TURBOMACHINE TURBINE INCLUDING A HOUSING AND A TURBINE RING

Abstract

The invention relates to a turbine for an aircraft turbomachine, comprising a turbine ring (4) and a housing (5, 6) including: - an annular wall, and - at least one annular flange (53), the turbine ring comprising: - an annular wall (41), and - at least one annular flange (43) applied axially to said at least one flange (53) of the housing (5, 6). According to the invention, the turbine ring further comprises, on said at least one flange (43), a coating (100) adapted to cooperate by axial bearing with said at least one flange (53) of the housing (5, 6), this coating (100) being made of a composite material based on discontinuous ceramic fibers embedded in a ceramic matrix. The invention also relates to a method for manufacturing such a turbine ring. Abstract figure: Figure 3

Description

Title of the invention: TUBOMACHINE TURBINE COMPRISING A HOUSING AND A TURBINE RING Technical field of the invention

[0001] The invention relates to the technical field of turbomachinery, particularly for aircraft. More particularly, the invention relates to a turbomachine turbine comprising a housing and a turbine ring, as well as a method for manufacturing such a turbine ring. Technical background

[0002] The technical background includes in particular the documents FR-A1-3 131 598 and FR-A1-3 131 597.

[0003] Generally speaking, an aircraft turbomachine such as a turbofan engine comprises, from upstream to downstream, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine and a low-pressure turbine.

[0004] A high-pressure turbine of the turbomachine includes at least one stage comprising a distributor formed of an annular row of fixed straightening blades and a blade wheel mounted rotatably downstream of the distributor in a turbine ring also called a sealing ring.

[0005] When the turbine ring is made of a metal alloy, it is necessary to cool it with a ventilation airflow because it is subjected to relatively high temperatures during operation. This cooling has a significant impact on engine performance since the airflow used is taken from the engine's main airflow. Furthermore, the use of metal for the turbine ring limits the possibilities of increasing the turbine temperature, which would otherwise improve the performance of aircraft engines.

[0006] In an attempt to solve these problems, it was envisaged to make the turbine ring out of ceramic matrix composite (CMC) material to avoid the use of a metallic material.

[0007] CMC materials exhibit good mechanical properties, making them suitable for use as structural components and advantageously retaining their properties at high temperatures. The use of CMC materials has advantageously reduced the cooling flow required during operation, thus increasing the performance of the turbomachine. Furthermore, the use of CMC materials advantageously reduces the mass of the turbomachine and minimizes the thermal expansion effect encountered with metallic parts.

[0008] The turbine ring is generally sectorized and formed of several ring sectors arranged circumferentially end to end. The ring sectors are fixed to a metal housing.

[0009] There are several technologies for fixing a turbine ring or ring sectors to a housing and here we are interested in fixing by flanges.

[0010] The housing comprises an annular wall having an internal annular surface and an external annular surface, and at least one annular flange extending radially inwards from the internal annular surface of its annular wall.

[0011] The ring is mounted inside the housing and comprises an annular wall having an internal annular surface and an external annular surface, and at least one annular flange extending radially outwards from the external annular surface of its annular wall.

[0012] The flanges of the housing and the ring are axially supported against each other and can further be fixed to each other by fastening or centering elements that pass through openings in these flanges. The axial support of the flanges ensures a seal between the housing and the ring and prevents the passage of hot air through them.

[0013] During operation, the CMC material flanges of the turbine ring rub against the metal flanges of the housing, resulting in wear of the housing. This wear is exacerbated by the difference in thermal expansion of the CMC parts compared to the metal parts and by the surface appearance of the CMC parts, in particular because the hardness of the SiC matrix of the CMC material and of the SiC fibers coated with this matrix make the CMC parts particularly aggressive towards the metal parts during relative displacements and under differential thermal expansion.

[0014] Furthermore, since the flange support is essentially linear, the housing flange experiences very localized wear around its entire circumference. This wear results in a loss of sealing in this bearing area. This loss of sealing allows air from the turbine stream to enter the metal housing. Moreover, this leads to a loss of engine performance.

[0015] Moreover, the distribution of contact forces between the flanges leads to accelerated wear phenomena and to the generation of local over-stresses in these flanges.

[0016] In addition, the machined CMC flanges have a surface appearance composed of undulations with an amplitude of approximately 25 µm and a roughness of 1.7 µm, whereas the metal flanges have a surface appearance composed of undulations with an amplitude of approximately 2 µm and a roughness of 0.8 µm. It should be noted that, regardless of wear issues, the difference in surface undulation between the CMC flanges and the metal flanges results in a leakage rate greater than that of a metal-on-metal contact.

[0017] The present invention provides a solution to at least some of these problems, which is simple, effective and economical. Summary of the invention

[0018] To this end, the invention proposes a turbine for an aircraft turbomachine, comprising a casing made of metallic material and a turbine ring comprising a main body made of composite material based on ceramic fibers woven and embedded in a ceramic matrix,

[0019] the housing having an annular shape around an axis and comprising:

[0020] - an annular wall comprising an internal annular surface and a surface outer ring, and

[0021] - at least one annular flange extending radially inwards from the internal annular surface of the annular wall,

[0022] the main body of the turbine ring being mounted around the shaft and inside the housing, and comprising:

[0023] - an annular wall comprising an internal annular surface and a surface outer ring, and

[0024] - at least one annular flange extending radially outwards from the external annular surface of the annular wall,

[0025] said at least one annular flange of the main body of the turbine ring being applied axially to said at least one annular flange of the housing.

[0026] According to the invention, the turbine ring further comprises, on said at least one annular flange of its main body, a coating which is able to cooperate by axial support with said at least one annular flange of the casing, this coating being made of composite material based on discontinuous ceramic fibers embedded in a ceramic matrix.

[0027] The invention thus proposes a coating forming an interface between said at least one annular flange of the main body of the turbine ring and said at least one annular flange of the housing.

[0028] This coating is made of a composite material based on discontinuous ceramic fibers embedded in a ceramic matrix, exhibiting surface conditions similar to the opposing metal flanges, in particular reduced surface roughness and amplitude waviness compared to the ceramic matrix composite material. This notably allows: - to reduce surface defects by a factor of ten, - to limit the effects of wear due to differential expansion, and - to significantly reduce leakage at the flanges, in order to guarantee the performance of the turbine.

[0029] Another advantage of the invention is that it can be applied locally opposite the bearing area of ​​the metal flange, or over the entire height of the flange, for ease of implementation.

[0030] The turbine according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0031] - the coating extends over only a part of the height or radial dimension of said at least one annular flange of the main body of the turbine ring;

[0032] - the coating extends over the entire height or radial dimension of said au minus an annular flange of the main body of the turbine ring;

[0033] - the coating has a free bearing surface on said at least one annular flange of the casing which has a roughness, for example of type Rz, less than 1.3qm, and preferably less than or equal to Ipm;

[0034] - the coating has a free bearing surface on said at least one annular flange of the casing which has undulations, for example of the Wz type, with an amplitude less than 10qm, and preferably less than or equal to 5qm;

[0035] - the coating is located on a surface of said at least one annular flange of the main body of the turbine ring which has a roughness, for example of type Rz, greater than 1.3qm, and preferably greater than or equal to 1.5qm;

[0036] - the coating is located on a surface of said at least one annular flange of the main body of the turbine ring which has undulations, for example of the Wz type, with an amplitude greater than 10p,m, and preferably greater than or equal to 20qm;

[0037] - the main body of the turbine ring comprises a preform formed by weaving of ceramic fibers in three dimensions or a superposition of layers formed by weaving ceramic fibers in two dimensions, this preform or these layers being embedded in the ceramic matrix;

[0038] - the ceramic matrix is ​​based on silicon carbide (SiC).

[0039] The invention further relates to a method for manufacturing a turbine ring for a turbine as described above, in which it comprises the following steps:

[0040] a) fabrication of the main body of the turbine ring, in composite material based on woven ceramic fibers,

[0041] b) forming the coating on said at least one annular flange of the main body, or producing and depositing the coating on said at least one annular flange of the main body, the coating being made of a composite material based on discontinuous ceramic fibers,

[0042] c) co-consolidation of the two materials so as to embed them in a common ceramic matrix.

[0043] Advantageously, in step b), the coating is formed directly on said at least one annular flange of the main body, by a technique selected from ceramic injection molding, additive manufacturing and pressure sintering.

[0044] Advantageously, in step b), the coating is produced by a technique selected from ceramic injection molding, additive manufacturing and pressure sintering, and then the coating is assembled on said at least one annular flange of the main body.

[0045] Advantageously, before step c), the process includes a step i) of debinding the coating. Brief description of the figures

[0046] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0047] [Fig-1] [Fig.1] is a partial schematic half view in axial section of a turbomachine turbine;

[0048] [Fig.2] [Fig.2] is a schematic perspective view of a housing and turbine ring of the turbine of [Fig.1];

[0049] [Fig.3] [Fig.3] is a very schematic half view in axial section of a turbine according to the invention equipped with a coating according to a first embodiment of the invention;

[0050] [Fig. 4] [Fig. 4] is a very schematic half-view in axial cross-section of a turbine according to the invention equipped with a coating according to a second embodiment of the invention; and

[0051] [Fig.5] [Fig.5] is an enlarged view of the coating of [Fig.3]. Detailed description of the invention

[0052] Generally speaking, in this application, the terms "longitudinal" and "axial" refer to the orientation of structural elements extending along a longitudinal axis. This longitudinal axis can be considered the axis of rotation of a turbomachine engine. The term "radial" refers to the orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "interior" and "exterior," and "internal" and "external," are used with reference to positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an interior face facing the longitudinal axis and an exterior surface opposite its interior surface.

[0053] By convention, in the present application, the terms "upstream" and "downstream" are defined with respect to the direction of flow of a gas flow in the turbomachine.

[0054] A turbomachine classically comprises, from upstream to downstream, a blower, at least one compressor (for example a low pressure compressor and a high pressure compressor), a combustion chamber, and at least one turbine (for example a high pressure turbine and a low pressure turbine).

[0055] More particularly, [Fig. 1] illustrates a portion (such as a module) of a turbomachine 10 extending along a longitudinal axis X, and comprising, from upstream to downstream, a combustion chamber 1a, a high-pressure (HP) turbine 1b, and a low-pressure (LP) turbine 1e. Each turbine stage 1b, 1e comprises an annular row of guide or fixed stator blades 20, 20' and a blade wheel 3 arranged alternately in a known manner. The annular row of fixed blades 20 of the HP turbine 1b forms a distributor 2. The rotor wheel 3 is mounted to rotate downstream of the distributor 2 in a turbine ring 4 or seal. The annular row of fixed blades 20' of the LP turbine 1e forms another distributor 2'.

[0056] The turbine ring 4 comprises a single piece or comprises a plurality of ring sectors 40 arranged circumferentially end to end and surrounding the wheel 3. The turbine ring 4 is mounted inside a turbine housing 6 or an annular support 5 of this housing 6. The annular support 5 can thus be considered as forming part of the housing 6. The housing 6, and in particular its annular support 5, comprises on its inner periphery first and second annular radial flanges 52, 53, respectively upstream and downstream, which are connected to each other by an annular wall 51.

[0057] The ring sectors 40 comprise a main body 45 (visible in [Fig. 2]) made of a composite material based on woven ceramic fibers embedded in a ceramic matrix. The main body 45 comprises at its upstream and downstream ends first and second radial annular flanges 42, 43 for attachment to, respectively, the first and second radial annular flanges 52, 53 of the housing 6.

[0058] Fig. 2 shows further details of the turbine ring 4, and in particular of the ring sectors 40 and their attachment to the housing 6 or to its annular support 5.

[0059] Each ring sector 40 has a cross-section substantially in the shape of the inverted Greek letter "Pi" (ji). Each ring sector 40 thus comprises an annular wall 41 and first and second annular radial flanges 42, 43.

[0060] The annular wall 41 comprises an internal annular surface 41a and an external annular surface 41b opposed to each other. The internal annular surface 41a of the annular wall 41 can be coated with a layer of abradable material 44 to define a gas flow channel in the turbine.

[0061] The first and second radial annular flanges 42, 43 project outwards from the external annular surface 41b and at a distance from the upstream and downstream ends 421a, 421b of the annular wall 41 of each ring sector 40. The first and second annular radial flanges 42, 43 extend over the entire width of the turbine ring 4, in particular over the entire width of the ring sector 40, that is to say over the entire arc of the circle described by the ring sector 40, or over the entire circumferential length of the ring sector 40.

[0062] As described above, the housing 6, and in particular its annular support 5, comprises:

[0063] - a central annular wall 51, and

[0064] - a first annular radial flange 52 and a second annular radial flange 53, respectively upstream and downstream, the first and second radial annular flanges 52, 53 extending radially inwards from an internal annular surface 51a of the annular wall 51. The annular wall 51 includes in particular an external annular surface 51b.

[0065] The first annular radial flange 52 comprises a first free end 524 and a second opposite end 525 which is connected to the internal annular surface 51a of the annular wall 51.

[0066] The second annular radial flange 53 comprises a first portion 531, a second portion 532, and a third portion 533 situated between the first and second portions 531, 532. The first and third portions 531, 533 can form an internal periphery of the second annular radial flange 53, and the second portion 532 can form an external periphery of the second annular radial flange 53.

[0067] The first portion 531 has a first free end 534 and the second portion 532 has a second end 535 connected to the internal annular surface 51a of the annular wall 51.

[0068] The first portion 531 extends between the first end 534 and the third portion 533, and the second portion 532 extends between the third portion 533 and the second end 535.

[0069] In the example of [Fig.2], the inner periphery of the first portion 531 (in particular a radial annular face 536 of the first portion 531) is axially supported against the second radial annular flange 43 of the turbine ring 4. The second radial annular flange 43 of the main body 45 of the turbine ring 4 is therefore axially applied to the second radial annular flange 53 of the housing 6.

[0070] The first portion 531 and the third portion 533 have an increased thickness compared to that of the second portion 532 to provide increased rigidity to the second annular radial flange 53 compared to the upstream part including in particular the first annular radial flange 52, so as to reduce axial leakage of the turbine ring in the case of a straight support.

[0071] With reference to [Fig.2], the turbine further comprises first and second annular flanges 56, 57 which are removably fixed to the first radial flange annular 52 of the annular support 5. The first and second flanges 56, 57 are arranged upstream of the turbine ring 4 with respect to the direction of gas flow in the turbine. The first and second flanges 56, 57 can be considered as forming part of the housing 6.

[0072] The first flange 56 is arranged downstream of the second flange 57. The first flange 56 is in one piece while the second flange 57 can be sectored into a plurality of annular sectors of second flange 57 or be in one piece.

[0073] The first flange 56 has a first free end 564 and a second end 565 removably fixed to the housing 6, and more particularly to the first annular radial flange 52.

[0074] In addition, the first flange 56 has a first portion forming an inner periphery 561 and a second portion forming an outer periphery 562. The inner periphery 561 extends between the first end 564 and the outer periphery 562, and the outer periphery 562 extends between the inner periphery 561 and the second end 565.

[0075] When the turbine ring 4 is mounted, the inner periphery 561 of the first flange 56 (and in particular a radial annular face 566 of the first flange 56) is in axial contact against the first annular radial flange 42 of each of the ring sectors 40, and the outer periphery 562 is in contact against at least a part of the first annular radial flange 52.

[0076] The second flange 57 has a first free end 574 and a second end 575 opposite the first end 574 and in contact with the annular wall 51. The second end 575 of the second flange 57 is also removably fixed to the housing 6, and more particularly to the first annular radial flange 52. The second flange 57 further comprises a first portion forming an inner periphery 571 and a second portion forming an outer periphery 572. The inner periphery 571 extends between the first end 574 and the outer periphery 572, and the outer periphery 572 extends between the inner periphery 571 and the second end 575.

[0077] The first and second flanges 56, 57 are shaped to have the inner peripheries 561, 571 axially separated from each other and the outer peripheries 562, 572 in contact, the two flanges 56, 57 being removably fixed to the first annular radial flange 52 by means of screws 82 and fixing nuts 83, the screws 82 passing through orifices 570, 560 and 520 provided respectively in the outer peripheries 572 and 562 of the two flanges 56, 57 as well as in the first annular radial flange 52.

[0078] To hold the ring sectors 40, and therefore the turbine ring 4, in position with the housing 6 and in particular its annular support 5, two first axial pins 84 cooperate with the first annular radial flange 42 and the first flange 56, and two second axial pins 86 cooperate with the second annular radial flange 43 and the second annular radial flange 53.

[0079] For each corresponding ring sector 40, the inner periphery 561 of the first flange 56 includes receiving ports for the first two pins 84, and the third portion 533 of the second annular radial flange 53 includes ports configured to receive the second two pins 86.

[0080] For each ring sector 40, each of the first and second annular radial flanges 42, 43 includes orifices configured to receive the first pins 84 and the second pins 86.

[0081] Each ring sector 40 of the turbine ring 4 is made of ceramic matrix composite (CMC), while the first and second annular radial flanges 52, 53 of the housing 6, and the first and second flanges 56, 57 are made of metallic material. This configuration presents several drawbacks mentioned above in the technical background, notably a risk of generating wear by friction of the housing 6 and in particular of its first and second annular radial flanges 52, 53, in the bearing areas of these flanges on the first and second annular radial flanges 42, 43 of the ring sectors 40. In the example shown in [Fig. 2], a risk of wear exists, for example, in the circled area ZI, due to the bearing between the second annular radial flanges 43, 53.

[0082] The invention addresses this problem by virtue of the fact that the turbine ring 4 comprises, on said at least one first and second annular radial flange 42, 43 of its main body 45, a coating 100 which is adapted to cooperate by axial support with said at least one first and second annular radial flange 52, 53 of the housing 6, this coating 100 being made of a composite material based on discontinuous ceramic fibers embedded in a ceramic matrix. This material exhibits surface finishes similar to the opposing metal flanges, in particular reduced surface roughness and amplitude waviness compared to the ceramic matrix composite (CMC). This notably allows: - to reduce surface defects by a factor of ten, - to limit the effects of wear due to differential expansion, and - to significantly reduce leakage at the flanges, in order to guarantee the performance of the turbine.

[0083] The coating of the invention is particularly visible in figures 3 to 5. In these figures, the elements already described above are designated by the same references.

[0084] This coating 100 preferably has an annular shape around the X axis and forms an interface between the annular radial flange 42, 43 and the annular radial flange 52, 53. The coating 100 is located here between the second annular radial flange 43 and the second annular radial flange 53, but it can be located between any one of the first and second annular radial flanges 42, 43 and any one of the first and second annular radial flanges 52, 53 and / or any one of the flanges 56 / 57. This coating 100 has an annular bearing portion 100a oriented radially, i.e. perpendicular to the X axis, in contact with the annular radial flange 42, 43 and a free bearing surface 100b oriented radially, i.e. perpendicular to the X axis, in contact with the annular radial flange 52, 53.

[0085] In the embodiment shown in [Fig.3], the coating 100 may extend over only part of the height or radial dimension of the second annular radial flange 43 of the main body 45 of the turbine ring 4. Alternatively, and as illustrated in [Fig.4], the coating 100 extends in particular over the entire height or radial dimension of the second annular radial flange 43 of the main body 45 of the turbine ring 4.

[0086] Figure 5 schematically illustrates and dimensions the differences between the surface finishes (amplitude, roughness, etc.) of the main body 45, the radial annular flange 42, 43, the coating 100, and the radial annular flange 52, 53. The free bearing surface 100b of the coating 100 bears against the second radial annular flange 53 of the housing 6, specifically against the radial annular face 536 of the first portion 531, and exhibits, for example, a low roughness, such as of type Rz, in particular less than 1.3 µm, and preferably less than or equal to 1 µm. The second radial annular flange 53 of the housing 6 has a roughness of approximately 0.8 µm. The free bearing surface 100b has undulations 110, for example of the Wz type, with an amplitude in particular less than 1 Opm, and preferably less than or equal to 5 pm. The second annular radial flange 53 of the housing 6 has undulations with an amplitude of approximately 2 pm.The surface condition (in particular the roughness and the amplitude of the undulations) of the coating 100 is therefore here close to that of the second annular radial flange 53 of the housing 6.

[0087] The coating 100 is, for example, located on a surface 436 of the second annular radial flange 43 of the main body 45 of the turbine ring 4, which has, in particular, a roughness greater than 1.3 pm, and preferably greater than or equal to 1.5 pm. The second annular radial flange 43 of the main body 45 of the turbine ring 4 has undulations 120 with an amplitude, in particular, greater than 1 pm, and preferably greater than or equal to 20 pm.

[0088] The main body 45 of the turbine ring 4 comprises a preform formed by weaving ceramic fibers in three dimensions or a superposition of layers formed by weaving ceramic fibers in two dimensions, this preform or these layers being embedded in the ceramic matrix.

[0089] The invention also relates to a method for manufacturing the turbine ring 4, comprising in particular a step a) of producing the main body 45 of the turbine ring 4 from a composite material based on woven ceramic fibers (for example, SiC / SiC). In this step, a preform is woven using ceramic fibers, for example, silicon carbide (SiC). This preform is then shaped in a former (mold), and an interphase is deposited on the surface of the ceramic fibers, for example, by a CVI (Chemical Vapor Infiltration) process. The preform is removed from the former, and then a second densification by a CVI process can be carried out to deposit silicon carbide in the preform. Subsequently, a slurry comprising ceramic particles, for example, SiC, suspended in a solvent, can be injected into the preform.Once the solvent has been removed by drying, the deposited ceramic particles undergo a heat treatment which produces an intermediate part with a certain degree of porosity.

[0090] The method may also include a step b) of forming the coating 100 on said at least one annular radial flange 42, 43 of the main body 45, or of making and depositing the coating 100 on said at least one annular radial flange 42, 43 of the main body 45, the coating 100 being made of composite material based on discontinuous ceramic fibers.

[0091] During this step b), the coating 100 is, for example, formed directly on said at least one annular radial flange 42, 43 of the main body 45, in particular by a technique selected from ceramic injection molding, additive manufacturing and pressure sintering. According to this embodiment, the coating 100 is formed in-situ on the annular radial flange 42, 43.

[0092] Alternatively, during this step b), the coating 100 is produced, in particular, by a technique selected from ceramic injection molding, additive manufacturing, and pressure sintering. Subsequently, the coating 100 is assembled, in particular, onto said at least one annular radial flange 42, 43 of the main body 45. Thus, in this alternative embodiment, the assembly takes place after the coating 100 has been produced.

[0093] The process of the invention may also include a step i) of debinding the coating. Indeed, when the discontinuous fiber CMC coating 100 is produced by ceramic injection or additive manufacturing (in particular additive processes using organic auxiliaries), that is to say during step b), and in order to allow the fibers of the coating 100 to be held together with each other and on the ring of For turbine 4, it is necessary to embed them in a binder. This binder must then be removed by means of step i) of debinding.

[0094] In pressure sintering, powder without organic binder can be used and therefore no debinding step is required.

[0095] The process of the invention may also include a step c) consisting of co-consolidating the two materials so as to embed them in a common ceramic matrix. During this step c), the woven ceramic fiber composite material of the main body 45 of the turbine ring 4 is thus co-consolidated with the discontinuous ceramic fiber composite material of the coating 100.

[0096] Co-consolidation is notably co-consolidation by infiltration of a molten silicon-based composition (the so-called "melt infiltration" step). This co-consolidation (or densification) step is carried out, for example, by infiltrating and then solidifying a liquid densifying material, generally liquid silicon, into the parts to be co-consolidated. In this technique, a molten silicon composition can be introduced into the porosity of a fibrous structure (here, the main body 45 and the coating 100) pre-densified by a silicon carbide deposit and loaded with silicon carbide particles. This method makes it possible to obtain a fully dense, high-modulus Si-SiC matrix and a composite with a high linearity limit.

[0097] This technique is generally used at the end of manufacturing to further densify the part or parts made of composite material based on woven ceramic fibers and composite material based on embedded discontinuous ceramic fibers. The process of the invention thus provides that the coating 100 is present during the final co-consolidation phase of the main body 45 by infiltration of a molten silicon-based composition, which allows the main body 45 and the coating 100 to be bonded by co-consolidation and to benefit from the monolithic and continuous appearance of the matrix.

[0098] The parts co-consolidated according to this technique exhibit a very good surface condition with in particular the suppression of the smearing effect linked to the textile geometry of a CMC material made up of 2D or 3D layers.

[0099] In fine, the flanges can be rectified, if necessary, mechanically or by an electro-erosion sinking process also called EDM (“electrical discharge machining” in English) to obtain the integration dimensions and associated surface conditions.

Claims

Demands

1. Turbine (1b) for an aircraft turbomachine (10), comprising a casing (5, 6) made of metallic material and a turbine ring (4) comprising a main body (45) made of a composite material based on ceramic fibers woven and embedded in a ceramic matrix, the casing (5, 6) having an annular shape about an axis (X) and comprising: - an annular wall (51) comprising an internal annular surface (51a) and an external annular surface (51b), and - at least one annular flange (52, 53) extending radially inward from the internal annular surface (51a) of the annular wall (51), the main body (45) of the turbine ring (4) being mounted around the axis (X) and inside the casing (5, 6), and comprising: - an annular wall (41) comprising an internal annular surface (41a) and a surface external annular (41b), and - at least one annular flange (42,43) extending radially outwards from the external annular surface (41b) of the annular wall (41), said at least one annular flange (42, 43) of the main body (45) of the turbine ring (4) being applied axially to said at least one annular flange (52, 53) of the housing (5, 6), characterized in that the turbine ring (4) further comprises, on said at least one annular flange (42, 43) of its main body (45), a coating (100) which is capable of cooperating by axial support with said at least one annular flange (52, 53) of the housing (5, 6), this coating (100) being made of a composite material based on discontinuous ceramic fibers embedded in a ceramic matrix.

2. Turbine (1b) according to claim 1, wherein the coating (100) extends over only a part of the height or radial dimension of said at least one annular flange (42, 43) of the main body (45) of the turbine ring (4).

3. Turbine (1b) according to claim 1, wherein the coating (100) extends over the entire height or radial dimension of said at least one annular flange (42, 43) of the main body (45) of the turbine ring (4).

4. Turbine (1b) according to any one of the preceding claims, wherein the coating (100) has a free bearing surface (100b) on said at least one annular flange (52, 53) of the housing (5, 6) which has a roughness of less than 1.3qm, and preferably less than or equal to 1pm.

5. Turbine (1b) according to any one of the preceding claims, wherein the coating (100) has a free bearing surface (100b) on said at least one annular flange (52, 53) of the housing (6) which has undulations with an amplitude less than 100m, and preferably less than or equal to 50m.

6. Turbine (1b) according to any one of the preceding claims, wherein the coating (100) is located on a surface (436) of said at least one annular flange (42, 43) of the main body (45) of the turbine ring (4) which has a roughness greater than 1.3qm, and preferably greater than or equal to 1.5qm.

7. Turbine (1b) according to any one of the preceding claims, wherein the coating (100) is located on a surface (436) of said at least one annular flange (42, 43) of the main body of the turbine ring (4) which has undulations with an amplitude greater than 100m, and preferably greater than or equal to 200m.

8. Turbine (1b) according to any one of the preceding claims, wherein the main body (45) of the turbine ring (4) comprises a preform formed by weaving ceramic fibers in three dimensions or a superposition of layers formed by weaving ceramic fibers in two dimensions, this preform or these layers being embedded in the ceramic matrix.

9. A method for manufacturing a turbine ring (4) for a turbine (1b) according to any one of the preceding claims, wherein it comprises the following steps: a) making the main body (45) of the turbine ring (4), of composite material based on woven ceramic fibers, b) forming the coating (100) on said at least one annular flange (42, 43) of the main body (45), or making and depositing the coating (100) on said at least one annular flange (42, 43) of the main body (45), the coating (100) being of composite material based on discontinuous ceramic fibers, c) co-consolidating the two materials so as to embed them in a common ceramic matrix.

10. A method according to claim 9, wherein, in step b), the coating (100) is formed directly on said at least one annular flange (42, 43) of the main body (45), by a technique selected from ceramic injection molding, additive manufacturing and pressure sintering.

11. A method according to claim 9, wherein, in step b), the coating (100) is produced by a technique selected from ceramic injection molding, additive manufacturing and pressure sintering, and then the coating is assembled on said at least one annular flange (42, 43) of the main body (45).

12. A method according to any one of claims 9 to 11, wherein, prior to step c), the method comprises a step i) of debinding the coating (100).

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