Acta Physica Sinica, Volume. 69, Issue 11, 117701-1(2020)

Preparation and properties of spodumene/silicon carbide composite ceramic materials

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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    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 ℃.

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    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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    Paper Information

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    Received: Feb. 18, 2020

    Accepted: --

    Published Online: Dec. 2, 2020

    The Author Email: Huang Yi-Neng (ynhuang@nju.edu.cn)

    DOI:10.7498/aps.69.20200232

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