Residual strength of hot pressed zirconium diboride (ZrB2) after exposure to high temperatures

ZrB2 with different amounts of B4C additive (0–5 wt.%) has been hot pressed at 2000 °C and 25 MPa for 1 h. By addition of B4C, density as well as micro-hardness increased. For lower B4C content (0.5 and 1 wt.%), hot pressed ZrB2 shows considerable improvement in flexural strength after exposure in air at 1000 °C for 5 h, while higher B4C content (3 and 5 wt.%) leads to marginal or no improvement. For any content of B4C, flexural strength after exposure in air at 1500 °C for 5 h is lower than as-hot pressed ZrB2.