Nanomechanical properties evaluation of bioactive glass coatings on titanium alloy substrate

Abstract

Bioinert metallic implants such as titanium and titanium alloys could be coated with bioactive materials with good adhesion to metal and which could be also bonded to the bone. In order to predict the mechanical behavior of coatings during the implant insertion, mechanical properties of the surface and through the thickness of deposited bioglass coatings are necessary to be studied. We report an investigation of the mechanical characteristics of bioglass coatings using the nanoindentation and nanoscratch techniques. The coating topography with residual imprints was analyzed by in situ imaging method. The dependence of the friction coefficient on load in constant and ramped load tests as well as on the scratch speed is compared. Elastic modulus and hardness results after indentation on the coating surface with higher loads showed more consistent results with less pile up around imprints. The nanohardness and reduced elastic modulus of the coating is in the expected boundaries of theoretical values for glass and alloy with a moderate distribution through the coating thickness. Nanoscratch testing showed that the surface deform plastically with no visible debris or cracks.