Fabrication of Large Aerogel-Like Carbon/Carbon Composites with Excellent Load-Bearing Capacity and Thermal-Insulating Performance at 1800 °C

Abstract

Carbon aerogels (CAs) are attractive candidates for the thermal protection of aerospace vehicles due to their excellent thermostability and thermal insulation. However, the brittleness and low mechanical strength severely limits their practical applications, and no significant breakthroughs in large CAs with a high strength have been made. We report a high-pressure-assisted polymerization method combined with ambient pressure drying to fabricate large, strong, crack-free carbon/carbon (C/C) composites with an excellent load-bearing capacity, thermal stability, and thermal insulation. The composites are comprised of an aerogel-like carbon matrix and a low carbon crystallinity fiber reinforcement, featuring overlapping nanoparticles, macro-mesopores, large particle contact necks, and strong fiber/matrix interfacial bonding. The resulting C/C composites with a medium density of 0.6 g cm–3 have a very high compressive strength (80 MPa), in-plane shear strength (20 MPa), and specific strength (133 MPa g–1 cm3). Moreover, the C/C composites of 7.5–12.0 mm in thickness exposed to an oxyacetylene flame at 1800 °C for 900 s display very low back-side temperatures of 778–685 °C and even better mechanical properties after the heating. This performance makes the composites ideal for the ultrahigh temperature thermal protection of aerospace vehicles where both excellent thermal-insulating and load-bearing capacities are required.

An Unusual Carbon–Ceramic Composite with Gradients in Composition and Porosity Delivering Outstanding Thermal Protection Performance up to 1900 °C

“…It was prepared by the simple high-pressure-assisted polymerization with ambient pressure drying of a linear phenolic resin and needled phenolic fiber felt as the respective matrix and filler precursors. [13] The C/CA had a low density of 0.6 g cm -3 and a high compressive strength of 80 MPa. A ceramic layer was then synthesized on top of the C/CA composite using the following method.…”

“…[12] We have developed a large, strong, crack-free carbon fiber reinforced analogous CA matrix (C/CA) composite, which has a low density of 0.6 g cm -3 , a high specific strength of 133 MPa g -1 cm 3 , and excellent thermal insulation and stability at ultra-high temperatures. [13] However, their major weakness is oxidation at temperatures above 400 °C, just like other carbon-based materials.…”

“…However, to the best of our knowledge, there are only some reports on the formation of ceramic layers on the surface of traditional dense C/C and porous CBCF composites. These methods can be divided into three categories: 1) spreading ceramic particles on the specimen surface to form a continuous coating by physical means such as slurry brushing, [ 14 ] dipping or thermal spraying; [ 15 ] 2) forming a ceramic coating by a reaction between the carbon substrate and silicon or metals by pack cementation, [ 16 ] liquid silicon infiltration, [ 17 ] or gaseous silicon infiltration; [ 18 ] and 3) depositing a ceramic coating such as SiC, HfC, and TaC by decomposition of gaseous precursors by chemical vapor deposition (CVD). [ 19 ] However, the unique structural characteristics of the C/CA composite make it very difficult to prepare a ceramic layer on its surface using these traditional methods.…”

Recent Progress in 1D Nanostructures Reinforced Carbon/Carbon Composites

“…[1][2][3][4][5] With the rapid development of aerospace vehicles and the complexity of service environ ment, it is urgent to develop new generation of C/C composites with the greatly improved performance and integrated multifunctions. [6][7][8][9][10][11][12] For example, for traditional C/C composites, carbon matrix is strengthened by carbon fibers in macroscale, but carbon matrix between carbon fiber bundles and between carbon fibers in bundle cannot be effectively strengthened in nanoscale. [13] Thus, the properties of thinwalled and sharp C/C composites are not ideal due to the limited amount of carbon fibers and the brittleness of carbon matrix.…”

Design of Economical and Achievable Aluminum Carbon Composite Aerogel for Efficient Thermal Protection of Aerospace

“…A tremendous amount of research is currently focused on carbon-based materials, which have the ability to withstand ultrahigh temperatures up to 3000 °C [ 5 ], making them the most promising candidates for lightweight aerospace materials [ 6 ]. Carbon aerogel (CA) possesses an abundant mesoporous and superimposed nanoparticle network, which confers it various unique properties, such as high specific surface area and extremely low density [ 7 ].…”