Granted Patent
Utility
US 4,812,425 · App. 07/148,462
Purifying refractory metal borides
Inventor:
Joseph K. Walker
Patented Case
View Patent ↗
Granted: Mar 14, 1989
Filed: Jan 26, 1988
Inventor
Joseph K. Walker
Assignee (at issue)
Eltech Systems 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.