Microstructural evolution of phenolic resin-based carbon/carbon composites during pyrolysis

The carbon/carbon (C/C) composites within the matrix-crack microstructure were prepared by pyroly-zing carbon fiber/phenolic resin composite which was compacted by hot pressing. The material density of C/C composites was about 1.27 g/cm³, and the open porosity was 27% alter pyrolysis at 900°C. The alterations of density, open porosity and mass loss during pyrolysis from 200°C to 900°C were investigated. The microstructural evolution of phenolic resin-based C/C composites during pyrolysis was analyzed. The phenolic resin mainly decomposed from 400°C to 700°C, and the decomposition rate was 4 times that of other temperature ranges. A high amount of regularly spaced segmentation cracks formed above 400°C, and further increased and expanded with elevated temperature. A microscopic network of the characteristic interconnecting crack pattern within C/C composites was developed after pyrolysis at 900°C. The total pore volume of C/C composites was 0.17 cm³/g, and 81% of the pores were in the radius range of 122.190-2.440 μm.