Dynamic Fatigue of Na2O-CaO-SiO2-P2O5 and Li2O-2SiO2 Glasses

Reference	Presenter	Authors (Institution)	Abstract
09-066	Iolanda Justus Dechandt	Dechandt, I.J.(State University of de Ponta Grossa); Zanotto, E.D.(Federal University of Sao Carlos); Serbena, F.C.(State University of Ponta Grossa);	The purpose of this study is to characterize and understand the fatigue properties of the Biosilicate® precursor and lithium disilicate glasses under dynamic conditions. Biosilicate® is a highly bioactive glass-ceramic based on the Na2O-CaO-SiO2-P2O5 system, and lithium disilicate is the basis of several glass-ceramics for dental applications. Both glasses present volume crystallization when properly heated and their dynamic fatigue properties are unknown. As a first step, the fatigue of the Biosilicate® and lithium disilicate (LS2) glass were investigated under dynamic conditions. LS2 glass samples were submitted to biaxial flexure tests at different displacement rates - from 5 to 5000 $\mu$m/min - at 10% air humidity and under water immersion at room temperature. The Biosilicate® precursor glass was tested immersed in a SBF solution at room temperature. The fatigue exponents (${\mathrm{log\sigma }}_0=\frac{1}{\mathrm{n}+1}\log \frac{d\mathrm{\sigma }}{d\mathrm{t}}+\mathrm{logD}$) for the LS2 glass were 15$\pm$3 in water and n=16$\pm$6 under 10% air humidity. For the Biosilicate precursor glass, n=11$\pm$2. Experiments are under way to investigate the effect of crystallization on the fatigue properties of the glasses.
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