Duxin Li

Improvement in the tribological properties of polyamide 6: Talc, glass fiber, graphite, and ultrahigh-molecular-weight polyethylene

Improvement in the tribological properties of the polyamide 6 (PA6) with various fillers, for example, talc, glass fiber (GF), combined solid lubricants such as graphite, and ultrahigh-molecular-weight polyethylene was systematically studied. The results revealed that GF could reduce the coefficient of friction (COF) and wear rate of pure PA6 more efficiently than talc, and the optimum content was 15 wt%. The COF and wear rate increased with the increase of load, except the wear rate of the composite with 20 and 25 wt% GF, which decreased with the increase of load. The incorporation of combined solid lubricants to PA6 contributed to increases in COF and wear rate. Further addition of 15 wt% GF enhanced the tribological properties remarkably. To further understand the wear mechanism, the worn surfaces were examined using scanning electron microscopy.

Tribological and Mechanical Behaviors of Polyamide 6/Glass Fiber Composite Filled with Various Solid Lubricants

The effects of polytetrafluoroethylene (PTFE), graphite, ultrahigh molecular weight polyethylene (UHMWPE), and their compounds on mechanical and tribological properties of glass-fiber-reinforced polyamide 6 (PA6/GF) were studied. The polymeric materials were blended using twin-screw extruder and subsequently injection molded for test samples. Mechanical properties were investigated in terms of hardness, tensile strength, and impact strength. Friction and wear experiments were run under ambient conditions at a rotating speed of 200 rpm and load of 100 N. The morphologies of the worn surfaces were also observed with scanning electron microscope. The results showed that graphite could increase the tensile strength of PA6/GF-15 composite, but the material became soft. Graphite/UHMWPE complex solid lubricants were effective in increasing the already high impact strength of PA6/GF-15 composite. 5% PTFE gave the maximum reduction in the coefficient of friction. However, PTFE/UHMWPE complex solid lubricants were the best choice for improving both friction and wear behaviors due to the lower friction coefficient and mass wear rate. Moreover, the worn surface of PA6 composites revealed that adhesive wear, abrasive wear, and fatigue wear occurred in this study.