Granted Patent
Utility
US 4,879,260 · App. 07/204,597
Alumina-zirconia ceramic
Inventor:
William R. Manning
Patented Case
View Patent ↗
Granted: Nov 7, 1989
Filed: Jun 8, 1988
Inventor
William R. Manning
Assignee (at issue)
Champion Spark Plug Company
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.