Mechanical behavior and corrosion resistance of sol-gel derived 45S5 bioactive glass coating on Ti6Al4V synthesized by electrophoretic deposition.

The purpose of this work is the synthesis and the characterization of sol-gel derived 45S5 bioactive glass coatings deposited onto Ti6Al4V alloy substrates. This coating aims the improvement of the biocompatibility of metallic implants for use in dentistry and orthopedy. The 45S5 bioactive glass powder was synthetized by the sol-gel process and the coatings were produced by the electrophoretic deposition technique (EPD). A grinding protocol was developed to reduce the particle size distribution of the sol-gel powder in order to obtain a stable suspension needed for the electrophoretic deposition. The particle size distribution of the sol-gel powder was determined using Dynamic Light Scattering (DLS). Different characterization techniques including X-ray diffraction (XRD), Scanning electron microscopy (SEM) associated to X-ray microanalysis (EDXS), were used to investigate the microstructure and the morphology of the coatings before and after an optimized thermal treatment. Homogeneous 45S5 bioactive glass coatings were obtained with no observable defects. However these coatings are functional if they present good mechanical properties. Thus, a mechanical study using nano-indentation and micro-scratch testing was carried out. The obtained results showed that well adherent and cohesive coatings were obtained. The Young's modulus and the hardness are improved with the thermal treatment. Indeed, they increased from 11 ± 0.54 GPa and 100 ± 4.34 MPa respectively to 28 ± 1.34 GPa and 300 ± 14.21 MPa. The corrosion resistance of the coatings was also studied. The electrochemical were carried using a Potentiostat-Galvanostat PGZ301 in 3.5% NaCl solution at 37 °C. It was observed that the 45S5 sol-gel derived bioactive glass coatings allowed the enhancement of corrosion resistance of the implant.