[Sol-gel preparation of ultrathin nano-hydroxyapatite coating and its characterization]

Present study used dip-coating techniques to fabricate ultrathin nano-HA coating on titanium in organic sol-gel of Ca (NO3)2. 4H2O and PO(CH3)3 and inorganic sol-gel of Ca (NO3)2. 4H2O and (NH4)2HPO4. Scanning electron microscope (SEM) and grazing-incidence X-ray diffraction (XRD) were used to observe the morphology and distribution of crystallite size (D) and lattice strain (epsilon) of ultrathin nano-HA coating. After heated at 400 degrees C, the apatite structure of coatings on titanium began to appear. At heating temperature of 400 degrees C-600 degrees C, the effect of heating temperature on D and epsilon of both coatings was obvious. Precursor types significantly affected the particle diameters of nano-HA coatings, which were 25-40 nm for organic sol-gel and about 100 nm for inorganic sol. The thickness of ultrathin nano-HA coatings was 2.5 microm for organic sol-gel and 5 microm for inorganic sol and morphology of interfaces between coating and titanium was intact and homogenous.