Influence of Ti, Zr or Nb carbide adhesion layers on the adhesion, corrosion resistance and cell proliferation of titania doped hydroxyapatite to the Ti6Al4V alloy substrate, utilizable for orthopaedic implants

Abstract

In the present paper, we study the enhancement of the adhesion between the titania doped hydroxyapatite coating and the Ti6Al4V alloy substrate by the addition of three different biocompatible carbides. The coatings were prepared by the magnetron sputtering technique. The addition of interlayer preserved the crystalline structure of hydroxyapatite. The morphology of the coating is influenced by the interlayer composition. The adhesion of the coatings was significantly improved by the interlayer, independent of it's composition. The best adhesion was found for the coatings with NbC interlayer, which also showed the best corrosion resistance in simulated body fluid at 37 °C, due to its flat surface grown without any distinct features. As expected, the results of the in vitro biological tests were almost similar for all coatings comprising an adhesion layer, as the same titania doped hydroxyapatite layer was on top. The experimental results revealed that the adhesion between Ti6Al4V and titania doped hydroxyapatite was improved by a hard metal carbide interlayer, without affecting the required biomedical properties such as good corrosion resistance, high proliferation level of osteoblast cells, and good gene expression levels.