Three-Dimensional Printing of Rigid–Flexible Ceramic–Epoxy Composites with Excellent Mechanical Properties

Inspired by the Bouligand structure of the mantis shrimp’s dactyl club, in this study, we employed direct ink writing 3D printing technology to fabricate bioinspired gradient ceramic samples with varying gradient spacings and rotation angles. A rigid–flexible coupled bioinspired gradient ceramic–epoxy resin composite was successfully constructed based on epoxy resin infiltration. The effects of gradient variations and rotation angles on mechanical properties were systematically investigated with flexural strength and fracture toughness tests. The experimental results revealed that, at a fixed rotation angle, both the flexural strength and fracture toughness initially increased and then decreased with an increase in gradient spacing. The infiltration of epoxy resin significantly enhanced the mechanical performance of the composite samples. Specifically, the maximum flexural strength of 63.35 MPa was achieved at Δd = 0.08 and a rotation angle of 12°, while the highest fracture toughness of 2 MPa/m2was observed at Δd = 0.1 and a rotation angle of 12°. A failure analysis indicated that the introduction of gradient structures and epoxy resin infiltration altered the failure forms of traditional ceramics, with the primary toughening mechanisms including crack deflection, fiber pull-out, and crack branching. In this study, we successfully developed a rigid–flexible coupled bioinspired gradient ceramic–epoxy resin composite with excellent mechanical properties based on bioinspired design and gradient optimization, providing new insights and methodologies for the design and fabrication of high-performance ceramic materials.