Granted Patent
Utility
US 4,640,693 · App. 06/723,222
Coated silicon nitride cutting tool and process for making
Inventors:
Deepak G. Bhat, Dhirajlal Shah, John R. Kyle, Paul F. Woerner
Patented Case
View Patent ↗
Granted: Feb 3, 1987
Filed: Apr 15, 1985
Inventors
Deepak G. Bhat
Dhirajlal Shah
John R. Kyle
Paul F. Woerner
Assignee (at issue)
GTE Valeron Corporation
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.