Influence of TiO2 on the Microstructure, Mechanical Properties and Corrosion Resistance of Hydroxyapatite HaP + TiO2 Nanocomposites Deposited Using Spray Pyrolysis

Abstract

Titanium oxides and their alloys are widely used in medical applications because of their biocompatibility. However, they are characterized by their low resistance to corrosion. The HaP + TiO2 nanocomposites’ coating was applied in different experiments, especially on a Ti-6Al-4V substrate with the spray pyrolysis process to deal with such weakness. The TiO2 content effects on the surface morphology and the phase composition were investigated using a scanning electron microscopy, X-ray microanalysis (SEM-EDXS) and X-ray diffraction (XRD). The mechanical properties were determined with nanoindentation. The potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and simulated body fluid (SBF) solution environment tests were carried out to investigate the corrosion resistance of HaP + TiO2/Ti6Al4V systems. The experimental findings revealed that sprayed thin films possessed uniform morphology. The coatings’ nanoindentations proved that the HaP + 20% TiO2 coating hardness (252.77 MPa) and the elastic modulus (52.48 GPa) overtopped those of the pure hydroxyapatite coatings. The corrosion test demonstrated that the corrosion current density of about 36.1 µA cm−2 and the corrosion potential of the order of −392.7 mV of HaP + 20% TiO2 was lower compared to the pure HaP coating.