In-situ formed silicon oxycarbide nanowires into porous SiC(rGO) PDCs enable balanced enhancement of robustness and thermal management

With ongoing development of rocket combustion and hypersonic vehicles, urgent needs are created on thermal structures, protection and thermal insulating materials, particularly balanced enhancement of mechanical and antioxidant properties. Herein, we propose a design strategy to construct continuous in-situ formed SiOC nanowires (SiOCnws)-toughened self-healing SiOx coatings into porous SiC(rGO) PDCs. The key production technique is re-pyrolyzing coassembled flexible precursors/SiC(rGO)p/graphite blends, followed by decarbonization and silica sol impregnation-sintering (SIS) process. Well-distributed hierarchical pores are built to heighten thermal insulation properties by the integrated decarburization of graphite coupled with free carbon. High-yield SiOCnws, with high surface activity, are first cultivated via graphite-assisted vapor-solid (VS) mechanism without transition metal catalysts. They interconnect to form intricate 3D meshwork by graphite-assisted melt-spinning and have good compatibility with ceramic matrix and SiOx coatings by carbothermal reaction. Hierarchically porous SiOCnws/SiC(rGO)40% PDCs after once SIS exhibit favorable thermal conductivity of 0.27 W‧m−1‧K−1 and exceptional high robustness (compressive strength: 39.02 MPa, hardness: 10.27 GPa). Such composites display low reflection loss of −48.14 dB at 11.22 GHz and even good structural stability at about 1300 °C as burned by a butane blowtorch for 3600 s, shedding light on competitive components for uses in thermal protection fields. [Display omitted] •SiOCnws-toughened self-healing SiOx coatings ingeniously modify porous SiC(rGO) PDCs.•Hierarchical pores by graphite-assisted decarburization ensure good thermal insulation.•Composite realizes balanced enhancement of robustness/anti-oxidation/EMW absorption.•3D-net SiOCnws are in-situ formed/interconnected via graphite-assisted melt-spinning.•Assembled interfaces make high heterogeneous compatibility of SiOCnws/SiOx/SiC(rGO).