In vitro behavior of silicate glass coatings on Ti6Al4V

The in vitro response in simulated body fluid (SBF) of silicate glass coatings on Ti6Al4V was evaluated. Glasses belonging to the SiO2–CaO–MgO–Na2O–K2O–P2O5 system were used to prepare 50–70 μm thick coatings on Ti6Al4V, employing a simple enameling technique. Glasses with silica content higher than 55 wt% can be used to prepare coatings that do not crack or delaminate and exhibit good adhesion to the alloy. It has been found that coatings with silica content lower than 60 wt% are more susceptible to corrosion and precipitate carbonated hydroxyapatite on their surface during in vitro tests. However, these coatings have a higher thermal expansion than the metal and are under tension. After 2 months in SBF cracks grow in the coating that reach the glass/metal interface and initiate delamination. Glasses with silica content higher than 60 wt% are more resistant to corrosion and have lower thermal expansion. These coatings do not crack but they do not precipitate apatite even after 2 months in SBF.