Conditions Extrêmes et Matériaux : Haute Température et Irradiation

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J.Baborák, M.Yembele, P.Vařák, S.Ory, E.Véron, M.J.Pitcher, M.Allix, P.Nekvindová, A.Zandonà, 'Key melt properties for controlled synthesis of glass beads by aerodynamic levitation coupled to laser heating', Int J Appl Glass Sci. 14 455 (2023) doi:10.1111/ijag.16627

Binary alkali silicate glasseswere synthesized as beads by aerodynamic levitation coupled to laser heating to test the applicability of the method to this compositional range. While bubble-free lithium disilicate beads could be easily obtained, sodium and potassium silicates proved more challenging to melt without significant alkali evaporation: the final samples contained bubbles and exhibited compositional drifts compared to the starting stoichiometry, especially at high SiO2 content. The risk of volatilization fromthe melts was evaluated empirically: the volatility of each oxide component scaled to the ratio between itsmelting temperature Tm and the Tm of the target composition (revap), while the difference between such ratios (Δevap) provided a qualitative estimation of the risk of differential evaporation. The formulated approach enables to evaluate the suitability of aerodynamic levitation synthesis for a given target glass composition: while low melting temperature and low liquidus viscosity (η < 100 Pa s) represent the primary optimal conditions,more viscous materials can still be preparedwithout major compositional drifts using a more careful melting procedure, especially if revap and Δevap are minimized.