomes to have more excellent properties concerning wear resistance, scuffing resistance and an opponent attacking property, combined with the effect of coated with the Cr—B—N alloy film.
According to the sliding member of the present invention, since the Cr—B—N alloy film is formed on a sliding surface of the sliding member, the sliding member has more excellent effect or function concerning wear resistance, scuffing resistance and an opponent attacking property, than the siding member made practicable partially, which has an Cr—N alloy film.
The sliding member according to the present invention can apply to a high-powered engine, and a high temperature/high intensity engine which is expected to be developed in future.
REFERENCES:
patent: 4412899 (1983-11-01), Beale
patent: 5743536 (1998-04-01), Komuro et al.
patent: 407018414 (1995-01-01), None
patent: 07150337 A (1995-06-01), None
patent: 10068070 A (1998-03-01), None
ASM International Handbook Committee, “ASM Handbook, vol. 18: Friction Lubrication, and Wear Technology”, pp. 553-562, Mar. 1995.*
Kappl et al., “Results on the thermal stability of cathodic arc-deposited (Cr,B)N coatings”, Surface and Coatings Technology, vol.: 73, Issue:1/2, pp. 14-17, Jul. 1995.
Kanemitsu Keiichi
Ogawa Katsuaki
Onoda Motonobu
Nippon Piston Ring Co. Ltd.
Nixon & Vanderhye
Oltmans Andrew L.
Sheehan John
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