A promising high-temperature thermal protection performance of silicide-based ceramic coating based on multi-particles/multilayer synergistic design strategy

Multilayer composite design for thermal protective coating has proven to be promising for improving the high-temperature oxidation resistance of aerospace components. However, a series of problems such as the interface mismatch, dependable production method, and difficulty in forming a stable oxide scale, etc., make the scalable production of the multilayer composite coating with high efficiency, and low cost, along with achieving superior high-temperature oxidation resistance remains a long-time endeavor. Herein, a brand-new NbSi₂/Nb₂O₅-SiO₂/HfC-HfO₂-MoSi₂-Yb₂O₃ multilayer protective ceramic coating is synthesized by the multi-particles/multilayer synergistic design strategy. The multi-particles outer layer acts as the first oxygen erosion barrier, while the in-situ Nb₂O₅-SiO₂ layer and the NbSi₂ bottom layer are the second and third oxygen shielding layer for niobium alloys separately. Moreover, the in-situ Nb₂O₅-SiO₂ layer also provides a good interface matching, and the co-existent multilayer makes a powerful thermal protection system. The incorporation of the high content of multi-particles in the outer layer is not only beneficial to reduce the inward oxygen flux through the oxygen diffusion barrier layer, but also improves the stress damage tolerance and thermal stability of the oxide scale by forming HfSiO₄-Yb₂O₃-SiO₂ skeleton layer. Thereby, the multilayer-coated sample reduces the oxide scale thickness to 128 μm after being exposed to 1200 ℃ for 120 h, which is only 67 % compared to the NbSi₂-coated sample (100 h, 192 μm), and simultaneously holding the intact structure after a short-time oxygen acetylene ablation above 1800 ℃. This work paves a new way to design next-generation thermal protective coatings with great potential for applications.