Granted Patent
Utility
US 4,248,440 · App. 06/074,735
Titania-alumina-yttria piston ring facing
Inventor:
Harold E. McCormick
Patented Case
View Patent ↗
Granted: Feb 3, 1981
Filed: Sep 12, 1979
Inventor
Harold E. McCormick
Assignee (at issue)
Ramsey Foundation
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.