Oxidation protection of C/C composites: Coating development with thermally stabile SiC@PyC nanowires and an interlocking TaB₂-SiC structure

To improve the thermal stability of SiC nanowires at ultra-high temperatures, pyrolytic carbon (PyC) is deposited on them by chemical vapor deposition. The results suggest that the PyC can effectively protect nanowires from phase transition and crystal growth up to 2373 K. Meanwhile, a PyC-coated SiC (SiC@PyC) nanowire-reinforced interlocking zigzag interface is designed and constructed between TaB₂-SiC coating and carbon/carbon (C/C) composites. Due to more survivals of nanowires and the constructed zigzag interface, adhesion strength of TaB₂-SiC coating is enhanced. During the thermal cycling test between 1873 K and room temperature in air, SiC@PyC nanowire-reinforced interlocking TaB₂-SiC coating prepared by pack cementation (PC) technique, exhibits good oxidation-resistant performance. The alleviation of coefficient of thermal expansion and the buffering roles of PyC effectively decrease the thermal stress of TaB₂-SiC coating and restrain the formation of microcracks. These results can provide useful information for nanomaterial-reinforced ceramics and ceramic coatings to be employed at ultra-high temperatures.