Thermal damage and ablation evaluation of carbon fiber/CNT-phenolic composites with cnt and carbon fibers

Abstract

Since carbon reinforcements are known to enhance the mechanical and thermal properties of high temperature composites, they can be used as heat resistant parts such as in engine nozzles for spacecraft applications. The ablation properties and thermal conductivity of carbon nanotube (CNT) and carbon fiber (CF)/phenolic composites were evaluated for different structures and orientations of carbon fiber/CNT/phenolic composites. It was found that the mechanical and thermal properties of polymer matrix composites were improved significantly with the addition of carbon reinforcement. The concentrations of CF and CNT reinforcing materials used in this study were 30vol% and 0.5wt%, respectively. An oxygen-kerosene (1:1) flame torch was used in the ablation testing of 10 mm thick specimens. During these flame torch tests, the time required to obtain hole-penetration and the temperature at selected sample locations were measured for the different specimens. Thermal conductivity analyses revealed that filler orientation had a significant effect on thermal properties, in that the thermal conductivity of CF mat/phenolic composites was higher than that of random CF/phenolic composites. CF mat and CNT/phenolic composites exhibited much better thermal conductivity and ablation properties than did neat phenolic resin. Heat transfer in the composite structure is affected by the orientation and type of the carbon reinforcements. The more conductive carbon materials helped conduct and dissipate heat from the flame location, thereby minimizing local thermal damage.