Fabrication and characterization of electrophoretically deposited functionally graded HA/TiO۲ nanostructured coatings

چکیده مقاله

The Ti-6Al-4V alloy with favorable mechanical properties has been widely used in fabrication of bioceramic coatings on metallic substrate. Hydroxyapatite, the main constituent of the bone and teeth, is known as a biocompatible ceramic material with high osseoconductivity. In this work, functionally graded coatings of HA/TiO2 nanoparticles were fabricated by electrophoretic deposition on Ti-6Al-4V substrate. The sharp variation in thermal stresses at coating-substrate interface was reduced by using graded structure of coating. The functionally graded structure of HA/TiO2 coatings was formed by gradual addition of HA suspension into the deposition cell containing TiO2 nanoparticles. The results of micro-scratch tests and potentiodynamic polarization measurements showed that the graded structure of the coating could efficiently increase the bonding strength between coating and substrate as well as corrosion resistance. The microstructure and chemical composition of coatings before and after sintering were characterized by scanning electron microscope equipped with energy dispersive spectrometry. The X-ray diffraction was used for phase analyses of coatings before and after sintering.