methods for chemical damfphaseninfiltration a pyrokohlenstoffmatrix inside a porous substrate with recruitment of a thermal gradient in the substrate

摘要

PCT No. PCT/FR94/01074 Sec. 371 Date Apr. 25, 1996 Sec. 102(e) Date Apr. 25, 1996 PCT Filed Sep. 14, 1994 PCT Pub. No. WO95/11867 PCT Pub. Date May 4, 1995The substrate (10) is placed in an enclosure (12) and is heated so as to establish a temperature gradient within the substrate such that the substrate has a temperature in its portions remote from its exposed surfaces that is greater than its temperature at said surfaces. A gas constituting a precursor of carbon and comprising at least one saturated or unsaturated hydrocarbon is admitted into the enclosure, with the formation of pyrolytic carbon be favored in the higher temperature portions of the substrate. The gas comprises a mixture containing at least one saturated or unsaturated hydrocarbon and hydrogen, and the substrate is heated in such a manner as to establish a temperature gradient within the substrate on either side of a temperature of 1500 K, with hydrogen having an inhibiting role at temperatures below 1500 K.