Tribo-characteristics of Hybrid Ceramic Ball Bearing in Liquid Nitrogen

The tribo characteristics of a high speed, self lubricating hybrid ball bearing, with Si 3N 4 ceramic balls and GCr18 steel rings were tested in liquid nitrogen atmosphere(LN 2). The bearing was tested under axial load of 2.6 kN and radial load of 2 kN at a speed up to 40 000 r/min. The hybrid bearing had a lower bearing friction torque and bearing temperature than those of the steel self mated bearing coated with TiN+Ag film. The crushing load test shows that the crushing load of Si 3N 4 ball is larger than taht of 9Cr18 ball in cryogenic atmosphere. The pitting on the steel races of hybrid bearing was found. On the contrary,no signs of pitting were observed on the race of steel self mated bearing.