压汞法分析C/C复合材料平板的孔隙结构

Investigation of Pore Structures of C/C Composite Plates by Mercury Intrusion Method

以PAN基炭纤维针刺整体毡为预制体,经CVI增密获得了C/C复合材料平板,采用压汞法分析了该材料的孔隙结构。结果表明,随着CVI增密过程的进行,材料的孔隙率和平均孔径下降,但孔隙数量先上升后下降,在密度为1.2 g/cm3时达到最高点;孔隙的最可几孔径随密度升高而降低并向15μm趋近;大于60μm的大孔体积分数随密度升高而下降,小于1μm的微孔体积分数上升;比表面主要贡献来自孔径小于20 nm的微孔,在密度为1.46 g/cm3时,比表面最大。

Plates of C/C composite were prepared by using needle-punched felt as preforms and densifying the composite with CVI. The pore structure was investigated by means of mercury intrusion method. The results showed that the porosity and the average pore diameter decreased, however, the pore quantity increased first and decreased later and reached to the highest point at 1.2 g/cm^3 during the densification process. The most probable pore size decreased with the increase of the density and approached to 15 p.m. The volume fraction of macropores over 60 μm decreased while that of micropores below 1 μm increased with the increase of the density. The specific area can be mainly attributed to micropores below 20 nm, which reaches the highest point at 1.46 g/cm^3.