Tribological Behavior of Self‐Lubricating <scp>PEEK</scp>/Graphite/<scp>Ti₃SiC₂</scp> Composites Under Dry Sliding Friction

ABSTRACT Most polymers and composites suffer from high friction and wear due to their inherent lack of self‐lubrication under dry sliding friction. Herein, the lamellar Ti 3 SiC 2 MAX material is prepared via vacuum sintering of a powder mixture containing Ti, Si, and TiC in the molar ratio of 1:1.1:1.8 at 1500°C under a pressure of 30 MPa for 2 h. Combined with a soft graphite phase (5 wt%), self‐lubricating PEEK/Graphite/Ti 3 SiC 2 (PG‐T) composites are successfully prepared, dependent on Ti 3 SiC 2 (5 and 15 wt%) as a hard reinforced phase and lubrication additive. PG‐T composites are fabricated via a multistep compounding approach using a twin‐screw extruder. The incorporation of Ti 3 SiC 2 and graphite within the PEEK matrix manifests a highly pronounced synergistic effect, which not only facilitates effective lubrication but also significantly enhances the load‐bearing capability, thereby effectively circumventing direct contact between the counterface and the polymeric matrix. The sliding tests are conducted on the pins (diameter: 6.0 mm, height: 17.0 mm) and friction pair (45#steel, roughness Ra: 148 nm) under dry friction. In terms of PV‐condition (up to 6 MPa and 3 m/s) (PV is a parameter that reflects the load‐bearing capacity of polymer materials, which is defined by multi‐plying the pressure P by the sliding speed V), PG5‐T15 exhibits self‐lubricating properties, featured by an average coefficient of friction (ACOF) as low as 0.119 for the pin‐plate test and a specific wear rate (SWR) of only 0.58 × 10 −6 mm 3 /Nm. Meanwhile, PG‐T composites present excellent thermal properties based on the thermal expansion coefficients (CTEs) and storage moduli (G′) during friction and wear. Considering the practical applications of tribo‐composites, these findings highlight the potential of PG‐T composite as a candidate for demanding tribological applications.