Method For Chemical Infiltration in the Gas Phase For the Densification of Porous Substrates With Pyrolytic Carbon

A chemical vapor infiltration method for densifying porous substrates with pyrolytic carbon, the method comprising the steps of:

• loading one or more porous substrates for densifying in an oven;
• admitting into the oven a reaction gas containing a pyrolytic carbon precursor reagent gas having at least one gaseous hydrocarbon CxHy in which x and y are natural integers and x is such that 1<x<6, together with a vector gas comprising at least one gas selected from methane and inert gases;
• extracting from the oven an effluent gas containing residual components of the admitted gas and reaction products, including hydrogen;
• and
• recycling at least a fraction of a gas stream extracted from the effluent gas and containing pyrolytic carbon precursor reagent gas into the reaction gas admitted into the oven, whereby at least a portion of the pyrolytic carbon precursor reagent gas contained in the reaction gas comes from the recycled gas stream.