Nanostructured hydroxyapatite/TiO2 composite coating applied to commercially pure titanium by a co-sputtering technique

We demonstrate an approach for the coating of nanostructured hydroxyapatite(HAP)/TiO2 composite on commercially pure Ti (CP-Ti) by a co-sputtering process. HAP/TiO2 composite film was obtained by controlling the processing pressure. It was observed that decomposition of HAP into CaO was easily induced during sputtering at 0.53 Pa, a typical sputtering condition for film deposition. However, HAP/TiO2 composite film was obtained with the sputtering pressure of 2.67 Pa. The Ca/P ratio was nearly maintained at 1.66 by sputter deposition at 2.67 Pa. We further confirmed by analysis of plasma spectral emission that the variation of the hydroxyl (OH) radical present was due to the Ar pressure during sputtering. It has been shown that HAP coatings are dependent on the processing pressure, which the hydroxyl radical requires in order to create HAP.