Granted Patent
Utility
US 4,884,820 · App. 07/051,931
Wear resistant, abrasive laser-engraved ceramic or metallic carbide surfaces for rotary labyrinth seal members
Inventors:
John E. Jackson, Norman Louis Balmer
Patented Case
View Patent ↗
Granted: Dec 5, 1989
Filed: May 19, 1987
Inventors
John E. Jackson
Norman Louis Balmer
Assignee (at issue)
Union Carbide 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.