Spark plasma sintering, mechanical and in-vitro behavior of a novel Sr- and Mg-containing bioactive glass for biomedical applications

The so-called BGMS10, a bioactive glass containing 10 mol.% SrO and 10 mol.% MgO, displays a low inclination to crystallize, as confirmed by its high activation energy (538.9 kJ/mol). Such peculiar aspect and the beneficial use of SPS allow for the obtainment of 99.7 % dense and fully amorphous products at 750 °C. The incipient crystallization in the glass is observed when temperature is increased to 850 °C, while 95 wt. % crystallized ceramics are produced at 950 °C. Main crystalline phases are α- and β-CaSiO3, with grain size of 89 and 97 nm, respectively. Glass crystallization is accompanied by Young's modulus increase from 90.92 to 98.38 GPa. On the other hand, partially crystallized samples (850 °C) exhibit higher Vickers hardness (718.8) compared to fully crystallized ones (619.8), which show lower density (98.6 %). In-vitro tests in SBF indicate that the silica-gel film preceding apatite nucleation is mostly formed on the amorphous substrate region.