Mechanical and Tribological Properties of Polytetrafluoroethylene Composites Modified by Glass Fiber and MoS₂ for Seal Lip Application

The effects of glass fiber micro-powder(GF) and its compounds with molybdenum disulfide(MoS₂) on mechanical, friction & wear properties under dry sliding condition and wear mechanisms of polytetrafluoroethylene(PTFE) composites for seal lip application were investigated. The results show that the stretch resilience ratio reaches the maximum value of 92.5% and the friction coefficient increases to 0.29 compared with pure PTFE, while the wear rate decreases greatly, which was only 1.8×10⁻⁶mm³/ (N·m) for PTFE/GF specimens with 15% GF by weight. Based on this, the stretch resilience ratio of PTFE/GF/MoS₂ specimen with 5% MoS₂ decreases slightly, but still remains above 90%, its friction coefficient is 0.31 and volumetric wear rate further is reduced to 1.25×10⁻⁶mm³/(N·m). SEM analysis for worn surfaces indicated that pure PTFE presented severe plastic deformation and adhesive wear characteristics, while PTFE/GF mainly presented abrasive wear behavior. The PTFE/GF/MoS₂ specimen with appropriate MoS₂ content had only a very slight adhesive wear behavior during the friction process, its abrasive wear characteristic disappeared.