Magnesium alloys implants coated with 58S sol gel bioactive glass to retard first stage corrosion

Abstract

Two composition of 58S (60 mol% SiO2, 36 mol% CaO, 4 mol% P2O5) glass coatings were made by sol gel and applied by dip coating onto two commercial magnesium alloys (AZ31 and AZ91) as a strategy to retard the hydrogen evolution and accelerate the deposition of a hydroxyapatite layer to enhance bioactivity. Surface studies with XPS, Raman spectroscopy and SEM techniques are presented after coating deposition and after immersion in Hanks´ Balance Salt Solution (HBSS) at 37 C. Electrochemical tests were also conducted to evaluate the evolution of the coating with immersion. It is observed that even the coating present defects, it is able to retard substrate degradation and this effect is more pronounced for AZ91 as substrate. Coating performance is mainly governed by the substrate due the defective nature of the film.