Reinforcement of silica-based ceramic cores based on amorphous and polycrystalline mullite fibers |
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| Affiliation: | 1. Science and Technology on Advanced High Temperature Structural Materials Laboratory, Beijing Institute of Aeronautical Materials, Beijing, 100095, China;2. Leicester International Institute, Dalian University of Technology, Dalian, 124000, China;3. School of Materials Science & Engineering, Chang''an University, Xi''an, 710061, China;1. State Key Laboratory of New Textile Materials and Advanced Processing Technologies, Wuhan Textile University, Wuhan, Hubei, 430200, China;2. School of Textile Science and Engineering, Wuhan Textile University, Wuhan, Hubei, 430200, China;1. School of Physical Science and Technology, Yangzhou University, Yangzhou, 225002, PR China;2. Guangling College, Yangzhou University, Yangzhou, 225000, PR China;3. Microelectronics Industry Research Institute, Yangzhou University, Yangzhou, 225002, PR China;1. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, 510006, China;2. School of Material Science and Energy Engineering, Foshan University, Foshan, 528000, China;3. The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, China;4. Immobilisation Science Laboratory, Department of Materials Science and Engineering, University of Sheffield, Sheffield, S1 3JD, UK;5. Department of Radiochemistry, China Institute of Atomic Energy, Beijing, 102413, China |
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| Abstract: | In the investment casting of turbine blades, ceramic cores are key components to form complex hollow structures. Superior mechanical property and leaching rate are demanded for ceramic cores. Herein, ceramic cores were fabricated using fused silica powders as the matrix, and amorphous and polycrystalline mullite fibers as the reinforcement phases, respectively. The microstructure and property evolution of ceramic cores rely on the crystallization degree of mullite fibers are explored. Both of the mullite fibers lead to improved crystallization of cristobalite, reduced sintering shrinkage, increased apparent porosity, and benefited bending strength, creep resistance, and leaching rate of the cores. Compared to the polycrystalline mullite fibers, the amorphous fibers are metastable with large quantities of structural defects, promoting the diffusion mass transfer and forming strong interface between fibers and matrix. Therefore, the amorphous fibers have larger promotion on the bending strength and resistance to creep deformation of ceramic cores. Moreover, the structural defects of amorphous fibers ensures the high chemical activity in alkaline solutions and exhibits excellent leaching rate. The ceramic core with 4.5 wt% of amorphous mullite fibers exhibits excellent comprehensive performance with bending strengths of 28.9 MPa and 23.8 MPa at room temperature and 1550 °C, creep deformation of 0.3 mm, and leaching rate of 1.4 g/min, well meeting the casting requirements of hollow blades. |
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| Keywords: | Ceramic core Mullite fibers Fiber reinforcement Amorphous Mechanical property Leaching rate |
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