Lubricant Behavior in High Vacuum

Abstract
Pin on disc friction tests and crossed-cylinder load carrying tests were run in air and in vacuum. Dry friction behavior was found to be very sensitive to pressure level and previous history of the specimens. Lubricated friction behavior for the lubricants tested was essentially independent of pressure unless there was selective evaporation of friction-reducing additives in the lubricant. Most of the fluids tested evaporated very slowly in these room temperature tests. Load carrying ability was reduced in vacuum by more than 50% for several lubricants tested. This reduction was attributed to the absence of oxygen needed to form EP load carrying films.