Synthesis and characterization of corrosion-resistant and biocompatible Al2O3-TiB2 nanocomposite films on pure titanium

Alumina is widely used as a coating on a metal implant due to its favorable mechanical and biological properties. In this research, in order to improve mechanical and biological properties of alumina, a composition of nano-particles of alumina (instead of microparticles) and titanium diboride micro powder is introduced. The atmospheric plasma spray (APS) technique was applied to deposit Al2O3-TiB2 on the pure titanium substrate. The properties of Al2O3-TiB2 nanocomposite coatings with various weight percent of TiB 2 (20, 30 and 40 wt%) were experimentally studied. The characteristics of nanocomposite films of TiB2 (20, 30 and 40 wt%) were analyzed using Field Emission Scanning Electron Microscopy (FE-SEM), energy dispersive electron spectroscopy (EDX) and X-Ray Diffraction (XRD) tests. The XRD spectra exhibited that in addition to alumina and titanium diboride, the films contained titania. Thickness and morphology of the films were calculated from FE-SEM images and the thickness of the optimized coating (Al2O3-30 wt% TiB2) was about 30-45 mu m. Also, the roughness, corrosion resistance, hardness and cytotoxicity (MTT) tests were studied. The highest of hardness and roughness of the samples were obtained from Al2O3-30 wt% TiB2. According to the obtained results from the polarization test, Al2O3-30 wt% TiB2 coating had the highest corrosion resistance (222558.9962 Omega cm(2)). Therefore, the toxicity of Al2O3-30 wt% TiB2 was investigated as the optimized coating and the results confirmed its non-toxicity and biocompatibility.