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Journal of Advanced Ceramics

Keywords

Zr2SB, spark plasma sintering (SPS), reaction path, microstructure, properties

Abstract

In this paper, Zr2SB ceramic with purity of 82.95 wt% (containing 8.96 wt% ZrB2 and 8.09 wt% zirconium) and high relative density (99.03%) was successfully synthesized from ZrH2, sublimated sulfur, and boron powders by spark plasma sintering (SPS) at 1300 ℃. The reaction process, microstructure, and physical and mechanical properties of Zr2SB ceramic were systematically studied. The results show that the optimum molar ratio to synthesize Zr2SB is n(ZrH2):n(S):n(B) = 1.4:1.6:0.7. The average grain size of Zr2SB is 12.46 μm in length and 5.12 μm in width, and the mean grain sizes of ZrB2 and zirconium impurities are about 300 nm. In terms of physical properties, the measured thermal expansion coefficient (TEC) is 7.64×10−6 K−1 from room temperature to 1200 ℃, and the thermal capacity and thermal conductivity at room temperature are 0.39 J·g−1·K−1 and 12.01 W∙m−1∙K−1, respectively. The room temperature electrical conductivity of Zr2SB ceramic is measured to be 1.74×106 Ω−1∙m−1. In terms of mechanical properties, Vickers hardness is 9.86±0.63 GPa under 200 N load, and the measured flexural strength, fracture toughness, and compressive strength are 269±12.7 MPa, 3.94±0.63 MPa·m1/2, and 2166.74±291.34 MPa, respectively.

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