Foam glass obtained through high-pressure sintering

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Abstract

Foam glasses are usually prepared through a chemical approach, that is, by mixing glass powder with foaming agents, and heating the mixture to a temperature above the softening point (106.6 Pa s) of the glass. The foaming agents release gas, enabling expansion of the sintered glass. Here, we use a physical foaming approach to prepare foam glass. First, closed pores filled with inert gases (He, Ar, or N2) are physically introduced into a glass body by sintering cathode ray tube (CRT) panel glass powder at high gas pressure (5‐25 MPa) at 640°C and, then cooled to room temperature. The sintered bodies are subjected to a second heat treatment above the glass transition temperature at atmospheric pressure. This heat treatment causes expansion of the pores due to high internal gas pressure. We found that the foaming ability strongly depends on the gas pressure applied during sintering, and on the kinetic diameters of the gases. The pressure for attaining maximum expansion, that is, lowest density and highest porosity, is found to be around 20 MPa.
Original languageEnglish
JournalJournal of the American Ceramic Society
Volume101
Issue number9
Pages (from-to)3917-3923
Number of pages7
ISSN0002-7820
DOIs
Publication statusPublished - 2018

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Keywords

  • cathode ray tube panel glass
  • closed porosity
  • foam glass
  • inert gases
  • sintering

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