Preparation Methods and Improvement of Oxidation Resistance of Carbon Aerogel

Carbon foams based on polymeric resins and precursors، due to such properties as low thermal conductivity، good thermal stability، high specific strength and low density، are used in different industries، especially aerospace، as high temperature insulator، thermal shields and material protecting structures. In this study، current methods of preparing carbon nanostructures are introduced. By a polymeric template method polymeric foam and aerogel are produced using the foaming process of polymer precursors of phenolic resins and sol-gel formation. Then، the polymeric nanostructure transforms into carbon foams in a carbonization process. Nevertheless، structural destruction due to oxidation reaction has limited the application of these nanostructures at temperature higher than 400˚C in the air atmosphere. In the next step، the oxidation mechanism of carbon foams is studied. In addition to control and optimization of the process parameters such as temperature of carbonization process، the oxidation-resistant material such as silicon carbide compounds can be used to improve the oxidation resistance of carbon aerogel. Finally، the role of formation of a silicon carbide layer on the surface of carbon pores wall، and the formation of SiC bonds in the carbon aerogel structure by alkoxy silane polymers، as efficient methods that increase the oxidation resistance of the carbon foam، is investigated.