Fabrication and properties of pressure-sintered reaction-bonded Si3N4 ceramics with addition of Eu2O3–MgO–Y2O3.

Dense pressure-sintered reaction-bonded Si 3 N 4 (PSRBSN) ceramics were obtained by a hot-press sintering method. Precursor Si powders were prepared with Eu 2 O 3 –MgO–Y 2 O 3 sintering additive. The addition of Eu 2 O 3 –MgO–Y 2 O 3 was shown to promote full nitridation of the Si powder. The nitrided Si 3 N 4 particles had an equiaxial morphology, without whisker formation, after the Si powders doped with Eu 2 O 3 –MgO–Y 2 O 3 were nitrided at 1400 °C for 2 h. After hot pressing, the relative density, Vickers hardness, flexural strength, and fracture toughness of the PSRBSN ceramics, with 5 wt% Eu 2 O 3 doping, were 98.3 ± 0.2%, 17.8 ± 0.8 GPa, 697.0 ± 67.0 MPa, and 7.3 ± 0.3 MPa m1/2, respectively. The thermal conductivity was 73.6 ± 0.2 W m−1 K−1, significantly higher than the counterpart without Eu 2 O 3 doping, or with ZrO 2 doping by conventional methods. [ABSTRACT FROM AUTHOR]