Microwave assisted chemical vapor infiltration for the rapid fabrication of carbon/carbon composites

Microwave assisted chemical vapor infiltration for the rapid fabrication of carbon/carbon (C/C) composites was investigated at 1 000-1 150 °C for different times using carbon felts as substrates and methane as carbon precursor. The temperature and density distribution in the felts were measured and the densification kinetics were investigated. It is found that the highest density of the C/C composite prepared by this method is 1.84 g/cm³ with a densification rate of 0.063 g·cm⁻³·h^-1. The mechanism of the effective and rapid densification is accounted for by a densification from the inside to the outside of the felts under an inverted temperature gradient, an increase of the available active sites for carbon deposition, an increase of collision probability between hydrocarbon species and carbon fibers, and a catalytic effect of microwaves for the pyrolysis of methane.