STRUCTURAL-CHANGES OF MICROPORES IN CARBONS BY CHEMICAL-VAPOR INFILTRATION OF CARBON

Chemical vapor infiltration is now being used to produce advanced mate rials for aerospace applications. It is also applicable to carbons to enhance the resistance against oxidation. In the present study, methan e pyrolysis was conducted for several kinds of carbons such as electro de-grade graphite, electrode-grade carbon, coke and activated charcoal . The structural change of micropores (radius < 10 nm) accompanying in filtration and oxidation was investigated because oxidation is conside red mainly to occur in such small pores due to their large specific su rface area. The change of macropores measured by mercury porosimeter i s also shown for comparison with that of fine pores. Pore-size distrib ution measured by the BET method have shown that the filling mode depe nds on the pore structure of carbons.