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Abstract Residual stress profiles in silica glass were measured after water diffusion treatment under 47.33 kPa (355 Torr) water vapor at 350°C and 650°C. Earlier, it was found that water solubility in silica glass exhibited peculiar time dependence: Solubility increased with time exceeding the normal water solubility expected from higher temperatures. Then, the water solubility decreased with time. It was hypothesized that the stress induced by water diffusion and its subsequent relaxation is responsible for the phenomenon. Residual surface stress generation in silica glass was found to correlate closely with surface hydroxyl concentration, systematically increasing until eventual surface stress relaxation results in stress decrease for treatments beyond 265 hours at 650°C. This observation validates previous theories of time dependent diffusivity in silica glass.
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Photoelastic confirmation of surface stress relaxation in silica glasses: Fiber bending and rod torsion
Abstract Silica glass samples were given various heat treatments under stress at low temperatures and subsequently their residual stress distributions in terms of retardance were observed using a polarized light microscope, confirming previously reported fast surface stress relaxation while providing more detailed characterization. Retardance profiles of silica glass fibers heat‐treated under a constant bending strain in the presence of atmospheric water vapor were measured and fit to a previously developed diffusion‐based relaxation model. The retardance of a cross‐section of a silica glass rod heat‐treated at 650°C in lab air under applied torsional shear strain was also measured to confirm the presence of residual surface shear stress which was predicted by the decrease of torque with time for the rod. Together, these results confirm the low‐temperature fast surface stress relaxation which occurs when water vapor is present for both bending and shear stresses.
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- Award ID(s):
- 1713670
- PAR ID:
- 10472991
- Publisher / Repository:
- American Ceramic Society
- Date Published:
- Journal Name:
- Journal of the American Ceramic Society
- Volume:
- 104
- Issue:
- 7
- ISSN:
- 0002-7820
- Page Range / eLocation ID:
- 3087 to 3096
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/jace.17690
