Low-temperature preparation of porous SiC ceramics using phosphoric acid as a pore-forming agent and a binder |
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| Affiliation: | 1. Ceit-IK4 Technology Center, E-20018, San Sebastian, Spain;2. Universidad de Navarra, Tecnun, E-20018, San Sebastian, Spain;1. Department of Mining and Metallurgy Engineering, Amirkabir University of Technology, Tehran, Iran;2. Department of Mechanical Engineering, University of Mohaghegh Ardabili, Ardabil, Iran;3. Department of Materials Science and Engineering, University of Tabriz, Tabriz, Iran;4. Department of Mechanical Engineering, Quchan Branch, Islamic Azad University, Quchan, Iran;5. School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran;1. Department of Materials Science and Engineering, National Taiwan University, Taipei 106, Taiwan;2. Department of R&D, Hocheng Co., Taoyuan, Taiwan;1. Department of Metallurgical and Materials Engineering, Indian Institute of Technology Kharagpur, 721302, India;2. Institute for Applied Materials – Ceramic Materials and Technologies (IAM-KWT), Karlsruhe Institute of Technology, 76131, Germany;1. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China;2. State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, China;3. Department of Mechanical Engineering, Nagaoka University of Technology, Nagaoka 940-2188, Japan |
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| Abstract: | Porous SiC ceramics combine the properties of both SiC ceramics and porous materials. Herein, we design a facile method via pressureless sintering at relatively low temperatures for the synthesis of porous SiC ceramics. In the synthesis process, phosphoric acid was used as the sintering additive that reacted with SiO2 on the surface of SiC to form phosphates. The formed phosphates acted as a binder to connect the SiC particles. At a fixed temperature, the phosphates were partially decomposed and released a large amount of gas. This changed the pore structure of the ceramics and greatly improved their porosity. Finally, we obtained the porous SiC ceramics with high porosity and high strength. We investigate the effects of H3PO4 content on the phase composition, microstructure, porosity, mechanical properties and thermal expansion coefficient of the prepared porous SiC ceramics. It was shown that at the sintering temperature of 1200 °C, the highest porosity of the samples can reach 70.42% when the H3PO4 content is 25 wt%, and their bending strength reaches 36.11 MPa at room temperature when the H3PO4 content is 15 wt%. In addition, the porous SiC ceramics show good high-temperature stability with a bending strength of 42.05 MPa at 1000 °C and the thermal expansion coefficient of 3.966 × 10?6/°C. |
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| Keywords: | Porous SiC ceramic Pressureless sintering High porosity and bending strength High-temperature stability |
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