Abstract: A method of chemical vapor infiltration or deposition includes forming silicon carbide in pores of a porous substrate or on a surface of a substrate, the substrate being placed in a reaction enclosure, the silicon carbide being formed from a gas phase introduced into the reaction enclosure, the gas phase including a reagent compound that is a precursor of silicon carbide and that has the following formula in which n is an integer equal to 0 or 1; m is an integer lying in the range 1 to 3; p is an integer lying in the range 0 to 2 with m+p=3; and R designates —H or —CH3; a ratio C/Si between the number of carbon atoms and the number of silicon atoms in the introduced gas phase lying in the range 2 to 3.

Abstract: A shaping tooling for chemical vapor infiltration of a fiber preform includes a structural enclosure formed by supports each provided with a multiply-perforated zone. Each of the supports has in its inside face an uncased zone that includes the multiply-perforated zone. The shaping tooling further includes first and second shaping mold functional elements, each present in a respective one of the uncased zones of the support. Each shaping mold functional element has a first face of a determined shape corresponding to the shape of the part that is to be made and a second face that is held facing the inside face of a support. Each functional element has a plurality of perforations and presents a number of perforations, a size of perforations, or a shape of perforations that differs from the number, the size, or the shape of the perforations present in the facing support.

Abstract: A shaping tooling for chemical vapor infiltration of a fiber preform includes a structural enclosure formed by supports each provided with a multiply-perforated zone. Each of the supports has in its inside face an uncased zone that includes the multiply-perforated zone. The shaping tooling further includes first and second shaping mold functional elements, each present in a respective one of the uncased zones of the support. Each shaping mold functional element has a first face of a determined shape corresponding to the shape of the part that is to be made and a second face that is held facing the inside face of a support. Each functional element has a plurality of perforations and presents a number of perforations, a size of perforations, or a shape of perforations that differs from the number, the size, or the shape of the perforations present in the facing support.

Abstract: A method of chemical vapor infiltration or deposition includes forming silicon carbide in pores of a porous substrate or on a surface of a substrate, the substrate being placed in a reaction enclosure, the silicon carbide being formed from a gas phase introduced into the reaction enclosure, the gas phase including a reagent compound that is a precursor of silicon carbide and that has the following formula in which n is an integer equal to 0 or 1; m is an integer lying in the range 1 to 3; p is an integer lying in the range 0 to 2 with m+p=3; and R designates —H or —CH3; a ratio C/Si between the number of carbon atoms and the number of silicon atoms in the introduced gas phase lying in the range 2 to 3.

Abstract: An installation for chemical vapor infiltration of porous preforms of three-dimensional shape extending mainly in a longitudinal direction, the installation comprising a reaction chamber of parallelepiped shape, the side walls of the reaction chamber including heater means and a plurality of stacks of loader devices arranged in the reaction chamber. Each loader device being in the form of an enclosure of parallelepiped shape provided with support elements for receiving porous preforms for infiltrating.

Abstract: A loader device for loading porous substrates of three-dimensional shapes extending mainly in a longitudinal direction into a reaction chamber of an infiltration oven for densification of the preforms by directed flow chemical vapor infiltration. The device comprising at least one annular loader stage formed by first and second annular vertical walls arranged coaxially relative to each other and defining between them an annular loader space for the porous substrates to be densified. First and second plates respectively cover the bottom portion and the top portion of the annular loader space. The first and second annular vertical walls include support elements arranged in the annular loader space so as to define between them unit loader cells, each for receiving a respective substrate to be densified. The device also comprises gas feed orifices and gas exhaust orifices in the vicinity of each unit loader cell.

Abstract: A loader device is arranged for densifying porous preforms of stackable shape by means of directed stream chemical vapor infiltration in a reaction chamber of an infiltration oven. The device comprises a support tray, a first stack having a plurality of bottom rings arranged on the support tray and a plurality of injection orifices, a second stack comprising a plurality of top rings and a plurality of discharge orifices extending between the outer periphery and inner periphery of each ring. The device includes a first non-porous wall corresponding to the porous preforms and arranged on the support tray inside the bottom rings of the first stack, and a second non-porous wall corresponding to the porous preforms extending between the bottom ring situated at the top of the first stack and the top ring situated at the top of the second stack.

Abstract: A composite material part having a matrix made of ceramic, at least for the most part, is fabricated by a method including making a fiber preform from silicon carbide fibers containing less than 1 at % oxygen; depositing a boron nitride interphase on the fibers of the preform, deposition being performed by chemical vapor infiltration at a deposition rate of less than 0.3 ?m/h; performing heat treatment to stabilize the boron nitride of the interphase, after the interphase has been deposited, without prior exposure of the interphase to an oxidizing atmosphere and before depositing matrix layer on the interphase, the heat treatment being performed at a temperature higher than 1300° C. and not less than the maximum temperature to be encountered subsequently until the densification of the preform with the matrix has been completed; and thereafter, densifying the perform with a matrix that is made of ceramic, at least for the most part.

Abstract: A composite material part having a matrix made of ceramic, at least for the most part, is fabricated by a method comprising making a fiber preform from silicon carbide fibers containing less than 1 at % oxygen; depositing a boron nitride interphase on the fibers of the preform, deposition being performed by chemical vapor infiltration at a deposition rate of less than 0.3 ?m/h; performing heat treatment to stabilize the boron nitride of the interphase, after the interphase has been deposited, without prior exposure of the interphase to an oxidizing atmosphere and before depositing matrix layer on the interphase, the heat treatment being performed at a temperature higher than 1300° C. and not less than the maximum temperature to be encountered subsequently until the densification of the preform with the matrix has been completed; and thereafter, densifying the preform with a matrix that is made of ceramic, at least for the most part.

Abstract: An installation for chemical vapor infiltration of porous preforms of three-dimensional shape extending mainly in a longitudinal direction, the installation comprising a reaction chamber of parallelepiped shape, the side walls of the reaction chamber including heater means and a plurality of stacks of loader devices arranged in the reaction chamber. Each loader device being in the form of an enclosure of parallelepiped shape provided with support elements for receiving porous preforms for infiltrating.

Abstract: A loader device is arranged for densifying porous preforms of stackable shape by means of directed stream chemical vapor infiltration in a reaction chamber of an infiltration oven. The device comprises a support tray, a first stack having a plurality of bottom rings arranged on the support tray and a plurality of injection orifices, a second stack comprising a plurality of top rings and a plurality of discharge orifices extending between the outer periphery and inner periphery of each ring. The device includes a first non-porous wall corresponding to the porous preforms and arranged on the support tray inside the bottom rings of the first stack, and a second non-porous wall corresponding to the porous preforms extending between the bottom ring situated at the top of the first stack and the top ring situated at the top of the second stack.

Abstract: A loader device for loading porous substrates of three-dimensional shapes extending mainly in a longitudinal direction into a reaction chamber of an infiltration oven for densification of the preforms by directed flow chemical vapor infiltration. The device comprising at least one annular loader stage formed by first and second annular vertical walls arranged coaxially relative to each other and defining between them an annular loader space for the porous substrates to be densified. First and second plates respectively cover the bottom portion and the top portion of the annular loader space. The first and second annular vertical walls include support elements arranged in the annular loader space so as to define between them unit loader cells, each for receiving a respective substrate to be densified. The device also comprises gas feed orifices and gas exhaust orifices in the vicinity of each unit loader cell.

Abstract: To densify thin porous substrates (1) by chemical vapor infiltration, the invention proposes using loading tooling (10) comprising a tubular duct (10) disposed between first and second plates (12, 13) and around which the thin substrates for densification are disposed radially. The tooling as loaded in this way is then placed inside a reaction chamber (20) in an infiltration oven having a reactive gas admission inlet (21) connected to the tubular duct (11) to enable a reactive gas to be admitted into the duct which distributes the gas along the main faces on the substrates (1) in a flow direction that is essentially radial. The reactive gas can also flow in the opposite direction, i.e. it can be admitted into the tooling (10) from its outer envelope (16) and can be removed via the duct (11).

Abstract: To densify thin porous substrates (1) by chemical vapor infiltration, the invention proposes using loading tooling (10) comprising a tubular duct (10) disposed between first and second plates (12, 13) and around which the thin substrates for densification are disposed radially. The tooling as loaded in this way is then placed inside a reaction chamber (20) in an infiltration oven having a reactive gas admission inlet (21) connected to the tubular duct (11) to enable a reactive gas to be admitted into the duct which distributes the gas along the main faces on the substrates (1) in a flow direction that is essentially radial. The reactive gas can also flow in the opposite direction, i.e. it can be admitted into the tooling (10) from its outer envelope (16) and can be removed via the duct (11).

Abstract: To densify thin porous substrates (1) by chemical vapor infiltration, the invention proposes using loading tooling (10) comprising a tubular duct (10) disposed between first and second plates (12, 13) and around which the thin substrates for densification are disposed radially. The tooling as loaded in this way is then placed inside a reaction chamber (20) in an infiltration oven having a reactive gas admission inlet (21) connected to the tubular duct (11) to enable a reactive gas to be admitted into the duct which distributes the gas along the main faces on the substrates (1) in a flow direction that is essentially radial. The reactive gas can also flow in the opposite direction, i.e. it can be admitted into the tooling (10) from its outer envelope (16) and can be removed via the duct (11).

Abstract: A method of densifying porous substrates by chemical vapor infiltration comprises loading porous substrates for densification in a loading zone of an enclosure (10), heating the internal volume of the enclosure, and introducing a reagent gas into the enclosure though an inlet situated at one end of the enclosure. Before coming into contact with substrates (20) situated in the loading zone, the reagent gas admitted into the enclosure is preheated, at least in part, by passing along a duct (30) connected to the gas inlet and extending through the loading zone, the duct being raised to the temperature inside the enclosure, and the preheated reagent gas is distributed in the loading zone through one or more openings (33) formed in the side wall (32) of the duct, along the duct.

Abstract: A composite material part is made by forming a fiber preform (20), forming holes (22) extending within the preform from at least one face thereof, and densifying the preform with a matrix formed at least in part by a chemical vapor infiltration (CVI) type process. The holes (22) are formed by removing material from the preform with fibers being ruptured, for example by machining using a jet of water under pressure, the arrangement of the fibers in the preform with the holes being substantially unchanged compared with the initial arrangement before the holes were formed. This enables the densification gradient to be greatly reduced, and it is possible in a single densification cycle to obtain a density that, in the prior art, required a plurality of cycles separated by intermediate scalping.

Abstract: To densify thin porous substrates (1) by chemical vapor infiltration, the invention proposes using loading tooling (10) comprising a tubular duct (10) disposed between first and second plates (12, 13) and around which the thin substrates for densification are disposed radially. The tooling as loaded in this way is then placed inside a reaction chamber (20) in an infiltration oven having a reactive gas admission inlet (21) connected to the tubular duct (11) to enable a reactive gas to be admitted into the duct which distributes the gas along the main faces on the substrates (1) in a flow direction that is essentially radial. The reactive gas can also flow in the opposite direction, i.e. it can be admitted into the tooling (10) from its outer envelope (16) and can be removed via the duct (11).

Abstract: Annular substrates (20) are stacked in an enclosure where they define an inside volume (24) and an outer volume (26) outside the stack. A gas containing at least one precursor of a matrix material to be deposited within the pores of the substrates is channeled inside the enclosure to a first one (24) of the two volumes, and a residual gas is extracted from the enclosure from the other one (26) of the volumes. One or more leakage passages (22) allow the volumes to communicate with each other, other than through the substrates. The total section of the leakage passages has a value lying between a minimum value for ensuring that a maximum gas pressure in the first volume is not exceeded until the end of densification, and a maximum value such that a pressure difference is indeed established between the two volumes from the beginning of densification.

Abstract: A method of densifying porous substrates by chemical vapor infiltration comprises loading porous substrates for densification in a loading zone of an enclosure (10), heating the internal volume of the enclosure, and introducing a reagent gas into the enclosure though an inlet situated at one end of the enclosure. Before coming into contact with substrates (20) situated in the loading zone, the reagent gas admitted into the enclosure is preheated, at least in part, by passing along a duct (30) connected to the gas inlet and extending through the loading zone, the duct being raised to the temperature inside the enclosure, and the preheated reagent gas is distributed in the loading zone through one or more openings (33) formed in the side wall (32) of the duct, along the duct.