Fabrication, mechanical properties and thermal shock resistance of laminated TiB2–based ceramic

Abstract

In the present work, the bionic design of structures was introduced into the fabrication of the TiB2-based ceramics in order to improve their fracture toughness. The powder mixtures of 70vol.% TiB2+20vol.% SiC+10vol.% graphite flake were used as the rigid layer, and the powder mixtures of 10vol.% TiB2+5vol.% SiC+85vol.% graphite flake were used as the soft layer. The rigid and soft layers were first prepared separately using tape casting and then the rigid and soft layers were alternately stacked to form the laminated TSG ceramic. The flexural strength of the laminated TSG ceramic is lower than that of monolithic ceramic, whereas the fracture toughness is greater than that of monolithic ceramic. The remarkable improvement in fracture toughness of laminated TSG ceramic is attributed to the crack deflection, crack branch and interface delamination (stress relaxation near the crack tip). The reduction in flexural strength of laminated TSG ceramic is attributed to the presence of weak interfaces. Furthermore, the thermal shock resistance of laminated TSG ceramic is improved due to the improvement in fracture toughness and the reduction in flexural strength.