METHOD FOR MANUFACTURING A TURBOMACH MACHINE SHELL MADE OF CERAMIC MATRIX COMPOSITE MATERIAL

Description

Technical Field

[0001] The present invention relates to the general field of the design of ceramic matrix composite (CMC) materials, and more particularly to the design of a part made of CMC composite material integrating both a structural part and a functional part, distinct from the structural part. Prior art

[0002] CMC material parts can be made using woven textile preforms made from long continuous fibers. However, weaving can be complicated for functional parts of the part, which may have a complex shape.

[0003] Documents US 2016 / 177745 and US 2019 / 323363 describe a turbomachine blade made of CMC material comprising an abrasive tip. The blades of these two documents do not comprise a functional part of complex geometry, for example a functional part comprising several functional portions.

[0004] WO 2020 / 025878 describes a turbine blade made of CMC material having a smooth surface finish thanks to the application of pre-impregnated non-woven plies. FR 2 961 845 describes a turbomachine blade made of CMC material from a single three-dimensionally woven fiber preform. This document does not propose the use of short fibers to form a functional part.

[0005] It is therefore desirable to have a manufacturing process for a part made of functionalized CMC material and having the desired structural strength which is relatively simple to implement. Statement of the invention

[0006] The invention relates to a method for manufacturing a part made of ceramic matrix composite material comprising at least one structural part and one functional part secured to the structural part, the functional part comprising three functional portions: a downstream wall, an upstream wall and a platform of the blade root; the method comprising: obtaining an assembly comprising a first preform of the functional part mounted on a second preform of the structural part or on the structural part, the first preform comprising a fibrous reinforcement of short fibers and the second preform or the structural part comprising a woven fibrous reinforcement, and densifying at least the first preform of the assembly by infiltration with a molten composition.

[0007] The structural part gives the part the desired structural strength while the functional part is a part subject to little thermo-mechanical stress, allowing it to provide a non-structural function, such as a sealing or anti-tilt function. The use of a woven fiber reinforcement guarantees the desired mechanical strength for the structural part and the use of short fibers makes it possible to avoid a weaving step for the manufacture of the functional part and the associated limitations in terms of achievable geometry. The manufacture of a part in CMC material is thus simplified, thanks to the dissociation between the functions and geometric singularities, and the structure of the part.

[0008] The manufacturing method of the invention can also be used as a repair method to manufacture a repaired part.

[0009] According to a particular characteristic of the invention, the first preform is mounted on the second preform and there is co-densification of the first and second preforms by the molten composition.

[0010] Co-densification allows the two preforms to be bonded together by the infiltration of the molten composition into both preforms and also allows the formation of a common matrix for the structural and functional parts.

[0011] According to another particular characteristic of the invention, the first preform is mounted on the structural part and the molten composition makes it possible to braze the functional part to the structural part.

[0012] In the latter case, the first preform is mounted on the structural part which is made of CMC material and already densified. Densifying the preform of the functional part directly on the structural part allows the preform to be densified and this functional part to be brazed to the structural part by the molten composition. The functional part is thus linked to the structural part in the resulting part. This makes it possible in particular to repair and replace a functional part of a part made of CMC material. A defect, such as a damaged area of ​​a functional part of the part, can thus be repaired by adding a new portion on the damaged functional part to replace the defect, or by replacing the entire damaged functional part with a new functional part.Depending on its nature, size and location, it is also possible to repair a defect present in a structural part by brazing the first preform onto or in place of the defect in the structural part.

[0013] According to one embodiment of the invention, the method further comprises the formation of the first preform, this formation comprises a formation of a first blank comprising the fibrous reinforcement of short fibers present in a binder, a debinding of the first blank and a possible compaction of the debinded first blank so as to obtain the first preform.

[0014] The binder binds the short fibers together, as well as any other fillers present. Its effect is to reduce the friability of the blank before debinding. This makes it easier to handle the blank, for example, when inserting it into a mold.

[0015] According to a particular characteristic of the invention, the first blank further comprises first additional fillers present in the binder and distinct from the short fibers of the reinforcement, the first additional fillers having a metallic or ceramic surface.

[0016] According to another particular characteristic of the invention, the first preform is mounted on the second preform and obtaining the assembly comprises shaping a second blank comprising the woven fibrous reinforcement so as to obtain the second preform.

[0017] According to another particular characteristic of the invention, the second blank further comprises second additional fillers having a metallic or ceramic surface.

[0018] According to another particular characteristic of the invention, consolidation of the first preform is carried out by sintering the first additional fillers before densification.

[0019] According to another particular characteristic of the invention, consolidation of the second preform is carried out by sintering the second additional fillers before densification.

[0020] Sintering the first and / or second additional fillers in the preforms allows the volume rate of pores in the preforms to be reduced so that the preforms have better hold, particularly during densification. It also allows the rate of free silicon in the final part to be reduced, because the porosity to be filled is lower.

[0021] According to another particular characteristic of the invention, the functional part is at least one of a sealing part or an anti-tilt part of the part.

[0022] The functional part may also be a repair portion of a functional or structural part, for example in the form of a patch.

[0023] Alternatively, the functional part can also be an aerodynamic over-profile.

[0024] More specifically, in the case of an over-airfoil, the solid and central part of the blade can be a structural preform and the complex-shaped airfoil can be obtained by adding a functional part around the simple-shaped structural preform. In the case of a repair process, this makes it possible to easily reform and / or repair the complex airfoil after several thousand flight hours.

[0025] According to another particular characteristic of the invention, the part is a turbomachine part.

[0026] According to another particular characteristic of the invention, the part is a turbomachine blade. Brief description of the drawings

[0027] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature. [ Fig. 1 ] There figure 1 represents, schematically and partially, a part made of ceramic matrix composite material according to one embodiment of the invention. Fig. 2 ] There figure 2 represents, schematically and partially, a method of manufacturing a part in CMC material according to an embodiment of the invention. Fig. 3 ] There figure 3 represents, schematically and partially, a method of manufacturing a part in CMC material according to an embodiment of the invention. Description of the embodiments

[0028] There figure 1 represents, schematically and partially, a part 100 made of ceramic matrix composite (CMC) material according to one embodiment of the invention.

[0029] In this exemplary embodiment, the part 100 made of CMC material is a turbomachine blade comprising a structural part 110 and a functional part 120. In the illustrated example, the structural part 110 comprises in particular a blade part 114 defining the aerodynamic profile and comprising a pressure face and an extrados face, an upper platform 111 and a lower platform 113 which define the vein of the blade 100, and a blade root 112. According to the invention, the structural part 110 comprises a woven fiber reinforcement, that is to say it is made of a CMC material comprising a fiber reinforcement consisting of continuous fibers and densified by a ceramic matrix. The fiber reinforcement can be obtained by three-dimensional weaving, for example with an interlock weave armor.

[0030] The functional part 120 is a non-structural part, and is intended to provide a function other than a structural function. According to the invention, the functional part 120 comprises three functional portions: a downstream wall 121, an upstream wall 122 and the foot platform 123. According to the invention, these portions of the functional part are made of CMC material comprising a fibrous reinforcement consisting of short fibers and densified by a ceramic matrix.

[0031] The role of the walls 121 and 122 is to ensure axial sealing. The role of the foot platform 123 is to close the cavity in which the blade foot 112 is located to create a pressure chamber. This platform 123 also prevents the foot 112 from tilting.

[0032] The functional portions 121, 122 and 123 are integral with the structural part 110.

[0033] There figure 2 represents a method 200 for manufacturing a part made of CMC material according to an embodiment of the invention.

[0034] The final part made of CMC material comprises at least one functional part secured to a structural part. The method 200 first comprises obtaining an assembly 210. The assembly comprises a first preform of the functional part mounted on either a second preform of the non-densified or incompletely densified structural part, or the structural part made of CMC material, already densified.

[0035] The first preform comprises a fibrous reinforcement of short fibers while the second preform or the structural part comprises a woven fibrous reinforcement. More particularly, the structural part comprises a woven fibrous reinforcement densified by a ceramic matrix.

[0036] The method 200 then comprises the densification 220 of the first preform of the assembly. The densification 220 is carried out by infiltration of the first preform with a molten composition comprising for example silicon (melt infiltration technique, “Melt-Infiltration”). The densification 220 makes it possible to form a ceramic matrix in the first preform and to bond the first preform to the second preform or to the structural part.

[0037] If, when obtaining the assembly 210, the first preform is mounted on the second preform, it is also possible to co-densify the first and second preforms by the molten composition during the densification step 220. This also makes it possible to form a ceramic matrix in the second preform while binding the two preforms together. This thus forms a common ceramic matrix densifying the first preform and the second preform. The matrix continuity between the two preforms is improved and this makes it possible to reduce design singularities, in particular the weak zones of the final part.

[0038] There figure 3 represents a method 300 of manufacturing a part made of CMC material according to another embodiment of the invention.

[0039] The final part made of CMC material always includes a functional part attached to a structural part.

[0040] The method 300 first comprises the compaction 310 of a first blank. The first blank can be formed from a fibrous reinforcement of short fibers present in a binder which is debinded before carrying out the compaction 310. The compaction 310 of the debinded first blank makes it possible to obtain a first preform of the functional part. The binder makes it possible to reduce the friability of the blank and to handle the blank more easily before debinding it for the compaction 310.

[0041] Compaction 310 may result in a reduction of at least 10% in at least one dimension of the blank.

[0042] 310 compaction can be hot isostatic compaction, cold isostatic compaction or even flash sintering (“Spark Plasma Sintering” in English).

[0043] Then, this first preform is placed on a second preform of the structural part or on the structural part of the part so as to obtain an assembly 320. As indicated previously, the second preform or the structural part comprises a woven fibrous reinforcement, and more particularly the structural part comprises a woven fibrous reinforcement densified by a ceramic matrix.

[0044] Finally, the first preform 340 is densified by infiltration of the first preform with a molten composition. This densification 340 makes it possible to form a ceramic matrix in the first preform and to bond the first preform to the structural part or to the second preform.

[0045] As before, if the first preform is mounted on a second preform of the structural part and not directly on the structural part, the two preforms can be co-densified during densification 340. This makes it possible to form a common ceramic matrix in the first and second preforms.

[0046] In addition, the first blank may also include additional fillers in the binder distinct from the short fibers, and having a metallic or ceramic surface. Thanks to these additional fillers, the first preform can be consolidated before densification by the molten composition. The consolidation 330 of the first preform is optional and can be carried out between obtaining the assembly 320 and the densification 340 or before positioning the first preform on the second preform or on the structural part so as to form the assembly. The consolidation 330 can be carried out by sintering the first additional fillers. It is within the general knowledge of a person skilled in the art to determine the operating conditions of temperature and sintering duration depending on the materials used. It makes it possible to reduce the friability of the first preform and to increase its mechanical strength.

[0047] Furthermore, the second preform can be obtained from a second shaped blank comprising the woven fiber reinforcement.

[0048] The second blank may also comprise second additional fillers having a metallic or ceramic surface. Thus, as for the first preform, the second preform may be consolidated. This optional consolidation of the second preform may be carried out at the same time as the consolidation 330 of the first preform or before the positioning of the first preform. It may also be carried out by sintering the second additional fillers. It thus makes it possible to reduce the friability of the second preform and to increase the mechanical strength of the assembly of the two preforms.

[0049] It is also possible to separately densify the first and second blanks of the two preforms, then braze them together to form the assembly.

[0050] Regardless of the method of carrying out the process, the short fibers may have a length of between 50 µm and 5000 µm, for example between 50 µm and 1000 µm, for example between 100 µm and 500 µm, for example substantially 250 µm. Unless otherwise stated, an “average” dimension designates the dimension given by the statistical particle size distribution to half of the population, called d 50 .

[0051] In addition, these short fibers may be silicon carbide SiC fibers with an oxygen content of less than or equal to 1% atomic percentage. These SiC fibers may, for example, be fibers supplied under the name "Hi-Nicalon-S" by the Japanese company NGS.

[0052] Regardless of the embodiment of the manufacturing process, the short fibers and / or the long fibers included in the reinforcement of the second preform may be coated with an interphase layer, for example a boron nitride (BN) or pyrocarbon (PyC) interphase layer. This interphase layer deflects cracks in the ceramic matrix during use of the part. The interphase layer has, for example, a thickness of 500 nm. The interphase layer may also be coated with a protective layer, for example a silicon carbide layer a few microns thick. This protective layer protects the interphase from potential chemical attacks from the molten composition during infiltration of the first preform and possibly the second preform.

[0053] Regardless of the manufacturing process, the additional fillers can be particles of silicon carbide or metal disilides. They participate in the formation of the matrix during densification.

[0054] The additional fillers of the first preform of the functional part may be coated with a metal layer. The metal layer may have a thickness of between 100 nm and 5000 nm, for example between 500 nm and 1500 nm.

[0055] Regardless of the embodiment of the manufacturing process, the molten composition may correspond to molten silicon alone or to a silicon alloy in the molten state which also contains one or more other elements such as titanium, molybdenum, boron, iron or niobium. The mass content of silicon in the molten composition may be greater than or equal to 50%, or even 90%. The molten composition may also correspond to a fusible alloy that is thermochemically compatible with the fillers and fiber reinforcements used in the preforms and blanks. The molten composition may also correspond to metal disilicides, such as, for example, titanium disilicide TiSi 2 or molybdenum disilicide MoSi 2 .

[0056] Regardless of the method of carrying out the manufacturing process, the first preform and / or the second preform may also be previously silicided before assembly so as to fill only part of their porosity. This preliminary siliciding makes it possible in particular to combine materials of different composition in order to give, for example, the final part thermomechanical property gradients, for example thermal coefficient gradients in order to promote the integration of the final part.

[0057] Regardless of the embodiment of the manufacturing method, the binders that can be used to produce the blank of the first preform may comprise at least one thermoplastic polymer. For example, the binder may comprise at least one compound chosen from polyvinyl alcohol (PVA), polyethylene glycol (PEG), polypropylene (PP), polyoxymethylene (POM) or polyethylene terephthalate (PET).

[0058] The binders may also comprise at least one thermosetting polymer. For example, they may comprise at least one compound selected from epoxy resins, phenolic resins or pre-ceramic resins.

[0059] Regardless of the method of carrying out the manufacturing process, in the first roughing, before debinding, the binder volume content may be between 15% and 55%, the volume content of the fillers (i.e. short fibers and additional fillers) may be between 45% and 85%. Among the fillers, the short fibers may have a volume content of between 10% and 35%, for example between 15% and 25% and the additional fillers represent the complement of the short fibers. After infiltration by the molten composition, the residual porosity of the final part is less than or equal to 15%.

[0060] The expression "between ... and ..." must be understood as including the limits.

Claims

1. A method (200, 300) for manufacturing a turbomachine blade (100) made of ceramic matrix composite material, comprising at least a structural part (110) and a functional part (120) secured to the structural part, the functional part comprising three functional portions: a downstream wall (121), an upstream wall (122) and a root platform (123) of the blade and the method comprising: - obtaining an assembly (210, 320) comprising a first preform of the functional part that is mounted on a second preform of the structural part or on the structural part, the first preform comprising a fibrous reinforcement of short fibres having a length between 50 µm and 5000 µm, and the second preform or the structural part comprising a woven fibrous reinforcement, and - densification (220, 340) of at least the first preform of the assembly by infiltration with a molten composition.

2. The manufacturing method according to claim 1, wherein the first preform is mounted on the second preform and wherein there is a co-densification of the first and second preforms by the molten composition.

3. The manufacturing method according to claim 1, wherein the first preform is mounted on the structural part and wherein the molten composition solders the functional part to the structural part.

4. The manufacturing method (300) according to any one of claims 1 to 3, wherein obtaining the assembly (320) further comprises forming the first preform, this forming comprising of forming a first blank comprising the fibrous reinforcement of short fibres present in a binder, debonding the first blank and compacting (310) the first debonded blank so as to obtain the first preform.

5. The manufacturing method according to claim 4, wherein the first blank further comprises first additional fillers present in the binder and distinct from the short fibres of the reinforcement, the first additional fillers having a metallic or ceramic surface.

6. The manufacturing method according to any one of claims 1, 2, 4 or 5, wherein the first preform is mounted on the second preform and obtaining the assembly comprises forming a second blank comprising the woven fibrous reinforcement, so as to obtain the second preform.

7. The manufacturing method according to claim 6, wherein the second blank further comprises second additional fillers having a metal or ceramic surface.

8. The manufacturing method (300) according to any one of claims 5, 6 or 7, referring to claim 5, wherein a consolidation (330) of the first preform is carried out by sintering the first additional fillers before the densification.

9. The manufacturing method according to claim 7 or 8 referring to claim 7, wherein a consolidation of the second preform is carried out by sintering the second additional fillers before densification.