FROZEN DEFORMATIONS, FROZEN STRESSES, AND STRUCTURE-INDUCED Na DISTRIBUTIONS IN SODIUM-SILICATE GLASSES
作者:
Thorsten Alts,
Peter Strehlow,
期刊:
Journal of Thermal Stresses
(Taylor Available online 1984)
卷期:
Volume 7,
issue 3-4
页码: 317-359
ISSN:0149-5739
年代: 1984
DOI:10.1080/01495738408942215
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Sodium-silicate glass consists of a SiO2network and Na ions, which can diffuse through the network. The network structure freezes, whenever the local temperature decreases below the glass transition temperature Tg. Depending on the cooling process, different nonuniform network structures can be frozen in, this being the reason for frozen deformations, stresses, and structurally induced Na distributions. These are calculated adopting the following constitutive model in which it is assumed, that glass behaves like a thermoelastic material for temperatures above Tgand like a (structurally) rigid one below Tg. For spherical symmetric cooling of glass spheres we calculate under the classical boundary conditions and certain smoothness assumptions at the moving interface between the thermoelastic and the frozen glass analytical expressions for the frozen deformations, stresses, and Na distributions, ft turns out that these distributions depend strongly on the cooling history, such that the frozen network density increases from the center to the surface, the Na density decreases and the stress distributions decrease from strongly tensile at the center to slightly compressive at the surface of the sphere. Comparison of calculated and measured distributions show good agreement. The theoretically predicted and experimentally proven structurally induced Na diffusion might be of technical importance.
点击下载:
PDF (1153KB)
返 回