Method for depositing coating on wire in microwave field

Abstract

A method for treating a carbon or ceramic wire (150), the method comprising: forming a coating on the wire by heating a section (156) of the wire in a microwave field in the presence of a gas phase, at least in a reaction zone (115) of a reactor (220), characterised in that the gas phase comprises a mixture of a diluent gas (200a; 200b) and a coating precursor in the vapor state, and wherein the gas phase is formed at least by introducing the diluent gas into the reactor and mixing the introduced diluent gas with the coating precursor (140) in the reactor before the reaction zone.

Description

Technical Field

[0001] The present invention relates to the general field of methods for depositing coatings on carbon or silicon carbide yarns in the presence of coating precursors in the vapor state by coupling with a microwave field. Background Art

[0002] Ceramic matrix composites (CMCs) are renowned for their excellent mechanical properties, making them suitable for structural components and their ability to maintain these properties at high temperatures, making them a viable alternative to conventional metal components. Their reduced weight compared to their metal equivalents makes them a promising component for addressing the challenges of increasing engine efficiency and reducing polluting emissions in the aviation sector.

[0003] CMC material parts include a fiber reinforcement, generally in the form of a woven fabric, which is densified by a ceramic matrix. The fiber reinforcement can include long filaments grouped together in the form of a thread, the orientation of which can be adapted to the direction of the main stresses on the part during its use. The preform intended to form the fiber reinforcement must be woven from the thread to the part size using a suitable loom (e.g., by two-dimensional or three-dimensional weaving). In order to produce CMC material parts with improved mechanical properties, it is known to use a thread in the fiber preform, which is coated with a mesophase, before the preform is densified.

[0004] Chemical vapor infiltration ("CVI") is known for depositing a mesophase coating onto the threads of a woven fiber preform. Besides the high cost and low kinetics of this technique, the mesophase formed on the thread is often non-uniform, and mesophase thickness gradients can be observed locally between the preform surface and the core, and between the filaments located at the thread surface and the core. Deposition non-uniformity within the preform can reduce the final mechanical properties of the dense component.

[0005] To overcome this problem, the deposition of coatings from precursors in a microwave field has been proposed in document FR 3 075 829. This technique gives satisfactory results, but the homogeneity of the coatings obtained and the control of the stoichiometry still leave room for improvement. Summary of the Invention

[0006] The present invention relates to a method for treating a carbon or ceramic wire, the method comprising forming a coating on the wire by heating a section of the wire in a microwave field in the presence of a gas phase, at least in a reaction zone of a reactor, characterised in that the gas phase comprises a mixture of a diluent gas and a coating precursor in the vapor state, and that the gas phase is formed at least by introducing the diluent gas into the reactor and mixing the introduced diluent gas with the coating precursor in the reactor before the reaction zone.

[0007] A "thread segment" or "segment of a thread" herein corresponds to a certain length of the thread, in other words the segment extends along the length or longest dimension of the thread. The thread may comprise a plurality of filaments and a thread segment may contain a plurality of filaments.

[0008] The line section is heated in the reaction zone by direct coupling via microwaves, which allows its surface to reach a temperature sufficient to form a coating by the coating precursor in a vapor state. The line section is heated as a whole, which allows uniform and rapid coating formation on the line section with limited energy because the line section is directly heated by the microwave field. In addition, the present invention proposes to supply a diluent gas in the reactor before the reaction zone, which is mixed with the precursor. The use of the diluent gas allows dilution of the reagent rate and controls deposition kinetics, thereby obtaining a more uniform deposition. As will be described in detail below, the diluent gas can be mixed with the coating precursor that is in a liquid state or has been in a vapor state when introduced.

[0009] In an exemplary embodiment, the diluent gas reacts with excess carbon from the coating precursor prior to the reaction zone and / or with excess carbon from the coating formed in the reaction zone.

[0010] Therefore, the diluent gas can be reactive relative to the precursor and / or coating to consume excess carbon, which may result in a deviation from the desired stoichiometry of the coating. The reaction may be an oxidation reaction, or preferably a reduction reaction. For example, the reactive diluent gas may include hydrogen (H2) or ammonia (NH3). In this case, a reduction reaction is performed to consume the excess carbon. For example, in the case of a silicon carbide coating, hydrogen may be more preferably used relative to ammonia because it allows any risk of parasitic nitriding of the coating formed on the wire to be avoided. In other cases, ammonia may be more preferably used relative to hydrogen, for example in the case of a boron nitride coating, because ammonia provides additional nitrogen to adjust the stoichiometry of the formed coating. Alternatively, the excess carbon of the precursor and / or coating may be oxidized using a reactive diluent gas comprising hydrogen, nitrogen oxides (e.g., N2O) or carbon oxides (e.g., CO or CO2). The oxidation may be implemented in the case of forming an oxide coating.

[0011] Alternatively, the diluent gas is inert with respect to the coating precursor and / or with respect to the coating formed in the reaction zone. For example, the inert diluent gas may include nitrogen (N2) or argon (Ar).

[0012] It is noted that if the diluent gas includes a mixture of at least one reactive gas and at least one inert gas, such a technical solution does not exceed the scope of the present invention.

[0013] In an exemplary embodiment, forming the gas phase includes vaporizing the liquid coating precursor in a reactor by contact with a hot portion of the wire adjacent to a segment present in the microwave field.

[0014] The portion of the wire adjacent to the coating is heated by conduction and radiation from the wire segment in the microwave field. Therefore, dedicated heating means can be allocated to the liquid precursor. This makes the method simpler and more energy-efficient.

[0015] Specifically, the diluent gas can be mixed with the liquid coating precursor upon introduction into the reactor.

[0016] This characteristic is advantageous because it promotes evaporation of the liquid coating precursor and its entrainment in the reaction zone and allows adjustment of the flow rate of the precursor in the reaction zone.

[0017] Alternatively or in combination, the diluent gas is mixed with the vaporous coating precursor upon introduction into the reactor.

[0018] However, the present invention is not limited to evaporating the liquid pre-coating in a reactor. In fact, in one exemplary embodiment, forming the gas phase includes introducing the vaporous pre-coating into the reactor and mixing the diluent gas with the introduced vaporous pre-coating.

[0019] In an exemplary embodiment, the volume fraction of the dilution gas in the gas phase is greater than or equal to the volume fraction of the vapor-state coating precursor in the gas phase, for example, greater than or equal to twice the volume fraction of the vapor-state coating precursor.

[0020] This characteristic advantageously allows further improvement of the uniformity of the coating obtained on the line.

[0021] The volume fraction of the vapor-state coating precursor in the gas phase may be 15% to 75%, preferably 25% to 50%, and the volume fraction of the diluent gas in the gas phase may be 25% to 85%, preferably 50% to 75%.

[0022] The wire can be moved within the reactor during treatment. Thus, while a wire segment is being heated, the segment can be in a first position, and the method can further include moving the wire so that the segment is in a second position, where it exits the microwave field. In other words, the method can include the step of moving the wire within the microwave field and the reactor. This advantageous arrangement makes it easier to form a coating over the entire length of the wire. In this case, the winding of the wire can be performed continuously, that is, uninterrupted during deposition, or stepwise, with the wire being stopped during deposition and then moved so that, after deposition on the first segment, the second segment is positioned in the reaction zone.

[0023] In an exemplary embodiment, the coating precursor is a silicon carbide (SiC) precursor.

[0024] Thus, it is possible to deposit silicon carbide on the wire, this coating notably allowing the wire to be protected from oxidation and / or to be protected during subsequent steps of forming the composite material part.

[0025] Alternatively, the coating precursor is a boron nitride (BN) precursor.

[0026] Boron nitride is an interphase material, that is, it has the function of debrittlening the composite material, facilitating the deflection of any crack that propagates in the matrix and reaches the interphase, preventing or delaying line breakage caused by the crack.

[0027] Alternatively, the coating precursor is a silicon nitride (Si3N4) precursor.

[0028] Typically, the coating formed on the wire may be a ceramic coating, for example, a carbide or a nitride, such as boron carbide, boron nitride, or silicon nitride.

[0029] In one exemplary embodiment, the wire is moved in the reactor and the section of wire covered with the coating is transported to an additional treatment zone separate from the reaction zone, where the section of wire is subjected to a heat treatment.

[0030] The temperature applied in the additional treatment zone may be higher than or equal to the temperature in the reaction zone. The temperature applied in the additional treatment zone may be higher than or equal to 1100° C., for example, 1200° C. For example, the temperature may be 1100° C. to 1700° C., for example, 1200° C. to 1500° C.

[0031] Specifically, the heat treatment can lead to dehydrogenation of the coating covering the wire. This can be the case, for example, when the coating is formed from silicon carbide if the selected precursor results in a coating with excess hydrogen. Specifically, the heat treatment can lead to crystallization or stabilization of the coating covering the wire, such as when the coating is formed from boron nitride. Stabilization of the coating means making the coating less sensitive to air.

[0032] The present invention also relates to a method for manufacturing a composite material component, the method comprising:

[0033] - a fiber preform for forming a component from a thread processed by the method described above, and

[0034] - Formation of a matrix in the pores of the fiber preform obtained.

[0035] The matrix may be at least partially ceramic, eg, predominantly ceramic in volume.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] [ Figure 1 ] Figure 1A device for carrying out a first example of the method according to the invention is shown schematically.

[0038] [ Figure 2 ] Figure 2 A device for carrying out a second example of the method according to the invention is shown schematically.

[0039] [ Figure 3 ] Figure 3 A device for carrying out a third example of the method according to the invention is schematically shown.

[0040] [ Figure 4 ] Figure 4 A device for carrying out a fourth example of the method according to the invention is schematically shown.

[0041] [ Figure 5 ] Figure 5 is a photograph of a cross section of a coated wire obtainable within the scope of the present invention.

[0042] [ Figure 6 ] Figure 6 is a photograph of a cross section of another coated wire obtainable within the scope of the present invention. DETAILED DESCRIPTION

[0043] Figure 1 An apparatus 100 for carrying out one example of the method of the present invention is shown. In this example, the coating precursor 140 is present in a liquid state in the reactor 120, and the dilution gases 200a, 200b are injected directly into the liquid precursor 140.

[0044] Apparatus 100 includes a microwave generator 110, a reactor 120, and a reel (not shown) that allows a wire 150 to move within reactor 120. Treated wire 150 is made of carbon or ceramic, for example, silicon carbide. The material of wire 150 is selected so that the microwave field couples with it in reaction zone 115 to cause heating. In one exemplary embodiment, wire 150 can be made of silicon carbide having an oxygen content of less than or equal to 1% by atomic percentage. For example, Hi-Nicalon-type S-type wire sold by NGS Corporation of Japan can be used. It should be noted that treated wire 150 may or may not have been coated with another material.

[0045] The microwave generator 110 here comprises a resonator 111 defining a resonant cavity 112, which is connected to a wave generator (not shown). During operation, a microwave field passes through the resonant cavity 112. The microwave field can be characterized by its power (or amplitude) and its frequency, which can be easily determined by a person skilled in the art, to obtain a wire surface temperature suitable for forming a coating from a given coating precursor. The main frequency of the microwave field can be 2.35 GHz to 2.55 GHz. For example, the use of a microwave generator with a main frequency of 2.45 GHz allows heating of a wire made of approximately 500 silicon carbide filaments. The heating is then carried out only in a very localized manner on the wire: then, in a cold wall reactor, the heating reaches the standard of direct coupling.

[0046] Reactor 120 can be made of a material transparent to microwaves, such as quartz. Reactor 120 can have a tubular shape, such as a U-shaped tube. Reactor 120 can have a base portion (here, a horizontal portion) 121, a first branch (here, a first vertical portion) 122, and a second branch (here, a second vertical portion) 123, with vertical portions 122 and 123 each connected to horizontal portion 121. First vertical portion 122 can be connected to a first end of horizontal portion 121 and connected to second vertical portion 123 at a second end of horizontal portion 121 opposite the first end. Here, second vertical portion 123 of reactor 120 is at least partially present in resonant cavity 112 of resonator 111, that is, it traverses resonator 111. The portion of reactor 120 present in resonant cavity 112 forms reaction zone 115. Line 150 can be placed at the antinode of the microwave field in reaction zone 115. Only the branch or vertical portion 123 of reactor 120 is present in the microwave field. The shape of the reactor allows for the introduction of a liquid precursor 140. The liquid level can be adjusted by adding the precursor to one of the two vertical sections 122 and 123, for example, using a dropping funnel 143 connected to the reactor 120 in the first vertical section 122, as in the non-limiting example shown. The amount of liquid can be adjusted manually or controlled by a sensor at the precursor and an automatic precursor supply. In the latter case, a liquid flow meter connected upstream of the pressurized tank can be used, and the liquid level can be adjusted by an optical sensor of the liquid level in section 122, which controls the regulating valve of the flow meter. In addition, the reactor can be provided with a vent valve 126 to discharge the precursor 140 at the end of deposition. The meniscus 145 of the precursor 140 is located below the resonant cavity 112 or below the reaction zone 115. In particular, in the example shown, no liquid precursor 140 is present in the reaction zone 115. The wire section 156a adjacent to the wire segment 156 present in the microwave field is heated by thermal conduction. Portion 156a in contact with liquid precursor 140 allows it to evaporate at meniscus 145. The evaporated precursor 140 thereby diffuses toward reaction zone 115 for deposition on the thread. Pumping may be performed to force the precursor 140 to naturally propagate toward reaction zone 115. A coating is formed from the gas phase in the reaction zone by chemical vapor infiltration, covering the surfaces of the filaments forming thread 150 and depositing in the interfilament spaces. The distance from meniscus 145 to reaction zone 115 is d It may be greater than or equal to 1 cm, for example, greater than or equal to 5 cm, for example, from 1 cm to 15 cm, for example, from 5 cm to 15 cm. This distance may depend on the temperature applied to the centerline of the reaction zone, as described in detail below.

[0047] Reactor 120 is also equipped with two centralizers 125, located at the two junctions between the horizontal section 121 and the two vertical sections 122 and 123 of reactor 120. Centralizers 125 can be in the form of rollers with grooves (not visible in the figure) that help center wire 150 within reactor 120. Centralizers 125 are located inside reaction zone 120. Second vertical section 123 and horizontal section 121 each include at least one additional centralizer 124a and 124b. All or some of these additional centralizers 124a and 124b can locally narrow the cross-section of reactor 120. Additional centralizers (not shown) can also be added to first vertical section 122.

[0048] The apparatus is provided with a reeling device that may include a first mandrel (not shown) from which the wire 150 can be unwound, which may be a storage mandrel for the wire 150 prior to coating, and a second mandrel (not shown) onto which the wire 150 can be wound once coated. The wire 150 may be continuous, extending continuously through the reactor 120 between the first and second mandrels. The wire 150 may be moved within the reactor 120 during the process. The section of the wire 150 to be treated may thus be circulated within the reactor 120 from the first mandrel to the second mandrel. Elements 125 and 124a-b for centering the wire 150 within the reactor 120 reduce the risk of the wire 150 contacting the walls of the reactor 120. The reeling device may be controlled by a control device (not shown) to continuously or stepwise reel the wire 150 within the apparatus 100. The reeling of the wire 150 may be controlled according to process parameters, particularly the deposition dynamics, thereby enabling fine control over the thickness of the deposited coating.

[0049] exist Figure 1 In the example of FIG. 1 , a wire 150 circulates in the reactor 120 and is partially immersed in the liquid precursor 140. The movement of the wire can be continuous (uninterrupted) or stepwise. A section 156 of the treated wire initially circulates in the first vertical portion 122 without being immersed in the liquid precursor 140. The section is then immersed in the liquid precursor 140 in the first vertical portion 122 and then remains immersed in the liquid precursor 140 in the horizontal portion 121 and a portion of the second vertical portion 123. The section of wire 150 then leaves the liquid precursor 140 and is routed to the reaction zone 115, where a coating is formed on its surface from a gas phase in a microwave field. The formation of the gas phase in this example is described below.

[0050] Here, the liquid precursor 140 is evaporated by heat conduction along the line from the heated section 156 in the reaction zone 115 to the meniscus 145. The reactor 120 is provided with at least one channel 154a, 154b for introducing dilution gases 200a, 200b. The reactor 120 is provided with a plurality of channels 154a, 154b for introducing dilution gases 200a, 200b. When there are a plurality of channels 154a and 154b, the dilution gases 200a and 200b introduced into each channel may be the same or different, for example, the dilution gas 200b may be reactive, while the dilution gas 200c may be inert. Figure 1 In the example of FIG. 1 , the channels 154a, 154b appear below the meniscus 145 of the liquid precursor 140. The channels 154a, 154b may be implemented by and appear in the second vertical portion 1233. The channels 154a, 154b may be located below the reaction zone 115. The dilution gases 200a, 200b are directly mixed with the liquid precursor 140 when introduced into the reactor, as shown in FIG. Figure 1 . Here, the dilution gases 200a, 200b come into contact with the liquid precursor 140 when introduced into the reactor 120. The dilution gases 200a, 200b can be introduced into the second vertical portion 123. The mixing of the dilution gases 200a, 200b and the precursor 140 can be carried out in the second vertical portion 123. The mixing of the dilution gases 200a, 200b and the precursor 140 can be carried out in the moving area of ​​the line 150. The mixing of the dilution gases 200a, 200b and the precursor 140 can be carried out below the reaction zone 115. In this example, the dilution gases 200a, 200b are bubbled into the liquid precursor 140 present in the reactor 120. The mixing between the dilution gases 200a, 200b and the precursor 140 is carried out before the gas phase reaches the reaction zone 115. Regardless of the example considered, the distance between the mixing zone between the precursor and the dilution gas and the reaction zone can be less than or equal to 15 cm, for example, from 1 cm to 15 cm. In this case, in the example shown, the diluent gases 200a, 200b are first mixed with the liquid precursor 140, which is then evaporated to obtain a gaseous phase comprising a mixture of the diluent gas and the coating precursor in vapor form, which then propagates towards the reaction zone 115 and is introduced into this zone 115, thereby forming a coating on the treated wire. The diluent gas is separated from the coating precursor in vapor form. As mentioned above, the reaction zone 115 is particularly free of liquid coating precursors, which, in the example shown, are present therein only in vapor form. It should be noted that the reactor does not have a heating system at the liquid precursor 140. However, this system may include means (not shown) for regulating the temperature of the liquid precursor 140, thereby maintaining the liquid precursor at a moderate temperature (if necessary depending on the precursor used), for example less than or equal to 20°C.

[0051] The diluent gases 200a, 200b can be reactive or inert relative to the precursor 140. Thus, the diluent gases 200a, 200b can react with the carbon in the coating precursor, thereby consuming excess carbon compared to the stoichiometric amount required for deposition before the vaporous coating precursor is introduced into the reaction zone 115. The reaction can occur in the vapor phase before the vapor phase is introduced into the reaction zone 115, with the diluent gases 200a, 200b reacting with excess carbon in the vaporous precursor coating. Alternatively, or in combination, as described above, the diluent gases 200a, 200b can react with excess carbon in the coating formed in the reaction zone 115. Reactive diluent gases 200a, 200b can be hydrogen or ammonia. Inert diluent gases 200a, 200b can be nitrogen or argon.

[0052] For example, the liquid coating precursor 140 can be a silicon carbide precursor. In this case, the precursor 140 can contain one or more silicon atoms, one or more carbon atoms and optionally hydrogen. Specifically, the precursor 140 can contain at least one Si-C bond, and optionally at least one Si-H bond and / or at least one Si-Si bond. As examples of usable silicon carbide precursors 140, 1,3,5-trisilacyclohexane (TSCH), hexamethyldisilane (HMDS) or triethylsilane can be mentioned. In the case of using HMDS, in order to obtain pure SiC on line 150, it is advantageous to select a diluent gas that can consume the excess carbon of the precursor.

[0053] For example, in the case of depositing silicon carbide, the temperature of line 150 in reaction zone 115 may be from 800°C to 1300°C, such as from 950°C to 1200°C.

[0054] Alternatively, coating precursor 140 can be a boron nitride precursor. In this case, precursor 140 can include one or more boron atoms, one or more nitrogen atoms and hydrogen atoms, and optionally one or more carbon atoms. Precursor 140 can be aminoborane. Precursor 140 can include at least one BN bond, optionally at least one NC bond and / or at least one BC bond. As an example of available boron nitride precursor 140, tris(dimethylamino)borane (TDMAB) or triethylaminoborane (TEAB) optionally mixed with ammonia NH3 can be mentioned. The use of TDMAB can advantageously be accompanied by the use of a diluent gas reacted with carbon to consume excess carbon.

[0055] For example, in the case of depositing boron nitride, the temperature of line 150 in reaction zone 115 may be from 900°C to 1500°C, such as from 1200°C to 1400°C.

[0056] Alternatively, a silicon nitride coating can be formed, for example, by using hexamethyldisilazane as the coating precursor 140. The portion of the reactor 120 between the meniscus 145 and the reaction zone 115 can be placed under negative pressure to promote evaporation of the precursor into the reaction zone 115. However, the pressure in this portion can be maintained at or above the vapor pressure of the precursor at the temperature of the meniscus 145 to prevent excessive evaporation of the precursor. The pressure in this portion can typically be between 1 millibar (mbar) and 3 bar (bar). Selecting the applied pressure based on the precursor used is within the knowledge of those skilled in the art. For example, for TDMAB, the pressure in the reactor can be greater than or equal to 3 mbar at 30°C, or greater than or equal to 160 mbar at 100°C. For example, for TEAB, the pressure in the reactor can be greater than or equal to 3 mbar at 75°C, or greater than or equal to 16 mbar at 96°C. For example, for triethylsilane, the pressure in the reactor can be greater than or equal to 125 mbar at 50°C.

[0057] The flow rate of the dilution gas introduced into the reactor 120 can be greater than or equal to the flow rate of the precursor 140 vaporized or introduced into the reaction zone 115, for example, greater than or equal to twice the flow rate of the precursor 140. This allows a gas phase having a dilution gas volume fraction greater than or equal to the precursor volume fraction in the vapor state to be obtained.

[0058] It should be noted that reactor 120 also includes additional gas inlet 157a, 157c and outlet 159a, 159c channels downstream of reaction zone 115. Therefore, section 156 enters reaction zone 115 in sequence and then enters these channels 157a, 157c and 159a, 159c. Buffer gas (such as nitrogen or argon) can be introduced by channels 157a, 157b and 157c and 159a, 159b and 159c to avoid any risk of parasitic deposition at the mandrel of scrolling device. Gas outlet 159a-159c allows to discharge introduced buffer gas and any residual gaseous precursor. As shown in the figure, each of the two vertical sections 122 and 123 can include at least one pair of inlet channels 157a-c and outlet channels 159a-c pairs. The example of the reactor 120 shown includes a first pair of buffer gas inlet 157a and outlet 159a located between the reaction zone 115 and the centralizer 124a, a second pair of buffer gas inlet channels 157b and outlet channels 159b located on the vertical portion 122 upstream of the reaction zone 115, and a third pair of buffer gas inlet ducts 157c and outlet ducts 159c located downstream of the centralizer 124a. Specifically, it should be noted that the channel cross-section is reduced at the centralizer 124a downstream of the reaction zone 115. This advantageously allows for further reduction in leakage of residual vapor-phase precursors and improves line centering. Of course, the reduction in channel cross-section is not necessarily achieved by adding a specific component 124a and can be achieved simply by locally changing the diameter of the tube forming the reactor. In a variant not shown, the system does not have a channel cross-section reduction.

[0059] Now we will describe Figure 2 An example use of the apparatus 101 is as follows Figure 1 The same structure as the device 100 in FIG. 1 is provided, but it is supplemented by adding an additional heat treatment zone 210. Figure 1 The same parts of the apparatus 100 have the same reference numerals and are not described again for the sake of brevity.

[0060] therefore, Figure 2 The reactor 220 is equipped with an additional treatment zone 210, which is different from and downstream of the reaction zone 115. Thus, the treated line segment 156 passes sequentially through the reaction zone 115 and then through the additional treatment zone 210, where it is subjected to heat treatment. Thus, this zone 210 can be provided with a heating device, which can also use microwave heating, but those skilled in the art will recognize that other heating devices are also possible. The temperature applied during the heat treatment in zone 210 can be higher than or equal to the temperature in the reaction zone 115. The temperature in zone 210 can be higher than or equal to 1100° C., for example, higher than or equal to 1200° C. The temperature can comprise 1100° C. to 1700° C., for example, 1200° C. to 1500° C.

[0061] As described above, heat treatment in zone 210 results in dehydrogenation, crystallization, or stabilization of the coating formed in reaction zone 115. For example, by applying a temperature of 1200° C. to 1500° C. to the wire, crystallization or stabilization of the boron nitride coating can be performed in zone 210. Alternatively, by applying a temperature of 1100° C. to 1500° C. to the wire 150, a silicon carbide coating can be heat treated to dehydrogenate.

[0062] Reactor 220 is also provided with an inlet 157d and an outlet 159d for a buffer gas on either side of zone 210 to inertize the zone and avoid parasitic deposition. Alternatively, a reactive gas may be introduced through inlet 157d to allow dehydrogenation of the coating formed in reaction zone 115.

[0063] Figure 2 An additional processing zone 210 is shown that is offset and moves in a different direction than the reaction zone 115 along line 150. However, it does not depart from the scope of the present invention when the reaction zone 115 is heated to a temperature sufficient to perform deposition on the line and to modify the thermal treatment of the deposition, such as dehydrogenation, crystallization, or stabilization performed in zone 210. In the latter case, it may be advantageous to provide a sufficient distance between the reaction zone 115 and the precursor meniscus 145, given the high temperatures applied in the reaction zone 115. d , so that the desired additional processing can be performed without the precursor evaporation being disturbed by heat conduction along the line. For example, the distance can be greater than or equal to 5 cm, such as 5 cm to 15 cm inclusive.

[0064] Just combined Figure 1 and Figure 2 The method described involves introducing the dilution gas directly into the liquid precursor 140. Figure 3 This relates to the apparatus 102 in which the diluent gas is directly mixed with the precursor in a vapor state. For the sake of brevity, the same parts as those described above are omitted.

[0065] Figure 3 The reactor 320 shown comprises at least one dilution gas introduction channel 254a, 254b present between the meniscus 145 and the reaction zone 115. The dilution gas is no longer bubbled in the liquid precursor 140, but is mixed with the precursor in the vapor state upstream of the reaction zone 115 after the liquid precursor has evaporated in the reactor 320. Here, the dilution gas is introduced above the liquid precursor meniscus 140. The gas phase obtained after this mixing then propagates to the reaction zone 115 to form the coating. In a variant not shown, the introduction of the dilution gas into the liquid precursor and the introduction of the dilution gas into the precursor in the vapor state can be combined. Moreover, as Figure 2 As shown, an additional treatment zone 210 may be added downstream of the reaction zone 115 .

[0066] Figure 4 A variant involves the case where the precursor is introduced directly into the reactor in the vapor state. Figure 4 In the example of the apparatus 103, the dilution gases 200a, 200b are injected into the reactor 420 and mixed directly with the precursor stream in the vapor state 240. The pressure in the reactor 420 may be between 1 mbar and 3 bar.

[0067] The flow rate of the dilution gas 200a, 200b introduced into the reactor 420 may be greater than or equal to the flow rate of the vapor phase precursor 240 introduced into the reaction zone 420, for example, greater than or equal to twice the flow rate of the precursor introduced into the reactor 420. This allows obtaining a vapor phase having a dilution gas volume fraction greater than or equal to the precursor volume fraction in the vapor phase.

[0068] The accompanying drawings illustrate apparatus 100-103 for processing a single strand 150, but the present invention is also applicable to processing multiple strands simultaneously in a reactor. Furthermore, strand processing can include multiple passes of the strand through the reactor, each time depositing an additional coating over the coating formed during the previous pass. The coating thus deposited can be a single material (monomaterial) or a multimaterial. In the illustrated example, no liquid precursor is present in the reaction zone; however, the scope of the present invention does not deviate from that when a liquid precursor is present in the reaction zone in addition to the gas phase introduced into the zone.

[0069] The method may continue by fabricating a composite component from a plurality of wires coated in the manner described above.

[0070] Thus, the manufacture of the component may comprise the manufacture of a fiber preform from a plurality of coated fibers intended to form a fiber reinforcement. The fiber reinforcement may be obtained by weaving the coated threads, for example by three-dimensional weaving. For example, an interlock weave pattern may be used.

[0071] The pores of the fiber preform can then be filled with a mold to obtain a composite component. The matrix can be an at least partially ceramic matrix. In a manner known per se, the matrix can be formed by chemical vapor infiltration or melt infiltration ("MI") techniques. The matrix can include silicon carbide.

[0072] The obtained component can be a component of a gas turbine, such as an aerospace engine or an industrial turbine. The obtained component can be a turbine component. The obtained component can be a turbine blade, such as a turbine blade. Alternatively, the obtained component can be a turbine ring segment.

[0073] Example

[0074] Example 1: Deposition of Silicon Carbide

[0075] use Figure 1 The apparatus 100 shown was tested. The precursor used was HMDS, and the temperature of the reaction zone 115 was maintained at 1070°C for 3 minutes. Nitrogen was used as the dilution gas 200a, 200b. The volume fractions of the dilution gas and the precursor in the gas phase were each 50%. SiC deposition was effective at a kinetic of 500 μm / min in the reaction zone. During the tests performed, the wire was static. Figure 5 is a cross-sectional view of the resulting coated wire.

[0076] Example 2: Deposition of Boron Nitride

[0077] use Figure 1 The apparatus 100 shown was tested. The precursor used was TDMAB, and the temperature of the reaction zone 115 was maintained at 1270°C for 12 minutes. Nitrogen was used as the diluent gas 200a, 200b. The volume fractions of the diluent gas and the precursor in the gas phase were each 50%. BN deposition was effective at a kinetic of 1.7 μm / min in the reaction zone. During the tests performed, the wire was static. The resulting coated wire was then used to form a composite component. Figure 6 is a cross-sectional view of the resulting coated wire.

[0078] The term "... to ..." should be understood to be inclusive.

Claims

1. A method for processing a carbon wire or a ceramic wire, the method comprising: forming a coating on the wire by heating a section of the wire in the presence of a gas phase in a microwave field, at least in the reaction zone of the reactor, wherein the gas phase comprises a mixture of a diluent gas and a coating precursor in a vapor state, and the gas phase is formed at least by introducing the diluent gas into the reactor and mixing the introduced diluent gas with the coating precursor in the reactor prior to the reaction zone, wherein the diluent gas is mixed with the coating precursor in a liquid state when introduced into the reactor, and the diluent gas is bubbled in the liquid precursor present in the reactor, wherein forming the gas phase comprises: evaporating the liquid coating precursor in the reactor by contact with a hot portion of a wire adjacent to a section present in the microwave field, the wire portion being immersed in the liquid precursor.

2. The method according to claim 1, wherein The diluent gas reacts with excess carbon from the coating precursor prior to the reaction zone and / or with excess carbon from the coating formed in the reaction zone.

3. The method according to claim 2, wherein: Reactive diluent gases include hydrogen or ammonia.

4. The method according to claim 1, wherein The diluent gas is inert with respect to the coating precursor and / or with respect to the coating formed in the reaction zone.

5. The method according to claim 1, wherein The volume fraction of the diluent gas in the gas phase is greater than the volume fraction of the vapor phase coating precursor in the gas phase.

6. The method of claim 1, wherein: The coating precursor is a silicon carbide precursor, a boron nitride precursor, or a silicon nitride precursor.

7. The method of claim 1, wherein: The wire moves in the reactor and the section of wire covered with the coating is conveyed to an additional treatment zone separated from the reaction zone, in which the section of wire (156) is subjected to a heat treatment, the temperature applied in the additional treatment zone being greater than or equal to 1100°C.

8. The method of claim 7, wherein: The heat treatment results in dehydrogenation of the coating covering the wire.

9. The method of claim 7, wherein: The heat treatment results in crystallization or stabilization of the coating covering the wire.

10. A method of manufacturing a composite material component, the method comprising: - a fiber preform for forming a component from a thread processed by the method according to claim 1, and - Formation of a matrix in the pores of the fiber preform obtained.

11. The method according to claim 10, wherein: The matrix is ​​at least partially ceramic.

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