STRUCTURAL RELATIONSHIPS IN VITREOUS INFRARED MATERIALS
Semiannual progress rept. 1 Apr-30 Sep 1967
MICHIGAN UNIV ANN ARBOR INST OF SCIENCE AND TECHNOLOGY
Pagination or Media Count:
Based on considerations of the important role of microyield in glass- structure studies, a linear relationship was found between the breaking strength of glass and microelasticity. This relationship disclosed that the wide spread observed in breaking strength values within one given glass system is due to localized variations in elasticity. Heretofore, these large deviations in strength have been attributed to unresolved factors such as surface contamination, handling defects, etc. Data presented demonstrate a spatial variability in microelasticity, the form of which determines the strength of glass under nonuniform loading conditions. The practical implications in terms of improving the mechanical properties of infrared glasses are discussed. Several predictions suggested by a previously defined unified theory of glass structure are examined and they generally substantiate the fact that variations in the basic glass structure are determined by surface flaw parameters and flaw interactions. In particular, this study confirmed that gases bound within vitreous networks can influence mechanical strength. The surface flaw characteristics and critical stress of flaw formation was determined both in infrared transmitting glasses in a single crystal. The differences in the flaw parameter values for the crystalline solid and the glasses were as predicted. Induced radiation effects were examined in three glasses representing the basic liquid models, and the changes in flaw characteristics are interpreted in relation to liquid model theory.