Glass - Back to the Future!

Presenting Author:
Carsten Blaeß

article posted 21 March 2016

Carsten Blaeß is at the German Standards Bureau...

New bioactive glasses with improved sintering behavior

Carsten Blaeß*2, Stefan Reinsch2, Ralf Müller2, Delia S. Brauer1
1 Otto-Schott-Institut für Materialforschung (OSIM), Friedrich-Schiller-Universität Jena, Fraunhoferstr. 6, 07743 Jena, Germany 2 Bundesanstalt für Materialforschung und –prüfung (BAM), Richard-Willstätter-Str. 11, 12489 Berlin, Germany;

Nowadays, the use of bioactive glasses is established for bone regeneration; however glasses are used mostly as powders, granules or in a paste. Sintered scaffolds are not used clinically, because of the inherent problem of crystallization during the sintering process, resulting in poor mechanical properties and reduced bioactivity. Therefore it was the aim to design new bioactive glasses, which combine improved processing and sintering with bioactivity.
Compared with the well-known Bioglass® 45S5 (SiO2–P2O5–CaO–Na2O) the calcium/alkali oxide ratio was increased, sodium oxide was partially replaced by potassium oxide and up to 8 mol% calcium fluoride were added, in order to stabilize the glass against crystallization. The sintering behavior of the new glasses was characterized by heating microscopy and compared to that of Bioglass® 45S5. Results show that the new glasses achieve a sintered density of 88–99% in contrast to only 57–67% for Bioglass® 45S5. In addition, FTIR and XRD analyses show that Bioglass® 45S5 crystallizes during sintering while for the new glasses no crystalline phases were detected. The thermal properties of all glasses were studied by DTA and DSC measurements, and the influence of grain size was characterized. These studies showed an increase of sintering temperature and final porosity with increasing particle size. The structure of sintered compacts during and after sintering was examined using light and electron microscopy (SEM).