Granted Patent
Utility
US 4,608,243 · App. 06/788,313
High hardness hafnium nitride
Inventor:
William D. Sproul
Patented Case
View Patent ↗
Granted: Aug 26, 1986
Filed: Oct 17, 1985
Inventor
William D. Sproul
Assignee (at issue)
BorgWarner Inc.
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.