In-situ foaming of phenolic-derived three-dimensionally interlocked carbon fiber/carbon foam composites for ultra-high-temperature thermal insulation

An integrated carbon fiber/carbon foam composite (ICCF) with a three-dimensionally interlocked architecture was constructed via precursor-directed capillary infiltration and gradient in-situ foaming. This strategy leverages the in-situ nucleation and growth of phenolic-derived precursors within the constrained spaces of the carbon fiber network, establishing robust physical anchoring and geometric constraints at the interface. In this unique architecture, the continuous carbon fiber skeleton provides mechanical robustness characterized by a delayed failure mode, while the embedded closed-cell carbon foam acts as a deep barrier to photon transport. Theoretically, this structure reduces the net radiative heat flux by approximately 17% compared to traditional soft felt. Experimentally, ICCF exhibits a low thermal conductivity of 0.351 W/(m·K) at 1550 °C alongside superior high-temperature stability. Validated in an industrial silicon monocrystalline furnace, ICCF reduced the actual seeding power from 55 kW to 51 kW. By fundamentally resolving the intrinsic brittleness of the porous matrix via structural interlocking, this work provides a universal design philosophy for high-performance functional composites through precursor regulation, demonstrating significant potential for next-generation ultra-high-temperature thermal management systems.