Mechanical and bioactive properties of PVD TiO2 coating modified PEEK for biomedical applications

Abstract

Polyetheretherketone (PEEK) is gaining popularity in the biomedical field due to its excellent mechanical properties, chemical resistance and biocompatibility. Although PEEK is an excellent biomaterial, it may require bulk surface modification to tailor its properties for specific biomedical applications. In this study, the surface modification of PEEK was achieved by depositing titanium dioxide (TiO₂) by PVD method. The microstructure and mechanical properties of TiO₂ coatings were studied by SEM/EDS and nanoindentation tests. Conventional scratch tests were performed to determine the adhesion and tribological properties of the TiO₂ films. An in vitro study was performed in simulated body fluids to evaluate the osteocompatibility of TiO₂ coated PEEK. According to the results The TiO₂ coating has a dense microstructure and good adhesion, the critical cohesive load Lc₁ is greater than 1N. The TiO₂ film improved the mechanical properties of the PEEK substrate: hardness and elastic modulus increased from ∼0.33 to ∼4.03 GPa to ∼3.6 and ∼21.85 GPa, respectively. In addition, compared with the PEEK substrate, the coating showed a 61% improvement in wear resistance and a reduction in the coefficient of friction from 0.38 to 0.09. The results also showed that the TiO₂ coating induces the formation of hydroxyapatite on the surface, which promotes the osteocompatibility of PEEK.

Keywords: Adhesion; Bioactivity; Friction and wear; Mechanical properties; PEEK; TiO(2) coatings.