Effect of the Matrix Volume Fraction on the Oxidation Resistance of Porous Cvi-Processed C/C Composites

The correlation between the amount of chemical vapor infiltrated matrix inside porous C/C composites and their resistance to oxidation was investigated. Three C/C samples with homogeneous matrix fractions from 17% to 59% were oxidized in a thermogravimetric apparatus where a diffusion-control regime was reached. The results showed that the materials effective kinetics are proportional to their initial geometric density. With a tripled matrix content, the recession rate dropped by 50% and the depth affected by oxidation fell by 34%. A high matrix fraction was proved to favor the smallest pore sizes and to increase the tortuosity of the diffusion paths.