Morphology of hydroxyapatite nanoparticles in coatings on nanotube-formed Ti–Nb–Zr alloys for dental implants

•Morphologies of HA coatings on nanotube-formed Ti–29Nb−xZr alloys were investigated.•HA coatings showed mixed morphologies with both particles and plate-like shapes.•High number of deposition cycles yielded thicker and more compact coatings depending on Ca and P concentrations.•HA coating layers contained the anatase phase of TiO2 along with crystalline HA.

The deposition and morphology of hydroxyapatite (HA) nanoparticles on nanotube-formed Ti–Nb–Zr alloys for dental implants has been investigated utilizing electrochemical, field-emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) methods. Ti–29Nb−xZr ternary alloys with 3 and 15 wt.% Zr content were prepared by arc melting. Nanotubular oxide layers were formed on these alloys by an anodic oxidation method in 1 M H3PO4 electrolyte containing 0.8 wt.% NaF at room temperature. Hydroxyapatite coatings were deposited onto the nanotubular surfaces via an electrochemical method (pulsed current). The HA layers were well-deposited and contained features of the underlying nanotube structure; observed morphologies consisted of particles, a mixture of particles and plate-like shapes, and entirely plate-like shapes. This variation in morphology occurred with an increasing number of deposition cycles and increases in Ca and P concentrations in the electrolyte. X-ray diffraction revealed that the nanotubular coating contained the anatase form of TiO2, and FTIR indicated that the electrochemically deposited calcium phosphate layer contained HPO42−, PO43−, H2O, and OH− indicative of the HA composition.