Evaluación electroquímica de recubrimientos de biovidrio/Al₂O₃ soportados sobre acero inoxidable AISI 316L y su relación con el carácter bioactivo de las películas

(Graph Presented). Bioglass/ Al₂O₃ powders and coatings at different ratios were synthesized by sol-gel process in order to evaluate the effect of alumina in the bioactive and electrochemical properties of the bioglass coatings. The ceramic powders were structurally characterized using the x-ray diffraction and Infrared spectroscopy techniques, which evidenced that aluminum ions replace calcium ions in the bioglass and that Si-O-Al bond is formed in the composites. From in vitro bioactivity tests in simulated body fluid could be inferred that the new bonds decrease the bioglass bioactivity because aluminum acts as a barrier to the generation of Si-OH bonds, which are necessary for nucleation of apatites from the simulated body fluid. The electrochemical characterization performed through linear polarization resistance, potentiodynamic polarization and electrochemical impedance spectroscopy testing showed that the increasing of the alumina content of the bioglass/Al₂O₃ composite promotes the AISI 316L steel substrate polarization resistance. Although bioglass coating provides a lower protection to the substrate against corrosion, because of its high reactivity in the simulated body fluid, such behavior is reversed once the apatite layer has been formed, since it acts as a diffusional barrier to medium electroactive species.