Mechanical Properties of Mullite |
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Authors: | TAI-IL MAH K S MAZDIYASNI |
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Affiliation: | Systems Research Laboratories, Inc., Dayton, Ohio 45440;Air Force Wright Aeronautical Laboratories, Wright-Patterson Air Force Base, Ohio 45433 |
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Abstract: | The mechanical properties of alkoxy-derived, high-purity, translucent, theoretically dense mullite (3AI2O3.2SiO2) were investigated over the temperature range room temperature to 1500°C. Large agglomerates were found to contribute to the formation of porosity nests which act as strength-controlling flaws at room temperature as well as at high temperatures. Despite the slow crack growth above 1300°C, a slight increase in fracture stress and a large increase in KIc were observed up to 1500°C. These increases are explained by the dominance of energy dissipation through plastic relaxation in the plastic zone over grain-boundary sliding due to the presence of the glassy phase. |
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