Structural changes of micropores in carbons by chemical vapor infiltration of carbon

Chemical vapor infiltration is now being used to produce advanced materials for aerospace applications. It is also applicable to carbons to enhance the resistance against oxidation. In the present study, methane pyrolysis was conducted for several kinds of carbons such as electrode-grade graphite, electrode-grade carbon, coke and activated charcoal. The structural change of micropores (radius < 10 nm) accompanying infiltration and oxidation was investigated because oxidation is considered mainly to occur in such small pores due to their large specific surface area. The change of macropores measured by mercury porosimeter is also shown for comparison with that of fine pores. Pore-size distribution measured by the BET method have shown that the filling mode depends on the pore structure of carbons.