Ultralow density carbon aerogels with low thermal conductivity up to 2000 °C

Ultralow density (0.052 g cm(-3)) carbon aerogels (CAs) were prepared for ultrahigh temperature thermal insulation, and their thermal conductivities were determined by laser flash method. The CAs have a total thermal conductivity as low as 0.601 W m(-1) K(-1), which is only one third of the value for closed-pore carbon foam (CF) with a density of 0.054 g cm(-3), at 2000 degrees C under 0.15 MPa argon. The solid, gaseous, and radiative conductivities of the CA are all much lower than those of the CF, because of the special nanoporous and pearl-necklace nanoparticle structures of the CA. The ultralow density CA clearly demonstrates its great potentials as thermal insulations for extreme applications. (C) 2011 Elsevier B.V. All rights reserved.