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 degrees C. The incipient crystallization in the glass is observed when temperature is increased to 850 degrees C, while 95 wt. % crystallized ceramics are produced at 950 degrees C. Main crystalline phases are alpha- and beta-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 degrees 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.