Fabrication and characterization of nanometer CaP(aggregate)/Al₂O₃ composite coating on titanium

Nanometer CaP(aggregate)/Al₂O₃ composite coating on titanium for implant application has been successfully fabricated using a hybrid technique of anodization and hydrothermal treatment. Techniques, such as X-ray diffraction (XRD), scanning electron microscopy and energy disperse X-ray analysis (SEM+EDX), and transmission electron microscopy (TEM), have been used to investigate the composition, microstructure and morphology of the fabricated CaP(aggregate)/Al₂O₃ composite coating. SEM and EDX studies show that pure Al thin film is uniformly deposited on titanium substrate using magnetron sputtering physical vapor deposition (PVD) technique, and porous anodic aluminium oxide (AAO) film containing Ca and P are formed after anodization. XRD result indicates that the fabricated composite coating contains Al₂O₃ and various calcium phosphate phases. SEM and TEM results show that the crystals of CaP aggregates are in nanometers. It is also found that the fabricated nanometer CaP(aggregate)/Al₂O₃ composite coating is characterized by a porous cylindrical microstructure after hydrothermal treatment, which could lead to better biological and mechanical properties. In addition, anodization voltage is shown to have significant effects on the extent of anodization of the AAO film, and the optimal voltage is in the range 40-50 V.