Method of manufacturing a CMC component

Abstract

The invention relates to a method of manufacturing a ceramic matrix composite part, said part comprising at least one cavity, said method comprising the following steps: - filling (S1) the cavity (102) of a fibrous preform (101) of the part to be obtained with a non-wetting silicon particles (202) powder; then, - a step (S2) of infiltrating the fibrous preform with a liquid infiltration composition (212), wherein the infiltration composition comprises at least silicon; then, - a step (S3) of cooling the infiltrated preform (301) whose cavity is filled with said particles powder; then, - removing (S4) the non-wetting silicon particles powder from the cavity of the densified preform.

Description

Technical Field

[0001] This invention relates to a method for manufacturing ceramic matrix composite parts. Background Technology

[0002] Ceramic matrix composites (CMCs) can withstand a temperature range of 600°C to 1400°C.

[0003] Because CMC has better high-temperature resistance, it requires less cooling. Since this cooling is usually achieved by drawing airflow from the compressor, which affects the productivity of gas turbine engines, CMC materials allow for increased engine productivity, thereby reducing fuel consumption.

[0004] Furthermore, its use helps optimize the performance of gas turbine engines by reducing the overall mass of the turbine engine, which in turn helps reduce fuel consumption and thus significantly reduce pollution emissions.

[0005] These advantages illustrate the benefits of developing the aforementioned ceramic matrix composites industrially.

[0006] One known method for manufacturing the component is silicon infiltration, known as "molten infiltration," often simply referred to as MI.

[0007] In this method, the fiber preform is impregnated with a penetrating composition typically containing molten silicon to form a matrix of CMC material within the pores of the fiber preform. Typically, for penetration, one end of the preform is immersed in a bath of the penetrating composition, causing the composition to fill the pores of the preform under capillary action.

[0008] The method is satisfactory from an industrial perspective, but there are still areas for improvement.

[0009] In particular, because silicon is denser in the solid state than in the liquid state, its cooling and solidification causes some of the liquid silicon to flow out as droplets. These droplets solidify on the surface of the component, forming solid silicon nodules. These nodules cause significant difficulties because they cause component dimensional changes to exceed tolerances and reduce the adhesion of any subsequent surface coatings. Furthermore, the subsequent removal of these nodules by sandblasting or machining is time-consuming, tedious, and costly, and can also affect the material integrity of the final component.

[0010] Therefore, several solutions have been envisioned to suppress the formation of these nodules. One solution is to alter the composition of the densifying material or ceramic slurry, for example, by adding diamond particles, which are a carbon source and will consume excess silicon to form SiC. However, it is not always possible or desirable to alter the slurry composition in this way.

[0011] Another option is to create a sacrificial ceramic slurry layer around the intermediate component to protect the final component, particularly to reinforce it during sandblasting or machining of nodules. However, this option clearly results in significant overconsumption of raw materials and requires complete machining of the final component, which is both tedious and time-consuming.

[0012] Alternatively, thermal mass can be added at the point where the nodule is expected to form. However, this alternative does not provide complete control over the point of nodule formation and cannot be applied to all component geometries.

[0013] Therefore, there is indeed a need for a method for manufacturing CMC parts that can better control the densification process and at least partially overcome the inherent drawbacks of the aforementioned known methods. Summary of the Invention

[0014] This invention is specifically designed to meet this need.

[0015] Therefore, the present invention relates in a first aspect to a method for manufacturing a ceramic matrix composite component, the component comprising at least one cavity, the method comprising the steps of: - filling the cavity of a fiber preform of a component to be obtained with non-wetting silica particulate powder; then - permeating the fiber preform with a liquid permeation composition, the permeation composition comprising at least silica; then - cooling the permeated preform, the cavity of which is filled with the particulate powder; then - removing the non-wetting silica particulate powder from the cavity of the densified preform.

[0016] Using non-wetting particulate powder protects the cavity interior from the effects of excessive silicon. If any silicon-containing penetrating composition flows from the preform into the cavity interior, it will not form nodules there, but will be trapped in the particulate network, which has surfaces to which the penetrating composition has no affinity. It will then form dispersed small clusters within this network, similar to oil forming bubbles in water. Therefore, it will no longer be able to adhere to the inner surface of the preform, thus preventing the formation of silicon nodules.

[0017] Therefore, this provides a relatively simple means of protecting the internal cavity of a fiber preform from the formation of silica nodules during the infiltration step with an infiltration composition containing molten silicon.

[0018] In fact, silicon nodules are often found precisely within the internal cavity of the component, especially because cooling is slower there than on the outer surface of the preform.

[0019] Furthermore, on the surface of the internal cavity, envisioning subsequent machining steps to remove the nodules once they are formed is very complex, which is why the proposed method allows for the attainment of a guaranteed excellent surface condition through a simplified approach.

[0020] In one embodiment, the particles of the non-wetting silicon particle powder may include particles selected from the following: boron nitride particles, alumina particles, yttrium oxide particles, silicon dioxide particles, silicon nitride particles, or a mixture of two or more of the above particles.

[0021] In this application, the term "non-wetting" should be interpreted in the usual sense of physical wetting between a surface and a liquid, where the surface is the surface of particles and the liquid is silicon.

[0022] Wettability can be measured by the contact angle between a liquid and a surface, as is commonly defined, using the liquid tangent at the point of contact at the air / liquid / surface interface. The smaller the contact angle, the greater the wettability.

[0023] In the foregoing, since non-wetting particles are specifically designed to have poor wettability with liquids, in the sense of this invention, "non-wetting" particles are defined by their ability to have a contact angle of 60° or greater, or even 90° or greater, more preferably 120° or greater with liquid silicon.

[0024] In one embodiment, the particles of the powder may contain more than 90% by mass, or even more than 95% by mass, or even more than 99% by mass of particles selected from the following: boron nitride particles, alumina particles, yttrium oxide particles, silicon dioxide particles, silicon nitride particles, or a mixture of two or more of the above particles.

[0025] In one embodiment, the particulate powder may comprise particles with a size between 0.1 μm and 1000 μm, for example, between 1 μm and 1000 μm.

[0026] The “size” of a particle can be defined as the maximum dimension along the length of the particle, that is, the diameter of the smallest sphere containing the particle.

[0027] In one embodiment, the particulate powder may comprise particles with a size distribution such that the median size d50 of the particulate powder is between 100 μm and 1.0 mm.

[0028] The median particle size d50 can be determined in the conventional way in the field of powder materials using a particle size analyzer, such as a particle size analyzer that applies the Mie method.

[0029] As is known and will not be described in detail herein, the measurement is based on detecting the angle of refraction of the laser beam irradiating the sample.

[0030] In one embodiment, the fiber preform may be selected from preforms of aerospace components, such as preforms of turbine blades or preforms of turbine nozzle sections.

[0031] The preforms of the components typically include cavities designed to form complex cooling circuits, for which improved surface conditions are advantageous.

[0032] In one embodiment, the fiber preform has a three-dimensional weave.

[0033] In this article, “three-dimensional weaving” or “3D weaving” refers to a weaving method of a preform in which at least some warp yarns are combined with weft yarns on multiple weft layers, such as “interlocking weaving”.

[0034] In this article, "interlocking weaving" refers to a 3D weaving in which each warp layer combines with multiple weft layers, and all yarns in the same warp row have the same movement in the weaving plane.

[0035] In one embodiment, the preform may include silicon carbide fibers and / or carbon fibers.

[0036] The molten silicon infiltration method is particularly advantageous for the aforementioned preform.

[0037] In one embodiment, the permeation step of the fiber preform can be carried out by immersing a portion of the preform in a bath of the permeation composition.

[0038] In one embodiment, the permeation step of the fiber preform can be performed by inserting a drain between the permeation composition and the preform.

[0039] This embodiment avoids direct contact between the infiltrating composition and the fiber preform, which imparts a better surface condition to the preform. This reduces the risk that the densified preform may require machining steps after infiltration to improve its surface condition, which would be necessary if the preform were immersed in the infiltrating composition bath.

[0040] In one embodiment, the permeation composition may comprise pure silicon or a silicon alloy.

[0041] Since the penetrating composition contains molten silicon, or a molten silicon alloy, or is composed of molten silicon, non-wetting particles of molten silicon will have similar behavior to the penetrating composition, namely, non-wetting.

[0042] In one embodiment, the internal cavity of the fiber preform can be filled by dry filling of the cavity with powder.

[0043] "Dry deposition" refers to the method of the present invention, which does not require the use of a carrier fluid when depositing particulate powder in a preform cavity, unlike prior art methods that use, for example, slurries.

[0044] In a dry deposition method, the solid composition can still be sprayed in liquid, solid, or paste form without any carrier liquid, and once deposition is complete, it forms a solid deposit.

[0045] For example, once the powder is placed in the cavity, it can be compacted by placing the preform on a vibrating table.

[0046] In one embodiment, the cavity can be filled using a slurry composed of non-wetting silicon particles dispersed in a liquid solution.

[0047] In one embodiment, the liquid solution may contain distilled water or reverse osmosis water, ethanol, or a mixture of two of these substances.

[0048] For example, non-wetting silicon particles intended to form particulate powder can be dispersed in a liquid solution to form a slurry, the cavity of the preform is filled with the slurry, and finally the liquid solution is removed, for example, by evaporation. Attached Figure Description

[0049] Figure 1 A flowchart is provided to illustrate a method in one embodiment.

[0050] Figure 2 This is a schematic diagram of a prefabricated structure, used to illustrate one step of the method.

[0051] Figure 3 This is a schematic diagram of the preform after filling, used to illustrate an embodiment of one step of the method.

[0052] Figure 4 This is a schematic diagram of the penetration process, used to illustrate one embodiment of the method's steps.

[0053] Figure 5 This is a schematic diagram of an impregnated preform, illustrating one embodiment of the method steps.

[0054] Figure 6 This is a schematic diagram of an impregnated preform, used to illustrate a component obtained in one embodiment of the present invention. Detailed Implementation

[0055] The invention will now be described with the aid of the accompanying drawings, which are used for descriptive purposes to illustrate some embodiments of the invention, but should not be construed as limiting the invention.

[0056] Figure 1 A flowchart is provided to illustrate the method steps in one embodiment.

[0057] Figure 1 The method includes four steps numbered S1 to S4:

[0058] - Filling S1: Fill the cavity of the fiber preform of the part to be obtained with non-wetting silicon particulate powder; then - Infiltration step S2: Infiltrate the fiber preform with a liquid infiltration composition, the infiltration composition containing at least silicon; then - Cooling step S3: Cool the infiltrated preform whose cavity is filled with particulate powder; then - Removal S4: Remove the non-wetting silicon particulate powder from the cavity of the densified preform.

[0059] Figure 2 A preform 101 is shown in one embodiment of the method.

[0060] The preform 101 can be a preform of an aerospace component, such as a preform of a turbine engine blade or a preform of a turbine nozzle section.

[0061] The fiber preform 101 has a cavity 102.

[0062] Cavity 102 is a through cavity because the inside of the cavity is fluidly connected to the outside of the cavity.

[0063] In one embodiment, the fibers forming the fiber preform 101 are selected from silicon carbide (SiC) fibers and / or carbon fibers.

[0064] The cavity 102 can be filled using a dry method, that is, without using a carrier fluid to deliver the particles 202 into the cavity 102.

[0065] Alternatively, cavity 102 can be filled with a slurry consisting of a liquid solution in which particles are dispersed.

[0066] The slurry is placed in cavity 102, and then the liquid solution is removed, for example, by exposing the preform and slurry components to a temperature higher than or equal to the evaporation temperature of the liquid solution.

[0067] For example, the cavity can be filled by sealing one end and filling the other end.

[0068] Figure 3 The preform 101 after step S1 is shown, i.e., after the cavity 102 is filled with powder containing non-wetting silicon particles 202.

[0069] Figure 4 The implementation of step S2 of permeating preform 101 with liquid permeation composition 212 is shown.

[0070] In one embodiment, such as Figure 4 As shown, the preform 101 can be directly positioned to contact the permeation solution 212, which is placed in the crucible 210.

[0071] In an embodiment not shown, the preform 101 may be separated from the permeation composition 212 by a drainage element. The drainage element prevents a portion of the preform from directly contacting the permeation composition. This embodiment provides an improved surface condition of the preform after permeation.

[0072] The method of infiltration using liquid infiltration composition 212 will not be described in detail here, because the advantages of the described method are not specific to the parameters selected in the infiltration step of the preform using the infiltration composition.

[0073] For example, an assembly formed by a preform 101, particles 202, a crucible 210 and a permeation composition 212 contained therein is placed in a chamber heated to a temperature higher than or equal to the melting temperature of the permeation composition 212.

[0074] The porosity of the preform 101 is sufficient to cause capillary action and impregnation of the preform 101 upon contact with the permeating composition 212.

[0075] In one embodiment, the permeation composition 212 may be selected from silicon or silicon alloy compositions.

[0076] Preferably, the permeation composition 212 contains more than 90% by mass, or even more than 95% by mass, silicon.

[0077] When the permeation composition 212 is a silicon alloy, the non-wetting behavior of the silicon particles still allows the following desired technical effects to be achieved.

[0078] Figure 5 The preform 301 after infiltration step S3 is shown, which is the preform 101 after infiltration step S3, at which point the infiltration composition 212 has impregnated its pores, preferably by capillary action.

[0079] Furthermore, the permeation composition contained in the pores of the preform may have overflowed from the preform 101 into the cavity 102 after cooling.

[0080] However, unlike existing methods, the infiltration composition does not form silicon nodules on the surface of the cavity 102 of the preform 101, but rather forms non-wetting contact with particles 202 of non-wetting silicon powder present in the cavity 102.

[0081] Therefore, as Figure 5 As shown, due to poor wetting between the powder particles 202 and the penetrating composition 212, the penetrating composition overflowing from the preform 101 is trapped in the network of particles 202 and forms small clusters 310 therein.

[0082] Due to the non-wetting nature of the contact between the penetrating composition and the particles 202, the penetrating composition does not adhere to the inner surface of the cavity 102, which would occur in the absence of powder.

[0083] Therefore, in step S4, when the particles are removed from the cavity 102 of the permeated preform 301, the clusters 310 of the permeated composition thus formed in the particles 202 are eliminated, while ensuring that the permeated composition does not form nodules.

[0084] This greatly improves the surface condition of the cavity 102 of the part 301 obtained after the penetrating composition 212 has penetrated into the preform, because the surface is free of nodules.

[0085] Figure 6 The composite material component 301 obtained by step S4 is shown, i.e., after the particulate powder 202 is removed from the cavity 102.

[0086] The now-permeated preform 101 forms a composite component 301, the fiber preform being formed from the preform 101 and the matrix being formed from the permeated composition 212.

[0087] It is particularly important to note that during the removal of particles 202, clusters 310 formed during the cooling of the permeation composition are also removed.

[0088] In one embodiment, the method may include subsequent final machining steps, such as obtaining the final dimensions of the part for integration into a turbine engine.

[0089] For example, the final machining may include machining, contouring, drilling, or any other steps designed to adjust the size of the part.

[0090] As shown in the figure, this method allows for the densification of the preform 101 while ensuring that the cavity 102 of the preform exhibits excellent surface condition when the method is completed, without complicating the densification steps of the fiber preform and without requiring machining of the inner surface of the cavity.

Claims

1. A method for manufacturing a ceramic matrix composite component (301), the component comprising at least one cavity, the method comprising the following steps: - Fill (S21) the cavity (102) of the fiber preform (101) of the part to be obtained with non-wetting silicon particle (202) powder; then - permeate the fiber preform with a liquid permeation composition (212) containing at least silicon; then - cool the permeated preform (301) whose cavity is filled with particulate powder; then - remove (S4) the non-wetting silicon particle powder from the cavity of the densified preform.

2. The method according to claim 1, wherein the particles (202) of the non-wetting silicon particle powder comprise particles selected from: boron nitride particles, alumina particles, yttrium oxide particles, silicon dioxide particles, silicon nitride particles, or a mixture of two or more of the particles.

3. The method according to claim 2, wherein the particles (202) of the non-wetting silicon particle powder comprise more than 90% by mass of particles selected from boron nitride particles, alumina particles, yttrium oxide particles, silicon dioxide particles, silicon nitride particles, or mixtures of two or more of said particles.

4. The method according to any one of claims 1 to 3, wherein the particulate powder comprises particles (202) with a size between 0.1 μm and 1000 μm.

5. The method according to any one of claims 1 to 4, wherein the preform (101) comprises silicon carbide fibers and / or carbon fibers.

6. The method according to any one of claims 1 to 5, wherein the permeation composition (212) may comprise pure silicon or a silicon alloy.

7. The method according to any one of claims 1 to 6, wherein the filling step of the internal cavity (102) of the preform (101) is carried out by a slurry composed of non-wetting silicon particles (202) dispersed in a liquid solution.

8. The method according to any one of claims 1 to 7, wherein the fiber preform (101) is selected from preforms of aerospace components, such as preforms of turbine blades or preforms of turbine nozzle portions.

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