Synthesis and property characterization of ternary laminar Zr₂SB ceramic

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·m^1/2, and 2166.74±291.34 MPa, respectively.