Biomimetic crossed-lamellar architecture: Elevating mechanical performance of continuous SiCf/SiC composites via robot-assisted 3D printing

Continuous silicon carbide fiber-reinforced silicon carbide (SiC_f/SiC) composites with lightweight, high-strength, excellent high-temperature and oxidation resistance have received increasing attention in aerospace, nuclear energy, and transportation engineering. However, it is difficult for current processing techniques to form SiC_f/SiC composites with complex shapes, and their mechanical properties are limited. In this study, we report the fabrication of SiC_f/SiC composites via robot-assisted 3D printing technology and the innovative introduction of biomimetic crossed-lamellar structures with varied summit angles to improve their mechanical properties. The effect of the summit angles on the forming quality and mechanical properties of the SiC_f/SiC composites was investigated, and the toughening mechanism of the crossed-lamellar structure was analyzed. Results reveal that robot-assisted 3D printing technology can achieve excellent printing quality at different summit angles, and the multi-orientation fiber alignment in crossed-lamellar structure promotes synergistic toughening through intralayer and interlayer crack propagation. When the summit angle is 120°, the SiC_f/SiC composite exhibits significant reinforcement, achieving ultra-high flexural strength and fracture toughness of 307.38 ± 7.9 MPa and 20.74 ± 1.05 MPa·m^1/2, respectively, especially the fracture toughness is increased by 72 % compared to the unidirectional structure. This work provides a novel approach for the fabrication of high mechanical performance continuous fiber-reinforced ceramic composites.