Fabrication of Si <sub>3</sub> N <sub>4</sub> ceramics substrates with high thermal conductivity by tape casting and gas pressure sintering
Jixue Zhao, Yun Liu, Yuanhang Zheng, Xiaolei Li, Tianyi Sui, Bin Lin
Abstract
Abstract In this paper, high thermal conductivity Si 3 N 4 ceramics were successfully fabricated through exploring and optimizing the tape casting process. The impact of various organic additives on the rheological characteristics of Si 3 N 4 slurry was explored, and the pore size distribution and microstructure of the green tapes at different solid loadings were investigated, as well as the microstructure of Si 3 N 4 ceramics. Green tapes with a narrow pore size distribution, a small average pore size, and a high density of 1.88 g cm −3 were prepared by the investigation and optimization of the Si 3 N 4 slurry formulation. After gas pressure sintering, Si 3 N 4 ceramics with a density of 3.23 g cm −3 , dimensions of 78 mm × 78 mm, and a thickness of 0.55 mm were obtained. The microstructure of the Si 3 N 4 ceramics showed a bimodal distribution and a low content of glassy phases. The thermal conductivity of the Si 3 N 4 ceramics was 100.5 W m −1 K −1 , the flexural strength was 735 ± 24 MPa, and the fracture toughness was 7.17 MPa m 1/2 .