The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 13, 1992
Filed:
Jun. 14, 1991
Yoshio Naruse, Tokyo, JP;
Teikoku Piston Ring Co., Ltd., Tokyo, JP;
Abstract
A piston ring comprises a martensitic stainless steel ring having a nitrided layer formed in the surface portion thereof, and a titanium nitride film coated on the outer sliding surface of the ring by an ion-plating process. According to a first embodiment of the present invention, the titanium nitride film has a nitrogen concentration which is gradually increased toward the top surface thereof to gradually lower a toughness of the film toward the top surface and to make a surface portion of the film more brittle than the other portion of the film. On the other hand, according to a second embodiment of the present invention, the titanium nitride film has a nitrogen concentration which is gradually decreased toward the top surface and to make a surface hardness of the film HV 1800 or less.