Preparation of Si <sub>3</sub> N <sub>4</sub> ceramics with enhanced thermal conductivity and mechanical properties using nitride sintering additives
Binbin Fan, Wei Sun, Zunlan Hu, Dengke Zhao, Bohan Wang, Shuo Zhao, Shijia Zhang, Fei Li, Xie Zhipeng, Kexin Chen, Guanghua Liu
Abstract
Abstract Si 3 N 4 ceramics with enhanced thermal conductivity and mechanical properties were prepared by using nitride sintering additives of YN and MgSiN 2 . In addition to the conventional oxide sintering additives such as Y 2 O 3 and MgO, the use of nitride sintering additives offered more possibilities for the optimization of the microstructure and properties of Si 3 N 4 ceramics. The Si 3 N 4 sample with binary nitride additives of YN‒MgSiN 2 showed a coarse‐grained microstructure and the maximum thermal conductivity of 112 W m −1 K −1 after heat treatment. However, the binary nitride additives were insufficient to supply sufficient liquid phase during the sintering of Si 3 N 4 ceramics, which caused porosity and impaired the mechanical properties. A good balance between thermal conductivity and mechanical properties was achieved by using nitride‐oxide hybrid sintering additives of YN‒MgO, where the Si 3 N 4 sample showed both high thermal conductivity of 109 W m⁻ 1 K⁻ 1 and good mechanical properties with flexural strength of 707 ± 7 MPa, fracture toughness of 9.5 ± 0.2 MPa m 1/2 , and Vickers hardness of 14.9 ± 1 GPa.