Sol–gel derived hydroxyapatite coating on TiB 2 /TiB/Ti substrate

The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB₂ was formed at 1000°C on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol–gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by scanning electron microscopy, whereas X-ray diffraction patterns clearly revealed the growth of a calcium phosphate phase on top of the surface. Results showed that both wear resistance and biocompatibility of the hydroxyapatite coated samples on boronised films were improved.