Investigation of Dry Sliding Friction Wear Behavior of CuSn11 Bronze Plain Bearing Applying Impregnated Graphite-Filled PTFE

Abstract

Self-lubricating bearings are produced by using copper-based materials and solid lubricating polymer materials, which are widely used in industrial applications. Self-lubricating bearings have been developed to improve systems that do not have the possibility of continuous lubrication. This study describes the experimental investigation of tribological properties of graphite-filled polytetrafluoroethylene (PTFE) composites. First, the CuSn11 porous specimens were produced by powder metallurgy. The superior properties of bronze and PTFE were used to create the composite specimens. Solid lubricants, namely, pure PTFE and two different graphite-filled PTFE (PTFE + 10 wt% graphite and PTFE + 20 wt% graphite) mixtures were impregnated into pores of the bronze specimens using a spray coating method. Thus, bronze composite specimens with graphite-filled PTFE were obtained. Then changes in the friction coefficient and wear loss were achieved differently under three loads and sliding speeds with wear tests performed under dry test conditions. The results showed that the graphite additive reduced the friction coefficient and the wear loss. The lowest friction coefficient was obtained from the 20 wt% graphite-filled specimen under the lowest sliding distance (4500 m) and the highest load (70 N) test conditions. However, a 2.95% reduction in the friction coefficient and 16.28% reduction in the wear loss of PTFE + 10 wt% graphite specimen were detected compared to the 20 wt% graphite specimen, depending on the increase in sliding distance under the highest sliding distance (13,500 m) and the highest applied load (70 N) test conditions.

Keywords:

• Graphite impregnate
• friction coefficient
• powder technology
• self-lubricated bearing
• PTFE

Acknowledgements

The authors express their gratitude to Eskişehir Technical University and Sakarya University of Applied Sciences for their support and opportunity in the preparation of the specimens with the implementation of SEM and EDS analyses.