Mechanical Properties and Microstructure of Hot-Pressed Silica Matrix Composites |
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Authors: | Weili Wang Jianqi Chen Xiaoning Sun Guoxun Sun Yanjie Liang Jianqiang Bi |
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Institution: | 1.Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, School of Materials Science & Engineering, Shandong University, Jinan 250061, China; (J.C.); (X.S.); (G.S.); (Y.L.); (J.B.);2.Suzhou Institute of Shandong University, Suzhou 215123, China |
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Abstract: | Silica is one of the most widely used ceramics due to its excellent chemical stability and dielectric property. However, its destructive brittle nature inhabits it from wider application as a functional ceramic. An improvement in toughness is a challenging topic for silica ceramic, as well as other ceramics. In the paper, silica ceramic with different types of boron nitride powders and alumina platelets was fabricated by hot-pressing. Introduction of the additives had great influence on the composites’ mechanical properties and microstructure. The silica matrix composite containing micro-sized boron nitride powders possessed the best mechanical properties, including the bending strength (134.5 MPa) and the fracture toughness (1.85 Mpa·m1/2). Meanwhile, the introduction of alumina platelets combined with boron nitride nanosheets achieved an effective enhancement of fracture toughness while maintaining the bending strength. Compared with the monolithic silica, the composite with simultaneous addition of alumina platelets and boron nitride nanosheets had a fracture toughness of 2.23 Mpa·m1/2, increased by approximately 27% (1.75 Mpa·m1/2). The crack deflection and platelet pullout were contributing to enhancement of the fracture toughness. The improved mechanical properties, combined with the intrinsic excellent dielectric and chemical properties, make the silica matrix composites promising wave transparent and thermal protection materials. |
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Keywords: | silica boron nitride alumina platelets mechanical property microstructure |
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