Enhanced thermal properties of silica-based ceramic cores prepared by coating alumina/mullite on the surface of fused silica powders |
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| Affiliation: | 1. Jiangsu Collaborative Innovation Center for Advanced Inorganic Function Composites, Nanjing Tech University, Nanjing, 210009, China;2. College of Materials Science and Engineering, Nanjing Tech University, Nanjing, 210009, China;3. Electron Microscope Lab, Nanjing Forestry University, Nanjing, 210037, China;4. Hunan Engineering Laboratory for Preparation Technology of Polyvinyl Alcohol Fiber Materials, Huaihua Key Laboratory for the Preparation of Ceramics Materials and Devices, College of Chemistry and Materials Engineering, Huaihua University, Huaihua, 418000, China;1. School of Materials Science and Engineering, Hebei Provincial Key Laboratory of Traffic Engineering Materials, Shijiazhuang Tiedao University, Shijiazhuang 050043, China;2. State Key Laboratory of Advanced Special Steels, School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China;1. 3D Printing Materials Center, Korea Institute of Materials Science (KIMS), Changwon, 51508, Republic of Korea;2. Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48105, USA;1. Institute of Power Engineering Ceramic Department CEREL, Research Institute, 1 Techniczna St., 36-040 Boguchwa?a, Poland;2. Warsaw University of Technology, Faculty of Materials Science and Engineering, 141 Wo?oska St., 02-507 Warsaw, Poland;3. WSK “PZL – Rzeszów” S.A., 120 Hetmańska St., 35-078 Rzeszów, Poland;1. Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, China;2. NPU-SAS Joint Research Center of Advanced Ceramics, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, China;3. Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China;4. State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China;5. Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China |
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| Abstract: | In this study, an alumina/mullite coating was synthesized on the surface of fused silica powders to form an alumina/mullite-silica core-shell structure. The effects of the alumina/mullite coating on the cristobalite crystallization, thermal properties, and leachability of the silica-based ceramic cores were investigated using the simulated casting process. The X-ray diffraction results indicated that the crystallization of cristobalite was significant at the simulated casting temperature of approximately 1400 °C. An increase in the cristobalite content during this stage resulted in a large thermal expansion because of its higher coefficient of thermal expansion compared with that for fused silica. The addition of optimum amounts of the alumina/mullite powders resulted in an increase in the initial shrinkage temperature and a decrease in the shrinkage of the specimens. When the coating powders were added at 43 wt%, the initial shrinkage temperature increased from 1092 °C to 1200 °C and the shrinkage decreased sharply. Leaching tests showed that the silica-based ceramic cores were removed in the form of stripped layers. The washing and shaking process accelerated the disintegration of the ceramic core and improved its leachability. |
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| Keywords: | Alumina/mullite coating Silica-based ceramic core Thermal property Leachability |
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