Sol-gel derived calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂; CHA) thin films were deposited on stainless steel substrates with transverse and longitudinal patterned roughness employing a spin-coating technique. Each layer in the preparation of CHA multilayers was separately annealed at 850 °C in air. Fabricated CHA coatings were placed in simulated body fluid (SBF) for 2, 3, and 4 weeks and investigated after withdrawal. For the evaluation of obtained and treated with SBF coatings, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), X-ray diffraction (XRD) analysis, Raman spectroscopy, XPS spectroscopy, scanning electron microscopy (SEM) analysis, and contact angle measurements were used. The tribological properties of the CHA coatings were also investigated in this study.

Aqueous sol-gel chemistry route has been developed to prepare nanostructured calcium hydroxyapatite (Ca10(PO4)6(OH)2; CHA) thin films on a 316L stainless steel substrate. In the sol-gel processing, calcium acetate monohydrate and phosphoric acid were used as Ca and P precursors, respectively. For the deposition of thin films spin-coating and dip-coating methods were used by coating the stainless steel substrate 5, 15 and 30 times in both cases. Each layer was consistently annealed at 850 °C in air. The obtained CHA coatings were examined using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle measurements (CAM). The quality and specific features of CHA thin films obtained by spin- and dip-coating methods were compared in this study. It was demonstrated that both methods are suitable for the fabrication of CHA films on the 316L stainless steel substrate, however, the preference to the spin-coating technique could be given.