Experimental Analysis of Friction and Wear of Self-Lubricating Composites Used for Dry Lubrication of Ball Bearing for Space Applications

Abstract

Lubricating space mechanisms are a challenge. Lubrication must be sustained in different environments, for a very long period of time, and without any maintenance possible. This study focuses on the self-lubricating composite used in the double transfer lubrication of ball bearing. Ball/races contacts are lubricated via the transfer of materials from the cage that is made of the composite. A dedicated tribometer has been designed for the study. A specificity of the tribometer is to not fully constrain the composite sample but to let it move, as the cage would do in the bearing. Four composites (PTFE, MoS2, glass or mineral fibers) where tested in ultrahigh vacuum and humid air environments. Transfer was achieved with morphologies and composition similar to what is observed on real bearings. Adhesion measurements performed on composite materials before and after friction allowed one to explain the differences in tribological behaviors observed (transfer quality and contact instabilities). Beyond strengthening the composites, fibers are shown to be critical in trapping mechanically and chemically the transferred material to lubricate and prevent instabilities. Equilibrium between internal cohesion of transferred material, and adhesion to counterparts must be satisfied. Mass spectrometry showed that water appears also critical in the establishment of stable transfer film, even in vacuum.

Multi-scale wear mechanism of material surface and hinge interface based on TC4 alloy in space environment

“…TC4 alloy, utilized as the executive component in spacecraft, has seen increasing applications in space missions (Liu et al , 2014; Bantounas et al , 2007). The successful execution of space missions critically hinges on the normal operation and life expectancy of space activity components within the spacecraft (Series et al , 2022; Colas et al , 2021; Lince, 2020). Among these components, the friction and wear performance of TC4 alloy, particularly in space-moving components, assume a pivotal role.…”

Evaluation for Crack Defects of Self-Lubricating Sliding Bearings Coating Based on Terahertz Non-Destructive Testing

“…The analysis and optimization of microstructure for self-lubricating coating can only be achieved empirically through trial and error [16], which is due to the lack of detection methods for defects beneath the coating. At present, using scanning electron microscopy (SEM) to observe the morphology of the coating structure is the main detection method for self-lubricating coating [17][18][19]. However, it can only observe in a local range, and it is thus difficult to analyze the coating comprehensively.…”

A new coated self-lubricating spherical plain bearing with high performance and excellent security

“…[24][25][26][27][28][29][30][31][32][33] MoS 2 coatings can quickly form a lubricating transfer film due to its twodimensional layered structure. [34][35][36] However, the coating will fail rapidly under high loads caused by its low loadbearing capacity. [37][38][39] In Qiu et al, 40 a composite coating consisting of MoS 2 and graphite doped was applied to the surfaces of the SPBs.…”