Microstructures, mechanical properties and electrochemical behaviors of nano-structured HA/Ti composite coatings deposited by high-velocity suspension flame spray (HVSFS).

In order to improve the mechanical and electrochemical properties of hydroxyapatite (HA) coating, nanostructured HA/Ti (nHA/Ti) composite coatings with different Ti contents of 30, 50 and 70 wt% were deposited on 316L stainless steel (SS) substrates by high-velocity suspension flame spray (HVSFS) and compared to HVSFS-deposited nanostructured HA (nHA) coatings. Microstructures and phase compositions of as-sprayed coatings were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The deposition mechanism of nanostructured HA/Ti composite coatings was also examined. Microhardness and Young's modulus were measured. Electrochemical corrosion behaviors of all coatings were tested in Hanks’ simulated body fluid using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that the nHA/Ti composite coatings contained HA and Ti in addition to some Ti-O compounds. Compared to nHA coatings, nHA/Ti composite coatings presented dense and typical lamella structures formed mostly by flattened splats. Microhardness and Young's modulus of nHA/Ti composite coatings increased with increasing Ti content. Potentiodynamic polarization and EIS measurements illustrated that nHA/Ti composite coatings had excellent corrosion resistance compared to nHA coatings and bare SS substrate. [ABSTRACT FROM AUTHOR]