Improving the tribological performance of CFRPTFE at elevated temperature by sliding against Ti-TiC x /DLC film

Abstract

Polytetrafluoroethylene (PTFE) has been widely used in industrial field for sealing parts. However, it is well known that PTFE is always subject to serious wear at high temperature (over 150 °C), which has become the main drawback limiting serve life of important equipment such as compressors. In this paper, a new solution is proposed for improving the wear resistance of carbon fibers-reinforced PTFE (CFRPTFE). Multilayer Ti-TiC_x/DLC film is prepared and used as the counterface of CFRPTFE. Friction and wear tests at high temperature (200 °C and 250 °C) are carried out. The uncoated 17-4PH steel disks precisely polished by abrasive papers with different grain sizes are used as the reference counterface (SS80 and SS7000). It is found that by sliding against Ti-TiC_x/DLC film, the tribological behaviors of CFRPTFE at high temperature can be improved. The friction coefficient between CFRPTFE and DLC under different test conditions can be kept in stable state. The wear rates of CFRPTFE reduce by 50%–70% compared to SS80, and reduction of 20%–40% can be observed when compared to SS7000. It can be found that graphitization transition at high temperature promotes the transfer layer formation and contributes to lower friction and lower wear compared to traditional processed counterface at high temperature. These significant improvements can prolong the lifetime of CFRPTFE moving parts used in high-temperature and heavy-load applications. Finally, engineering verification of the proposed friction pair is carried out in miniature oil-free high-pressure compressor.