Microstructure, Strength, and Oxidation of a 10 wt% Zyttrite-Si3N4 Ceramic |
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Authors: | SUNIL DUTTA BRUNO BUZEK |
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Affiliation: | NASA-Lewis Research Center, Cleveland, Ohio 44135 |
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Abstract: | Hot-pressed Si3N4 doped with 10 wt% zvttrite as a sinterine aid was studied. An equiaxed, fine-grainid microstructure was predominant, with no apparent porosity. Bend strengths were determined at room temperature and high temperatures (up to 1370°C/2500°F). Oxidation was measured by weight gain at 1370°C in air. The resulting material exhibited very good room-temperature strength (755 MPa/110 ksi). The work showed that room-temperature strength can be improved significantly by using controlled Si3N4 powder with 10 wt% zyttrite. High-temperature strength (514 MPd75 ksi) at 1370°C was nearly double that of hot-pressed Si3N4 (NC-132). The oxidation resistance at 1370°C was also higher than that of NC-132. |
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