Preparation of Si3N4 ceramics with high thermal conductivity and mechanical properties using novel Gd3Si2C2 as a sintering aid

In this study, self-synthesized Gd 3 Si 2 C 2 and MgO were used as sintering aids to fabricate Si 3 N 4 ceramics via gas-pressure sintering. The results indicated that Gd 3 Si 2 C 2 reacted with inherent SiO 2 on the Si 3 N 4 surface to form Gd 2 O 3 and β-Si 3 N 4 in situ, thereby increasing the N/O ratio of the liquid phase. In addition, in situ β-Si 3 N 4 induced grain growth, enhancing the thermal conductivity of Si 3 N 4 ceramics while maintaining excellent mechanical properties. Compared to the samples with Gd 2 O 3 and MgO as sintering aids, those with Gd 3 Si 2 C 2 and MgO as sintering aids demonstrated superior overall performance with the thermal conductivity, bending strength, fracture toughness, and Vickers hardness of 101.96 W⋅m −1 ⋅K −1 , 848.26 ± 4.66 MPa, 6.23 ± 0.15 MPa⋅m 1/2 , and 16.56 ± 0.43 GPa, respectively.