Abstract: Triobological experiments are performed in a reciprocating oil-free compressor arrangement to investigate the friction force, power consumption and friction temperature of three materials of pressure packing seals. These rings are respectively made in common filled polytetrafluroethylene (Filled PTFE), PTFE filled with 30% carbon fiber (30% CF + PTFE), and carbon-carbon composites with PTFE infiltrated (C/C+PTFE). Tests are performed at mean piston speed of 0.4, 0.8, 1.2, 1.6, 2.0 m/s and under a sealing pressure of 0.5, 1.0, 1.5, 2.0 MPa. The influence of mean sliding velocity on friction force of filled PTFE rings is greater than on that of the two other rings. And the power consumption and friction temperature of filled PTFE rings is the highest among the three materials. C/C+PTFE presents the lowest friction temperature, although its power consumption is slightly greater than 30% CF + PTFE. Owing to its good mechanical performances and tribological behaviors, C/C+PTFE is an optimum and promising material under conditions with sealing pressure up to 10 MPa and sliding velocity of more than 4.0 m/s.

Key words: Oil-free lubrication, Packing rings, PTFE composites, Tribological characteristic