Si3N4-ZrB2 ceramics prepared at low temperature with improved mechanical properties

Si 3 N 4 -ZrB 2 ceramics were hot-pressed at 1500 °C using self-synthesized fine ZrB 2 powders containing 2.0 wt% B 2 O 3 together with MgO-Re 2 O 3 (Re = Y, Yb) additives. Both Si 3 N 4 and ZrB 2 grains in the hot-pressed ceramics were featured with elongated and equiaxed morphology. The presence of elongated Si 3 N 4 and ZrB 2 grains led to the partial texture of the ceramics under the applied pressure. Vickers hardness and fracture toughness of Si 3 N 4 -ZrB 2 ceramics with MgO-Re 2 O 3 additives prepared at low temperature were about 19–20 GPa and 9–11 MPa m 1/2 , respectively, higher than the reported values of Si 3 N 4 -based ceramics prepared at high temperature (1800 °C or above) under the same test method.