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

Abstract 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.