Performance of Solid-Lubricated Ceramic Ball Bearings at High-Temperature in a Vacuum.

Silicon-nitride (Si3N4) ball bearings were tested at 500°C in a vacuum. Excellent tribological performance was obtained for more than 1.5×108 revolutions (about 4200 hours) by lubricating the bearings with both a sputtered molybdenum disulfide film on balls and races and a transfer film formed from a hot-pressed self-lubricating composite retainer. A 650°C test is under way, in which the bearings have been showing low and stable frictional torque up to 500 hours of operation.