Enhanced thermal conductivity and flexural strength of sintered reaction‐bonded silicon nitride with addition of (Y0.96Eu0.04)2O3

Abstract Sintered reaction‐bonded silicon nitride (SRBSN) with high thermal conductivity was obtained using (Y 0.96 Eu 0.04 ) 2 O 3 and MgO as sintering additives. Green compacts were nitrided at 1400°C for 4 h. Post‐sintering was carried out at 1850 and 1900°C for 4 h, respectively. In reaction‐bonded silicon nitride (RBSN) doped with Y 2 O 3 and MgO, the β‐Si 3 N 4 content and nitridation degree were 51.1% and 93.8%, respectively. However, the β‐Si 3 N 4 content and nitridation degree were 72.6% and 96.7% in a nitrided compact doped with (Y 0.96 Eu 0.04 ) 2 O 3 and MgO. After post‐sintering, the phase composition, microstructure, mechanical properties, and thermal conductivity were investigated. After sintering at 1900°C for 4 h, the thermal conductivity of SRBSN doped with (Y 0.96 Eu 0.04 ) 2 O 3 and MgO was increased by 16.5% compared to that of the samples doped with Y 2 O 3 and MgO. The highest hardness of 1639 HV and the good flexural strength of 776.4 MPa were also achieved in the sample doped with 2‐mol.% (Y 0.96 Eu 0.04 ) 2 O 3 and 5‐mol.% MgO.