Appeal No. 2003-0208 Page 9
Application No. 08/578,996
The obviousness rejections
We will not sustain the rejection of claims 3, 6, 8 and 10 under 35 U.S.C. § 103.
Claim 3, the only independent claim on appeal, reads as follows:
A piston ring for internal combustion engines for use with a piston and a
cylinder, having an external circumferential sliding surface adapted to slide
against the internal wall of said cylinder, said piston ring having an ion-plating
deposition layer formed over said external circumferential sliding surface thereof,
said deposition layer having pores and being made of a mixture of a first
chromium nitride of CrN, a second chromium nitride of Cr2N, and metallic
chromium, the mixing ratios in said mixture being more than 45.0 and less than
98.0 weight percent for said first chromium nitride, more than 0.5 and not more
than 15.0 weight percent for said metallic chromium, and the balance portion for
said second chromium nitride, and wherein the porosity for said pores in said
deposition layer made of said mixture is more than 0.5 and not more than 20.0
percent, and wherein the metallic chromium is caused to be in an intercrystal
grain boundary of the CrN and Cr2N.
Takiguchi discloses a coating that may be used as the sliding surface of a piston
ring of an internal combustion engine. Takiguchi teaches that the coating comprises a
layer adjacent to the base material consisting substantially of chromium, while the layer
adjacent the outer surface may consist substantially of a mixture of Cr2N and CrN
(abstract). Takiguchi does not disclose the mixing ratios for these alloys. Takiguchi
does teach that the Cr, Cr2N and CrN alloys are combined to obtain a high wear
resistant piston ring coating with a high resistance to peeling off (pp. 1 and 3).
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