Bio-Inspired B4C-TiB2 With Symmetric Sandwich-Structure for Synergistic Improvement in the Comprehensive Properties

A synergistic enhancement in bending strength, hardness, and fracture toughness while maintaining low density in B 4 C ceramics remains a challenge. Herein, we propose to design a simple three-layer symmetrical sandwich-type laminated structure of B 4 C-TiB 2 by imitating the nacre's structure, which effectively minimizes interfacial defects and achieves stronger interfacial bonding via reactive sintering using B 4 C, TiC, and B as starting materials. The simple symmetric design generates residual compressive stress in both outer layers and tensile stress in the middle layer. It has been found that the residual compressive stress can counteract external loads and lead to a remarkable improvement in hardness and bending strength. Furthermore, a rising R-curve behavior is observed in the fracture toughness testing of laminated B 4 C-TiB 2 ceramics, indicating superior resistance to crack propagation. Compared to monolithic ceramics, the as-synthesized laminated B 4 C-TiB 2 ceramic exhibits amazing comprehensive properties with a high hardness of 37.1 ± 0.4 GPa, bending strength of 834.3 ± 62.8 MPa, and fracture toughness of 5.0 MPa·m 1/2 . This work provides precise guidance for the design of impact-resistant ceramics by offering an in-depth understanding of how residual compressive stress affects mechanical properties.