Microstructures and bending property of mesophase based C/C composites with air oxidation process

Carbon-carbon composites were fabricated in short period by LPIC (low pressure impregnation carbonization) process with 225°C air oxidation using mesophase pitch as precursor. The microstructures were observed by PLM (polarizing microscope). The bending property and fracture surface were tested by universal testing machine and SEM (scanning electron microscope), respectively. The results show that the carbon yield is improved remarkably with 225°C air oxidation compared with the samples without air-oxidation. After four cycles of LPIC, the density of C/C composites reaches 1.73 g/cm³. Its bending property is 152.39MPa, which is increased 62.87% compared with the samples without air oxidation process. It is concluded that the C/C composites with air oxidation exhibit pseudo-plastic failure behavior and the samples without air-oxidation rupture from interlays with low bending strength. The microstructures of C/C composites without air oxidation are mainly small domains with few mosaic and domain textures. Nevertheless, the composites with 225°C air oxidation present domain textures mainly with small domain and flow domain.