Rolling Contact Evaluation of Self-Lubricating Ball Bearing Retainer Materials at 482°C and 650°C

High temperature lubrication of ceramic and metal surfaces is critical technology for many developing commercial, military, space and aerospace applications. Conventional lubricants will not be effective for many of these applications and hostile bearing environments. An alternative approach to conventional lubrication systems is the use of a self-lubricating retainer. This paper describes rolling contact evaluation of three high temperature self-lubricating bearing retainers fabricated by a hot isostatic pressing (HIP) technique. Rolling contact tests were conducted using a micromelt T-15 tool steel rod-silicon nitride (Si₃N₄) balls at 482°C and Si₃N₄ rod-Si₃N₄ balls at 650°C using a ball-on-rod type rolling fatigue tester. Transfer of lubricating material from retainer to the rod via the balls was observed. The transfer films were analyzed using surface profile traces, Auger Electron Spectroscopy (AES) and Energy Dispersive X-ray (EDAX) analysis. EDAX showed the presence of retainer material on the rods and balls. Two retainers disintegrated completely during the 650°C test. The feasibility of a self-lubricating composite retainer to meet the demanding thermal, oxidative and tribological requirements up to 650°C was shown.