The mechanism of glass foaming with water glass

Uroš Hribar*, Martin Bonderup Østergaard, Niels Iversen, Matjaž Spreitzer, Jakob König


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Water glass is a common additive in the process of direct foaming of glass, however, the currently accepted foaming mechanism lacks experimental validation. A foaming mixture of waste cathode ray tube panel glass and water glass was investigated for its expansion and gas evolution behavior via hot stage microscopy and thermogravimetry coupled with mass spectroscopy, respectively. The evolution of a significant amount of CO2 during the heating of the foaming mixture was detected and an overwhelming presence of CO2 within the pores of the foamed glass was confirmed with gas chromatography. With this investigation, we reveal an underlying foaming mechanism, where a carbonate phase forms after mixing water glass with the glass powder and later acts as the foaming agent. The unveiled mechanism could help further research in the field of foamed glass, with the potential to produce more sustainable materials with better performance via less energy-demanding processes.

TidsskriftJournal of Non-Crystalline Solids
StatusUdgivet - 15 jan. 2023

Bibliografisk note

Funding Information:
Authors would like to thank S. Smiljanić for fruitful discussions and S. Zupančič, M. Kurtjak and U. Trstenjak for performing HSM-, FTIR- and XRD measurements, respectively. This work was financially supported by the Slovenian Research Agency (Grant number PR-08980 ).

Publisher Copyright:
© 2022 The Authors


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