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

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