Preparation of TiN–TiB2–hBN ceramics with layered structure via secondary reactive hot pressing

TiN–TiB 2 –hBN ceramic composites were prepared using nitride boronisation with TiN–B as the raw material. The bulk samples exhibited layered structures through secondary reactions at higher temperatures. In the outer layer of the bulk sample, hBN was consumed, and the content of the hard phase (TiB 2 ) increased because of the secondary reaction, which increased the hardness of the outer layer to 20.54 GPa, i.e., 68.64% higher than that of the inner layer (12.18 GPa). In addition, the mechanical properties of TiN–TiB 2 –hBN ceramic composites with a layered structure were not adversely affected by the higher sintering temperature: the bulk sample maintained a high bending strength of 477 MPa, and the fracture toughness was improved to 4.02 MPa m 1/2 by twins and stacking dislocations.