Obtaining and characterization of bioglass coatings on the AZ31 Mg alloy

The ideal material for a metal bone prosthesis must undergo a gradual corrosion in vivo, without releasing toxic components, while acting as a support and facilitating the growth of bone tissue, until a replacement is completed by the regenerated bone.. Biodegradable magnesium alloys have been studied because of their excellent mechanical properties and biocompatibility. The obstacle that these materials have is its high corrosion rate. Once initiated the process, the pH around tissues rises, interfering with cell growth on the surface of the magnesium alloy. In order to improve the corrosion resistance, the application of protective coatings as an effective solution to this problem is used. A protective film designed for this purpose must have the following characteristics: (i) provide bioactivity required to facilitate bonding between the bone and the material (ii) be compact enough to retard penetration of physiological medium to the alloy facilitating regeneration bone (iii) to have sufficient cohesive strength and adhesion between the coating and the substrate to avoid the film cracking during implantation. This study was prepared by sol-gel material called 45S5 Bioglass (R) (46.14% SiO2, 26.91% CaO, 24.35% Na2O, 2.60% P2O5,% m) and was deposited on samples of AZ31 magnesium alloy (3% Al, 1% Zn, 0.2% Mn, Fe <0.005%,% m / m), previously polished and washed in ultrasound. The coatings were obtained by the technique of immersion-emersion (dip-coating). Some of the samples were in a pretreatment with aqueous solutions of hot NaOH, in order to provide greater adherence of the vitreous coating. Then a thermal treatment was conducted in air at different temperatures, 400 degrees C and 430 degrees C. To determine the coatings' corrosion resistance, the polarization curves in simulated physiological medium (SBF) were determined.