FR2960242A1 - PROCESS FOR MANUFACTURING MULTI-LAYER COMPONENTS HAVING INCLINED HOLES AND RESISTANT TO HIGH THERMAL CONSTRAINTS AND USE OF THE PROCESS FOR REPAIRING WORKPIECES - Google Patents

Abstract

The present invention relates to a method for manufacturing a multilayer workpiece (0) comprising holes (4) whose axes (41) are inclined and must withstand high temperatures, having an underlayer (2) for gripping and a layer ( 3) thermal barrier coating (TBC) comprising at least one step of depositing the underlayer (2) of attachment to the substrate (1) of the part (0), a step of depositing the layer (3) ) of TBC, a step of plasma spraying a layer (5) with a variable composition gradient or defined between the TBC layer and the underlayer stringer after the step of depositing the underlayer ( 2) hooking and a step of drilling holes (4) by a laser beam. The invention also relates to a use of the method for the repair of a defective part.

Description

The present invention relates to the field of combustion chambers or industrial turbines, in particular the production of bores or the production of bores. holes in a multilayer material part such as a ceramic coated metal substrate. Patent application FR 2 909 297 discloses laser drilling techniques for cooling holes for hot parts that must withstand high temperatures, such as combustion chamber walls of a turbojet engine or turbine blades. industrial. These hot parts are protected by a layer of coating creating a thermal barrier often ceramic which is attached to the substrate of the hot room by a sub-layer is hanging. The Thermal Barrier Coating (TBC) is also protected by a film of air produced by the cooling holes. It is also known from patent application US 2008/0241560 to deposit, by plasma diffusion on a nickel-based superalloy substrate, a layer of ceramic powder mixed with a powder of a nickel aluminide intermetallic compound ( NiAI) to increase the life of the thermal barrier or the thickness of the layer. It is also known from the patent application EP 0 799 904 to deposit by physical vapor deposition under an electron beam (EB-PVD or Electron Beam Physical Vapor Deposition) a layer whose various compounds consisting of Ceramics and mixtures of aluminum oxides, chromium, nickel, yttrium and zirconium are distributed in the thickness along a gradient to improve the layer bond reliability (page 4, 3rd example).

The combustion chamber manufacturing technology is evolving. For a long time, the combustion chamber walls consisted of stepped panels (FIG. 4) separated by zones having cooling holes of diameter of the order of 1.2 mm to a few millimeters. A film of air circulates through these cooling holes which creates a protective screen. Now, this type of wall is replaced by one or more panels (Figure 5) having a very large number of cooling holes of very small diameters of the order of 0.3 mm to 0.8 mm. This new wall technique makes it possible to obtain a much more homogeneous air film and better protects the thermal barrier coating thus enabling a considerably increased operating temperature of the combustion chamber. The axis of the holes relative to the surface of the hot room is determined according to the configuration of the air film that is desired. This means that a number of holes will have an axis inclined relative to the surface. Various techniques allow the drilling of holes such as the uncorking technique and the laser drilling technique. The uncorking technique consists of thermal spraying of the bonding sub-layer on the substrate of the hot part and then laser drilling of the substrate and the underlayer. Plasma spraying of a first thermal barrier layer TBC is then applied followed by uncoupling by an abrasive process. A second layer of TBC is then applied to be followed by a second uncorking by an abrasive process. This technique involves a long and unreliable process. The laser piercing technique, in turn, consists of a drilling by a laser beam of the substrate, the underlayer stringer and the TBC together thereby reducing the steps of the process implemented. However, the interaction between the high energy laser and the substrate coated with the underlayer and the TBC causes laser detonation creating a shock wave. This shock wave associated with the differential expansion of the materials constituting the substrate, the anchoring sub-layer and the TBC (whose physicochemical properties are different), combined with the phenomena of tension and resolidification of the liquid layers, generates a delamination. even a detachment of the TBC layer in the case of very low incidence of the laser beam, less than 25 °. The delamination of each hole can lead to plate delamination immediately or during operation of the combustion chamber. In the first case, the part is not usable. In the second case, the service life of the part is reduced hence a major risk for the turbojet engine comprising the combustion chamber. The present invention aims to overcome these disadvantages by Io proposing a parts manufacturing process having inclined holes and having to withstand high temperatures. This object is achieved by a method of manufacturing multilayer parts having holes whose axes are inclined and having to withstand high thermal stresses having a tie layer and is a thermal barrier coating layer (TBC) comprising minus the following steps: a step of depositing the bonding sub-layer on the substrate of the part; a step of depositing the TBC layer. The method is characterized in that it comprises, in addition, the following steps: a step of depositing a gradient layer of variable or defined composition between two materials by plasma spraying after the deposition step of the underlayer hanging; A step of drilling the holes by a laser beam. According to another particularity, the gradient layer of variable composition between two materials progressively passes from a composition of 100% undercoat material and 0% TBC material in the area near the undercoat layer. attaches to a composition of 0% underlayer material and 100% TBC material in the area near the TBC layer.

According to another particularity, the gradient layer of defined composition is a homogeneous mixture of the materials constituting the underlayer stringer and the TBC layer and is deposited between the underlayer stringer and the TBC layer.

According to another particular feature, the mass proportion of underlayer adhesion material is preferably 50% to 75% relative to the total weight of the undercoat and TBC layer forming layer forming materials. composition gradient According to another feature, the TBC layer is ceramic. Io According to another feature, the underlayer attachment is alloy NiCrAIY type, for a substrate based on cobalt or nickel or chromium. According to another feature, the substrate of the piece is made of alloy based at least on cobalt and chromium. According to another feature, the composition gradient layer has a thickness of between 0.15 mm and 0.30 mm. According to another feature, the underlayer stringer has a thickness between 0.08 mm and 0.25 mm. In another feature, the TBC layer has a thickness of between 0.20 mm and 0.60 mm. Another object is achieved by providing a use of the multilayer component manufacturing method having holes whose axes are inclined at low incidence and must withstand high temperatures having a tie layer, a gradient layer of 25 variable or defined composition and a layer of ceramic material forming TBC for the repair of a combustion chamber of a machine characterized in that it comprises at least the following steps: a cutting step of a portion of the defective part; - A welding step instead of the part of the defective part of a metal substrate part based on cobalt and chromium; a step of depositing a material forming the underlayer of adhesion on the substrate of the part; a plasma projection deposition step of a gradient layer of variable or defined composition between the two materials; a step of depositing the TBC material layer; a step of drilling the holes by a laser beam. According to another feature, the use further comprises a step of verifying the efficiency of an air film generated by a flow of air passing through the room through the holes. Other features and advantages of the present invention will become more apparent upon reading the following description, made with reference to the accompanying drawings, in which: FIG. 1 shows a section of a piece of the multilayer part according to hole axes without composition gradient layer; Figure 2 shows a section of a piece of the multilayered piece along hole axes with the composition gradient layer; Figure 3 shows a schematic section of a turbo reactor having the part according to the invention; Figure 4 shows a cross-section of the combustion chamber wall formed of stepped panels; Figure 5 shows a cross section of the part forming the walls of the combustion chamber consisting of one or more panels having a very large number of cooling holes. In the present description, reference will be made to FIGS. 1, 2, 3, 5, 4 and 5.

The invention relates to a method for manufacturing parts shown in FIG. 5 comprising holes (4) whose axes are inclined with a small angle of incidence A included, in a nonlimiting manner, between 15 ° and 25 °, and having to withstand thermal stress or high temperatures.

This type of part can be the jacket (0) of a combustion chamber of a turbojet engine (100). But it should be understood that the method according to the invention can be used for other fields such as industrial turbine blades. FIG. 4 shows the part as it was made in prior art where the combustion chamber walls consisted of stepped panels (400) separated by zones with cooling holes (401). FIG. 3 represents a schematic figure of a section of a turbojet engine. The thrust produced by the turbojet engine (100) is generated by the acceleration of the air flow between the inlet (101) and the outlet (108) at the level of a nozzle (107). The acceleration is obtained by the combustion (105) in a combustion chamber (104) of a fuel, for example kerosene, introduced by injectors (103) with the oxygen of the air entering the turbojet engine. Part of the energy produced is recovered by a turbine (106) which uses a compressor (102) which compresses the air at the inlet of the turbojet engine (100). The temperatures reached at the outlet of the combustion chamber (104) can go up to 2000 ° C. The combustion chamber (104) is delimited by a part (0) called a jacket whose walls is, for example, an alloy based on cobalt and chromium. Without limitation, the alloy consists of at least 39% cobalt, 22% chromium, 22% nickel, tungsten and iron. The walls of the combustion chamber (104) form a substrate (1) on which at least one anchoring layer (2) is deposited for hanging on the walls a layer (3) of thermal barrier coating ( TBC) which protects the walls from heat generated by combustion and oxidation (Figure 1 and Figure 2).

The underlayer (2) hook is, for example, NiCrAIY alloy material (nickel, chromium, aluminum, yttrium) for a substrate based on cobalt and / or nickel and / or chromium. For example, for a nickel base substrate, the alloy may be composed of 22% chromium, 10% aluminum and 1% yttrium. The TBC layer is made of ceramic material, for example, zirconium oxide (ZrO 2). The deposits of the different layers follow the following procedure. In a first step, the anchoring sub-layer (2) is deposited on the substrate (1), for example by plasma spraying. Plasma spraying is performed by a plasma torch which projects hot particles injected into the torch and that it is desired to deposit. These soft particles or in melted droplets then crash on the surface to be treated. In a next step, a layer (5) with a composition gradient is between two materials is deposited by plasma spraying. According to a configuration, the composition gradient layer (5) progressively passes from a composition of 100% underlayer material (2) and 0% TBC material to the area near the underlayer (2) adhering to a composition of 0% underlayer material (2) and 100% TBC material in the area near the TBC layer (3). The deposition of the variable-gradient layer (5) of variable composition between the two materials is carried out by a plasma torch in which 100% of the particles of material of the underlayer (2) of attachment are injected and 0% of amount of TBC material particles at the beginning of the plasma spraying. Then, the amount of material particles of the underlayer (2) of attachment is progressively decreased by progressively increasing the amount of particles of TBC material until 0% of the amount of particles of material is reached. of the underlayer (2) of attachment and 100% amount of particles of TBC material. The amount of particles to be sprayed can be adjusted using a device for controlling the plasma torch. A program is implemented by a processor of the control device thus making it possible to adjust the composition and the thickness of the composition gradient layer (5). According to another configuration, the defined composition gradient layer (5) is a homogeneous mixture of material constituting the anchoring sub-layer (2) and the TBC layer (3). Particles of each material are mixed using a mixer to obtain a homogeneous mixture of particles. In a nonlimiting manner, the mass proportion of particles of undercoat material (2) is preferably 50% to 75% relative to the total mass of the particles forming the layer (5) composition gradient. This layer is deposited between the anchoring sub-layer (2) and the layer (3) of TBC.

In a next step, a layer (3) of TBC is deposited, for example, by plasma spraying. Without limitation, the layer (5) of composition gradient has a thickness between 0.15 mm and 0.30 mm, preferably between 0.20 mm and 0.25 mm.

In a nonlimiting manner, the underlayer (2) of attachment has a thickness of between 0.08 mm and 0.25 mm, preferably between 0.10 mm and 0.15 mm. In a nonlimiting manner, the layer (3) of TBC has a thickness of between 0.20 mm and 0.60 mm, preferably between 0.25 mm and 0.55 mm. In a next step, the holes (4) are pierced by at least one laser beam along an axis (41) calculated so that the air film is optimized for protection of the layer (3) of TBC. The laser beam is directed according to a program contained in a processor which determines the position of the laser beam as a function of the position of each hole (4) and the angle to be made by the axis (41) of each hole (4) relative to the surface of the workpiece (0). Without limitation, each hole has a diameter of the order of 0.3 mm to 0.8 mm, preferably of the order of 0.4 mm. Without limitation, a hole (4) is made in two steps. A first percussion step of using the fixed laser beam with an incidence Å of, for example, between 15 ° and 25 ° in a pulsed mode to penetrate the thickness of the workpiece (0) and the layers (2, 3, 5) of protection. A second step of trepanning involves cutting the hole (4) by moving the laser beam circularly. This part manufacturing process (0) can be used for the repair of a combustion chamber of a machine for example having a defective part.

In a first step, the defective piece is cut, for example, by laser or a torch. In a next step, a piece of material forming the substrate, for example, based on cobalt, chromium and nickel is welded in place of the defective piece cut. This piece then undergoes the previously described workpiece manufacturing process. After this process, a step of checking the efficiency of the air film is performed. An air flow similar to the effective air flow during operation of the turbojet engine is generated. It is thus possible to check the efficiency of the air film generated by the flow of air passing through the room through the 25 holes (4). It should be apparent to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims (12)

REVENDICATIONS1. Method for manufacturing a multilayer workpiece (0) comprising holes (4) whose axes (41) are inclined and have to withstand high thermal stresses having an underlayer (2) for gripping and a layer (3) for coating thermal barrier (TBC) comprising at least the following steps: - a step of depositing the sub-layer (2) of attachment to the substrate (1) of the part (0); a deposition step of the TBC layer (3); characterized in that it further comprises the following steps: a step of depositing a layer (5) with a gradient of variable composition or defined between two materials by plasma spraying after the step of depositing the underlayer ( 2) teaser; a step of drilling the holes (4) by a laser beam. 2. Method according to claim 1, characterized in that the layer (5) gradient of variable composition between two materials passes gradually from a composition of 100% underlayer material (2) of attachment and 0% of TBC material (3) in the area near the underlayer (2) of attachment to a composition of 0% undercoat material (2) and 100% TBC material (3) in the area close to the layer (3) of TBC. 3. Method according to claim 1, characterized in that the layer (5) with defined composition gradient is a homogeneous mixture of the materials constituting the underlayer (2) of attachment and the layer (3) of TBC and is deposited between the anchoring sub-layer (2) and the layer (3) of TBC. 4. Method according to claim 3, characterized in that the mass proportion of undercoat material is preferably from 50% to 75% relative to the total mass of the materials sublayer (2) d and adhesion layer (3) of TBC forming the layer (5) composition gradient 5. Method according to claim 1, characterized in that the layer (3) of TBC is ceramic. s 6. Method according to claim 1, characterized in that the underlayer (2) hook is NiCrAIY type alloy, for a substrate based at least cobalt or nickel or chromium. 7. The method of claim 1, characterized in that the substrate (1) of the part (0) is at least based on cobalt and chromium alloy. io 8. The method of claim 1, characterized in that the layer (5) composition gradient has a thickness of between 0.15 mm and 0.30 mm. 9. The method of claim 1, characterized in that the underlayer (2) hooking has a thickness between 0.08 mm and 0.25 mm. 15 10. The method of claim 1, characterized in that the layer (3) of TBC has a thickness of between 0.20 mm and 0.60 mm. 11. Use of a production process of parts (0) having holes (4) whose axes (41) are inclined with a low incidence and must withstand high thermal stresses having a sub-layer (2) d hooks, a layer (5) of variable or defined composition gradient and a layer (3) of ceramic material forming TBC for the repair of a combustion chamber of a machine characterized in that it comprises at least the steps following: - a step of cutting a part of the part (0) 25 defective; 10- a welding step in place of the part of the defective part of a part (0) metal substrate based on cobalt and chromium; a step of depositing a material forming the underlayer (2) for hooking onto the substrate (1) of the part (0); a step of plasma spraying a layer (5) with a defined or variable composition gradient between the two materials; a deposition step of the layer (3) of material forming TBC; a step of drilling the holes (4) by a laser beam. 12. Use according to claim 11, characterized in that it further comprises a step of verifying the efficiency of an air film generated by a flow of air passing through the workpiece (0) through the holes (4). ). 15