ZrB2-Based "Brick-and-Mortar" Composites Achieving the Synergy of Superior Damage Tolerance and Ablation Resistance.

The intrinsic brittleness and poor damage tolerance of ultrahigh-temperature ceramics are the key obstacles to their engineering applications as nonablative thermal protection materials. Biomimetic layered or "brick-and-mortar" hybrid composites composed of alternative strong/weak interfaces exhibit excellent strength and high toughness; however, the commonly used interfacial materials are weak and have poor thermal stability and ablation resistance, which strictly limit their use in high-temperature and oxidative environments. In this work, ZrB2-based "brick-and-mortar" hybrid ceramics were constructed with a hierarchical biomimetic design to improve the fracture resistance and damage tolerance. ZrB2-20vol %SiC ceramics containing 30 vol % reduced graphene oxide nanosheets were used as the weak interface to increase crack growth resistance without destroying the excellent ablation resistance. Finally, the ZrB2-based "brick-and-mortar" composites achieve the synergy of superior damage tolerance and ablation resistance.