The impact of binary and ternary ZrC additive systems on silicon nitride's microstructure and properties

The rapid development of the integrated circuit industry has significantly increased the demand for high-performance substrates. Silicon nitride (Si 3 N 4 ) ceramics, recognized for their excellent thermal and mechanical properties, have become a key focus of research. This study first examines the use of ZrC, characterized by low oxygen content and strong oxygen absorption capacity, as a sintering aid to enhance the thermal conductivity of Si 3 N 4 . The effects of ZrC-MgO binary additives and ZrC-Sc 2 O 3 -MgO/MgSiN 2 ternary additives on the density, phase composition, microstructure, thermal conductivity, and mechanical properties of Si 3 N 4 were investigated. Results indicate that in the binary system, ZrC reacted with oxygen on the surface of Si 3 N 4 during sintering, reducing the secondary phase content, and thinning the intergranular phase. This process resulted in abnormal grain growth and improved thermal conductivity (103.73 W·m −1 ·K −1 ) but decreased bending strength (464.33 ± 19.31 MPa). In contrast, the ternary system with Sc 2 O 3 effectively inhibited abnormal grain growth, thereby enhancing mechanical properties. Samples with MgSiN 2 exhibited higher thermal conductivity (90.01 W·m −1 ·K −1 ) but slightly reduced bending strength (646.00 ± 22.93 MPa) compared to those with MgO. These findings offer strategies for optimizing additive systems in Si 3 N 4 ceramics to achieve thinner grain boundaries and a balance between thermal conductivity and mechanical performance.