Microstructure and Mechanical Properties of Hot-Pressed α-Al2O3-Seeded γ-Alumina Ceramics |
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| Authors: | Jiang Li Yubai Pan Yusong Wu Huamin Kou Jingkun Guo |
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| Affiliation: | State Key Lab of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China; Graduate School of the Chinese Academy of Sciences, Beijing 100039, China |
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| Abstract: | High-quality alumina ceramics were fabricated by a hot pressing with MgO and SiO2 as additives using α-Al2O3-seeded nanocrystalline γ-Al2O3 powders as the raw material. Densification behavior, microstructure evolution, and mechanical properties of alumina were investigated from 1250°C to 1450°C. The seeded γ-Al2O3 sintered to 98% relative density at 1300°C. Obvious grain growth was observed at 1400°C and plate-like grains formed at 1450°C. For the 1350°C hot-pressed alumina ceramics, the grain boundary regions were generally clean. Spinel and mullite formed in the triple-grain junction regions. The bending strength and fracture toughness were 565 MPa and 4.5 MPa·m1/2, respectively. For the 1300°C sintered alumina ceramics, the corresponding values were 492 MPa and 4.9 MPa·m1/2. |
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