Analysis of process of densification of pitch-based carbon-carbon composites

The modulated coal tar pitch (CTP) was used as the precursor of matrix of carbon-carbon composite. The carbonization of the modulated CTP under low and high pressure was investigated with thermal analysis, X-ray diffraction and microstructure analysis. It is shown that under low pressure, a large number of small molecules containing carbon are volatilized, the carbon yield of the modulated CTP is reduced and the densification efficiency of carbon-carbon composite is also reduced. But under high pressure (such as 40 MPa), the carbon yield is increased and the carbonization process is beneficial to structure transition of matrix from turbostatic to graphitic.