%0 Journal Article
%T Hybrid Carbon-Carbon Ablative Composites for Thermal Protection in Aerospace
%A P. Sanoj
%A Balasubramanian Kandasubramanian
%J Journal of Composites
%D 2014
%R 10.1155/2014/825607
%X Composite materials have been steadily substituting metals and alloys due to their better thermomechanical properties. The successful application of composite materials for high temperature zones in aerospace applications has resulted in extensive exploration of cost effective ablative materials. High temperature heat shielding to body, be it external or internal, has become essential in the space vehicles. The heat shielding primarily protects the substrate material from external kinetic heating and the internal insulation protects the subsystems and helps to keep coefficient of thermal expansion low. The external temperature due to kinetic heating may increase to about maximum of 500¡ãC for hypersonic reentry space vehicles while the combustion chamber temperatures in case of rocket and missile engines range between 2000¡ãC and 3000¡ãC. Composite materials of which carbon-carbon composites or the carbon allotropes are the most preferred material for heat shielding applications due to their exceptional chemical and thermal resistance. 1. Introduction Discovery of carbon-carbon composites in 1958 by Brennan Chance Vought Aircraft created an opportunity to these principle materials for heat shielding appliances due to their high strength and thermal resistance [1]. Rayon carbon fabric reinforced phenolic (C¨CPh) composites are the broadly used thermal protection systems due to the low thermal conductivity of the rayon fabric and high char yields of the phenolic resin. In general, carbon phenolic composites show better ablation resistance and continued enhancement of ablative property with the development of a thinner ablative composite structure for better pay load and fuel efficiency [2]. The Space Shuttle Columbia disaster occurred on February 1, 2003, due to the inadequate impact resistance of the thermal insulation foam in the external tank against air, as the spacecraft reentered the earth¡¯s planetary atmospheric domain. The displaced reinforcement foam damaged Columbia¡¯s left reinforced carbon-carbon (RCC) panels thereby causing the unfortunate accident. This incident paves way for a detailed research to enhance impact tolerances, thermal resistance, and fracture toughness of the RCC panels [3]. Polymer nanocomposites are the three phase composite systems invented by Toyota research group, wherein nanosize particles, dispersed in the two phase fiber reinforced composites, exhibit enhanced structural rigidity and ablation resistance [1]. Nanocomposites have the capability to withstand the simultaneous action of thermal stresses and mechanical impact
%U http://www.hindawi.com/journals/jcomp/2014/825607/