Some aspects of strength characteristics of glass

Abstract

Strength characteristics of glasses are reviewed with some new aspects, emphasizing their specific features different from those of polycrystalline ceramic materials. The absence of any strength-controlling, structurally inherent defects in glass discriminates between the pristine strength on the GPa order and the practical strength controlled by the presence of surface flaws externally induced. For investigating the nature of the pristine strength, hydrofluoric-acid etching of glass samples having a definite indentation is shown to be quite useful to get consistent experimental results. Some experimental examples clarify the degradation mechanism in glass strength when heated or coated with thin films as well as the fatigue nature of the pristine strength. In evaluating the practical strength of glass, the strength-degrading effect of blisters and strengthening by providing surface compressive stress are discussed. A strength scale of glass and glass ceramics is given.