Tribology of unfilled and filled polymeric surfaces in refrigerant environment for compressor applications

The current study examines the tribological performance of polymer/metal contacts in the presence of refrigerant versus ambient air under conditions simulating refrigeration compressors. Ten different polymers were employed as potential compressor bearing materials; four unfilled polymers and six blended polymers. All polymers were tested against cast iron samples of RMS roughness 0.3-0.5 mu m and representative testing was performed against aluminum alloy disks. Experiments conducted in R-134A refrigerant exhibited slightly favorable friction and wear characteristics compared to experiments conducted in ambient air. Moreover, all blended polymers have superior tribological characteristics to unfilled polymers and metals. PEEK and polyimide in both unfilled and blended forms exhibit minimal wear and do not adversely affect the metal disks. This study also shows that although coherent, uniform films were not produced under compressor-like conditions, as evidenced by scanning electron microscopy and energy dispersive X-ray spectroscopy, the tested polymers still have favorable tribological properties and are good candidates for tribological contacts in refrigeration compressors.