Sliding member

Details Sliding member Sliding member

1999-08-24

2001-05-15

Jones, Deborah (Department: 1775)

Stock material or miscellaneous articles

Composite

Of inorganic material

C428S469000, C428S702000

Reexamination Certificate

active

06232003

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a sliding member, such as a piston ring for use in internal combustion engines, having an ion-plating deposition layer, or film, of chrome nitride formed on the sliding surface thereof.
BACKGROUND OF THE INVENTION
For a sliding member, such as a piston ring for use in internal combustion engines, a technique of enhancing the abrasion resistance thereof has been made public in Japanese Patent Laid-Open Publication (JP-A) 8-296030 (1996), where the enhancement is enabled by forming an ion-plating deposition layer of CrN, also including Cr
2
N, on the external circumferential sliding surface thereof, by means of a physical vapor deposition (PVD) method.
There are two types in the publicly known ion-plating deposition layers composed mainly of chrome nitride including Cr
2
N and CrN, i.e., one type of deposition layer having the CrN of the chrome nitride which has a preferred orientation of the plane {111}, and the other type having the CrN of the chrome nitride which has a preferred orientation of the plane {100}. A deposition layer of the CrN having the preferred orientation of the plane {111}, is superior in abrasion resistance and scuffing resistance, but, due to having high internal stress, is inferior in peeling resistance, to a deposition layer of CrN having the preferred orientation of the plane {100}. On the contrary, or inversely, a deposition layer of the CrN having the preferred orientation of the plane {100}, is inferior in abrasion resistance and scuffing resistance, but, because of the porosity thereof being easily controllable, is superior in peeling resistance, to a deposition layer of the CrN having the preferred orientation of the plane {111}.
An object of the present invention therefore is to provide a sliding member having an ion-plating deposition layer, composed mainly of chrome nitride including Cr
2
N and CrN, that has abrasion resistance and scuffing resistance enhanced, or improved, while maintaining the excellent peeling resistance level of a deposition layer of the CrN having the preferred orientation of the plane {100}.
SUMMARY OF THE INVENTION
According to an embodiment of the present invention, an improved sliding member is provided that has a sliding surface and a deposition layer formed on the sliding surface by means of an ion-plating method, where the deposition layer is composed mainly of chrome nitride, including CrN. The improvement comprises the CrN of the chrome nitride which has a preferred orientation of the plane {100}, where the deposition layer contains boron at a containing ratio not less than 0.05 and not more than 20 weight percent.
According to another embodiment of the present invention, an improved sliding member is provided that has a sliding surface and a deposition layer formed on the sliding surface by means of an ion-plating method, where the deposition layer is composed mainly of chrome nitride, including CrN. The improvement comprises the CrN of the chrome nitride which has a preferred orientation of the plane {100}, where the deposition layer contains boron, at a containing ratio not less than 0.05 and not more than 20 weight percent, and either one or both of oxygen and carbon, at a containing ratio of the either one of oxygen and carbon, or a total containing ratio of the both oxygen and carbon, not more than 15 weight percent, respectively.
With an improved sliding member obtained by the arrangement as described above, according to the present invention, enhanced abrasion resistance and scuffing resistance are obtained that are better than those of the conventional sliding members having an ion-plating deposition layer not containing boron, with the CrN having the preferred orientation of the plane {100}, while maintaining the peeling resistance as excellent as that of the conventional sliding members having an ion-plating deposition layer not containing boron, with the CrN having the preferred orientation of the plane {100}.
The reason that abrasion resistance and scuffing resistance of the deposition layer are enhanced by adding boron, may be described in that, boron is considered to have a higher free composing energy in chrome than other elements, such as carbon, oxygen and nitrogen, have in chrome, and boron therefore is hard to form boride, and tends to form solid solution either in chrome or chrome nitride of CrxN, thereby producing a greater effect on strengthening the base of the deposition layer, resulting in enhanced abrasion resistance and scuffing resistance.


REFERENCES:
patent: 4702769 (1987-10-01), Fukuhara et al.
patent: 5370364 (1994-12-01), Kenmoku et al.
patent: 5503912 (1996-04-01), Setoyama et al.
patent: 5993978 (1999-11-01), Kim et al.
patent: 8296030 (1996-11-01), None
Rother et al. Effects of low boron concentration on the thermal stability of hard coatings. Surface and Coatings Technology, pp. 163-168, Feb. 1997.*
Meunier et al. X-Ray diffractometry analysis of r.f. magnetron-sputtered chromium/chromium nitride coatings. Surface and Coatings Technology, pp. 149-158, Jun. 1998.*
Collard et al. The reactive magnetron deposition of CrNxOy films: first results of property investigations. Surface and Coatings Technology, pp. 181-184, Feb. 1997.

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