TORQUE AND WEAR OF LEAD-FILMED BALL BEARINGS IN AIR

摘要

As part of an experimental programme to investigate the behaviour of lead films as a lubricant technique for satellite mechanisms, angular contact bearings, coated by vacuum evaporation of lead, have been examined in air, at a number of rotational speeds, for their wear and torque characteristics. The recorded torque level fluctuation (noise) at 20 revolutions per minute (rpm) and above shows either progressive or sudden deterioration. This deterioration to an arbitrary failure point (corresponding to an effective friction coefficient of about 0.1) is dispropor¬tionately more rapid, the higher the speed, ie, the time to failure is not inversely proportional to speed. Electron probe micro-analysis of ball and track surfaces has allowed identification of the transferred material as well as measure¬ment of its thickness to a high resolution.nIt is concluded that continuous oxidation allows the build-up of lead deposits on the ball. At a speed of 1 rpm however this build-up is slow and no degradation in torque noise during more than 1000 hrs' run was found.