Characterization and formation of bioactive hydroxyapatite coating on commercially pure zirconium by micro arc oxidation

摘要

Hydroxyapatite (HA, Ca_(10)(PO_4)_6(OH)_2) based coatings are used in biomaterial applications and biomedical industrial applications due to its bioactive and biocompatible properties. In this study, commercially pure zirconium was coated in the solution consisting of calcium acetate (CA, (CH_3COO)_2Ca)) and β-calcium glycerophosphate (β-Ca-GP, (β-C_3H_5(0H_2)PO_4Ca)) by micro arc oxidation (MAO) in a single-step process for 1,10 and 30 min duration times to produce HA-based coatings.The phase structures, surface morphologies, functional groups of molecules, chemical composition of surface and the binding energies of atoms on the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Zirconium (Zr), monociinic and cubic zirconium oxide (ZrO_2), cubic calcium zirconium oxide (Ca_(0.15)Zr_(0.85)O_(1.85)), orthorhombic calcium zirconium oxide (CaZrO_3) and HA phases on the coatings were detected by XRD analysis. The strongest intensity of crystal HA was also observed in XRD for the coating produced at 30 min. The surface morphologies of coatings produced by MAO method at 1 min have very porous structures because of the existence of micro discharge channels during the process. The surface coatings morphologically have HA microstructure owing to the crystallization of HA particles at 10 min and the existence of growing HA particles in MAO process at 30 min. The HA phase is confirmed by V_3 (PO~(-3)_443) and v_s (OH~-) FTIR band assignments in ATR-FTIR and by the binding energies of Ca2p, P2p and O1s in XPS for coating produced at 30 min.