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Extension of the ‘Inorganic Gel Casting’ Process to the Manufacturing of Boro-Alumino-Silicate Glass Foams

Department of Industrial Engineering, University of Padova, Via Marzolo 9, 35131 Padova, Italy
National Research Council of Italy (CNR), Institute of Condensed Matter Chemistry and Technologies for Energy (ICMATE), Corso Stati Uniti 4, 35127 Padova, Italy
Institute of Physics of Materials (IPM), Žižkova 22, 61662 Brno, Czech Republic
CEITEC—Central European Institute of Technology, Masaryk University, Kamenice 5, 62500 Brno, Czech Republic
Author to whom correspondence should be addressed.
Materials 2018, 11(12), 2545;
Received: 26 November 2018 / Revised: 10 December 2018 / Accepted: 11 December 2018 / Published: 14 December 2018
(This article belongs to the Special Issue Advanced Glasses, Composites and Ceramics for High Growth Industries)
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A new technique for the production of glass foams, based on alkali activation and gel casting, previously applied to soda-lime glass, was successfully extended to boro-alumino-silicate glass, recovered from the recycling of pharmaceutical vials. A weak alkali activation (2.5 M NaOH or NaOH/KOH aqueous solutions) of fine glass powders (below 70 µm) allowed for the obtainment of well-dispersed concentrated aqueous suspensions, undergoing gelation by treatment at low temperature (75 °C). Unlike soda-lime glass, the progressive hardening could not be attributed to the formation of calcium-rich silicate hydrates. The gelation was provided considering the chemical formulation of pharmaceutical glass (CaO-free) to the formation of hydrated sodium alumino-silicate (N-A-S-H) gel. An extensive direct foaming was achieved by vigorous mechanical stirring of partially gelified suspensions, comprising also a surfactant. A sintering treatment at 700 °C, was finally applied to stabilize the cellular structures. View Full-Text
Keywords: glass recycling; alkali activation; gel casting; glass foams glass recycling; alkali activation; gel casting; glass foams

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Rincon Romero, A.; Tamburini, S.; Taveri, G.; Toušek, J.; Dlouhy, I.; Bernardo, E. Extension of the ‘Inorganic Gel Casting’ Process to the Manufacturing of Boro-Alumino-Silicate Glass Foams. Materials 2018, 11, 2545.

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