Microstructural investigation and performance of carbon matrix composites developed through facile pitch modification route

Abstract

Increasing demand of high-performance materials lead to development of composites with affordable cost and processing route. Present work involves facile chemical modification (nitric acid and melamine) route to produce carbon matrix composites exhibiting progressive performance. Modified pitches and resultant carbon matrix composites were characterized by FTIR, Optical microscopy, SEM, XRD, TGA, TMA, Tribological study and Compression strength. Chemical treatment given to pitch imparts active functional groups which help to improve affinity between pitch particles. Additionally, to evaluate influence of high temperature treatment, composites were also heated to 1400 °C. Optical images show that microstructure of carbonized (1000 °C) and further heat-treated (1400 °C) composites contain fine isotropic grains and flow domains, attributed to the effective influence of chemical modification. SEM images and Raman spectroscopy also confirmed the similar results of arrangement of carbon layers. TGA analysis revealed that heat-treated composites with acid modified pitch have better thermal stability at 800 °C in zero air. Coefficient of thermal expansion of all composites was measured and found very low i.e. 5 to 10 ppm/°C. Chemical treatment applied to the pitch yielded improved results for tribological performance, coupled with enhanced compressive strength. Notably, up until the present, it was difficult to find report on fabrication of carbon matrix composites from chemically modified pitch.