Nanometre CaP/Al2O3–Ti
biocomposites for implant applications were successfully fabricated using
a hybrid technique of anodization and hydrothermal treatment, in which
CaP/Al2O3
formed a double-layer coating on titanium with porous CaP as the top layer and anodic
Al2O3
film as the intermediate layer. Techniques, such as x-ray diffraction (XRD),
electron scanning microscopy and energy disperse x-ray analysis (SEM
+
EDX), transmission electron microscopy (TEM) and atomic force microscopy (AFM), were
used to investigate the composition, microstructure and morphology of the fabricated
CaP/Al2O3 composite
coating and the CaP/Al2O3–Ti
biocomposites. XRD results showed that the fabricated composite coating contained
Al2O3
and various calcium phosphate phases. SEM and TEM micrographs confirmed
that CaP crystals were in nanometres, embedded in situ in the walls of the
cylindrical structure of anodic alumina, and finally formed a thin and porous top
layer on the anodic alumina intermediate layer. The nanometre and T-shape
effects of the CaP top layer, and the porous and cylindrical microstructure of
CaP/Al2O3
composite coating could produce an excellent combination of bioactivity and mechanical integrity of
the CaP/Al2O3–Ti
biocomposites.
It was also found that the anodization voltage of the anodization process played
an important role on the composition and microstructure of the fabricated
CaP/Al2O3–Ti
biocomposites. The contents of Ca and P incorporated in anodic alumina
depended strongly on the anodization voltage. Their variations could result in
different CaP phases, CaP crystal shapes and sizes, and topography of the
CaP/Al2O3–Ti
biocomposites. The optimal anodization voltage in this study was found to be in the range
40–60 V.