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

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 B₄C/CNT composite films using sequential boric acid precipitation on carbon nanotube (CNT) films, followed by spark plasma sintering (SPS)-driven in situ B₄C formation. This approach combines the lightweight and high energy-absorption properties of CNTs with the structural robustness of B₄C, resulting in a synergistic composite. This material mimics the "brick-and-mud" structure of pearl layers, with alternating "brick" layers rich in B₄C and "mud" layers rich in CNTs. The maximum density of B₄C/CNT composite films is 1.78 g/cm³, 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 B₄C grain deflection. During the air erosion process at 1000°C, B₄C selectively oxidizes to form a dense B₂O₃ 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.