Lubricant Life Tests on Ball Bearings for Space Applications

Abstract

An ex perime ntal program has been conducte d to compare th e cffective lives of ball bearings operat ing in vacuum with various types of MaS, solid film s, an d with a special high vacuum oil, as lubrican ts. The test bearings u'ere size 205 bearings runn ing at 30 rpm under a ten-pound radial load . T wo parti cular com binati ons were also ev aluated in oscillating motion tests. Torque was used as th e criterion fo r failure. Prior to test th e bearings Il' ere subjec ted to a f2 100-pound static load to simulate laun ch loading . Th e results of th ese t ests showed that mo st of th e solid film -lubri cat ed bearings were effecti ve fur th e first sev eral hun d red hours, th en gave high and erratic torq ue values as th e result of deb ris being formed by wear of th e lubl'ican t film. A sodiu m -silicate bonded solid lubricant film, which con tained MaS, and graphite, was fo und to be partic ularly promising in both rot ation and oscillation. One partic ularly significan t result of this u -ork was th e finding that th e oil-lub ricat ed bearings showed a sudden , large increase in to rque aft er running effective ly fo r about 1400 hours in vacuum. This behavior has oft en been predicte d but has appar ently n ever bccn observed cxperim entallu, at least fo r rollinq-con tart hearings.

Layered 2D Nanomaterials to Tailor Friction and Wear in Machine Elements—A Review

“…[138] Initial studies on using TMDs, primarily MoS 2 , for the solid lubrication of rolling bearings were mainly driven by the need for tribologically efficient coatings for space exploration and aeronautics applications. [149,150] Christy [138] utilized thrust washer sliding wear tests under air-and nitrogen-atmosphere to study the influence of the PVD conditions, such as bias voltage (DC or RF), the relative orientation of the specimens to the target, as well as floating or grounding specimens, on the tribological performance of 200 nm thick MoS 2 -coatings. [122] Coatings' lifetime assessment indicated that the DC bias voltage had little influence on the coating properties, whereas grounding the specimens prior to the MoS 2 deposition resulted in an enhanced tribological behavior.…”