Development of graphene oxide and hydroxyapatite reinforced PEEK composites: a bio-tribological study with different stroke length and loading conditions

Designing the hybrid composite is an efficacious way to address the various biomedical complications, such as mechanical failures, high wear rate, inflammation, insufficient osteogenic capability and higher cytotoxicity. The present study explores the synergetic effects of graphene oxide (GO) and hydroxyapatite (HA) on the polyether ether ketone (PEEK) matrix in terms of tribological behavior under artificial body fluid lubrication (Bovine serum albumin (BSA) and Ethylenediaminetetraacetic acid (EDTA). The coefficient of friction and wear rate were quantified through a linear reciprocating tribometer with diverse stroke lengths and loading conditions. The Response Surface Methodology (RSM) was used to discover the optimum reinforcement levels and testing parameters. Remarkably, the employed wear mechanisms were observed from field emission scanning electron microscopy, whereas the executed chemical bonds and crystallographic nature were assessed through Fourier transform infrared spectroscopy and X-ray diffraction. The outcome underscores that the minimal concentration of GO (0.5 wt%) and HA (10 wt%) reinforced PEEK composites (HC1) show outstanding tribological properties due to their sound interfacial interaction and strong carbon-carbon bond between GO and PEEK matrix. RSM also highlighted that reinforcement 1 (HC1), load: 50n and stroke length: 20 mm, achieves a reduced coefficient of friction and higher wear resistance. The reinforcement and stroke length play a significant role in tribological behaviors. Interestingly, the wear mechanisms, including ploughing, cutting, adhesive wear and fatigue wear, were noticed from the microstructural analysis. The study corroborated that the GO and HA infusion notably enhances the tribological properties of the PEEK matrix due to their strong electrostatic and Π-Π stacking interaction and is a proficient candidate for various bioimplant applications.