Chapter 20. A Study of the Driving Force Behind AZS Glass Phase Exudation

  1. John B. Wachtman Jr
  1. Dennis Walrod

Published Online: 26 MAR 2008

DOI: 10.1002/9780470310533.ch20

Proceedings of the 49th Conference on Glass Problems: Ceramic Engineering and Science Proceedings, Volume 10, Issue 3/4

Proceedings of the 49th Conference on Glass Problems: Ceramic Engineering and Science Proceedings, Volume 10, Issue 3/4

How to Cite

Walrod, D. (1989) A Study of the Driving Force Behind AZS Glass Phase Exudation, in Proceedings of the 49th Conference on Glass Problems: Ceramic Engineering and Science Proceedings, Volume 10, Issue 3/4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470310533.ch20

Author Information

  1. Carborundum

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1989

ISBN Information

Print ISBN: 9780470374849

Online ISBN: 9780470310533

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Keywords:

  • fusion-cast materials;
  • corrosion;
  • crystals;
  • exudation;
  • oxidation

Summary

Glassmakers are keenly aware that fusion-cast AZS refractories sometimes exude a siliceous glass in service. This exudate can be a source of quality problems in the ware, and is seen also as a potentially weak link in the corrosion resistance of AZS. Recent studies of exudation involving image analyses of tested microstructures indicate that the mechanisms involved are more complex than earlier believed. This paper outlines the influence on exudation of cyclical versus sustained heating as a function of micropore formation. A case is also presented for the dissolution of gases dissolved in AZS as being a major driving force behind exudation.

  • 1
    Cyclical heating (from room temperature) produced approximately three times as much exudation as resulted from heating at a sustained temperature.
  • 2
    The volume of microstructural porosity of the tested samples increased in near-direct proportion to the volume of exudation, indicating a displacement.
  • 3
    Analyses by mass spectroscopy of the gas contained within the internal porosity indicated that air (as N2, O2, Ar) comprised the major species. Some analyses also indicated lesser levels of CO2 and SO2.