Turbine assembly with inter-sector sealing

Abstract

Turbine assembly with inter-sector sealing. A turbine assembly comprises a plurality of adjacent sectors (40), each sector comprising at least one connecting edge of ceramic matrix composite material (42, 43), each connecting edge having at least one groove or recess (420, 421, 422) and at least one sealing tab (150, 151, 152) present in each groove or recess. Each sealing tab comprises at least one substrate of metallic material, the external surface of which is covered by an outer coating. The outer coating comprises at least one layer of a material selected from one of the following: alumina, nitride, oxide ceramic, aluminoforming alloy, and aluminide. Figures for the abstract: Fig. 4.

Description

Title of the invention: Turbine assembly with inter-sector sealing technical field

[0001] The present invention relates to turbomachine or gas turbine parts between which a seal must be achieved by means of at least one sealing tab present in grooves or housings at the level of the connecting edges of the adjacent parts.

[0002] The invention relates, for example, but not exclusively, to a turbine ring assembly for a turbomachine, which assembly comprises a plurality of ring sectors made of ceramic matrix composite material. Sealing between adjacent ring sectors is achieved by one or more sealing tabs housed in grooves machined in the connecting edges of the sectors.

[0003] Ceramic matrix composites, or CMCs, are known for their good mechanical properties, which make them suitable for use as structural elements, and for their ability to retain these properties at high temperatures. The use of CMCs for various hot parts of aircraft engines has already been considered, especially since CMCs have a lower density than traditionally used refractory metals. In the field of aircraft engines, CMC materials make it possible to increase the temperatures to which parts are subjected, thereby improving engine efficiency and reducing fuel consumption. Furthermore, their use helps optimize the performance of turbomachinery, particularly by reducing the overall mass of the turbomachine, which further contributes to lower fuel consumption and thus to a significant reduction in pollutant emissions.

[0004] The fabrication of a turbine ring assembly from CMC ring sectors is described in particular in document WO 2017 / 060604. Sealing between adjacent ring sectors is achieved by one or more sealing tabs housed in grooves machined in the connecting edges of the sectors. The tabs currently used for sealing between sectors are made of metallic materials such as nickel-based or cobalt-based alloys (e.g., Haynes® 188).

[0005] While the CMC ring sectors can withstand relatively high temperatures, particularly above 1000°C, this is not the case for the metal sealing tabs located between the sectors. Indeed, at these temperature levels, the metallic material of the sealing tabs can oxidize and chemically interact with the free silicon contained in the CMC matrix.

[0006] The CMC material used is generally based on silicon carbide (SiC) fibers and a SiC matrix. However, due to its manufacturing process, the material still contains silicon in metallic form, known as "free silicon." Free silicon can react at high temperatures with the metallic component(s) of the sealing tabs, typically above 700°C. Since the metallic tabs housed in the sealing grooves are potentially subjected to temperatures exceeding 700°C, they will react with the CMC in the machined recess.

[0007] The consequences of oxidation and chemical interaction are a local deterioration of the sealing tab and / or the CMC which can lead to a loss of sealing.

[0008] There is therefore a need to achieve a seal between parts of a compartmentalized assembly without risk of interaction and chemical reaction at high temperature. Description of the invention

[0009] To this end, the invention proposes a turbine assembly comprising a plurality of sectors adjacent to each other, each sector comprising at least one connecting edge in ceramic matrix composite material, each connecting edge having at least one groove or housing and at least one sealing tab present in each groove or housing, characterized in that each sealing tab comprises at least one substrate in metallic material whose external surface is covered by an external coating, the external coating comprising at least one layer of a material selected from one of the following materials: oxide ceramic, alumino-forming alloy, aluminide, alumina and nitride.

[0010] The portions of the sealing tab(s) intended to be in contact with the CMC of the assembly sectors, namely the lower and upper faces, are covered with an outer coating made of a material that is chemically inert with respect to the CMC material. This prevents any risk of reaction or chemical diffusion at high temperatures between the sealing tab(s) and the CMC material of the sectors. The presence of the outer coating also prevents the risk of degradation of the metallic substrate of the tab(s).

[0011] According to a particular feature of the assembly of the invention, the metallic material substrate has a thickness of between 0.05 mm and 0.5 mm, the outer coating having a thickness of between 10 microns and 50 microns.

[0012] According to another particular feature of the assembly of the invention, the substrate is made of a metallic material chosen from one of the following materials: nickel-based alloy, cobalt-based alloy and iron-based alloy.

[0013] According to another particular feature of the assembly of the invention, said at least one layer of the outer coating is made of a material selected from one of the following oxide ceramic materials: alumina, zirconia, yttria zirconia, zirconia alumina and mullite.

[0014] According to an example of an embodiment of the assembly of the invention, the external coating comprises a first layer in contact with the substrate made of metallic material, the first layer being made of alumina and / or zirconia and a second layer present on the first layer, the first layer being made of a material chosen from one of the following materials: oxide ceramic, alumino-forming alloy, aluminide and nitride.

[0015] According to another embodiment of the assembly of the invention, each sealing tab comprises first and second metallic substrates, the external surface of each of which is covered by the outer coating, and a metallic core interposed between the first and second metallic substrates covered by the outer coating. A fugitive binder may be present between the metallic core and the first and second metallic substrates covered by the outer coating.

[0016] According to another particular feature of the assembly of the invention, the sectors are turbine ring sectors each comprising an annular base having an inner face intended to define the inner face of a turbine ring when the ring sector is mounted to a ring support structure and an outer face from which extends one or more attachment portions of the ring sector to the ring support structure, each ring sector further comprising two inter-sector connecting edges of ceramic matrix composite material present at the circumferential ends of the sector, each inter-sector connecting edge being intended to be opposite a neighboring ring sector when the ring sector is mounted on the ring support structure, each inter-sector connecting edge having one or more grooves in which a sealing tab is partially housed.

[0017] According to another particular feature of the assembly of the invention, the sectors are distributor sectors comprising a structural sector body having an aerodynamic profile extending in a radial direction between a lower platform and an outer platform and, in an axial direction, between a leading edge and a trailing edge, said sector further comprising two inter-platform connecting edges made of ceramic matrix composite material present at the circumferential ends of each platform, each inter-platform connecting edge being intended to be opposite a platform of a neighboring sector, each inter-platform connecting edge comprising one or more grooves in which a sealing tab is partially housed. Brief description of the drawings

[0018] [Fig. 1] Fig. 1 is a schematic perspective view of a sealing tab according to the invention,

[0019] [Fig.2] Fig.2 is a schematic cross-sectional view of the sealing tab of Fig.1 according to an exemplary embodiment of the invention,

[0020] [Fig.3] Fig.3 is a schematic cross-sectional view of the sealing tab of Fig.1 according to another embodiment of the invention,

[0021] [Fig.4] [Fig.4] is a schematic perspective view of the turbine ring sector equipped with sealing tabs according to the invention,

[0022] [Fig.5] The [Fig.5] is a schematic perspective view of a turbine stator sector equipped with sealing tabs according to the invention. Description of the implementation methods

[0023] The invention applies generally to all turbine assemblies or assemblies comprising a plurality of sectors adjacent to each other by connecting edges of ceramic matrix composite material or CMC, each connecting edge having at least one groove or housing and a sealing tab present in each groove.

[0024] Figures 1 and 2 illustrate a sealing tab 10 according to an embodiment of the invention. The sealing tab 10 comprises a metallic material substrate 11, the external surface of which is covered by an outer coating 12. More specifically, the lower face 10a of the sealing tab 10, which is intended to come into contact with a lower portion of a groove present on a connecting edge of a sector of a turbine assembly as explained below, and the upper face 10b of the sealing tab, which is intended to come into contact with an upper portion of a groove present on a connecting edge of a sector of a turbine assembly, both have the outer coating 12.

[0025] According to the invention, the outer coating 12 comprises at least one layer of a material selected from one of the following: alumina, nitride, oxide ceramic, alumino-forming alloy, and aluminide. This prevents any chemical reaction or diffusion between the CMC material of the bonding edge and the sealing tab because the contact surfaces presented by the tab are made of a material that is chemically inert with respect to the CMC material.

[0026] In the example shown here, the outer coating 12 comprises a layer 120 which can be:

[0027] - in oxide ceramic material such as yttria-stabilized zirconia (ZrO2 / Y2O3), alumina zirconia (Al2O3 / ZrO2) or mullite (alumina-silica Al2O3 / SiO2) or alumina (Al2O3),

[0028] - in an alumino-forming alloy such as a nickel / aluminum / platinum (NiAIPt) alloy, Or

[0029] - in simple and / or platinum-modified aluminide, such as NiAl, NiAlRu, NiAlPd, NiAlZr and / or NiAIPt or NiAlPtHfSi, rare earth or any other reactive element.

[0030] The layer 120 is deposited over the entire external surface of the metallic substrate 11 using known deposition processes such as PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), or the slurry technique. The layer 120, and consequently the outer coating, is bonded to the external surface of the metallic substrate 11.

[0031] The substrate 11 can in particular be made of a nickel-based alloy such as, for example, Hastelloy® alloy, a cobalt-based alloy such as, for example, Haynes® 188 alloy, or an iron-based alloy such as, for example, FeCrAlY alloy

[0032] The metallic substrate 11 has a thickness En which can be between 0.05 mm and 0.5 mm, while the layer 120, which here forms the outer coating 12, has a thickness E[2 0] which can be between 10 microns and 50 microns. The overall thickness Ei0 of the sealing strip 10 corresponds to the sum of the thickness En of the metallic substrate 11 and twice the thickness En0 of the layer 120 constituting the outer coating 12.

[0033] Figures 1 and 3 illustrate a sealing tab 10 according to another embodiment of the invention. As described above, the sealing tab 10 comprises a metallic material substrate 11, the external surface of which is covered by an outer coating 12. More specifically, the lower face 10a of the sealing tab 10, which is intended to come into contact with a lower portion of a groove present on a connecting edge of a sector of a turbine assembly as explained below, and the upper face 10b of the sealing tab, which is intended to come into contact with an upper portion of a groove present on a connecting edge of a sector of a turbine assembly, both have the outer coating 12.

[0034] The embodiment described here differs from that of [Fig. 2] in that the outer coating 12 comprises a first layer 121 in contact with the external surface of the metallic material substrate 11 and a second layer 122 present on the first layer 121. According to the invention, the second layer 122 of the outer coating 12 is made of a material selected from one of the following: alumina, nitride, oxide ceramic, alumino-forming alloy, and aluminide. This prevents any chemical reaction or diffusion between the CMC material of the bonding edge and the sealing tab because the contact surfaces presented by the tab are made of a material that is chemically inert with respect to the CMC material.

[0035] In the example shown here, the second layer 122 of the outer coating 12 can be:

[0036] - in oxide ceramic material such as yttria-stabilized zirconia (ZrO2 / Y2O3), alumina zirconia (Al2O3 / ZrO2) or mullite (alumina-silica Al2O3 / SiO2),

[0037] - in an alumino-forming alloy such as a nickel / aluminum / platinum (NiAIPt) alloy, Or

[0038] - in simple and / or platinum-modified aluminide, such as NiAl, NiAlRu, NiAlPd, NiAlZr and / or NiAIPt or NiAlPtHfSi) rare earth or any other reactive element

[0039] The first layer 121 of the outer coating 12 can be made of alumina and / or zirconia, the alumina allowing the diffusion of oxygen towards the substrate while the zirconia is inert with respect to the CMC and adheres perfectly to the alumina.

[0040] Layers 121 and 122 are deposited respectively over the entire external surface of the metallic substrate 11 and over the entire external surface of the first layer 121 by known deposition processes such as PVD or CVD. The first layer 121 of the outer coating 12 is anchored to the external surface of the metallic substrate 11, while the second layer 122 of the outer coating is anchored to the external surface of the first layer 121. The first layer 121 has a thickness Ei2i of between 5 µm and 10 µm, while the second layer 122 has a thickness Ei22 of between 5 µm and 50 µm.

[0041] The substrate 11 can in particular be made of nickel-based alloy such as Hastelloy® alloy, or of cobalt-based alloy such as Haynes® 188 or of iron-based alloy such as FeCrAlY.

[0042] The overall thickness Ei0 of the sealing tongue 10 corresponds here to the sum of the thickness En of the metallic material substrate 11 and twice the thicknesses En i and Ei22 respectively of the first and second layers 121 and 122 of the outer coating 12.

[0043] According to a particular feature, the sealing tab may comprise first and second metallic substrates, the external surface of each of which is covered by an outer coating such as the outer coatings 12 and 120 described above, and a metallic core interposed between the first and second metallic substrates covered by the outer coating. According to an optional feature, a fugitive binder layer may be interposed between the core and the first and second metallic substrates covered by the outer coating to facilitate the assembly of the sealing tab. ensuring a secure connection between all its constituent parts. The binder being fugitive, it is quickly eliminated upon the first temperature rise of the sealing strip.

[0044] The sealing tabs just described are used to achieve a seal between sectors of a turbine assembly, the assembly being able in particular to correspond to a turbine ring or a sectored distributor.

[0045] Figure 4 illustrates a sector of ring 40 having a cross-section substantially in the shape of :t inverted with an annular base 44 whose inner face defines the gas flow path in a turbine. Upstream and downstream lugs 45, 46 extend from the outer face of the annular base 44 and are intended to be fixed to annular flanges of a ring support structure not shown in [Fig. 4]. The ring sector 40 is a sector of a plurality of ring sectors together constituting a turbine ring, with a seal being made between all adjacent ring sectors of the ring.

[0046] The turbine ring sector 40 is made of ceramic matrix composite (CMC) material and has two inter-sector connecting edges 42 and 43 located respectively at the circumferential ends of the sector 40. The connecting edge 42 has a first groove 420 receiving a portion of a first sealing tab 150, a second groove 421 receiving a portion of a second sealing tab 151 and a third groove 422 receiving a portion of a third sealing tab 152. The connecting edge 43 also has three grooves, not shown in [Fig. 4], similar to the grooves 420, 421 and 422 of the inter-sector connecting edge 42 receiving respectively portions of tabs identical to tabs 153, 154 and 155.

[0047] In the example described here, the sealing tabs 150 to 155 have a structure similar to that of the sealing tab in Figures 1 and 2, i.e., comprising a metallic substrate covered by a layer of alumina, nitride, oxide ceramic, alumino-forming alloy, or aluminide. However, the sealing tabs 150 to 155 may also have a structure similar to that of the sealing tab in [Fig. 4] or a laminated structure with a metallic core interposed between first and second metallic substrates covered by an outer coating as described above.

[0048] The presence of one or more metallic substrates in the tabs 150 to 155 gives them a flexibility that allows the tabs to be conformed to the shape of the grooves without risk of breakage. In particular, the tabs 152 and 155 can be formed into an angled shape so as to adapt to the shape of the groove 422 present on the connecting edge 42 and to the shape of the groove (not shown in [Fig. 4]) present on the connecting edge 43, respectively. Such Shaping cannot be achieved with a sealing tab made of a monolithic ceramic element without risk of breakage.

[0049] Figure 5 illustrates a turbomachine component corresponding to a turbine distributor sector 80. The distributor sector 80 comprises a structural sector body 81 made of CMC material including an aerodynamic profile 82 extending in a radial direction DR between a lower platform 83 and an outer platform 84 and, in an axial direction DA, between a leading edge 82a and a trailing edge 82b. The distributor sector 80 is a sector of a plurality of distributor sectors together constituting a turbine distributor, with a seal being provided between all adjacent distributor sectors of the distributor.

[0050] The turbine ring sector 80 further comprises, at the level of the lower platform 83, two inter-platform connecting edges 830 and 831 located respectively at the circumferential ends of the lower platform 83. Similarly, the turbine ring sector 80 comprises, at the level of the outer platform 84, two inter-platform connecting edges 840 and 841 located respectively at the circumferential ends of the outer platform 84.

[0051] The connecting edges 830 and 831 respectively have a groove 8300 and a groove 8310, the groove 8300 receiving a portion of a first sealing tab 290 while the groove 8310 receives a portion of a second sealing tab 291. The connecting edge 840 has two grooves 8400 and 8401 receiving respectively a portion of the third and fourth sealing tabs 292 and 293. The connecting edge 841 also has two grooves 8410 and 8411 receiving respectively a portion of a fourth sealing tab 294 and a portion of a fifth sealing tab 295.

[0052] In the example described here, the sealing tabs 290 to 295 have a structure similar to that of the sealing tab in Figures 1 and 2, i.e., comprising a metallic substrate covered by a layer of ceramic oxide, alumino-forming alloy, or aluminide. However, the sealing tabs 150 to 155 may also have a structure similar to that of the sealing tab in [Fig. 3] or a laminated structure with a metallic core interposed between first and second metallic substrates covered by an outer coating as described above.

[0053] The presence of one or more metallic material substrates in the tabs 209 to 295 gives them a flexibility which allows the tabs to be conformed to the shape of the grooves without risk of breakage.

Claims

Demands

1. Turbine assembly comprising a plurality of sectors (40) adjacent to each other, each sector comprising at least one connecting edge of ceramic matrix composite material (42, 43), each connecting edge having at least one groove or recess (420, 421, 422) and at least one sealing tab (150, 151, 152) present in each groove or recess, characterized in that each sealing tab comprises at least one substrate of metallic material (11) the external surface of which is covered by an outer coating (12), the outer coating comprising at least one layer (120) of a material selected from one of the following materials: alumina, nitride, oxide ceramic, alumino-forming alloy and aluminide.

2. Assembly according to claim 1, wherein the metallic material substrate (11) has a thickness (En) between 0.05 mm and 0.5 mm, the outer coating (12) has a thickness (E^o) between 10 microns and 50 microns.

3. Assembly according to claim 1 or 2, wherein the substrate (11) is made of a metallic material selected from one of the following materials: nickel-based alloy, cobalt-based alloy and iron-based alloy.

4. Assembly according to any one of claims 1 to 3, wherein, when the outer coating (12) is of ceramic oxide material, said ceramic oxide material is selected from one of the following materials: zirconia, yttria zirconia, zirconia alumina and mullite or alumina.

5. Assembly according to any one of claims 1 to 4, wherein the outer coating (12) comprises a first layer (121) in contact with the metallic material substrate (11), the first layer being made of alumina and / or zirconia and a second layer (122) present on the first layer (121), the second layer being made of a material selected from one of the following materials: nitride, oxide ceramic, alumino-forming alloy and aluminide.

6. An assembly according to any one of claims 1 to 5, wherein each sealing tab comprises first and second substrates of metallic material, the external surface of each of which is covered by the outer coating and a core in metallic material interposed between the first and second metallic material substrates covered with the outer coating.

7. Assembly according to claim 6, wherein a fugitive binder is present between the metallic material core and the first and second metallic material substrates covered by the outer coating.

8. An assembly according to any one of claims 1 to 7, wherein the sectors are turbine ring sectors (40), each comprising an annular base (44) having an inner face for defining the inner face of a turbine ring when the ring sector is mounted to a ring support structure and an outer face from which extend one or more attachment portions (45, 46) of the ring sector to the ring support structure, each ring sector (40) further comprising two inter-sector connecting edges (42, 43) of ceramic matrix composite material present at the circumferential ends of the sector (41), each inter-sector connecting edge being intended to be opposite a neighboring ring sector when the ring sector is mounted on the ring support structure, each inter-sector connecting edge having one or more grooves (420, 421, 422, 430, 431,432) in which a sealing tab (150, 151, 152, 153, 154, 155) is partially housed.

9. An assembly according to any one of claims 1 to 7, wherein the sectors are distributor sectors (80) comprising a structural sector body (81) having an aerodynamic profile (82) extending in a radial direction (DR) between a lower platform (83) and an outer platform (84) and, in an axial direction (DA), between a leading edge (82a) and a trailing edge (82b), said sector further comprising two inter-platform connecting edges (830, 831; 840, 841) of ceramic matrix composite material present at the circumferential ends of each platform (83; 84), each inter-platform connecting edge being intended to be opposite a platform of an adjacent sector, each inter-platform connecting edge having one or more grooves (8300; 8310; 8400, 8401; 8410, 8411) in which a sealing tab (290, 291, 292, 293, 294, 295) is partially housed.

10.

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