沥青基碳/碳复合材料压力浸渍-碳化机理分析

Analysis of Process of Densification of Pitch-Based Carbon-Carbon Composites

煤沥青是一种内部成分非常复杂的芳烃类混合物 ,含有许多稠环结构。由于其组成成分的复杂性导致其碳化过程的复杂。液态沥青向制件孔隙内的浸渍过程中 ,既要克服由于液态沥青表面张力所产生的阻力 ,还要克服制件内部孔隙中气体所产生的阻力。经研究表明 ,沥青在常压下碳化 ,大量含碳的低分子成分挥发出去 ,不但造成碳化收率的降低 ,而且也影响了致密效率。沥青在高压下碳化 ,不但提高了碳化收率 ,而且也影响碳化过程 ,有利于基体碳向石墨结构的转变。

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.