Abstract: A porous substrate having a concave inside face and an outside face is disposed in an enclosure, and reactive gas is introduced into the enclosure to densify the substrate. At least a portion of the gas is divided into two non-zero fractions. The first fraction of the gas is fed to the inside face of the substrate. The second fraction of the gas is fed to only the outside face of the substrate. Alternatively, the first fraction of the gas is fed via a tooling extending into an inside volume defined by the concave inside face of the substrate.

Abstract: Part of the flow of reactive gas admitted into the enclosure (10) is guided to the inside of the volume defined by a concave inside face of the or each hollow-shaped substrate (S1, S2, S3) so that said concave inside face is swept in full by a fraction of the total admitted gas flow.

Abstract: A chemical vapor infiltration method for densifying porous substrates disposed in annular stacks. The substrates to be densified (12) are loaded inside a reaction chamber (11) of an infiltration oven, being disposed in at least one annular stack (30) defining an interior passage (31) with spaces (33) being formed between the substrates. The gas admitted into the reaction chamber is channelled on leaving a preheating zone (18) towards one of the two volumes constituted by the inside and the outside of the, or each, stack of substrates, and preferably towards the smaller volume. This volume (31) is closed at its opposite end so that the gas flows from admission into the chamber to its exhaust from the chamber from the inside to the outside of the, or each, stack, or vice versa, with the gas passing through the spaces between the substrates and diffusing into them.