Untersuchungen zur Natur der primären Oberflächenkristallisation in bioaktiven Gläsern der Zusammensetzung SiO2-P2O5-CaO-Na2O-K2O-CaF2.
Zusammenfassung der Projektergebnisse
This research project investigated the influence of Na content and powder processing on crystallization behavior in the bioactive glass with the composition 44.8 mol% SiO2 - 2.5 P2O3 - 36.5 CaO - 6.6 Na2O - 6.6 K2O - 3.0 CaF2 (F3). NaCaPO4 (rhenanite) was identified as the primary and Na2Ca2Si3O9 (Combeit) as the secondary crystal phase. The occurrence of these phases causes a blockage of viscous sintering for particle sizes > 125 µm. A reduction of the Na content leads to the preference of wollastonite (CaSiO 3) and Ca2Na2F2P2O7 (cuspidine) in the higher polymerized glass network, while an increase in the lower polymerized glass promotes the crystallization of combeit and rhenanite. Fire-polished surfaces and fracture surfaces showed a lower sodium concentration before and an increased sodium concentration after heat treatment compared to the glass volume. The opposite was true for calcium. This and the tendency to crystallize were more pronounced on fracture surfaces. A 1.5-fold sodium content already led to an increased sodium concentration on the fracture surface and to an intensification of the observations. The findings thus support the initial hypothesis that it is possible to influence the tendency to crystallize and the resulting crystal phases through powder production by crushing. This finding is of particular interest for glasses with a high tendency to crystallize. This also applies in particular to bioactive glasses, where solubility and cell proliferation are strongly dependent on crystallinity.
Projektbezogene Publikationen (Auswahl)
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Sintering and Crystallization of Fluoride-Containing Bioactive Glass F3. Glass Europe, 3, 105-124.
Blaeß, Carsten; Boccaccini, Aldo Roberto & Müller, Ralf
