Vapor phase chemical infiltration process of a material into a porous substrate at controlled surface temperature

A method for infiltrating a material into a porous substrate by chemical vapor infiltration, comprising the steps of:

• providing a substrate made of an electrically conductive material;
• placing the substrate in an enclosure;
• heating the substrate in the enclosure by causing a current to flow through an induction winding located outside the enclosure, and induction coupled directly with the substrate, said heating being performed so as to create a temperature gradient within the substrate such that the temperature T.sub.S at an exposed surface of the substrate is lower than the temperature in portions of the substrate remote from said exposed surface;
• admitting into said enclosure a reaction gas that includes a precursor for the material to be infiltrated, transformation of the precursor into said material being enhanced in portions of the substrate of higher temperature;
• measuring the temperature of the substrate at the exposed surface;
• and
• controlling the current flowing through the induction winding at the beginning of the infiltration process and at least during the major portion thereof, in order to maintain the temperature at the exposed surface at a value which is no greater than a minimum deposition temperature required for said material to be formed, while the temperature in portions of the substrate remote from the exposed surface is greater than said minimum deposition temperature.