Smooth semicompact multilayer coating of TiO2 obtained by combining anodic oxidation and sol-gel techniques

Abstract

Titanium oxide provides biological and hemocompatible properties to different biomedical devices made of titanium or its alloys. However, since this oxide naturally has a very low thickness and low tribological performance, it would be interesting to obtain thicker and more resistant oxides. In this work, a nanoporous/compact titanium oxide coating was synthesized on the Ti-6Al-4V alloy by combining the anodic oxidation and sol-gel dip-coating techniques. This coating was characterized by optical microscopy, scanning electron microscopy, atomic force microscopy, profilometry and X-ray diffraction. A ~600 nm-thick coating with low roughness (Ra ≅ 50 nm and Sa ≅ 57 nm) and free of cracks was obtained. The coating does not hide the nano- and micro-roughness of the substrate on which it was synthesized. The crystalline structure of the coating is anatase and rutile, but, superficially (~100 nm), it is only anatase.