• Acta Physica Sinica
  • Vol. 69, Issue 11, 117701-1 (2020)
Yuan-Yuan Lu1, Gui-Hua Lu1, Heng-Wei Zhou1、*, and Yi-Neng Huang1、2、*
Author Affiliations
  • 1Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters, College of Physical Science and Technology, Yili Normal University, Yining 835000, China
  • 2National Laboratory of Solid State Microstructures, School of Physics, Nanjing University, Nanjing 210093, China
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    DOI: 10.7498/aps.69.20200232 Cite this Article
    Yuan-Yuan Lu, Gui-Hua Lu, Heng-Wei Zhou, Yi-Neng Huang. Preparation and properties of spodumene/silicon carbide composite ceramic materials[J]. Acta Physica Sinica, 2020, 69(11): 117701-1 Copy Citation Text show less

    Abstract

    Silicon carbide (SiC) is widely used due to the lower coefficient of thermal expansion (CTE), high thermal conductivity and excellent mechanical properties. However, the self-diffusion coefficient of SiC relative to that of oxide ceramics is very low, it is difficult to sinter at lower temperature. The β-spodumene has ultra low or even negative thermal expansion coefficient combined with good thermal and chemical durability, which melts at 1423 ℃. Accordingly, the present study focuses on the use of β-spodumene as a flux at lower sintering temperature and the preparation of lower CET composite ceramics. The effects of spodumene on the sintering behavior, phase relations, thermal expansion and mechanical properties of spodumene/silicon carbide composites are discussed. A high pure β-spodumene LiAlSi2O6 compound with nearly zero thermal expansion coefficient is synthesized via solid phase sintering. Spodumene/silicon carbide composites are fabricated by the adding 25, 30, 35 and 40 mass% synthesized β-spodumene powder to 75, 70, 65 and 60 mass% α-SiC matrix, respectively. Both β-spodumene and SiC are fabricated by conventional pressureless liquid sintering technique, and the batches are uniaxially pressed into discs and rectangular bars, then sintered at 1550 ℃ for 2 h in an Ar atmosphere. The results show that the SiC and β-spodumene do not react during sintering, and the β-spodumene changes from tetragonal phase into hexagonal phase, the cell volume has a considerable shrinkage. A certain amount of liquid phase can help to enhance the density, improve Young’s modulus and promote the sintering behavior of SiC. When the feedstock contains 35% β-spodumene, the Young’s modulus reaches to (204.2 ± 0.5) GPa. Excess porosity is formed when liquid phase is too much during sintering, The Young's modulus of the sample 40SP is (119.6 ± 0.5) GPa. It is determined that the Young’s modulus of these materials are affected by porosity and internal microcracks. This study indicates that the content of β-spodumene and porosity are the dominant factors to control the CET of composites, but the porosity has a stronger effect. Besides, the microcracks, which are formed by the interaction of various internal stresses, are also an impotant factor. The materials with nearly zero thermal expansion are developed in a lower temperature range from –150 ℃ to 25 ℃, the spodumene content in the most stable composite reaches 40 mass%, and the CET of composite is close to that of Si (α25 ℃ = 2.59 × 10–6–1) in a temperature range of 25–480 ℃.
    Yuan-Yuan Lu, Gui-Hua Lu, Heng-Wei Zhou, Yi-Neng Huang. Preparation and properties of spodumene/silicon carbide composite ceramic materials[J]. Acta Physica Sinica, 2020, 69(11): 117701-1
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