Microstructure and anisotropic mechanical properties of B6.5C-TiB2-SiC-BN composites fabricated by reactive hot pressing

B 6.5 C-TiB 2 -SiC-BN composite ceramics were prepared by a novel solid-state reaction using TiCN, B, and Si as raw materials. The final products obtained by hot pressing at 1950 °C possessed a fine microstructure, homogeneous distribution, and excellent mechanical properties . The obtained bulk B 6.5 C-TiB 2 -SiC-BN composite ceramic shows a high relative density (98.8 %). The mechanical properties of the composites are anisotropic because of the orientation growth and structural characteristics of TiB 2 and h-BN grains. The values of hardness, bending strength , and fracture toughness measured along the hot-pressing direction were 19.6 GPa, 801 MPa, and 4.30 MPa m 1/2 , respectively, which were higher than those measured perpendicular to the hot-pressing direction. The formation of twin structures in B 6.5 C and SiC grains and the crack deflections induced by h-BN and TiB 2 grains are beneficial for improving the mechanical properties of these composites.