Synthesis and performance characterization of Hafnium-based multilayer coating applied over carbon/carbon composites with sharp leading edge

Carbon/carbon (C/C) composites have been acknowledged as potential candidates in aerospace vehicles, but their oxygen sensitivity still remains an enormous challenge. In this work, a novel multilayer coating consisted of HfC-2.5 mol.% Hf₆Ta₂O₁₇, HfC-40 mol.% SiC, HfC-2.5 mol.% Hf₆Ta₂O₁₇ and HfC-60 mol.% SiC sublayers from surface to inside was designed and fabricated on the surface of C/C composites with sharp leading edge by plasma spraying. Its ablation resistance was assessed using oxyacetylene torch with a maximum temperature over 2300 °C and compared with monolayered coatings. The multilayer coating revealed preferable ablation retardation capacity evidenced by its integrated profile and less flaw quantity. Such benefits were primarily stemmed from the effective structural design and rational material selection. The former was able to reduce the thermal stress within the ablated scale, the latter contributed to rising the high-temperature resistance and oxygen barrier ability of the coating.