Synthesis and characterization of Zr2SC ceramics

MAX-phase Zr2SC ceramics were synthesized by hot pressing mixtures containing ZrH2, carbon or ZrC, and ZrS2, WS2, or FeS2 as sulfur sources. The Zr2SC synthesized with FeS2 had a typical MAX-phase laminated structure, good thermal shock resistance, thermal stability to 2100 °C, and were readily machineable. The flexural strength was about 250 MPa up to 800 °C. The thermal expansion coefficient was 8.8 × 10−6/°C in the 25–2000 °C-temperature range, thermal conductivity was 38 W/m-K at 100 °C and about 30 W/m-K at 1100 °C, and specific heat at temperatures from 100 to 1100 °C ranged from 0.4 to 0.5 kJ/kg °C. Load–deflection curves exhibited plastic deformation from RT to 2066 °C. The sample deflection at fracture demonstrated significant dependence on temperature with a minimum at 1510 °C. In arc heater testing at 2150 °C for 23 s, the material developed an adherent, protective scale.