THEORY AND PRACTICE OF SELF-LUBRICATED, OSCILLATORY BEARINGS FOR HIGH-VACUUM APPLICATIONS .2. ACCELERATED LIFE TESTS AND ANALYSIS OF BEARINGS

This paper describes a series of accelerated vacuum life tests, designed to monitor and map the performance characteristics of the dry-lubricated bearings throughout their lifetime of service by continuous monitoring of friction torque and periodic evaluation of the effects of temperature cycling and radial temperature gradients. Twenty-two bearing specimens were tested for periods up to 15,000 hours in high vacuum and operated successfully for up to 31 multiplied by 10**9 degrees of oscillatory travel. Friction, wear and bearing torque test data, combined with optical-scanning electron microscopic and X-ray energy dispersive spectroscopic examination of the test bearing components, were used to develop a theoretical model of wear behavior. The ultimate life capability of this system was estimated using the theoretical model and extrapolation of empirically determined wear rates.