Study of the mechanical behavior and corrosion resistance of hydroxyapatite sol–gel thin coatings on 316 L stainless steel pre-coated with titania film

Abstract

International audienceIn order to reinforce the clinical applications of hydroxyapatite (HAP) sol–gel coatings deposited onto 316 L stainless steel, we suggest the introduction of an intermediate thin layer of titania (TiO2) on the substrate. The titania sub-layer is introduced in order to improve both the corrosion resistance and the mechanical properties of the HAP/316 L stainless steel coated system. The two coatings, HAP and TiO2, were studied separately and afterwards, compared with the bi-layered coating. A film without any cracks is obtained under the optimum conditions in terms of annealing temperature, dipping rate and aging effect. Microstructural, morphological and profilometry analysis revealed the non-stoichiometric carbonated porous nature of the hydroxyapatite coatings, which were obtained after annealing at 500 °C during 60 min in the atmosphere. The obtained TiO2 coatings exhibit a dense and uniform surface. Addition of TiO2 as sub-layer of the HAP coating tends to increase the homogeneity and the crystallinity rate as compared to the HAP one.The mechanical properties, i.e. hardness and elastic modulus, are determined by means of nanoindentation experiments and the adhesion between the coating and substrate is estimated by scratch tests. The corrosion behavior is evaluated by potentiodynamic cyclic voltammetry tests. As a main result, the values of the elastic modulus and hardness, respectively of 30 GPa and 2.5 GPa, are relatively high for the HAP–TiO2 bilayer coating. This result allows the use of such coated material as a replacement material for hard tissues. The adhesion strength increased from 2925 mN up to 6430 mN after the addition of the TiO2 intermediate film. According to the Tafel's analysis, the 316 L stainless steel specimens coated with both HAP and titania layers (ECorr = − 234 mV, lCorr = 0.089 μA cm− 2) present a better resistance than the HAP-coated specimens (ECorr = − 460 mV, lCorr = 0.860 μA cm− 2)

Effect of Centrifugal Speed on the Anticorrosive Properties of Bismuth-Silicon Coatings by Sol-Gel on 316l Substrates

“…Table-4. 396.8x10 -3 To complement this study, the porosity percentage of the coatings of the BixSiyOz system is estimated by equation-1, 21,22.…”

“…The difference between the corrosion rate values between the values found in the films and the substrate are two orders of magnitude with respect to the target. It is also possible to determine the percentage of protective effect of the coatings of the BixSiyOz system as a function of spin velocities, as indicated in Equation 2 21,22 :…”

“…The results of the investigation established that the TiO2 films increase the degree of homogeneity, the crystallinity rate of the system and was determined their mechanical properties. The results showed the possibility of using such a coated material as a replacement material for hard tissues 12 . Salahinejad et al report the use of both inorganic and organic-inorganic coatings on stainless steel substrates.…”

Caracterización Anticorrosiva y de Biocompatibilidad en Recubrimientos Silicio-Titanio-Zirconio Sintetizados Vía Sol-gel y Depositados sobre Sustratos 316L

“…Es de resaltar que los aceros inoxidables tienen un amplio campo de aplicación en la industria y el campo de la salud en las cuales la efectividad anticorrosiva es de vital importancia (Cheraghia et al, 2012), (Sidanea et al, 2015), (Salahinejad et al, 2013), (Olivares, 2011), (De Mello y Balsamo, 2006) pero sufren procesos de corrosión por picadura al encontrarse en contacto son soluciones compuestas por iones Cl -. La protección superficial de materiales mediante recubrimientos cerámicos puede ser la solución de muchos problemas prácticos, especialmente cuando las condiciones de trabajo son adversas (temperaturas elevadas, ambientes químicamente agresivos, etc.)…”

Mechanical behaviour of brushite and hydroxyapatite coatings electrodeposited on newly developed FeMnSiPd alloys

“…Nanoindentation is the most suitable technique to assess the mechanical properties and the adhesion of thin films. This technique has been recently applied to study the mechanical properties of CaP on stainless steel [28,29], magnesium alloys [30] and titanium [31][32][33]. However, to the best of our knowledge, there is no data available in the literature on the mechanical properties of CaP coatings grown by electrodeposition onto Fe-based alloys.…”