Nanostructured hydroxyapatite coating obtained from scholzite with improved corrosion resistance

Abstract A novel coating method of transforming scholzite (SZ, CaZn2(PO4)2·2H2O) into hydroxyapatite (HA, Ca10(PO4)6(OH)2) coating on the surface of titanium (Ti) has been presented. It deposited a primary SZ coating through a phosphate chemical conversion (PCC) technology, and then transformed it to the HA coating via calcium (Ca) chelating. FE-SEM and XRD results proved that a nanostructured HA coating with a cauliflower-like shape and without zinc (Zn) element doping could be obtained from the primary petal-like SZ coating. It suggests that SZ may act as a simple and effective intermediate for HA precipitation. The electrochemical impedance spectroscopy (EIS) test was employed to evaluate the corrosion behavior of the coated samples in simulated body fluid (SBF). The results showed that the HA-coated sample obtained by Ca chelating post-treatment exhibited improved barrier performance compared with the primary SZ-coated one.