Bioinspired Integration of B ₄ C/CNT: Laminated Composites With Nacre‐Like Mechanics for Lightweight Impact‐Resistant Systems

ABSTRACT Biological composites, such as nacre, achieve exceptional mechanical performance through hierarchical architectures that balance strength and toughness‐characteristics rarely replicated in synthetic materials. In this study, we present a biomimetic strategy for fabricating B ₄ C/CNT composite films using sequential boric acid precipitation on carbon nanotube (CNT) films, followed by spark plasma sintering (SPS)‐driven in situ B ₄ C formation. This approach combines the lightweight and high energy‐absorption properties of CNTs with the structural robustness of B ₄ C, resulting in a synergistic composite. This material mimics the “brick‐and‐mud” structure of pearl layers, with alternating “brick” layers rich in B ₄ C and “mud” layers rich in CNTs. The maximum density of B ₄ C/CNT composite films is 1.78 g/cm ³ , with a dynamic compressive strength of 1098 MPa. The energy absorption capacity, as measured in laser‐induced projectile impact testing (LIPIT), is 3.5% higher than that of CNT films. Crack propagation is prevented through layer delamination, CNT bridging, and B ₄ C grain deflection. During the air erosion process at 1000°C, B ₄ C selectively oxidizes to form a dense B ₂ O ₃ glass phase, which acts as an in‐situ protective barrier, thereby exhibiting excellent anti‐erosion performance. This work provides a solution to intrinsic strength‐toughness‐density trade‐off in structural materials, with significant implications for aerospace and protective engineering.