High-toughness glass-ceramics. Final report, 1 July 1991-30 June 1994
Two different methods were used to prepare tough glass-ceramics containing ZrO2. One was to melt ZrO2-containing Li2O-Al2O3-SiO2 glasses and transform them by control led crystallization. The other was to sinter BaO-SiO2-Al2O3 glass powder together with ZrO2 powder. In both materials, some toughness improvement by the transformation of zirconia during fracture was observed. However, unexpectedly, the greater toughness improvement was realized when the zirconia particles in the glass-ceramics were transformed prior to the fracture by cooling to a lower temperature, e.g., liquid nitrogen temperature. This drastic increase of the fracture toughness was attributed to the deflection of the propagating crack by the large stress fields around the transformed (monoclinic) zirconia. The examination of the fracture surface demonstrated clearly that the crack deflection is taking place in the specimen with transformed zirconia.
- Research Organization:
- Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Engineering
- OSTI ID:
- 91505
- Report Number(s):
- AD-A-290562/8/XAB; CNN: Contract DAAL03-91-G-0211; TRN: 52261641
- Resource Relation:
- Other Information: PBD: 31 Aug 1994
- Country of Publication:
- United States
- Language:
- English
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