CONSOLIDATION METHOD USING GAS PHASE INFILTRATION

Abstract

A method of consolidation includes placing a fibrous preform in the shaping recess of a shaping tool, and supplying the shaping tool with a gas phase to obtain a deposit in the fibrous preform, the shaping tool for the vapor phase chemical infiltration including first and second portions, having respectively first and second shaping zones surrounded by a first and second edge zones, the first and the second shaping zone defining a shaping recess to receive the fibrous preform. A gas injection port is present at least partially in the first or second edge zone and a gas outlet port is present at least partially in the first or second edge zone, the gas injection port and the gas outlet port placing the shaping recess in fluid communication with the outside of the shaping tool. Outer faces of the first and second portion are impermeable to gas.

Claims

1. A consolidation method comprising: placing a fibrous preform in a shaping recess of a shaping tool, supplying the shaping tool with a gas phase to obtain a deposit in the fibrous preform, the shaping tool for the vapor phase chemical infiltration of a fibrous preform comprising a first portion, one face of which has a first shaping zone surrounded by a first edge zone, and a second portion, one face of which has a second shaping zone surrounded by a second edge zone, the first and the second shaping zone defining, when the first edge zone is brought into contact with the second edge zone, a shaping recess with a given shape intended to receive the fibrous preform, wherein at least one gas injection port is present at least partially in the first or in the second edge zone and a gas outlet port is present at least partially in the first or in the second edge zone, the gas injection port and the gas outlet port placing the shaping recess in fluid communication with the outside of the shaping tool, and wherein outer faces of the first and of the second portion are impermeable to gas.

2. The consolidation method according to claim 1, wherein the shaping tool comprises a first portion of a gas injection port provided in the first edge zone, and a second portion of a gas injection port in the second edge zone.

3. The consolidation method according to claim 1, wherein the shaping tool comprises a first portion of a gas outlet port provided in the first edge zone, and a second portion of a gas outlet port in the second edge zone.

4. The consolidation method according to claim 1, wherein the shaping tool further comprises a gasket between the first and the second edge zones.

5. The consolidation method according to claim 1, wherein at least one of the first and second shaping zones of the shaping tool comprises one or more gas phase flow relief(s).

6. An installation for the densification of fibrous preforms the implementation of a method according to claim 1, comprising a shaping tool, a heater for heating the shaping tool and a gas phase source connected to the gas injection port of the shaping tool.

7. The installation for the densification of fibrous preforms according to claim 6, further comprising an effluent reaction zone connected to the gas outlet port of the shaping tool.

8. The installation for the densification of fibrous preforms according to claim 6, further comprising an intermediate zone between the gas phase source and the shaping tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1 shows a shaping tool in an embodiment of a method according to the invention.

[0049] FIG. 2 shows a shaping tool in another embodiment of a method according to the invention.

[0050] FIG. 3 shows a shaping tool in an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

[0051] Shaping tools according to embodiments of methods of the invention will now be described in connection with the figures, which must not be interpreted as limiting the invention.

[0052] FIG. 1 shows a shaping tool 100 according to a first embodiment.

[0053] A tool 100 of this type is formed of a first portion 110 and a second portion 120. These two portions 110, 120 can be held together by means of screws 130 and nuts 140 passing through the first portion 110 through ports 111 and the second portion through ports 121 provided for this purpose in the edge zones of the first and second portions.

[0054] The second portion comprises a shaping zone 122 and an edge zone 123. The shaping zone 122 has, in this embodiment, an indentation with respect to the edge zone 123. The shape of the indentation in the shaping zone 122 can be selected to conform to the shape desired for the part that it is desired to obtain after consolidation.

[0055] What is meant here by “consolidation” is a partial densification of a fibrous preform to a level sufficient for obtaining a self-supporting preform which can subsequently be placed in a densification oven, without a shaping tool, to finalize its densification.

[0056] In the embodiment shown in FIG. 1, the first portion 110 can be identical to the second portion 120.

[0057] In this embodiment, the contacting of the edge zone 123 of the second portion with the edge zone of the first portion defines a shaping recess by the association of the indentation provided between the shaping zone 122 and the edge zone 123 of the second portion, and that of the shaping zone of the first portion not visible in the drawing. In the embodiment shown, the contacting of the two edge zones also allows forming, in the edge zones, a gas injection port 125 and a gas outlet port 124.

[0058] In an embodiment not shown in the figures, the gas injection port 125 can be entirely provided in the edge zone of the first portion or in that of the second portion.

[0059] In the shaping tool 100 shown, the gas injection port 125 and the gas outlet port 124 are formed by the reunion of two complementary openings provided in the edge zones of the first and second portions.

[0060] In an embodiment not shown in the figures, the gas outlet port can be entirely provided in the edge zone of the first portion or in that of the second portion.

[0061] In a shaping tool for a method of the invention, the passage of the reactive gas phase through the fibrous preform is forced by the geometry of the shaper. In fact, due to the sealing of the shaping recess between the gas injection port and the gas outlet port, the entirety of the gas phase passes into the fibrous preform.

[0062] In the embodiment presented, the outer face of the first portion 110 is impermeable to gas, and the same is true for the outer face of the second portion.

[0063] Thus, the gas phase can only enter into the shaping recess or leave it via the gas injection port 125 and the gas outlet port 124.

[0064] The impermeability to gas of the outer face of the first and of the second portion can be ensured by the material selected for the first and second portion.

[0065] In one embodiment, the first and the second portion can be produced in graphite. In another embodiment, the first and the second portion can be made of C/C composite material, sealed if necessary by a surface deposit or seal coat. In another embodiment, the first portion 110 and the second portion 120 can be made of sintered SiC material.

[0066] FIG. 2 shows a shaping tool according to another embodiment of a method of the invention.

[0067] As with the tool shown in FIG. 1, the tool has a first portion 210 and a second portion 220. The second portion has a shaping zone 222, and an edge zone 223. The first portion 210 is symmetrical with the second 220.

[0068] Ports 211 and 221 allowing the passage of screws 230 through the first and the second portion are present. They allow closing the shaping tool by means of screws 230 and nuts 240.

[0069] The tool shown further comprises gaskets 250 placed between the edge zones of the first and second portions 210, 220. These gaskets also have ports 251 allowing ensuring the passage of the screws 230.

[0070] In this embodiment, the gaskets insure improved sealing for the shaping recess. As described above, the sealing of the shaping zone allows ensuring a deposit from the gas phase solely in the fibrous preform housed in the shaping recess.

[0071] The gaskets 250 can have a width that is less than or equal to the width of the edge zone.

[0072] In the embodiment shown in FIG. 2, gas phase flow reliefs 226 are present in the second shaping zone 222. Gas phase flow reliefs can also be present in the first shaping zone not visible in the drawing.

[0073] These flow reliefs allow the gas phase to circulate in the shaping recess when the fibrous preform is present in it. Thus, the gas phase can penetrate into the fibrous preform all along the fibrous preform, and thus all plugging of the pores of the fibrous preform facing the gas injection port 225 is avoided.

[0074] Such flow reliefs 226 can for example be etched into the shaping zone 222. Of course, the dimension of the gas phase flow reliefs 226 is selected to not substantially modify the shape of the shaping recess.

[0075] In one embodiment, the grooves can have a width not exceeding 3.0 mm, comprised for example between 0.1 mm and 3.0 mm.

[0076] In one possibly complementary embodiment, the grooves form an angle comprised between 1° and 45°, preferably comprised between 1° and 20°, or between 2° and 10° with respect to the direction of the fibers in the texture introduced into the shaping zone.

[0077] An angle of this type between the grooves and the fibers of the preform allows ensuring that the yarns of the texture cannot expand in the groove, which further reduces the risk of the formation of pimples.

[0078] In one embodiment, the preform is introduced into the shaping zone 222 so that the fibers of the preform are substantially parallel to the direction between the gas injection port 225 and the gas outlet port 224. In this embodiment, the angle formed by the grooves is measured with respect to the direction between the gas injection port 225 and the gas outlet port 224.

[0079] For example, the gas phase flow reliefs 226 can be grooves etched in the shaping zone 222, parallel to the direction between the gas injection port 225 and the gas outlet port 224 or forming an angle with this direction as specified above. Such flow reliefs can for example have a depth comprised between 0.1 mm and 3.0 mm, a spacing between two grooves comprised between 2.0 mm and 5.0 mm, and a width comprised between 0.1 mm and 3.0 mm.

[0080] For example, the grooves can have a length comprised between 10% and 100% of the length of the shaping zone.

[0081] As specified above, such gas phase flow reliefs 226 are particularly advantageous in the case where the gas phase depletes rapidly when it passes through the fibrous preform, or there exists a deposit inhibition phenomenon. In fact, such flow reliefs allow the penetration of the gas phase into the preform all along the routing direction of the gas phase, from the gas injection port 225 to the gas outlet port 224, and thus the homogeneity and the densification of the part obtained after densification is better than in the absence of gas phase flow reliefs 226.

[0082] FIG. 3 shows an installation according to the invention allowing the consolidation of fibrous preforms by vapor phase chemical deposition.

[0083] And installation 300 of this type comprises a shaping tool 310, or shaper, according to an embodiment described above.

[0084] The installation 300 further comprises a means of heating the shaping tool 350. Any heating mode can be used provided that it allows attaining the desired deposition temperatures. For example, in the embodiment presented, heating is provided by radiation and convection via graphite bars 350 located in proximity to the shaping tool 310.

[0085] The densification installation 300 further comprises a gas phase source, not shown, and a pipe for routing the gas phase 320 receiving the gas from the gas phase source, the routing pipe 320 being in communication with the gas injection port of the shaper.

[0086] A densification installation according to the invention can comprise several gas phase sources. For example it is possible to have two distinct gas phase sources, and the user can select which of the two sources he wishes to connect to the routing pipe 320.

[0087] An embodiment of this type allows accomplishing two successive treatments of the same fibrous preform, without replacing the source, but simply by connecting the routing pipe 320 to one or to the other of the sources. This embodiment is particularly preferred with an interphase is deposited on the fibrous preform, before its densification.

[0088] In one embodiment of the invention, the same gas phase source allows supplying several consolidation installations 300.

[0089] In the embodiment shown, the densification installation 300 also comprises a gas outlet pipe 330 in communication with the gas outlet port of the shaper.

[0090] The installation 300 shown also has an insulating enclosure 340. An enclosure of this type allows optimizing the heating capacity of the heating system 350 by reducing the heat which is not transmitted to the shaping tool.

EXAMPLES

Example 1: Consolidation of a Preform with an Interphase

[0091] A 3D texture based on HiNiC type S silicon carbide fibers is introduced into a shaping tool made of graphite as described above.

[0092] The deposition of a BN interphase is accomplished by connecting a gas phase source to the gas injection port of the shaping tool. The gas phase source provides a supply of NH.sub.3 and BCl.sub.3, the flow rate ration between NH.sub.3 and BCl.sub.3 being comprised between 1 and 3 and NH.sub.3 and BCl.sub.3 being diluted in a gas selected among dihydrogen, dinitrogen or argon, advantageously dinitrogen. The BN deposit is accomplished at a temperature comprised between 700° C. and 900° C.

[0093] The gas phase source provides an NH.sub.3 flow rate comprised between 100 and 1000 standard cm.sup.3 per minute, a BCl.sub.3 flow rate comprised between 100 and 500 standard cm.sup.3 per minute and a diluting gas flow rate comprised between 100 and 5000 standard cm.sup.3 per minute. A BN deposit of approximately 0.3 to 1 μm in thickness is thus obtained.

[0094] The fibrous preform on which the BN has been deposited is then densified by SiC by connecting the gas injection port of the shaping tool to a supply source of methyltrichlorosilane and hydrogen.

[0095] The depositing temperature is comprised between 900° C. and 1050° C. and the pressure comprised between 0.5 and 100 mbar.

[0096] The flow rate ratio between hydrogen and methyltrichlorosilane is comprised between 3 and 15. The flow rate of methyltrichlorosilane is comprised between 20 and 200 standard cm.sup.3 per and the flow rate of hydrogen between 60 and 2000 standard cm.sup.3 per minute, and allows obtaining a deposit of SiC on the BN previously deposited of approximately 0.3 to 2 μm in thickness.

[0097] In this example, the duration of the rise in temperature is on the order of 1 to 2 hours. The duration necessary for the production of the BN interphase is on the order of one hour and the duration of the production of the silicon carbide deposit is on the order of 2 to 3 hours.

[0098] The consolidation of the fibrous preform is therefore obtained in a time approximately ten times less than the time necessary for a shaping method of the prior art.

Example 2: Consolidation of a Preform with an Interphase

[0099] A 3D texture based on HiNiC type S silicon carbide is introduced into a shaping tool made of graphite as described above.

[0100] The deposit of a BN interphase is accomplished by connecting a gas phase source to the gas injection port of the shaping tool. The gas phase source ensures a supply of borazine B.sub.3N.sub.3H.sub.6, diluted in a gas selected among dihydrogen, dinitrogen or argon, advantageously dinitrogen. The BN deposit is accomplished at a temperature comprised between 600° C. and 900° C.

[0101] To produce a BN deposit of approximately 0.3 to 1 μm in thickness, the gas phase source provides a flow rate of borazine comprised between 50 and 500 standard cm.sup.3 per minute and a diluting gas flow rate comprised between 200 and 2000 standard cm.sup.3 per minute.

[0102] The fibrous preform on which the BN has been deposited is then consolidated by SiC by connecting a supply source of silane SiH.sub.4, of ethylene (C.sub.2H.sub.4) and of hydrogen to the gas injection port of the shaping tool.

[0103] The deposition temperature is comprised between 700° C. and 900° C. and the pressure comprised between 0.5 and 10 mbar. The flow rate ratio between silane and ethylene is comprised between 0.5 and 3, advantageously 2.

[0104] The flow rate of silane is comprised between 20 and 200 standard cm.sup.3 per minute, the flow rate of ethylene is comprised between 20 and 150 standard cm.sup.3 per minute and the flow rate of hydrogen is comprised between 20 and 500 standard cm.sup.3 per minute.

[0105] A SiC deposit of approximately 0.3 to 2 μm thickness is thus obtained on the BN previously deposited.

[0106] In this example, the duration of the rise in temperature is on the order of 1 to 2 hours. The duration necessary for the production of the BN interphase is on the order of one hour and the duration of producing the silicon carbide deposit is on the order of 2 to 3 hours.

[0107] The consolidation of the fibrous preform is therefore obtained in a time approximately ten times less than the time necessary for a shaping method of the prior art.

Example 3: Pyrolytic Carbon Deposit

[0108] A 3D texture based on HiNiC type S silicon carbide fibers is introduced into a shaping tool made of graphite, as described above.

[0109] The gas injection port of the shaping tool is connected to a source of gaseous propane. The deposition temperature is comprised between 850° C. and 950° C., the pressure is comprised between 1 and 20 mbar.

[0110] The flow rate of propane from the source is comprised between 50 and 500 standard cm.sup.3 per minute.

[0111] A pyrolytic carbon deposit of approximately 0.3 to 1 μm thickness is obtained.

[0112] In this example, the duration of the temperature rise is on the order of 1 to 2 hours. The duration necessary for the production of the silicon carbide deposit is on the order of 2 to 3 hours.

[0113] The consolidation of the fibrous preform is therefore obtained in a time approximately ten times less than the time necessary for a shaping method of the prior art.

[0114] The examples above have shown that the shaping tool allows a much more rapid consolidation of the fibrous preforms than with the shaping methods of the prior art.