Tribological and mechanical performance of nano-SiO2 reinforced 3D printed multiscale PEEK composites

This study investigates the mechanical and tribological performance of 3D printed polyether-ether-ketone (PEEK) based composites. The starting filaments were produced in-house using melt-extrusion, and the testing specimens were obtained via fused filament fabrication (FFF) method. The incorporation of short carbon fibers (SCF) and silicon dioxide (SiO 2 ) in the PEEK matrix significantly improved the mechanical properties of 3D printed composites. The multiscale PEEK composites greatly enhanced the tribological performance compared to neat PEEK and SCF-PEEK at all testing conditions. Dry sliding friction and corresponding specific wear rates of SiO 2 -SCF-PEEK at 10 MPa pin-on-plate testing significantly reduced up to 50% and 60% compared to neat PEEK, respectively. The post-sliding surface analysis revealed that the combined incorporation of SCF and nano-SiO 2 greatly minimized abrasive wear and prevented the filler-matrix interfacial debonding. SiO 2 -SCF-PEEK showed similar wear mechanisms at two different tribo-testing configurations, exhibiting a remarkable load-carrying ability and self-lubricity even at elevated contact loads. Water lubrication effectively prevented the sliding instabilities and reduced friction for both PEEK composites. Additionally, 3D printed composites exhibited friction coefficients and wear mechanisms comparable to those of their corresponding compression-molded composites.