Wear Testing of Nonmetallic Materials for Bearing Applications

In recent years, the nonmetallic content of military and commercial aircraft has been steadily increasing; this trend is expected to continue for the next decade. In this study, nonmetallic materials have been evaluated for journal bearing and rolling bearing applications. Specifically, advanced polymer composites with different fillers are considered as self-lubricating journal-bearing materials. Both polymer composites and metal matrix composites have been evaluated as fretting-resistant bearing liner materials. Finally, the rolling contact fatigue resistance of ceramic hybrid bearings has been determined. Wear test methods for journal bearings under high-speed sliding, for bearing liners under reciprocating contact, and for ball bearings under rolling contact are described. Friction and wear data are presented. Two polymer composites, a filled polyetheretherketone (PEEK) and a filled polyphenolenesulfide (PPS) were found to be suitable for high pressure velocity (PV) journal bearings operating under intermittent lubrication starvation. An aluminum matrix composite (6061-T6 with 20 vol% SiC) and three polymer composites have been found to wear as well as, or better than, hardened steel as a bearing liner material. Ceramic hybrid bearings are shown to have a higher rolling contact fatigue resistance than all-metallic bearings.