GB993474A - Bearings - Google Patents

Abstract

A bearing surface contains nickel oxide and/ or cobalt oxide in sintered form and in an amount of between 10% and 50% by weight. Nickel and cobalt may be incorporated in the form of particles of the metals themselves, provided that the bearing is run in an oxidizing environment which will maintain the corresponding oxides in the surface film, at least to a sufficient extent to replace parts of the oxide patina which may be worn away in use. Prior to running the bearing, enough oxide particles must be present, standing proud of the rest of the surface, so that this patina is formed immediately on starting. In an embodiment, 30 parts by weight of nickel oxide of mesh sieve 300 British Standard Size were mixed with 70 parts of carbonyl nickel powder having an average size of 5 microns. The mixture is wetted with water and ball-milled for 24 hours, dried and mixed with 4% of a water wax emulsion. A bearing was then pressed to shape at 8 tons per square inch and then heated at 400 DEG C. to remove the wax. The bearing was finally fired in an argon atmosphere over a period of 8 hours up to a temperature of 1380-1400 DEG C.