Ablation-resistant (Hf,Zr)B₂–SiC composite coating with alternating lamellar architecture by one-step atmospheric plasma spraying

Inspired by the brick-and-mortar arrangement of mollusk shells, constructing an alternating lamellar architecture is an effective strategy to overcome the catastrophic damage of ablation-resistant coatings and their oxide scales in extreme environments. Here, we developed a coating dominantly composed of alternating layers of (Hf,Zr)B₂ and SiC by one-step supersonic atmosphere plasma spraying for C/C composites, which improves fabrication efficiency. The coating shows “zero” ablation and cycling reliability at 2200 °C. The resulting oxide scale based on a multilayered (Hf,Zr)O₂ skeleton with embedded glassy SiO₂ layers is responsible for the superior ablation resistance. The refractory skeleton ensures thermal stability and the SiO₂ layers inhibit the oxygen inward diffusion. Two energy dissipation mechanisms, including crack deflection and multilayered delamination, contribute to the structural integrity of the oxide scale due to numerous interfaces in the lamellar architecture. The alternating lamellar coatings enable simultaneously superior oxidation resistance and damage tolerance and have great application potential for reusable aerospace components requiring thermal protection.