Method for replacing a missing part on a ceramic matrix composite material component

Abstract

Method for replacing a missing part on a ceramic matrix composite material part A method for replacing a missing part of a ceramic matrix composite material part comprising a fibrous reinforcement densified by a matrix comprising at least a ceramic material and a first silicon-based composition, the method comprising: - the production of a replacement part (251) from a fibrous reinforcement consolidated by a first matrix phase, - the positioning of a first bonding edge (253) present on the replacement part (251) against a second bonding edge (153) present on a portion to be repaired (152) of the ceramic matrix composite material part, - the impregnation of the replacement part and the portion to be repaired with a second silicon-based composition.The second silicon-based composition has a lower melting point than the first silicon-based composition. Figure for the abstract: Fig. 2.

Description

Title of the invention: Method for replacing a missing part on a ceramic matrix composite material. Technical field

[0001] The invention relates to the repair of parts made of ceramic matrix composite (CMC), i.e. comprising a fibrous reinforcement densified by a matrix at least partially made of ceramic. Previous technique

[0002] Ceramic matrix materials (CMCs) exhibit good mechanical properties, making them suitable for use as structural elements, and they advantageously retain these properties at high temperatures. Due to their superior resistance to high temperatures, CMCs require less cooling. In the field of aircraft engines, cooling is traditionally achieved by drawing heat from the compressor, which impacts the turbomachine's efficiency. CMC materials therefore improve engine efficiency, thereby reducing fuel consumption. Furthermore, their use contributes to optimizing turbomachine performance, 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.

[0003] A well-known process for manufacturing parts from CMC material comprises the following steps:

[0004] - consolidation of a fibrous preform carried out by chemical infiltration in phase gaseous (CVI) of a carbide phase, for example SiC,

[0005] - injection of a ceramic powder slip, for example of SiC, into the fibrous preform ("Slurry Cast" or "Slurry Transfer Molding") to fractionate the porosity in the preform, and

[0006] - infiltration of the preform with a molten silicon-based composition of in order to fill the porosity still present in the preform, densification process known as MI process ("Melt Infiltration").

[0007] CMC parts can be damaged as a result of shock or impact. This is the case, for example, with turbine or aeronautical engine stator blades, which can be damaged by shocks during handling or by impacts with foreign objects such as debris from parts upstream of the engine during operation. These shocks or impacts can cause a portion of the part to break, requiring replacement before the part can be returned to service. Description of the invention

[0008] The invention aims to provide a solution for replacing one or more missing parts on a ceramic matrix composite material part.

[0009] This goal is achieved by means of a method for replacing at least a missing part of a ceramic matrix composite material component comprising a fibrous reinforcement of refractory fibers densified by a matrix comprising at least one ceramic material and a first silicon-based composition, characterized in that it comprises: - a step of producing a replacement part from a fibrous reinforcement of refractory fibers at least consolidated by a first matrix phase, the replacement part corresponding to the shape of said at least one missing part, - a step of positioning a first bonding edge present on the replacement part against a second bonding edge present on a portion to be repaired of the part in ceramic matrix composite material, - a step of impregnating the replacement part and the portion to be repaired with a second silicon-based composition in a molten state, and in that the second silicon-based composition has a melting point lower than the melting point of the first silicon-based composition.

[0010] With the process of the invention, it is possible to reconstruct one or more damaged parts of a part made of ceramic matrix composite material and thus put the part back into service.

[0011] Furthermore, by using a second silicon-based composition having a melting point lower than the melting point of the first silicon-based composition, the melting point of said first silicon-based composition present in the part is not reached during the co-silicidation of the replacement part and the portion to be repaired. This preserves the material integrity of the part.

[0012] According to a particular feature of the process of the invention, the second silicon-based composition has a melting temperature that is at least 20°C, or even at least 50°C, lower than the melting temperature of the first silicon-based composition.

[0013] According to another particular feature of the process of the invention, the first silicon-based composition is chosen from one of the following compounds or alloys: Si, Si-B, Si-Mo and Si-Ta while the second silicon-based composition is chosen from one of the following silicon alloys: Si-Zr and Si-Ti.

[0014] According to another particular feature of the process of the invention, the step of making the replacement part includes the introduction of a powder of ceramic material particles into the porosity of the fibrous reinforcement of refractory fibers consolidated by the first matrix phase.

[0015] According to another particular feature of the method of the invention, it further comprises, prior to the impregnation step, a step of depositing an anti-wetting agent on surfaces of the replacement part located outside the first bonding edge and on surfaces of the portion to be repaired located outside the second bonding edge. This makes it possible to maintain the dimensions of the part in the areas outside the repair bonding. In the case of a part having aerodynamic functions, its aerodynamic performance is also preserved.

[0016] According to a particular feature of the method of the invention, the first connecting edge has at least one first overlapping portion and the second connecting edge has at least one second overlapping portion, said at least one first overlapping portion being superimposed on said at least one second overlapping portion when the first connecting edge is positioned against the second connecting edge. This increases the assembly surface between the connecting edges, thereby improving the mechanical strength of the connection. The first and second connecting edges may, for example, each have a beveled or crenellated shape.

[0017] According to another particular feature of the method of the invention, it further comprises, before the impregnation step of the replacement part and the portion to be repaired, the positioning of one or more retaining pins extending through said at least first and second overlapping portions of the first and second bonding edges. The retaining pins improve the strength of the assembly between the replacement part and the portion of the part to be repaired, as well as their retention in position before and during co-silicilation. Brief description of the drawings

[0018] Other features and advantages of the invention will become apparent from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0019] [Fig-1] Fig. 1 is a schematic perspective view of a turbine blade presenting a missing part,

[0020] [Fig.2] Fig.2 is a schematic perspective view of the turbine blade of Fig.1 with a replacement part,

[0021] [Fig.3] [Fig.3] shows a portion of the blade of [Fig.2] after positioning of the replacement portion,

[0022] [Fig.4A] Fig.4A shows an example of connecting edges with overlapping portions,

[0023] [Fig.4B] Fig.4B shows another example of connecting edges with overlapping portions,

[0024] [Fig.4C] Fig.4C shows another example of connecting edges with overlapping portions,

[0025] [Fig.4D] Fig.4D shows another example of connecting edges with overlapping portions,

[0026] [Fig.4E] Figure [Fig.4E] shows another example of connecting edges with overlapping portions,

[0027] [Fig.4F] Fig.4F shows another example of connecting edges with parts of overlap,

[0028] [Fig. 5A] [Fig. 5A] shows an example of connecting edges with overlapping parts and retaining pins,

[0029] [Fig.5B] Fig.5B shows another example of connecting edges with overlapping parts and retaining pins. Description of the implementation methods

[0030] The invention applies generally to any part made of ceramic matrix composite (CMC), that is to say comprising a fibrous reinforcement made for example with refractory fibers, such as carbon or ceramic fibers and densified by a matrix comprising at least one ceramic material, which may be for example silicon carbide (SiC), and a silicon-based composition.

[0031] The invention will be described below in the context of its application to the repair of a turbine blade of an aeronautical gas turbine engine made of SiC / SiC composite material.

[0032] Fig. 1 shows a turbine blade 100 which is here made of SiC / SiC composite material. As is well known, parts made of SiC / SiC material are formed by a fibrous reinforcement of SiC fibers which is densified by a matrix at least partially made of SiC.

[0033] The blade is manufactured from a fibrous structure intended to form the fibrous reinforcement of the blade which is here made with high performance SiC fibers such as the fibers supplied by the Japanese company Nippon Carbon under the reference "Hi-Nicalon®" or, preferably, under the reference "Hi-Nicalon Type-S®" having a high elastic elongation limit.

[0034] The fibrous structure is preferably obtained by three-dimensional weaving or by multilayer weaving.

[0035] By "three-dimensional weaving" or "3D weaving", we mean here a weaving method in which at least some of the warp yarns link weft yarns over several weft layers such as for example an "interlock weave".

[0036] By "multilayer weave" is meant here a 3D weave with several layers of weft, the basic weave of each layer being equivalent to a classic 2D fabric weave, such as a plain weave, satin or twill weave, but with certain points of the weave which link the weft layers together.

[0037] The creation of the fibrous structure by 3D or multilayer weaving makes it possible to obtain a bond between the layers, thus ensuring good mechanical strength of the fibrous structure and the resulting composite part, in a single textile operation. A detailed example of the creation of a fibrous preform intended to form the fibrous reinforcement of an aircraft engine blade from a 3D woven fibrous blank is described in detail in US documents 7,101,154, US 7,241,112 and WO 2010 / 061140.

[0038] The fibrous structure can also be achieved by stacking two-dimensional layers or folds of SiC fibers.

[0039] The fibrous structure is shaped and maintained in its shape by means of a shaping tool, to obtain a fibrous preform having a shape close to that of the part to be manufactured. Examples of shaping fibrous preforms from a fibrous structure can be found, in particular, in US patent application 2011 / 0293828.

[0040] With the preform held in its forming tooling, for example made of graphite, a weakening interphase is formed in a known manner by chemical vapor infiltration (CVI) onto the fibers of the preform, this interphase being notably based on boron nitride (BN). The thickness of the interphase is preferably between 10 nm and 1000 nm.

[0041] A predensification or consolidation of the fibrous preform is then carried out, comprising the formation of a first matrix phase preferably produced by chemical infiltration in gas phase (CVI) with a first precursor of SiC.

[0042] A slip loaded with a powder of refractory solid fillers, here a SiC powder, is then preferably injected into the fibrous preform to fractionate its internal porosity ("Slurry Cast"),

[0043] The densification of the preform is completed by infiltrating it with a first molten silicon-based composition to form a ceramic matrix, a densification process known as the MI (Melt Infiltration) process. Hereinafter, "silicon-based composition" means a composition comprising silicon in a minimum mass content of 85%. The first silicon-based composition may, in particular, comprise pure silicon. having a melting point of about 1414°C, silicon boride Si-B in which the proportion of boron is for example between 2% and 8% by mass and having a eutectic temperature of about 1385°C, a silicon / molybdenum alloy Si-Mo in which the proportion of molybdenum is for example between 2% and 10% by mass and having a eutectic temperature of about 1406°C, or a silicon / tantalum alloy Si-Ta having a eutectic temperature of about 1393°C.

[0044] The turbine blade 100 comprises a blade 110 extending in a longitudinal direction from a foot 120 formed by a thicker part, for example with a bulb-shaped cross-section, connected by a strut 130 to the blade 110. The turbine blade 100 is mounted on a turbine rotor (not shown in [Fig.1]) by engaging the foot 120 in a correspondingly shaped housing arranged at the periphery of the rotor. The turbine blade 100 also includes, at the level of a strut, an upstream cover spoiler 140 and a downstream cover spoiler 150. The turbine blade 100 further includes, at the level of the outer end of the blade 110, two blade tips 160 and 170. The upstream cover spoiler 140, the downstream cover spoiler 150 and the blade tips 160 and 170 correspond to areas of the turbine blade 100 which are liable to break in the event of a shock or impact.In the example described here, the turbine blade 100 suffered a shock or impact at the downstream cover flap 150 resulting in the loss of a part of it corresponding to a missing part 151.

[0045] In accordance with the method of the invention, the missing part is replaced at the level of an area of ​​the part to be repaired corresponding in the example described here to the replacement of the missing part 151 at the level of a remaining part 152 of the downstream cover beak 150 of the turbine blade 100.

[0046] The process preferably begins by machining the edge of the remaining portion of the part to be repaired, here the edge 1520 of the remaining portion 152 of the downstream cover spoiler 150 ([Fig. 1]). The machining aims to form a connecting edge on the part that facilitates contact with the replacement part during assembly. The machining consists of forming a connecting edge with a specific geometry that facilitates its assembly with the replacement part, such as the connecting edge 153 illustrated in [Fig. 2]. As explained below, the connecting edges of the part and the replacement part may have specific complementary geometries.

[0047] In the event of a clean break of part of the piece, the machining step is not necessary, the edge of the remaining part of the piece from which the missing part detached directly forms a connecting edge for the replacement part.

[0048] The method also includes the production of a replacement part intended to allow the repair of the turbine blade 100. The replacement part is formed from a fibrous reinforcement of refractory fibers, preferably of the same type as the refractory fibers of the part to be repaired. The fibrous reinforcement is shaped to match the shape of the missing part to be replaced. It is then consolidated by a first matrix phase, preferably identical to that of the part. Figure 2 illustrates a replacement part 251 thus obtained and intended to replace the missing part 151 of the cover flap 150 of the turbine blade 100. The replacement part 251 has a connecting edge 253 intended to cooperate with the connecting edge 153 of the remaining part 152 of the downstream cover flap 150 during the assembly of the replacement part 251 with the remaining part 152 of the downstream cover flap 150.

[0049] In the example described here, the replacement part is assembled with the remaining part, which has been consolidated by a first matrix phase. However, this does not depart from the scope of the invention when the replacement part is further impregnated with a ceramic powder slurry ("Slurry Cast" or "Slurry Transfer Molding"), for example, SiC, before being assembled with the remaining part. Similarly, this does not depart from the scope of the invention when the replacement part has been consolidated by a first matrix phase, then impregnated with a ceramic powder slurry ("Slurry Cast" or "Slurry Transfer Molding"), and then infiltrated with a molten silicon-based composition ("Melt Infiltration").

[0050] Once the replacement portion 251 is produced, the connecting edge 253 on the replacement portion 251 is positioned against the connecting edge 153 on the remaining portion 152 of the downstream cover spoiler 150, which corresponds to the portion of the CMC part to be repaired, as shown in [Fig. 3]. A holding tool (not shown in [Fig. 3]) can be used to hold the replacement portion in position against the portion to be repaired. The replacement portion can also be bonded to the portion to be repaired. In this case, the holding tool is used only during the bonding process; the replacement portion is subsequently held in place by the bond.

[0051] The replacement part, here the replacement part 251 of the downstream cover spoiler 150, and the portion of the part to be repaired, here the remaining portion 152 of the downstream cover spoiler 150, are then impregnated with a second silicon-based composition in a molten state. The replacement part is thus bonded to the portion to be repaired by co-silicilation, which forms a solid bond between the replacement part and the portion to be repaired while filling the residual porosity of the replacement part material.

[0052] According to the invention, the second silicon-based composition has a melting point lower than the melting point of the first silicon-based composition used to manufacture the CMC part, here the blade Turbine 100. By using a second silicon-based composition with a melting point lower than that of the first silicon-based composition, the melting point of the first silicon-based composition in the part is not reached during the co-silicidation of the replacement and repaired sections. This preserves the material integrity of the part. The second silicon-based composition has a melting point at least 20°C, or even at least 50°C, lower than that of the first silicon-based composition.

[0053] The melting temperature of the second silicon-based composition is preferably higher than the operating temperature of the ceramic matrix composite part, which for a turbine blade can reach up to 1000°C. By way of non-limiting example, the melting temperature of the second silicon-based composition is between 1200°C and 1400°C. Also by way of non-limiting example, silicon-zirconium alloys (Si-Zr) comprising approximately 10 mol% zirconium and having a eutectic temperature of approximately 1370°C, silicon-titanium alloys (Si-Ti) comprising approximately 74 mol% silicon and having a eutectic temperature of approximately 1330°C, or silicon-nickel alloys (Si-Ni) can be used as the second silicon-based composition.

[0054] According to one particular aspect, before the impregnation step, an anti-wetting agent such as boron nitride (BN) can be deposited on the surfaces of the replacement part outside the bonding edge, here on all exposed surfaces of the replacement part 251 except for the bonding edge 253, as well as on the surfaces of the portion to be repaired outside the other bonding edge, here the exposed surfaces of the remaining part 152 except for the bonding edge 153. This preserves the dimensions of the part in the areas outside the repair bonding. In the case of a part with an aerodynamic function, its aerodynamic performance is also preserved.

[0055] According to another particular aspect, the replacement part and the portion to be repaired can be impregnated (co-silicidated) via a carbon drain (wire, mat, etc.) in contact, on the one hand, with the second silicon-based composition in the molten state and, on the other hand, with the replacement part and / or the portion to be repaired. The second silicon-based composition is then conveyed to the assembly interface by capillary action. The carbon drain can be placed at the assembly interface between the replacement part and the portion to be repaired, i.e., interposed between the bonding edges. In this case, the carbon of the drain reacts with the silicon of the composition to form silicon carbide, which strengthens the bonding interface between the replacement part and the portion to be repaired.

[0056] As indicated above, the connecting edges of the part and the replacement part may have particular complementary geometries to facilitate anchoring between these two elements.

[0057] Figures 4A to 4F show, respectively, replacement parts 20, 30, 40, 50, 60, and 70, each comprising a first connecting edge 200, 300, 400, 500, 600, and 700, and portions of a part to be repaired 21, 31, 41, 51, 61, and 71, each comprising a second connecting edge 210, 310, 410, 510, 610, and 710. The first connecting edges 200, 300, 400, 500, 600, and 700 have one or more overlapping parts, while the second connecting edges 210, 310, 410, 510, 610, and 710 have one or more overlapping parts whose shape is complementary to the shape of the part(s). Overlapping sections of the first connecting edges, such as the beveled shape of the first connecting edge 253 of the replacement section 251 of the second connecting edge 153 of the portion to be repaired 152 described previously. Other shapes such as crenellated, stepped, Z-shaped, etc., can be considered.The overlapping portion(s) present on the first and second connecting edges are superimposed when the first connecting edge is positioned against the second connecting edge. This increases the assembly surface between the connecting edges, thus improving the mechanical strength of the connection.

[0058] Figures 5A and 5B illustrate replacement parts 80 and 90, each comprising a first bonding edge 800 and 900, and portions of a part to be repaired 81 and 91, each comprising a second bonding edge 810 and 900. These differ from the replacement parts and portions to be repaired in Figures 4A and 4B in that one or more retaining pins 82 and 92 extend through the first and second overlapping portions of the first and second bonding edges. The retaining pins 82 and 92 are preferably made of a ceramic material such as SiC. The retaining pins are positioned before the replacement part and the portion to be repair are impregnated with the second silicon-based composition (co-silicidation). The retaining pins improve the strength of the assembly between the replacement part and the portion of the part to be repaired, as well as their retention in position before and during co-siliciration.

[0059] By way of non-limitation, the invention is advantageously applicable to the repair of moving turbine blades, outlet guide vanes (OGV), distributors and turbine ring sectors of gas turbine engine.

Claims

Demands

1. A method for replacing at least one missing part (151) of a ceramic matrix composite material part (100) comprising a fibrous reinforcement of refractory fibers densified by a matrix comprising at least one ceramic material and a first silicon-based composition, characterized in that it comprises: - a step of producing a replacement part (251) from a fibrous reinforcement of refractory fibers at least consolidated by a first matrix phase, the replacement part corresponding to the shape of said at least one missing part (151), - a step of positioning a first bonding edge (253) present on the replacement part (251) against a second bonding edge (153) present on a portion to be repaired (152) of the ceramic matrix composite material part (100),- a step of impregnating the replacement part (251) and the portion to be repaired (152) with a second silicon-based composition in a molten state, and in that the second silicon-based composition has a melting point lower than the melting point of the first silicon-based composition.

2. A method according to claim 1, wherein the second silicon-based composition has a melting temperature that is at least 20°C, or even at least 50°C, lower than the melting temperature of the first silicon-based composition.

3. A method according to claim 1 or 2, wherein the first silicon-based composition is selected from one of the following compounds or alloys: Si, Si-B, Si-Mo and Si-Ta while the second silicon-based composition is selected from one of the following silicon alloys: Si-Zr and Si-Ti.

4. A method according to any one of claims 1 to 3, wherein the step of making the replacement part (251) includes introducing a powder of ceramic material particles into the porosity of the fibrous reinforcement of refractory fibers consolidated by the first matrix phase.

5. A method according to any one of claims 1 to 4, further comprising, prior to the impregnation step, a step of depositing an anti-wetting agent onto surfaces of the replacement part (251) present outside the first connecting edge (253) and on surfaces of the portion to be repaired (152) present outside the second connecting edge (153).

6. A method according to any one of claims 1 to 5, wherein the first connecting edge (253) has at least one first overlapping portion and the second connecting edge (153) has at least one second overlapping portion, said at least first overlapping portion being superimposed on said at least second overlapping portion when the first connecting edge is positioned against the second connecting edge.

7. Method according to claim 6, wherein the first and second connecting edges each have a beveled or crenellated shape.

8. Method according to claims 6 or 7, further comprising, before the step of impregnating the replacement part and the portion to be repaired, the positioning of one or more retaining pins (82) extending through said at least first and second overlapping parts of the first and second connecting edges (800, 810).

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