Abstract: The invention relates to a method of making a refractory carbide layer on the accessible surface of a C/C composite material, the method including a step consisting in placing the composite material in contact with a reactive composition in solid form that contains an atomic proportion greater than or equal to one-third and less than or equal to 95% of a metal that is a precursor of a determined carbide having a melting temperature greater than 2000° C., and an atomic proportion of silicon that is greater than or equal to 5% and less than or equal to two-thirds. The method further includes a step consisting in impregnating the accessible surface of the C/C composite material with the reactive composition melted at a temperature that is greater than or equal to the melting temperature of the metal that is a precursor of a determined carbide.

Abstract: A method of densifying a porous substrate with pyrolytic carbon includes loading the substrate into an oven, admitting a reaction gas mixture to the oven, extracting an effluent gas from the oven, and recycling components of the effluent gas into the reaction gas mixture. The reaction gas mixture contains a pyrolytic carbon precursor gas together with a vector gas. The effluent gas contains residual components of the reaction gas mixture together with reaction products, including hydrogen. The recycling is performed after eliminating heavy hydrocarbons contained in the effluent gas.

Abstract: The invention relates to a method of making a refractory carbide layer on the accessible surface of a C/C composite material, the method including a step consisting in placing the composite material in contact with a reactive composition in solid form that contains an atomic proportion greater than or equal to one-third and less than or equal to 95% of a metal that is a precursor of a determined carbide having a melting temperature greater than 2000° C., and an atomic proportion of silicon that is greater than or equal to 5% and less than or equal to two-thirds. The method further includes a step consisting in impregnating the accessible surface of the C/C composite material with the reactive composition melted at a temperature that is greater than or equal to the melting temperature of the metal that is a precursor of a determined carbide.

Abstract: One or more porous substrates for densification (10) are loaded into an oven (12) into which there is admitted a reaction gas containing a pyrolytic carbon precursor gas comprising at least one gaseous hydrocarbons CxHy in which x and y are 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. Effluent gas containing residual components of the admitted gas together with reaction products, including hydrogen, is extracted from the oven and at least a fraction of a gas stream extracted from the effluent gas and containing pyrolytic carbon precursor reagent gas is recycled (circuit 80) into the reaction gas admitted into the oven, the recycling being performed after eliminating heavy hydrocarbons (treatment 40) contained in the effluent gas.

Abstract: Carbon nanotubes are incorporated in the fiber structure by growing them on the refractory fibers of the substrate so as to obtain a three-dimensional substrate made of refractory fibers and enriched in carbon nanotubes. The substrate is densified with a matrix to form a part of composite material such as a friction part of C/C composite material.

Abstract: Carbon nanotubes are incorporated in the fiber structure by growing them on the refractory fibers of the substrate so as to obtain a three-dimensional substrate made of refractory fibers and enriched in carbon nanotubes. The substrate is densified with a matrix to form a part of composite material such as a friction part of C/C composite material.

Abstract: The invention concerns (1) thermochemically treating by pack-cementation a carbon-containing material, which may have an open porosity, to generate a refractory carbide coating on its surface and, if the material is porous, within the material; and (2) the use of specific alloys as a pack for thermochemically treating carbon-containing materials, optionally with an open porosity, in a halogenated atmosphere. Pack-cementation is carried out under reduced pressure using an element E (to be transported and to be reacted with the carbon in the material to generate the expected carbide) alloyed to an element M, and using a halide (chloride or fluoride, preferably a fluoride) of the same element M, of low volatility, present in the solid form.

Abstract: The present invention provides a method of densifying porous structures by chemical vapor infiltration. In characteristic manner, said densification method is implemented using toluene as a precursor for carbon. Said toluene is generally used mixed with at least one carrier gas.

Abstract: A reaction gas containing methyltrichlorosilane (MTS) and hydrogen is injected into the infiltration chamber (30) in which the substrate is placed and where predetermined infiltration temperature and pressure conditions obtain. The gas entering the infiltration chamber is preheated (by plates 46) so as to bring it up to temperature before coming into contact with the substrate. The residual gas containing the remainder of the reaction gas together with gaseous reaction products is extracted from the chamber. Infiltration is performed at a temperature lying in the range 960.degree. C. to 1050.degree. C., and preferably in the range 1000.degree. C. to 1030.degree. C., under a total pressure of not more than 25 kPa, and preferably equal to 7 kPa to 12 kPa, and the concentration of silicon-containing species in the residual gas is lowered at the outlet from the infiltration chamber, e.g. by injecting an inert gas (via 70).

Abstract: The substrate (10) is placed in an enclosure (12) and is heated so as to establish therein a temperature gradient such that the substrate has a higher temperature in portions that are remote from its exposed surfaces than at its exposed surfaces. A reaction gas constituting a precursor for the material to be infiltrated is admitted into the enclosure, with formation of the material being enhanced in those portions of the substrate that are at higher temperature. At the beginning of the infiltration process, and at least during the major portion thereof, substrate heating is controlled in such a manner as to maintain the temperature of its exposed surfaces at a value that is no greater than the minimum temperature for the reaction gas to deposit the material that is to be infiltrated, while portions of the substrate that are remote from its exposed surfaces are at a temperature that is greater than the minimum temperature for deposition.

Abstract: A fiber preform is initially consolidated by being impregnated with a thermosetting impregnation composition that contains a ceramic precursor, and by heat treatment at the end of which the precursor has been transformed into ceramic, without passing through a meltable phase. The consolidated preform is then densified. The impregnation composition is constituted by a mixture of a thermosetting monomer and a ceramic precursor polymer, and the monomer is cross-linked during the heat treatment so as to achieve "in situ" cross-linking of the polymer mixture prior to transforming the precursor into ceramic.