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

Si3N4-ZrB2 ceramics were hot-pressed at 1500 °C using self-synthesized fine ZrB2 powders containing 2.0 wt% B2O3 together with MgO-Re2O3 (Re = Y, Yb) additives. Both Si3N4 and ZrB2 grains in the hot-pressed ceramics were featured with elongated and equiaxed morphology. The presence of elongated Si3N4 and ZrB2 grains led to the partial texture of the ceramics under the applied pressure. Vickers hardness and fracture toughness of Si3N4-ZrB2 ceramics with MgO-Re2O3 additives prepared at low temperature were about 19-20 GPa and 9-11 MPa m1/2, respectively, higher than the reported values of Si3N4-based ceramics prepared at high temperature (1800 °C or above) under the same test method.