Sintering and foaming of bioactive glasses
Carsten Blaeß, Ralf Müller
Abstract
Abstract Sintering, crystallization, and foaming of 44.8SiO 2 –2.5P 2 O 3 –36.5CaO–6.6Na 2 O–6.6K 2 O–3.0CaF 2 (F3) and 54.6SiO 2 –1.7P 2 O 3 –22.1CaO–6.0Na 2 O–7.9K 2 O–7.7MgO (13–93) bioactive glass powders milled in isopropanol and CO 2 were studied via heating microscopy, differential thermal analysis, vacuum hot extraction (VHE), Infrared spectroscopy, and time‐of‐flight secondary ion mass spectrometry. Full densification was reached in any case and followed by significant foaming. VHE studies show that foaming is driven by carbon gases and carbonates were detected by Infrared spectroscopy to provide the major foaming source. Carbonates could be detected even after heating to 750°C, which hints on a thermally very stable species or mechanical trapping. Otherwise, dark gray compact colors for milling in isopropanol indicate the presence of residual carbon as well. Its significant contribution to foaming, however, could not be proved and might be limited by the diffusivity of oxygen needed for carbon oxidation to carbon gas.