Abstract: Due to their intrinsic brittleness and high sensitivity to structural flaws, ceramics face fundamental limitation in applications that require mechanical load-bearing capacity, impact resistance, and reliable performance under complex service conditions. Natural ceramic-based materials, such as nacre, have evolved intricate multiscale structures through long-term evolutionary processes, effectively integrating high strength and fracture toughness, offering valuable inspiration for the design of synthetic ceramics. This study utilized an accumulative rolling technique combined with a layer-by-layer assembly process to fabricate bioinspired ceramic-polymer composites featuring nacre-like layered and gradient structures at the multiscale. The composites exhibit a characteristic nacre-like brick-and-mortar architecture at the microscale, as well as periodic or gradient variations in ceramic content at the mesoscale, collectively forming bioinspired multiscale layered and gradient structures. The mechanical properties of the bioinspired composites were systematically investigated and compared with uniform composites with equivalent ceramic content. The relationships between the bioinspired structures, mechanical properties, and damage characteristics were elucidated. The results demonstrate that the bioinspired composites exhibit variations of up to several times in local hardness and elastic modulus along the thickness direction. In particular, the gradient composite with a “soft-hard-soft” configuration achieves superior strength-toughness synergy, demonstrating significantly higher strength, work of fracture, and fracture and impact toughness compared to the uniform materials with the same ceramic content. This enhancement is primarily attributed to the ability of this architecture to broaden stress distribution, reduce local stress concentrations, and facilitate extensive dissipation of mechanical energy. This study provides useful reference and guidance for the structural design of strong and tough bioinspired ceramic-polymer composites.

Key words: ceramic-polymer composites, bioinspired design, multiscale structures, gradient, mechanical property