Controlling densification of porous substrate with pyrolytic carbon by chemical vapor infiltration with hydrocarbon-containing gas comprises measuring allene, propyne and/or benzene content of effluent gas

摘要

Controlling the densification of a porous substrate with pyrolytic carbon by chemical vapor infiltration with a hydrocarbon-containing gas comprises measuring the allene, propyne and/or benzene content of the effluent gas and, as a function of the measured content, controlling the gas injection rate, gas composition, gas residence time, furnace temperature and/or furnace pressure. Controlling the densification of a porous substrate with pyrolytic carbon by chemical vapor infiltration, in which the substrate is placed in a furnace, the substrate is heated, a hydrocarbon-containing gas is injected, the pressure is adjusted so that the gas diffuses into the pores of the substrate to form a deposit of pyrolyric carbon, and effluent gas is withdrawn through discharge conduit, comprises measuring the allene, propyne and/or benzene content of the effluent gas and, as a function of the measured content, controlling at least one parameter selected from gas injection rate, gas composition, gas residence time, furnace temperature and furnace pressure.