Electrochemical study of hydroxyapatite coatings on stainless steel substrates

Hydroxyapatite coatings were synthesized electrochemically onto stainless steel. In this study, the composition and morphology of the coatings changed with the deposition and sintering conditions. The electrolyte was kept close to the composition of simulated body fluid with an adjusted pH of 8.0. Deposition temperature affected the purity of the deposits with higher temperatures (65 °C) giving better coatings. The sintering techniques were also shown to affect the deposits, with x-ray diffraction patterns showing well-defined peaks for hydroxyapatite when sintering under vacuum conditions. Coating density and corrosion resistance was improved when applying a double-layer coating technique versus a single-layer. Grain sizes were 30 to 40 nm even after sintering of these coatings in air. The formed coatings were characterized by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and x-ray photoelectron spectroscopy.