ROLLING AND SLIDING CHARACTERISTICS OF POWDER-LUBRICATED CERAMICS AT HIGH-TEMPERATURE AND SPEED

As part of a high-temperature, dry-lubricated bearing technology and lubricant system development program, a high-speed, high-temperature disk-on-disk tribometer was utilized and a matrix of traction data covering a range of load, speed and temperature were obtained. The influence of dry powder lubricants (TiO2 powders with different particulate sizes, ZnMoO2S2 and NiO) on the traction coefficients between two tribo-ceramic materials (Si3N4 vs. Si3N4) was investigated. The most important results of this investigation were characteristic curves for the traction coefficient vs. the slide/roll ratio with dry powders which are reminiscent of fluids, and the observation that dry powder lubricants lowered traction coefficients and wear. Measured tractions were found to be a strong function of powder lubricant type, and values decreased moderately with slide-to-roll ratio and load. The powder data, unlike the unlubricated condition (dry), showed a slight sensitivity to temperature.