Healing of Glass in Humid Environments

Chill checks of controlled depth were produced in soda‐lime‐silica glass, and an optimum humidity of 30 kPa (300 mbar) water vapor pressure was found to heal these checks in an annealing cycle. Critical factors were found to be a fluxing effect, having a direct dependence on moisture, followed by a...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 1989-11, Vol.72 (11), p.2189-2193
Main Authors: Holden, Mary Kay Clark, Frechette, Van Derck
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Chemical industry and chemicals
cracks
Exact sciences and technology
Glasses
humidity
silica
sodalime
stress
Structure, analysis, properties
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Summary:Chill checks of controlled depth were produced in soda‐lime‐silica glass, and an optimum humidity of 30 kPa (300 mbar) water vapor pressure was found to heal these checks in an annealing cycle. Critical factors were found to be a fluxing effect, having a direct dependence on moisture, followed by a drying operation at the annealing temperature. A four‐step model is proposed for crack healing: (1) exposure of the crack surface to moisture at temperatures below Tg, (2) formation of a gel layer, (3) closure of the crack resulting from the relief of stress (a minimum of 10 to 20 MPa applied compressive stress was determined to be necessary for complete closure), and (4) drying in the presence of a controlled atmosphere.
ISSN:0002-7820
1551-2916
DOI:10.1111/j.1151-2916.1989.tb06057.x