Nanocrystal Formation in Hydroxyapatite Films Electrochemically Coated on Ti-6Al-4V Alloys

Abstract

Hydroxyapatite (HAp) and HAp/yttria-stabilized zirconia (YSZ) nanopowders were coated on Ti-6Al-4V alloys using an electrochemical method, microarc process (MAP). Both the HAp and HAp/YSZ films were uniformly coated with ∼8−20 μm thickness on the alloys. X-ray diffraction (XRD) analysis results show that HAp film is XRD amorphous and HAp/YSZ is nanocrystalline with a rutile phase. Scanning electron microscopy (SEM) analyses on the films show uniform microporous structures, and these pores are observed as closed ones. Transmission electron microscopy (TEM) analyses reveal that HAp films are almost amorphous, containing anatase nanocrystals with ∼30−40 nm size. TEM analyses on the HAp/YSZ films show formation of rutile nanocrystals with ∼200−300 nm size as well as antase nanocrystals of ∼20−30 nm size.