Electrocodeposition of hydroxyapatite nanoparticles with zinc–iron alloys

We report on the preparation of composite films consisting of ultrafine hydroxyapatite (HAp) nanoparticles in a zinc–iron (ZnFe) matrix. The films have been prepared by electrocodeposition from an alkaline electrolyte containing pyrophosphate as complexing agent. The HAp nanoparticles, synthesized by chemical precipitation, feature a needle-like shape with a diameter of ~ 10 nm and a length ~ 100 nm. The effects of a variety of deposition conditions, viz. current density, pH, temperature and composition of the plating bath on the codeposition of HAp nanoparticles with ZnFe-alloys were investigated by evaluating the alloy composition, nanoparticle content, structure and microhardness of the composite coatings. The presence of HAp nanoparticles in the bath was found to increase the iron content in the alloy and decrease the current efficiency of the cathodic deposition. Furthermore, a distinct increase in the Vickers microhardness appeared as a result of the nanoparticle incorporation.