Method for depositing a coating by chemical vapor deposition

Abstract

The present invention relates to a method for chemical vapor deposition coating on a substrate, the method comprising at least the following steps: - placing a substrate (100, 200) in a reaction chamber; - obtaining a first layer (101, 201) by supplying a mixture of dihydrogen and methyltrichlorosilane to the reaction chamber at a first H2 / methyltrichlorosilane volume ratio, the reaction chamber being subjected to a first temperature and a first pressure; and - obtaining a second layer (102, 203) by supplying a mixture of dihydrogen and methyltrichlorosilane to the reaction chamber at a second H2 / methyltrichlorosilane volume ratio different from the first ratio, the reaction chamber being subjected to a second temperature and a second pressure, at least one of the second volume ratio, the second temperature and / or the second pressure being different from the first volume ratio, the first temperature and / or the first pressure, respectively.

Description

Technical Field

[0001] This disclosure relates to a method of coating a substrate with a coating comprising silicon and carbon. Background Technology

[0002] Ceramic matrix composites (CMCs) can withstand temperatures ranging from 600°C to 1400°C. Due to their excellent high-temperature resistance, CMCs require less cooling. Since this cooling is typically derived from the compressor, affecting turbine efficiency, CMCs improve engine efficiency, thereby reducing fuel consumption.

[0003] Furthermore, the use of ceramic matrix composites helps optimize turbine performance, particularly by reducing the overall mass of the turbine, which further contributes to reduced fuel consumption and thus significantly reduces pollutant emissions.

[0004] Due to their industrial value, the manufacturing methods of composite materials have been improved in recent years.

[0005] Among the methods for manufacturing such materials, chemical vapor infiltration (or "CVI") is known.

[0006] Such methods can be used not only to form ceramic substrates for CMC materials, but also to deposit coatings on components (especially CMC components), such as to allow subsequent adhesion of antioxidant or temperature-resistant protective coatings.

[0007] The CVI method requires the use of a gaseous precursor, which allows the formation of the desired layer through chemical decomposition under temperature.

[0008] Although this method has been used in industry, it requires complex furnaces when the properties of the layers to be deposited are diverse.

[0009] In practice, it is necessary to be able to introduce predefined precursors into the furnace to obtain the desired layer at the required time. This complicates the furnace programming, which must be specifically prepared to allow the introduction of the required precursors at the correct moment.

[0010] Therefore, it is desirable to have a CVI method that allows for the deposition of multiple coatings simultaneously using a method that is simpler than existing techniques. Summary of the Invention

[0011] The present invention is intended to solve the above-mentioned problems.

[0012] According to the first aspect, it relates to a method for chemical vapor deposition of a coating on a substrate, the method comprising at least the following steps: - The step of placing the substrate in the reaction chamber; -The step of obtaining a first layer by feeding a mixture of dihydrogen and methyltrichlorosilane into a reaction chamber at a first H2 / methyltrichlorosilane volume ratio, wherein the reaction chamber is at a first temperature and a first pressure. - A step of obtaining a second layer by supplying a mixture of dihydrogen and methyltrichlorosilane to a reaction chamber at a second H2 / methyltrichlorosilane volume ratio different from the first ratio, wherein the reaction chamber is at a second temperature and a second pressure, at least one of the second volume ratio, the second temperature and / or the second pressure being different from the first volume ratio, the first temperature and / or the first pressure, respectively.

[0013] The proposed method allows for the deposition of a two-layer coating in a single reaction chamber, both containing silicon and carbon in different proportions.

[0014] The phrase "complementary content" means that, in the layers of this invention, the sum of the atomic content of silicon and the carbon content accounts for more than 99.5%, or even more than 99.9%, or even more than 99.95% of the composition of the layer.

[0015] The definition of this layer is intended to allow for the presence of impurities that are unavoidable for the CVI method, provided that these impurities are present in an atomic content of less than 0.5%, or even 0.1%, or even less than or equal to 0.05%.

[0016] In one embodiment, the silicon content of the second layer differs from that of the first layer by at least 10%.

[0017] The statement "the second content differs from the first content by at least X%" means that the absolute difference between the first and second contents is at least X%. The first content can be higher or lower than the second content, as long as the absolute difference is greater than X.

[0018] In one embodiment, the temperature and pressure used to obtain a given layer are understood as the temperature and pressure present in the reaction chamber where the deposition method is performed.

[0019] In one implementation, a preparation step is performed directly prior to the layer-obtaining step, which includes heating and pressurizing the reaction chamber to the temperature and pressure required for the layer-obtaining step, but without introducing a precursor during this period.

[0020] The “H2 / methyltrichlorosilane volume ratio” is understood in the conventional sense of the term “ratio”, that is, the volume of dihydrogen present in the precursor divided by the volume of methyltrichlorosilane present in the precursor.

[0021] Preferably, the method does not include any precursors other than dihydro and methyltrichlorosilane.

[0022] However, in one implementation, the precursor can be dissolved in the carrier gas.

[0023] For the purposes of this application, carrier gas is understood to be a gas that does not participate in the reaction and is only used to dissolve gaseous precursors, for example, to facilitate their transport or proper mixing.

[0024] In one embodiment, one layer is a layer comprising a silicon atom content of 95% or more and a complementary carbon atom content, said layer being obtained at a H2 / methyltrichlorosilane volume ratio of 20 or more, at a temperature between 850°C and 920°C, and at a pressure between 200 mbar and 400 mbar.

[0025] This implementation allows for the deposition of a slightly carbon-doped silicon layer labeled Si(C).

[0026] In one embodiment, one layer is a silicon carbide layer comprising a silicon atom content of 45% to 55% and a complementary carbon atom content, said layer being obtained at an H2 / methyltrichlorosilane volume ratio of 7 to 10, at a temperature of 920°C to 1050°C, and at a pressure of 100 mbar to 300 mbar.

[0027] This implementation allows for the deposition of a silicon carbide layer labeled SiC.

[0028] In one embodiment, one layer is a silicon carbide layer comprising a silicon atom content of 49% to 51% and a complementary carbon atom content, said layer being obtained at a volume ratio of H2 to methyltrichlorosilane of 7 to 10, at a temperature of 920°C to 1050°C, and at a pressure of 100 mbar to 300 mbar.

[0029] In one embodiment, one layer is a layer comprising less than or equal to 20% silicon atoms and complementary carbon atoms, said layer being obtained at a volume ratio of H2 / methyltrichlorosilane less than or equal to 3, at a temperature between 950°C and 1020°C, and at a pressure between 50 mbar and 100 mbar.

[0030] This implementation allows for the deposition of silicon-doped carbon layers labeled C(Si).

[0031] The inventors' contribution lies in their determination that SiC, C(Si), or Si(C) layers can be obtained using the same precursors simply by changing one or more deposition parameters selected from the volume ratio between precursors, temperature, or pressure.

[0032] In particular, the described implementation thus allows for the resolution of the problem in existing methods, namely the need to use specific precursors to deposit specific layers.

[0033] It is worth noting that the Si(C), SiC, and C(Si) layers are fully compatible with each other. In other words, the method of the present invention allows for the preparation of coatings comprising at least two different layers selected from the above-mentioned layers, while ensuring excellent resistance to delamination.

[0034] Therefore, thanks to the method described above, it becomes possible to deposit a coating comprising two different layers without using different precursors for the different layers.

[0035] In one implementation, the method is not limited to a coating consisting of two layers.

[0036] In one implementation, the method further includes: - The step of obtaining a third layer by supplying a mixture of dihydrogen and methyltrichlorosilane to the reaction chamber at a third H2 / methyltrichlorosilane volume ratio, a third temperature, and a third pressure, wherein at least one of the third volume ratio, the third temperature, and / or the third pressure is different from the second volume ratio, the second temperature, and / or the second pressure, respectively.

[0037] This implementation allows for the production of coatings with particularly advantageous compositions without altering the properties of the precursors or complicating the furnace in which such methods are implemented.

[0038] In one embodiment, the third layer may have a composition similar to that of the first layer. In other words, in one embodiment, the third volume ratio, the third temperature, and the third pressure may be equal to the first volume ratio, the first temperature, and the first pressure, respectively.

[0039] In one embodiment, the coating may be applied to a substrate, and the substrate may be a component made of composite materials, such as a component made of SiC / SiC composite materials, or even an aerospace component made of composite materials.

[0040] In fact, the method of the present invention subsequently allows the deposition of a coating comprising a first Si(C) layer, a second SiC layer, and a third Si(C) layer on the surface of such SiC / SiC material.

[0041] Compared to existing technologies, this coating can be obtained in a simplified manner.

[0042] This three-layer coating is also an excellent adhesive layer, with performance at least equivalent to existing adhesive layers, but obtained in a simpler way and with a less complex furnace.

[0043] In one implementation, the thickness of the layer is controlled by the duration of the layer deposition step, i.e., the duration for which the precursor is introduced at a given volume ratio, required pressure, and temperature.

[0044] For example, the time required to obtain one or more layers can be between 5 and 15 hours.

[0045] This allows for the production of layers with thicknesses ranging from 10 µm to 50 µm.

[0046] In one implementation, the step of obtaining a given layer is separated from the step of obtaining the next layer by a purging step, during which all precursors present in the reaction chamber are removed.

[0047] This purging step can be carried out, for example, by filling the reaction chamber with an inert gas (such as dinitrogen or argon) to remove the precursors from the step of obtaining the layer.

[0048] Alternatively, and in this case preferably before filling with an inert gas, the purging step may include evacuating the reaction vessel.

[0049] This purging process enables a clear transition from one layer acquisition step to the next.

[0050] The result was a coating with very clear layer boundaries.

[0051] Furthermore, the vacuuming step improves the purging step, thus enabling a clearer transition from the layer acquisition step to the next step.

[0052] In another embodiment, the method includes a transition step between two consecutive layer-obtaining steps, during which a mixture of dihydrogen and methyltrichlorosilane is supplied to the reaction chamber at an H2 / methyltrichlorosilane volume ratio, the volume ratio varying between the proportions of the first and second layer-obtaining steps during the transition step, the reaction chamber being at a temperature varying between the temperatures of the first and second layer-obtaining steps during the transition step, and at a pressure varying between the pressures of the first and second layer-obtaining steps during the transition step.

[0053] This implementation allows for the formation of a transition region in the coating between two consecutive layers produced by this method. In this transition region, the carbon and silicon content varies between the contents of the two layers defining the transition region.

[0054] This implementation is particularly important because it ensures even better chemical compatibility between the two consecutive layers. In fact, the gradual change in composition from the first layer to the second layer ensures the mechanical continuity of the deposition, resulting in better overall resistance to stratification.

[0055] In one implementation, the transition steps can be carried out over a period of 0.5 to 2 hours.

[0056] This ensures that the transition area has sufficient thickness to guarantee excellent compatibility between the two areas, while keeping the transition area small enough not to negatively impact the overall weight of the component.

[0057] In implementations that include such transition steps, all changing parameters can change within the same time period.

[0058] In one embodiment, at least one of the H2 / methyltrichlorosilane volume ratio, temperature, or respective pressure used in the transition step varies affinely between the H2 / methyltrichlorosilane volume ratio in the step of obtaining the layer before the transition step and the H2 / methyltrichlorosilane volume ratio in the step of obtaining the layer after the transition step; varies between the temperature in the step of obtaining the layer before the transition step and the temperature in the step of obtaining the layer after the transition step; and / or varies between the pressure in the step of obtaining the layer before the transition step and the pressure in the step of obtaining the layer after the transition step.

[0059] "Affine transition" should be understood as the changing parameters changing constantly throughout the duration of the transition. In other words, the changing parameters can be written as an affine function of the time elapsed since the start of the transition step.

[0060] In one embodiment, the substrate may be an aerospace component made of ceramic matrix composite material.

[0061] In one embodiment, the substrate may be selected from turbine blades, distributor portions, or annular sectors.

[0062] In one embodiment, the substrate may be a fiber, such as silicon carbide fiber, glass fiber, or carbon fiber.

[0063] In this embodiment, the substrate may also be the aforementioned fiber coated with a solidified interface phase.

[0064] For example, such a consolidated interface phase may include a first layer, such as containing boron nitride (BN) or pyrolytic carbon (PyC), which is configured to be in direct contact with the fiber.

[0065] In one embodiment, the interface phase may further include a second outer layer, which is configured to directly contact and protect the first layer, thereby ensuring the integrity of the consolidated interface phase.

[0066] Interfacial phase deposition can be performed in a manner known per se, and the interfacial phase should not be construed as a layer of coating that can be obtained by the methods described herein.

[0067] This interfacial phase can impart further improved properties to the fiber, especially in terms of crack resistance and oxidation resistance.

[0068] Therefore, the manufacturing method is simplified compared to existing technologies, and this provides a major advantage for this substrate.

[0069] Brief description of the attached figures

[0070] [ Figure 1 ] Figure 1 This is an example of a component that can be obtained in one implementation of the method.

[0071] [ Figure 2 ] Figure 2 This is an example of how temperature changes over time when implementing a method in one embodiment.

[0072] [ Figure 3 ] Figure 3 This is an example of how the proportion of precursors changes over time when implementing a method in one embodiment.

[0073] [ Figure 4 ] Figure 4 This is an example of a component that can be obtained in one implementation of the method.

[0074] [ Figure 5 ] Figure 5 This is an example of how temperature changes over time when implementing a method in one embodiment.

[0075] [ Figure 6 ] Figure 6 This is an example of how the proportion of precursors changes over time when implementing a method in one embodiment. Detailed Implementation

[0076] The invention will now be described with reference to the accompanying drawings, which are provided for illustrative purposes to show certain embodiments of the invention and should not be construed as limiting the invention.

[0077] In one embodiment, the substrate may be an aerospace component made of ceramic matrix composite material.

[0078] For example, it could be a turbine blade made of SiC / SiC material, such as a high-pressure turbine or a low-pressure turbine, a distributor section made of SiC / SiC material, or a turbine ring sector.

[0079] Such components typically have an environmental barrier layer that provides the substrate with better resistance to oxidation and corrosion.

[0080] Typically, the adhesive layer is composed of silicon and is placed between the substrate and the environmental barrier layer. It allows for good chemical compatibility with both the substrate and the environmental barrier layer, thereby giving the whole excellent resistance to delamination.

[0081] The coating obtained by the above method allows for an adhesive layer of at least comparable quality to that obtained by existing methods, and can be obtained in a less complex furnace.

[0082] For example, such an adhesive layer may include a first layer and a third layer containing 95% or more silicon atoms and complementary carbon atoms, labeled Si(C), and a second silicon carbide layer SiC.

[0083] Inserting this silicon carbide (SiC) layer in the middle of the coating allows for better oxidation resistance of the underlying substrate without altering the adhesion between the Si(C) adhesive layer and the substrate.

[0084] Using the above method to manufacture this adhesive layer is particularly advantageous because it allows this coating to be obtained in a single reaction chamber.

[0085] Figures 1 to 3 This implementation method is involved.

[0086] Figure 1 The substrate 100, coated with a first layer 101, a second layer 102 and a third layer 103, is shown in very general terms.

[0087] The third layer 103 itself is coated with an environmental barrier layer 104.

[0088] The environmental barrier layer 104 is known and may contain rare earth disilicates, such as yttrium Y₂Si₂O₇ or ytterbium Y₂Si₂O₇. It will not be described in further detail.

[0089] As described above, the connection of layers 101, 102 and 103 can be achieved in a single reaction chamber using the method of the present invention.

[0090] In fact, and as stated above, the inventors’ contribution is that they have been able to determine that by using the same dihydrogen H2 and methyltrichlorosilane CH3SiCl3 precursors, layers of different compositions can be deposited simply by changing the H2 / methyltrichlorosilane ratio, pressure and temperature during the deposition step.

[0091] Unintentionally bound by theory, the inventors determined that temperatures between 850°C and 920°C cannot dehydrogenate the methyl radical CH3, but still allow the reduction of silicon from SiCl3, thereby enabling a method to form a layer (Si(C)) containing greater than or equal to 95% silicon atoms and complementary carbon atoms.

[0092] Furthermore, they determined that increasing the H2 / methyltrichlorosilane ratio promoted the hydrogenation of methyl radical CH3 to methane, which prevented carbon deposition.

[0093] The inventors also determined that raising the temperature, for example, between 920°C and 1050°C, allows both the reduction of SiCl3 to silicon and the dehydrogenation of methyl radicals to promote carbon deposition.

[0094] By further adjusting the H2 / methyltrichlorosilane ratio supplied to the reaction chamber, it becomes possible to deposit silicon carbide (SiC) with a silicon atom content between 45% and 55%, or even 49% and 51%, and a complementary carbon atom content.

[0095] Therefore, in order to obtain Figure 1 The coating described herein can be used Figure 2 The temperature condition T shown in the figure is given by... Figure 3 The precursor ratio R shown in the figure is supplied to the reaction chamber, and the precursor is dihydrogen H2 and methyltrichlorosilane CH3SiCl3.

[0096] To deposit a Si(C) layer 101 on the surface of the substrate 100, dihydrogen H2 and methyltrichlorosilane CH3SiCl3 precursors are supplied in a ratio greater than or equal to 20, or even 20, such as Figure 3 As shown, the temperature of the reaction chamber is between 850°C and 920°C, or even 920°C. Figure 2 As shown.

[0097] This ratio can be understood as the volume of dihydrogen supplied divided by the volume of methyltrichlorosilane.

[0098] For example, the pressure can be between 200 mbar and 400 mbar throughout the process.

[0099] These conditions are maintained for a duration t1, which is the duration of the step to obtain the first Si(C) layer.

[0100] The duration t1 can be determined based on the required thickness e1 of the first layer 101.

[0101] exist Figure 2 and Figure 3 In the embodiment shown, discontinuous changes in temperature and proportion can be seen between two consecutive layer production steps, indicated by dashed lines.

[0102] These dashed lines may correspond to the step of purging the reaction vessel, for example by filling the reaction vessel with dinitrogen or argon, to remove all precursors present in the previous step.

[0103] As mentioned above, the purging step may optionally include the step of evacuating the reaction vessel.

[0104] In the illustrated embodiment, after the purging step, a second step of depositing layer 102 can be carried out by maintaining a different temperature and precursor ratio than in the first step for a duration of t2, which is the duration of the step of obtaining the second silicon carbide Si layer.

[0105] In one implementation, the layer obtained during a given obtaining step can directly contact the layer obtained during a subsequent obtaining step.

[0106] If a purging step is performed, the distinction between the two layers becomes even clearer.

[0107] Preferably, the duration t2 is determined based on the required thickness e2 of the second layer 102.

[0108] To deposit a SiC layer 102 on the surface of the first layer 101, the precursors dihydrogen H2 and methyltrichlorosilane CH3SiCl3 are supplied in a ratio between 7 and 10, or even 10, such as... Figure 3 As shown, the temperature of the reaction chamber is between 920℃ and 1050℃, or even 1030℃, as... Figure 2 As shown.

[0109] At the end of duration t2, a new purging step can be implemented, for example, indicated by a dashed line.

[0110] Following this purging step, in one embodiment, a third step of depositing layer 103 may then be performed, here under the same conditions as the first deposition step, for a duration of t3, the duration of t3 being determined according to the required thickness e3 of the third layer 103.

[0111] In the accompanying drawings, the durations t1, t2, and t3 are represented as the same, and the thicknesses e1, e2, and e3 are also represented as the same, but this is by no means necessary.

[0112] Figures 4 to 6 This illustrates another embodiment of the method of the present invention.

[0113] This method allows coatings to be applied to fibers 200, such as silicon carbide fibers, glass fibers, or carbon fibers.

[0114] For example, fiber 200 can be directly coated by a solidified interface phase 210. For example, such solidified interface phase 210 may include a first layer, such as a first layer containing boron nitride (BN) or pyrolytic carbon (PyC), which is configured to be in direct contact with fiber 200.

[0115] In one embodiment, the interface phase 210 may further include a second outer layer, which is configured to directly contact and protect the first layer, thereby ensuring the integrity of the solidified interface phase 210.

[0116] The deposition of interface phase 210 can be carried out in a manner known per se, and interface phase 210 should not be construed as a layer of coating that can be obtained by the methods described herein. It should be noted that... Figure 4 There is no distinction between the first and second layers of the consolidation interface phase 210.

[0117] The consolidation interface phase 210 primarily allows for the improvement of certain properties of fiber 200, particularly its oxidation resistance or crack resistance.

[0118] This fiber 200 (whether or not it contains the interface phase 210) is used in a variety of technical fields and often requires a coating.

[0119] Therefore, it will be understood from the following that the coating can be obtained on the interface phase 210 or on the fiber 200. Figure 4 The diagram illustrates the case where an interface phase exists.

[0120] The method can obtain a thin coating and can also change the composition of the coating to achieve optimal fiber functionalization, while using a furnace that is less complex than existing technologies.

[0121] The coating in this example includes a first silicon carbide layer 201, a carbon layer C(Si) 203 containing less than or equal to 20% silicon atoms, and a second silicon carbide layer 205.

[0122] Between layers 201 and 203, and between layers 203 and 205, the coating includes transition regions 202 and 204, the carbon and silicon contents of which vary between the composition of the layers defining these transition regions 202 and 204 within the thickness of the transition regions 202 and 204.

[0123] In other words, the transition region 202 includes the carbon and silicon content that varies from the composition of layer 201 to the composition of layer 203.

[0124] Similarly, the transition region 204 includes carbon and silicon content that varies from the composition of layer 203 to the composition of layer 205.

[0125] In order to obtain Figure 4 The coating described herein can be used Figure 5 The temperature condition T shown in the figure is given by... Figure 6 The precursor ratio R shown in the figure is supplied to the reaction chamber, and the precursor is dihydrogen H2 and methyltrichlorosilane CH3SiCl3.

[0126] Figure 5 and Figure 6 This represents the changes in temperature T and precursor ratio R over time t.

[0127] In the illustrated embodiment, the temperature is initially maintained at a constant duration t1, which is the duration of the step of obtaining the first layer 201.

[0128] The temperature is then varied affinely to achieve the temperature required for the second layer 203.

[0129] However, during this transition step, the supply of precursors to the reaction chamber is not cut off, but rather... Figures 1 to 3 In the illustrated embodiment, there may be a situation where the supply is interrupted, but the precursor supply is maintained, and the precursor ratio is, for example... Figure 4 As shown, the proportion R of the step to obtain the first layer varies between the proportion R of the step to obtain the second layer.

[0130] This implementation allows for the formation of a transition region 202 between the step of obtaining the first layer 201 and the step of obtaining the second layer 203.

[0131] These transition regions improve the lifetime of the deposited layer and the maintenance of its performance over time because they ensure the “material” continuity of the layer system throughout the coating’s lifespan.

[0132] Furthermore, the gradual change in carbon and silicon content in transition region 202 ensures excellent chemical compatibility of layers 201 and 203, giving the whole structure better resistance to delamination.

[0133] In the illustrated embodiment, and typically in embodiments that include a transition step, the transition region may be in direct contact with the layer obtained during the obtaining step, and the layer obtained during subsequent obtaining steps may be in direct contact with the transition region.

[0134] also, Figure 5 and Figure 6 The meaning of the affine transformation of the parameter between the first and second values ​​is shown.

[0135] Once the required parameters for obtaining the second layer 203 have been achieved, the parameters are maintained for a duration t2.

[0136] Unintentionally, the inventors determined that a temperature between 920°C and 1050°C could both reduce SiCl3 to silicon and dehydrogenate methyl radicals, which promoted the deposition of silicon carbide.

[0137] By further adjusting the H2 / methyltrichlorosilane ratio supplied to the reaction chamber, for example by selecting a ratio between 7 and 10, or even 10, as shown in the figure, stoichiometric silicon carbide (SiC) can be deposited.

[0138] The inventors also determined that carbon-rich deposits could be obtained at temperatures between 950°C and 1020°C with a reduced H2 / methyltrichlorosilane ratio of less than or equal to 5, or even less than or equal to 3.

[0139] Figure 5 and Figure 6 The steps for obtaining the third layer 205 are also presented, with a duration of t3 and parameters similar to those for obtaining the first layer.

[0140] For example, the transition steps that allow the formation of transition region 204 are presented again, during which the temperature and precursor ratio vary affinely between the step parameters for obtaining the second layer 203 and the step parameters for obtaining the third layer 205.

[0141] In one implementation, the pressure between the two steps of obtaining the layer may or may not be changed.

[0142] For example, pressure can follow a similar variation to other parameters such as temperature and precursor supply ratio, that is, it has a constant value during the layer-gaining step and a variable value during the transition step.

[0143] In one implementation, the pressure can vary between 50 mbar and 400 mbar during the method.

[0144] For example, the step of obtaining a layer containing between 45% and 55% or even between 49% and 51% silicon atoms and complementary carbon atoms, or the step of obtaining a layer containing greater than or equal to 95% silicon atoms and complementary carbon atoms, can be carried out at 300 mbar.

[0145] In other words, used to obtain the basis Figure 1 The pressure of the product can be constant and 300 millibars.

[0146] For example, the step of obtaining a C(Si) layer containing less than or equal to 20% silicon atoms and complementary carbon atoms can be achieved under a pressure of 100 mbar.

[0147] In other words, for Figure 5 and Figure 6 The method shown in the figure is used to obtain according to Figure 4 The method for obtaining the product, wherein the steps of obtaining the first layer 201 and the third layer 205 can be carried out at 300 mbar, the step of obtaining the second layer 203 can be carried out at 100 mbar, and the pressure is varied in an affine manner between 300 mbar and 100 mbar in the first transition step, and in an affine manner between 100 mbar and 300 mbar in the second transition step.

[0148] The examples presented in the specific embodiments are only for illustrating the advantages of the method of the present invention, and should not be regarded as limiting the properties of the substrate or the deposited layer.

[0149] In particular, the figures are not shown to scale, and equal durations or values ​​in the figures should not be interpreted as necessarily being the same in the method of this application.

[0150] In this application, unless otherwise stated, a range of values ​​described as “between… and…” should be understood to include the endpoints.

Claims

1. A method for chemical vapor deposition of a coating on a substrate, the method comprising at least the following steps: - The step of placing the substrate (100, 200) in the reaction chamber; - The first layer (101, 201) is obtained by feeding a mixture of dihydrogen and methyltrichlorosilane into the reaction chamber; - The step of obtaining the second layer (102, 203) by feeding a mixture of dihydrogen and methyltrichlorosilane into the reaction chamber; - The step of obtaining the third layer (103, 205) by feeding a mixture of dihydrogen and methyltrichlorosilane into the reaction chamber; The first and third layers are layers containing 95% or more silicon atoms and complementary carbon atoms, obtained at a volume ratio of H2 / methyltrichlorosilane greater than or equal to 20, at a temperature between 850°C and 920°C, and at a pressure between 200 mbar and 400 mbar. The second layer is a silicon carbide layer containing 49% to 51% silicon atoms and complementary carbon atoms, obtained at a volume ratio of H2 / methyltrichlorosilane between 7 and 10, at a temperature between 920°C and 1050°C, and at a pressure between 100 mbar and 300 mbar.

2. The deposition method of claim 1, wherein, The steps of obtaining a given layer (101, 102, 103, 201, 203, 205) are separated from the steps of obtaining the next layer by a purging step, during which all precursors present in the reaction chamber are removed.

3. The deposition method according to any one of claims 1 or 2, wherein, The method includes a transition step between two consecutive steps of obtaining layers (101, 102, 103, 201, 203, 205), during which a mixture of dihydrogen and methyltrichlorosilane is supplied to the reaction chamber, and the volume ratio of H2 / methyltrichlorosilane varies between the proportions of the first and second obtaining layers steps during the transition step, the temperature of the reaction chamber varies between the temperatures of the first and second obtaining layers steps during the transition step, and the pressure varies between the pressures of the first and second obtaining layers steps during the transition step.

4. The deposition method of claim 3, wherein, At least one of the H2 / methyltrichlorosilane volume ratio, temperature, or respective pressure used in the transition step varies affinely between the H2 / methyltrichlorosilane volume ratio in the step for obtaining layers (101, 102, 103, 201, 203, 205) before the transition step and the H2 / methyltrichlorosilane volume ratio in the step for obtaining layers after the transition step; varies between the temperature in the step for obtaining layers before the transition step and the temperature in the step for obtaining layers after the transition step; and / or varies between the pressure in the step for obtaining layers before the transition step and the pressure in the step for obtaining layers after the transition step.

5. The deposition method of any one of claims 1 to 4, wherein, The substrates (100, 200) are selected from turbine blades, distributor portions, annular sector regions, and fibers, the fibers optionally being coated with a consolidation interface phase.

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