Toughened Laminated Alumina/Silica Ceramics Formed by Weakening Interlayer Bonded Strength

Low impact toughness is the major obstacle to impede the applications of brittle ceramics such that a very small crack may induce catastrophic fracture of the bulk components. Thus, enhancing the impact toughness of ceramics is virtually important. It is generally accepted that weakening the interlayer binding strength of the laminated material is beneficial to the fracture toughness of the laminated ceramics. In this paper, alumina / silica layered composite ceramics were prepared by impregnating the alumina interlayers with silica sol, wherein the interlayer bonding strength was controlled by adjusting the sintering temperatures from 1000°C to 1600°C. Lowing sintering temperature warrants the weak interlayer bonding strength, which results in the occurrence of the multiple bending strength-strain curves and improve the material's fracture strain and impact toughness. Crack deflection along the weak interface layer is the main mechanism for the enhanced toughness and crack tolerance. When the sintering temperature decreases from 1600°C to 1200°C, impact toughness increases from 4.42 kJ/m2 to 6.95 kJ/m2, and fracture strain measured by three-point bending increases from 0.25% to 0.36%. Finite element software was used to simulate the differences in stress distribution.