Improvement in the properties of quasi carbon composites by Tailor-made approach

Abstract

Carbon/carbon composites are class of advanced engineering materials that are known for remarkable properties at elevated temperature, possibly used for aircraft brake pad, rocket nozzle and nuclear reactor wall material. Present work deals with new approach to produce quasi carbon composite entirely from the inexpensive pitch material in a single step process, which eliminates the reimpregnation step to achieve desired density. Pitch is an inexpensive product of petroleum industries and it is suitable to produce carbon materials with varieties of structures. Work involves modification of pitch by acid treatment that can improve softening point, char yield, isotropicity and aromaticity of the pitch. Binder pitch was modified by 35 % v/v HNO3 acid and it showed the softening point of 154 °C. Heat treatment was used to eliminate lighter compounds and structural changes were observed. Softening point of modified pitch was measured by standard ring-ball method. Modified pitch was characterized by elemental analysis to know the aromaticity. Modified pitch was used to make quasi carbon composite pellets by Hot-Press method. Density and porosity of quasi carbon composites were measured by standard Mettler-Toledo density meter and kerosene porosity method respectively. Microstructure, isotropicity and thermal stability were also analysed by scanning electron microscope, optical microscope and TGA respectively. Results showed that acid treated pitch has significantly improved density, microstructure and thermal stability of quasi carbon composites by tailor-made approach. This approach can be ultimately used to fabricate fiber reinforced carbon/carbon composites with improved properties.