Carbon Foam-Reinforced Polyimide-Based Carbon Aerogel Composites Prepared via Co-Carbonization as Insulation Material

The weak inherent non-covalent interactions between carbon aerogel backbone nanoparticles obtained by the pyrolysis of conventional organic aerogel can lead to poor mechanical properties. When applied in the thermal protection system of a high-speed spacecraft, the preparation of carbon aerogel insulation materials with excellent formability and high mechanical strength still remains a huge challenge. This work reports an efficient approach for fabricating carbon foam-reinforced carbon aerogel composites by compounding the nanoporous polyimide aerogel into the microporous pre-carbonized phenolic resin-based carbon foam via vacuum impregnation, gelatinizing and co-carbonization. Benefiting from the co-shrinkage caused by co-carbonization, the thermal insulation capacity of the carbon aerogel and the formability of the pre-carbonized foam are efficiently utilized. The shrinkage, density and carbon yield of aerogels, pre-carbonized foams and the composites at different temperatures were measured to analyze the formation of the interfacial gap within the composite. The co-carbonization mechanism of the polyimide aerogels and phenolic resin-based pre-carbonized foams was analyzed through XPS, TG-MS, and FT-IR. Among the prepared samples, CF30-CPI-1000 degrees C with small interfacial gaps showed the lowest thermal conductivity, which was as low as 0.56 W/(m center dot K) at 1900 degrees C, and the corresponding compressive strength and elastic modulus were as high as 0.532 MPa and 9.091 MPa, respectively.

Automated summary

This study proposes an efficient approach for fabricating carbon foam-reinforced carbon aerogel composites. By compounding nanoporous polyimide aerogel with pre-carbonized phenolic resin-based carbon foam, co-shrinkage is achieved during co-carbonization, effectively utilizing the thermal insulation capacity of carbon aerogel and formability of pre-carbonized foam.