CONTACT RESIDUAL STRESS RELAXATION IN SODA-LIME GLASS. PT.2. ASPECTS RELATING TO STRENGTH RECOVERY

• Published in: Journal of the European Ceramic Society Vol. 26; no. 6; pp. 1013 - 1022
• Main Authors: Kese, K O, Li, Z C, Bergman, B
• Format: Journal Article
• Language: English
• Published: 01.01.2006
• ISSN: 0955-2219

Strength recovery of Vickers indented soda lime glass was measured and compared after annealing at two temperatures: one below and one above Tg. Atomic force microscopy was used to study the cracks. At 540 C, no changes were seen in crack morphology either below the surface or on the surface relative to the pre-anneal state. At 630 C, both sub-surface and surface crack morphology changes were seen. The trends in strength recovery were compared with residual stress relaxation as measured by a new method of stress estimation based on nanoindentation elastic response. At short hold times at 630 C, and regardless of the length of hold time at 540 C, strength recovery of only about 30% was measured while at moderately long hold times at 630 C, strong recovery of fracture strength, about 132% was measured. Trends in strength recovery above Tg are shown to match those of crack tip radius instead of trends in stress relaxation across the residual stress field. 25 refs.