RENSSELAER POLYTECHNIC INST TROY NY DEPT OF MATERIALS ENGINEERING
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The effect of the addition of zirconium oxides to lithium oxides aluminum oxidessilicon dioxide glass ceramics has been investigated. Specifically, the influences of the amount of ZrO2 added and the crystalline phase of the precipitated ZrO2 on fracture toughness were investigated. Upon heat treatment, metastable tetragonal ZrO2 was found to precipitate in the glass ceramics. It was found that the fracture toughness of the resulting glass ceramics. It was found that the fracture toughness of the resulting glass ceramics increased with increasing amounts of ZrO2 while that of the corresponding glasses were nearly independent of the ZrO2 content. With a constant zirconia content, the metastable tetragonal zirconia increased in size and transformed spontaneously to stable monoclinic zirconia with a prolonged heat-treatment. Fracture toughness of the resulting glass-ceramics was found to increase steadily with the increasing fraction of monoclinic zirconia. It was suggested that the strong stress field around the transformed zirconia particles are causing that the strong stress field around the transformed zirconia particles are causing crack deflection, increasing the fracture toughness.
- Physical Chemistry
- Ceramics, Refractories and Glass