A method for forming film holes in double-wall turbine blades with thermal barrier coatings

Abstract

The present invention relates to the field of aero-engine technology, and more specifically, to a method for forming film holes in double-walled turbine blades with thermal barrier coatings. The method comprises obtaining a first spacing between the outer wall and the inner wall of the turbine blade; performing the following steps based on the first spacing being less than or equal to a preset spacing between the outer wall and the inner wall of the turbine blade: obtaining a second depth of the first film hole obtained by processing the laser beam on the outer wall; obtaining a first stroke of the electrode when processing along the first film hole on the outer wall until the electrode punches through the outer wall to obtain a second film hole, wherein there is a second spacing between the electrode and the inner wall; obtaining a target film hole based on the sum of the punching of the electrode on the outer wall, the second depth, and the third depth of the second film hole being consistent with the first depth. The method of the present invention solves the problems of electric spark being unable to process film holes with thermal barrier coatings and laser processing being prone to damage to the back wall, interface delamination, and taper.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a method for forming film holes in a double-wall turbine blade with a thermal barrier coating. Background Art

[0002] The manufacturing of turbine blades for modern gas turbine engines relies on three core technologies: advanced air-cooling structures, high-performance high-temperature materials, and thermal barrier coatings (TBCs). These technologies ensure long engine life and reliable, high-strength operation in complex environments. Due to rising temperatures before the turbine, the heat resistance of current high-temperature alloys is currently being challenged. Therefore, in the development of new high-temperature structural materials, a comprehensive thermal protection strategy integrating air film cooling and thermal barrier coatings is primarily employed to improve their thermal protection performance.

[0003] Currently, the primary method for producing film holes on blades coated with thermal barrier coatings is to first drill the holes and then apply the thermal barrier coating. However, this method requires pre-enlarging the hole diameter to compensate for the shrinkage caused by coating deposition. While this method can mitigate the adverse effects on the performance of the cooling structure to some extent, given that the statistical laws governing shrinkage are not universally applicable, it still poses challenges to the film structure and cooling efficiency. In severe cases, it can even lead to blockage of the cooling channels, making it difficult to meet the desired hole specifications. Furthermore, some researchers have studied the production of film holes for TBC-coated blades. Using millisecond lasers to create holes in TBC superalloys and thermally cycle them can easily cause the ceramic coating to break off and delaminate during the hole-making process. This damage can further increase the likelihood of microcracks in the thermally grown oxide layer between the ceramic coating and the bonding layer during thermal cycling, thereby reducing the service life of the thermal barrier coating. During laser processing of thermal barrier coatings, the stress induced by the melt jet is a key factor in the separation of the ceramic and bonding layers, while delamination between the bonding layer and the substrate is primarily caused by thermal effects. When using ultrafast laser technology to process film holes in turbine blades, due to the narrow gap in the inner cavity of the double-walled blade, the laser hole is very likely to damage the opposite wall, and it is difficult to prevent damage. Therefore, proposing how to implement effective protective measures is a key technical problem faced by laser processing of film holes in blades.

[0004] For ceramic materials containing conductive phases (such as TiB2, TiN, or TiC), electrical discharge machining (EDM) can be used directly to drill holes. However, it is worth noting that EDM is not suitable for machining thermal barrier coatings, and laser machining may cause coating delamination and other problems, especially delamination and material spalling at the interface between the ceramic layer and the bonding layer, and at the bonding layer and the metal substrate.

[0005] In order to solve the problems mentioned above, such as the thermal barrier coating is not conductive and laser processing easily damages the back wall, the interface is delaminated, and the entrances and exits have obvious taper, this paper proposes a combined laser and electrospark processing technology to solve the problems that electrospark cannot process air film holes with thermal barrier coatings and laser processing easily damages the back wall, the interface is delaminated and taper. It aims to provide data support and theoretical basis for the subsequent composite processing technology of TBC air film holes coated on blades, which has important scientific significance and application value. Summary of the Invention

[0006] To solve the problems of the inability of electric spark machining of film holes with thermal barrier coatings and the easy damage to the back wall, interface delamination and taper caused by laser machining, the present invention provides a method for forming film holes in double-walled turbine blades with thermal barrier coatings, comprising the following steps:

[0007] Obtaining a first distance between an outer wall and an inner wall of the turbine blade;

[0008] According to the first distance being less than or equal to the preset distance between the outer wall and the inner wall of the turbine blade, the following steps are performed:

[0009] Obtaining a second depth of the first air film hole obtained by machining the laser beam on the outer wall according to the first spacing, the first thickness of the outer wall, the first depth of the preset air film hole, and the first laser energy of the laser beam, wherein the second depth is less than the first depth;

[0010] According to the first spacing, the first thickness, the first depth, and the second depth, a first stroke of the electrode is obtained when the electrode is processed along the first air film hole on the outer wall until the electrode punches the outer wall to form a second air film hole, wherein a second spacing is provided between the electrode and the inner wall, and 0<second spacing≤first spacing;

[0011] The target air film hole is obtained according to the electrode perforating the outer wall and the sum of the second depth and the third depth of the second air film hole being consistent with the first depth.

[0012] Preferably, 0.6 mm<second spacing ≤first spacing.

[0013] According to one embodiment of the present invention, the outer wall includes a thermal barrier coating segment and a metal substrate segment, the thermal barrier coating segment includes a ceramic layer and a bonding layer, the ceramic layer is a non-conductive layer, and the bonding layer and the metal substrate segment are conductive layers;

[0014] According to the first spacing, the first thickness of the outer wall, the second thickness of the non-conductive layer, the first depth of the preset air film hole and the first laser energy of the laser beam, the second depth of the first air film hole processed by the laser beam in the non-conductive layer is obtained, wherein the second depth is less than the first depth, and the second thickness of the non-conductive layer is ≤ the second depth of the first air film hole ≤ the sum of the second thickness of the non-conductive layer and the third thickness of the conductive layer.

[0015] According to one embodiment of the present invention, the method for processing the first air film hole in the non-conductive layer with a laser beam includes the following steps:

[0016] The laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular manner from the first axis to approach the first outer diameter of the preset air film hole until the movement trajectory of the laser beam coincides with the first outer diameter, and the laser beam processes the non-conductive layer to obtain the first air film hole;

[0017] Alternatively, the laser beam moves along the first outer diameter of the preset air film hole around the first central axis of the preset air film hole, and the laser beam moves in a circular manner from the first outer diameter to the first central axis until the laser beam is located at the first axis of the preset air film hole, and the laser beam processes the non-conductive layer to obtain the first air film hole;

[0018] Alternatively, the laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular motion from the first axis to approach the first outer diameter of the preset air film hole until the moving trajectory of the laser beam coincides with the second outer diameter of the preset air film hole. Thereafter, the laser beam revolves around the first central axis of the preset air film hole along the first outer diameter of the preset air film hole, and the laser beam moves in a circular motion from the first outer diameter to approach the first central axis until the moving trajectory of the laser beam coincides with the second outer diameter. The laser beam processes the first air film hole in the non-conductive layer, wherein the second outer diameter is less than the first outer diameter.

[0019] According to one embodiment of the present invention, the outer wall includes a thermal barrier coating segment and a metal substrate segment, the thermal barrier coating segment includes a ceramic layer and a bonding layer, the ceramic layer is a non-conductive layer, and the bonding layer and the metal substrate segment are conductive layers;

[0020] The method for processing the outer wall with a laser beam comprises the following steps:

[0021] Obtaining a first aperture of the preset air film hole;

[0022] The laser beam processes the non-conductive layer to form the first air film hole, the second aperture of the first air film hole is within the first aperture range, the first air film hole has a fourth depth, and the bottom of the first air film hole is at least partially located in the bonding layer;

[0023] The laser beam processes the first air film hole in the conductive layer to obtain a third aperture and a fifth depth of the second air film hole, wherein the third aperture is smaller than the second aperture, and the fifth depth is smaller than the third depth;

[0024] The second air film hole obtained by machining the electrode along the laser beam is machined on the conductive layer to obtain a fourth aperture and a sixth depth of the second air film hole, wherein the fourth aperture is greater than the third aperture, the sixth depth is greater than the fifth depth, or the sixth depth is less than the fifth depth;

[0025] The target air film hole is obtained according to the electrode penetrating the conductive layer, the fourth aperture being within the first aperture range, and the sum of the fourth depth, the fifth depth, and the sixth depth being consistent with the first depth.

[0026] According to one embodiment of the present invention, the electrode having a third outer diameter is obtained according to the first aperture of the preset air film hole, and the electrode has a hollow cooling water channel;

[0027] Obtaining the third aperture of the second air film hole according to the second diameter of the cooling water channel in the electrode;

[0028] The second diameter is less than the third outer diameter and the third aperture is less than the first aperture.

[0029] According to one embodiment of the present invention, when the bottom of the first air film hole is close to the conductive layer, the first laser energy is reduced to the second laser energy.

[0030] According to one embodiment of the present invention, the electrode processing along the second air film hole on the outer wall includes at least three electrode processing stages;

[0031] The three electrode processing stages include an electrode initial processing stage, an electrode intermediate processing stage and an electrode perforation stage which are performed in sequence;

[0032] When in the initial processing stage of the electrode, the electrode has a first discharge gap;

[0033] When in the intermediate processing stage of the electrode, the electrode has a second discharge gap;

[0034] When in the electrode perforation stage, the electrode has a third discharge gap;

[0035] The first discharge gap is greater than the second discharge gap, the third discharge gap is greater than the second discharge gap, and the first discharge gap is greater than or equal to the third discharge gap.

[0036] Preferably, the first discharge gap is larger than the third discharge gap.

[0037] According to one embodiment of the present invention, the preset distance between the outer wall and the inner wall of the turbine blade is: 0<preset distance≤0.8 mm.

[0038] Preferably, 0.6≤preset spacing≤0.8 mm.

[0039] According to one embodiment of the present invention, the first aperture of the preset air film hole is 0.3-3.0 mm, and the difference between the target film aperture of the target air film hole and the first aperture of the preset air film hole is ±0.05 mm.

[0040] According to one embodiment of the present invention, the laser comprises an ultrafast laser, a short pulse laser, or a long pulse laser;

[0041] The ultrafast laser includes a picosecond laser or a femtosecond laser; the short pulse laser includes a nanosecond laser; and the long pulse laser includes a millisecond laser.

[0042] According to one embodiment of the present invention, the laser processing parameters during the picosecond laser processing include a single pulse energy of 30 to 50 μJ, a scanning speed of 250 to 450 mm / s, and a repetition frequency of 84 to 500 kHz.

[0043] Preferably, the single pulse energy is 40 μJ, the scanning speed is 300 mm / s, and the repetition frequency is 500 kHz.

[0044] According to one embodiment of the present invention, the electrode comprises tubular brass, and electrode processing parameters during brass processing include a peak current of 1 to 2.35 A and a pulse width of 5 to 12 μs.

[0045] Preferably, the peak current is 2.03A, the pulse width is 5μs, the pulse time is 25μs, and the pulse peak voltage is 80V.

[0046] The present invention has the following beneficial effects:

[0047] 1. The present invention utilizes a laser and electrode composite to process the film holes of double-walled turbine blades with thermal barrier coatings. The laser is first used to process the non-conductive ceramic layer, and then the electrode is used to process the conductive layer. This avoids the problem of laser damage to the double-walled turbine blade's opposing wall surface after the laser penetrates the metal substrate when processing alone, as well as the phenomenon that laser processing easily causes cracking of the hole wall and interface delamination. The present method eliminates the need for additional filler to fill the gap between the inner and outer walls to prevent film hole processing from easily damaging the opposing walls of the double-walled turbine blade.

[0048] 2. The method of the present invention is used to make holes in a metal substrate with a ceramic coating on its surface. The surface morphology of the ceramic layer, the longitudinal section diagram of the hole wall and the thickness of the remelted layer of the metal substrate hole wall obtained by the method of the present invention demonstrate the feasibility of picosecond laser and electrospark composite processing of metal-based ceramic coating materials, solve the problems of electrodes being unable to process air film holes with thermal barrier coatings and laser processing easily causing interface stratification and taper, and provide data support and theoretical basis for the subsequent composite processing technology of air film holes in double-wall turbine blades, which has important scientific significance and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A flow chart of a method for forming film holes in a double-walled turbine blade with a thermal barrier coating according to the present invention is shown;

[0050] Figure 2 A schematic diagram of the partial structure of a double-walled turbine blade with thermal barrier coating is shown;

[0051] Figure 3 Metallographic microscope images of the surface morphology of the ceramic layer after laser beam and electrode processing in Examples 1-4 are shown, where (a), (b), (c), and (d) respectively show the changes in the surface morphology of the hole before and after EDM under different single pulse energies, scanning speeds, repetition frequencies, and processing times;

[0052] Figure 4 The metallographic microscope images of the blade obtained in Example 5 are shown, wherein (a) is the surface morphology of the hole, (b) is the longitudinal section of the hole wall, (c) is the thickness of the remelted layer on the left side of the hole wall of the substrate, and (d) is the thickness of the remelted layer on the right side of the hole wall;

[0053] Figure 5 The metallographic microscope images of the blade obtained in Example 6 are shown, wherein (a) is the surface morphology of the hole, (b) is the longitudinal section of the hole wall, (c) is the thickness of the remelted layer on the left side of the hole wall of the substrate, and (d) is the thickness of the remelted layer on the right side of the hole wall. DETAILED DESCRIPTION

[0054] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the present disclosure, rather than to imply any limitation on the scope of the present disclosure.

[0055] As used herein, the term "including" and its variations are to be interpreted as open-ended terms meaning "including, but not limited to." The term "based on" is to be interpreted as "based, at least in part, on." The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment." The term "another embodiment" is to be interpreted as "at least one other embodiment." Terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "vertical," "horizontal," "transverse," and "longitudinal" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are primarily intended to better describe the present application and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed and operated in a specific orientation. Furthermore, some of the above terms may be used to indicate other meanings besides orientation or positional relationships. For example, the term "on" may, in certain circumstances, be used to indicate a dependency or connection relationship. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances. Furthermore, the terms "installed," "disposed," "provided with," "connected," and "connected" are to be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements, or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise specified, "plurality" means two or more.

[0056] This embodiment discloses a method for forming film holes in a double-walled turbine blade with a thermal barrier coating. Figure 2 As shown, this may include:

[0057] Obtaining a first distance between an outer wall and an inner wall of the turbine blade;

[0058] According to the first distance being less than or equal to the preset distance between the outer wall and the inner wall of the turbine blade, the following steps are performed:

[0059] Obtaining a second depth of the first air film hole obtained by machining the laser beam on the outer wall according to the first spacing, the first thickness of the outer wall, the first depth of the preset air film hole, and the first laser energy of the laser beam, wherein the second depth is less than the first depth;

[0060] According to the first spacing, the first thickness, the first depth, and the second depth, a first stroke of the electrode is obtained when the electrode is processed along the first air film hole on the outer wall until the electrode punches the outer wall to form a second air film hole, wherein a second spacing is provided between the electrode and the inner wall, and 0<second spacing≤first spacing;

[0061] The target air film hole is obtained according to the electrode perforating the outer wall and the sum of the second depth and the third depth of the second air film hole being consistent with the first depth.

[0062] In this embodiment, the turbine blade is a turbine blade with a double wall, such as Figure 2 As shown, the portion near the center of the turbine blade is the inner wall, and the portion away from the center of the turbine blade is the outer wall. A first spacing between the outer wall and the inner wall is measured. When the first spacing is less than or equal to the preset spacing, the first thickness of the outer wall is measured to obtain the first depth of the preset film hole. The first laser energy of the laser beam is obtained. Based on the first spacing, the first thickness of the outer wall, the preset first depth of the film hole, and the first laser energy of the laser beam, the first depth of the first film hole obtained by the laser beam processing in the outer wall is determined. In other words, the depth of the outer wall ablated by the laser beam is determined. This ensures that the film hole can be processed more quickly using the laser beam, while also avoiding delamination of the film hole wall caused by prolonged use of the laser beam when processing the film hole in the outer wall, as well as the problem of easily damaging the contrasting wall after the laser beam perforation due to increased laser beam energy. The contrasting wall is the wall surface of the inner wall corresponding to the outer wall.

[0063] The second depth of the laser beam in the outer wall after the first air film hole is processed can be used to determine the required electrode travel when the electrode is inserted into the first air film hole to process the second air film hole. In order to avoid the electrode continuing to extend adaptively after each portion of the electric spark ablates after perforation, thereby ensuring that the electrode effectively ablates the portion to be processed, the electrode remains in a moving state while the discharge machining is being performed. When the electrode is about to perforate, the inertia generated by the movement of the electrode may cause the electrode to continue to move after perforation, resulting in contact with the inner wall and damaging the inner wall of the turbine blade. Therefore, the first travel of the electrode from the bottom of the first air film hole to the electrode after perforation is determined based on the first spacing, first thickness, first depth and second depth, so that one end of the electrode is located in the gap between the outer wall and the inner wall, and there is a second spacing between the electrode and the inner wall, that is, the electrode does not contact the inner wall, ensuring that there is a gap between the electrode and the inner wall. By obtaining the first stroke of the electrode, the maximum movable stroke of the electrode can be determined when the electrode is drilling the outer wall, thereby avoiding excessive movement of the electrode, which may cause the electrode to contact the inner wall and cause damage to the inner wall.

[0064] And after the sum of the electrode perforation on the outer wall, the second depth and the third depth of the second air film hole is consistent with the first depth, the target air film hole is obtained to ensure that the air film hole processed is the target air film hole, that is, it is necessary to ensure that the direction of the laser beam or electrode processing on the outer wall is consistent with the direction of extension of the target air film hole. Perforation refers to the electrode punching a hole on the outer wall until the electrode extends into the gap between the outer wall and the inner wall, that is, the state in which the electrode extends into the gap between the outer wall and the inner wall or the state in which the second air film hole is connected to the gap between the outer wall and the inner wall is electrode perforation. By using the method of laser beam processing first and then electrospark processing in this embodiment, the problems of electrospark being unable to process air film holes with thermal barrier coatings and laser processing being prone to damage to the walls of double-walled turbine blades, interface delamination and taper can be solved. There is no need to use additional filling glue to fill the gap between the inner wall and the outer wall in order to avoid the air film holes being prone to damage to the walls of double-walled turbine blades.

[0065] Preferably, 0.6 mm<second spacing ≤first spacing.

[0066] According to one embodiment of the present invention, the outer wall includes a thermal barrier coating segment and a metal substrate segment, the thermal barrier coating segment includes a ceramic layer and a bonding layer, the ceramic layer is a non-conductive layer, and the bonding layer and the metal substrate segment are conductive layers;

[0067] According to the first spacing, the first thickness of the outer wall, the second thickness of the non-conductive layer, the first depth of the preset air film hole and the first laser energy of the laser beam, the second depth of the first air film hole processed by the laser beam in the non-conductive layer is obtained, wherein the second depth is less than the first depth, and the second thickness of the non-conductive layer is ≤ the second depth of the first air film hole ≤ the sum of the second thickness of the non-conductive layer and the third thickness of the conductive layer.

[0068] In this embodiment, the outer wall is composed of a thermal barrier coating segment and a metal substrate segment. The thermal barrier coating segment is composed of a ceramic layer and an adhesive layer. The adhesive layer is made of metal, and the ceramic layer is bonded to the metal substrate segment via the metallic adhesive layer. Because the ceramic layer is non-conductive, while the adhesive layer and the metal substrate segment are conductive, this embodiment proposes using laser processing for the non-conductive portion and electrodes for processing the conductive portion. To simplify the processing locations and facilitate understanding, the adhesive layer and the metal substrate layer are referred to as conductive layers in some descriptions herein, and the ceramic layer is referred to as the non-conductive layer. Laser processing on the non-conductive layer solves the problem of electrodes being unable to process the ceramic layer. Furthermore, by setting the depth of the laser processing on the non-conductive layer (i.e., the second depth of the laser-processed first film hole), the second thickness of the non-conductive layer is set to ≤ the second depth of the first film hole ≤ the sum of the second thickness of the non-conductive layer and the third thickness of the conductive layer. This ensures that the film holes in the non-conductive layer are laser-processed. When electrodes are used for processing, the electrodes only process the conductive layer. Since laser processing can easily cause delamination of thermal barrier coatings, namely delamination between the ceramic layer and the bonding layer, delamination between the bonding layer and the metal substrate layer, and the occurrence of taper problems, laser processing is only used to form the first air film hole in the ceramic layer to reduce the adverse effects of laser processing.

[0069] In some embodiments, a first air film hole is machined by ablating a non-conductive layer at high temperature with a laser until a conductive layer appears at the location of the laser beam spot and the aperture of the first air film hole is within a preset air film hole aperture range. At this point, the laser beam machining operation can be stopped. An electrode is inserted into the first air film hole. When the gap between the electrode and the conductive layer is within a preset discharge gap range, a current is passed through the electrode. The discharge of the electrode generates an electric spark with the conductive layer, and the electric spark ablates the conductive layer, thereby achieving electric spark machining drilling.

[0070] In some embodiments, 0.05 mm ≤ the preset discharge gap ≤ 0.03 mm.

[0071] In some embodiments, the thickness of the metal base layer segment is 1 to 2 mm, the thickness of the bonding layer is 0.015 to 0.06 mm, and the thickness of the ceramic layer is 0.03 to 0.15 mm.

[0072] According to one embodiment of the present invention, the method for processing the first air film hole in the non-conductive layer with a laser beam includes the following steps:

[0073] The laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular manner from the first axis to approach the first outer diameter of the preset air film hole until the movement trajectory of the laser beam coincides with the first outer diameter, and the laser beam processes the non-conductive layer to obtain the first air film hole;

[0074] Alternatively, the laser beam moves along the first outer diameter of the preset air film hole around the first central axis of the preset air film hole, and the laser beam moves in a circular manner from the first outer diameter to the first central axis until the laser beam is located at the first axis of the preset air film hole, and the laser beam processes the non-conductive layer to obtain the first air film hole;

[0075] Alternatively, the laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular motion from the first axis to approach the first outer diameter of the preset air film hole until the moving trajectory of the laser beam coincides with the second outer diameter of the preset air film hole. Thereafter, the laser beam revolves around the first central axis of the preset air film hole along the first outer diameter of the preset air film hole, and the laser beam moves in a circular motion from the first outer diameter to approach the first central axis until the moving trajectory of the laser beam coincides with the second outer diameter. The laser beam processes the first air film hole in the non-conductive layer, wherein the second outer diameter is less than the first outer diameter.

[0076] In this embodiment, three processing methods are provided for laser beam processing on the non-conductive layer. The first processing method is to use the laser beam to process the first air film hole in the non-conductive layer from the hole axis to the hole outer diameter by circular cutting.

[0077] The second processing method is to use a laser beam to process the first air film hole through a circular cutting method from the outer diameter of the hole to the axis of the hole. Since the temperature generated by the laser beam is accumulated in the processed hole during the process of processing the air film hole, the accumulated heat causes interface delamination on the hole wall. In order to reduce this effect, the heat is concentrated toward the axis of the hole by processing from the outer diameter of the hole to the axis of the hole, reducing the heat of the outer diameter of the hole, that is, reducing the heat accumulation of the hole wall. At the same time, the outer diameter of the hole is processed first to allow the heat flow to have a larger flow space, thereby reducing the problem of temperature affecting the interface delamination of the hole wall.

[0078] The third processing method combines the first and second processing methods. Specifically, a first film hole with a portion of the first aperture and a portion of the second depth is first machined from the hole axis to the second outer diameter of the hole. The entire first film hole is then machined from the first outer diameter to the second outer diameter. By first machining the first film hole with a portion of the first aperture and a portion of the second depth, the area to be machined for the subsequent machining of the entire first film hole from the first outer diameter to the second outer diameter is reduced, reducing the continuous heat generated by the laser beam on the hole wall, thereby reducing the problem of temperature-induced delamination at the hole-wall interface.

[0079] According to one embodiment of the present invention, the outer wall includes a thermal barrier coating segment and a metal substrate segment, the thermal barrier coating segment includes a ceramic layer and a bonding layer, the ceramic layer is a non-conductive layer, and the bonding layer and the metal substrate segment are conductive layers;

[0080] The method for processing the outer wall with a laser beam comprises the following steps:

[0081] Obtaining a first aperture of the preset air film hole;

[0082] The laser beam processes the non-conductive layer to form the first air film hole, the second aperture of the first air film hole is within the first aperture range, the first air film hole has a fourth depth, and the bottom of the first air film hole is at least partially located in the bonding layer;

[0083] The laser beam processes the first air film hole in the conductive layer to obtain a third aperture and a fifth depth of the second air film hole, wherein the third aperture is smaller than the second aperture, and the fifth depth is smaller than the third depth;

[0084] The electrode is processed on the conductive layer along the second air film hole having the third aperture and the fifth depth to obtain a fourth aperture and a sixth depth of the second air film hole, wherein the fourth aperture is greater than the third aperture, the sixth depth is greater than the fifth depth, or the sixth depth is less than the fifth depth;

[0085] According to the electrode penetrating the conductive layer, the fourth aperture being within the first aperture range, and the sum of the fourth depth, the fifth depth, and the sixth depth being consistent with the first depth, a target air film hole is obtained.

[0086] In this embodiment, the sixth depth is a depth obtained by additional processing on the basis of the fifth depth. The sum of the fifth depth and the sixth depth is equal to the third depth of the second air film hole. By ensuring that the bottom of the first air film hole is at least partially located in the bonding layer, the laser beam can complete the processing of all the air film holes located in the non-conductive layer, ensuring that the electrode only processes air film holes in the conductive layer to avoid invalid processing. In this embodiment, the fourth depth and the second depth can be understood as the same depth, that is, the fourth depth is the same as the second depth. In order to facilitate the distinction between processing in different situations, the fourth depth is used here to represent the third aperture and fifth depth of the second air film hole obtained by processing the first air film hole in the conductive layer with a laser beam, so that the laser beam first processes part of the second air film hole with the third aperture and the fifth depth, and then uses the electrode to continue to process the second air film hole with the fourth aperture and the sixth depth. This processing method, while ensuring that the laser beam reduces the impact of the laser beam on the stratification of the hole wall interface, not only improves the processing efficiency, but also allows the laser beam to process part of the second air film hole in the conductive layer to form a cooling water tank that can accommodate part of the cooling water generated during the electrode processing. The cooling water tank can be used to temporarily accommodate cooling water, and the heat generated by the cooling water to cool the electrode can be partially released in the cooling water tank to reduce the temperature of the cooling water, thereby reducing the damage to the thermal barrier coating surface caused by the heat of the cooling water when the cooling water is discharged from the air film hole inlet.

[0087] Preferably, the sixth depth is less than the fifth depth, so that the laser can process air film holes with greater depths in the conductive layer.

[0088] In some embodiments, 0 mm < the sixth depth ≤ 0.5 mm, thereby ensuring that more air film holes can be processed in the conductive layer by the laser beam, further improving work efficiency.

[0089] According to one embodiment of the present invention, the electrode having a third outer diameter is obtained according to the first aperture of the preset air film hole, and the electrode has a hollow cooling water channel;

[0090] Obtaining the third aperture of the second air film hole according to the second diameter of the cooling water channel in the electrode;

[0091] The second diameter is less than the third outer diameter and the third aperture is less than the first aperture.

[0092] In this embodiment, by obtaining the third aperture of the second air film hole according to the second diameter of the cooling water channel in the electrode, it is ensured that part of the heat of the ablated metal material can still be released in the cooling water tank, and the contamination of the surface of the ceramic layer by the ablated matrix material can also be avoided.

[0093] Preferably, the ratio of the third outer diameter to the first aperture is 1-1.2:1.5. By setting the ratio of the electrode diameter to the preset air film aperture, it is ensured that the electrode is smoothly processed toward the conductive layer.

[0094] According to one embodiment of the present invention, when the bottom of the first air film hole is close to the conductive layer, the first laser energy is reduced to the second laser energy.

[0095] In this embodiment, when the bottom of the first air film hole processed by the laser in the non-conductive layer is close to the conductive layer, the laser energy of the laser beam is reduced, further reducing the damage caused by the laser beam processing to the double-wall turbine blade drilling.

[0096] In some embodiments, when the aperture of the first air film hole processed by the laser beam is close to the aperture range of the preset air film hole, the laser energy of the laser beam is reduced, thereby further reducing the damage caused by the laser beam processing to the double-wall turbine blade processing and drilling.

[0097] According to one embodiment of the present invention, the electrode processing along the second air film hole on the outer wall includes at least three electrode processing stages;

[0098] The three electrode processing stages include an electrode initial processing stage, an electrode intermediate processing stage and an electrode perforation stage which are performed in sequence;

[0099] When in the initial processing stage of the electrode, the electrode has a first discharge gap;

[0100] When in the intermediate processing stage of the electrode, the electrode has a second discharge gap;

[0101] When in the electrode perforation stage, the electrode has a third discharge gap;

[0102] The first discharge gap is greater than the second discharge gap, the third discharge gap is greater than the second discharge gap, and the first discharge gap is greater than or equal to the third discharge gap.

[0103] In this embodiment, the primary electrode processing stage is the stage where the electrode begins processing the conductive layer. The intermediate electrode processing stage is the stage where the electrode processes the conductive layer but does not perforate it. The electrode perforation stage is the stage where the electrode penetrates the film hole. During the initial stage of the second film hole processing, the surfaces of the electrode and the workpiece are typically rough. A larger gap ensures that even if there are some bumps or unevenness on the surface, the electrode and the workpiece will not come into direct contact, thus avoiding electrode damage or short circuits. However, a large discharge gap results in non-concentrated energy distribution, and in the initial stage, the working fluid flow is weak, resulting in low cooling efficiency. This causes the molten material to not be promptly flushed away and accumulates on the workpiece surface, forming a thick remelted layer, resulting in reduced film hole quality and a film hole diameter that does not meet the requirements. Therefore, when using the electrode for the conductive layer at the beginning of processing, the discharge gap is larger than the discharge gap during the intermediate processing stage, making the conductive layer in the middle more conductive than the non-conductive layer. Through this three-stage electrode processing approach, the integrity of the film hole is guaranteed.

[0104] Preferably, the first discharge gap is larger than the third discharge gap.

[0105] In some embodiments, the primary electrode processing stage is the stage where the electrode is processed in the adhesive layer, the intermediate electrode processing stage is the stage where the electrode is processed in the metal base layer without perforating it, and the electrode perforation stage is the stage where the electrode is perforated through the air film. The discharge gap of the adhesive layer is larger than the discharge gap of the metal base layer, making the metal base layer more conductive than the adhesive layer.

[0106] In some embodiments, when machining a single metal substrate (i.e., machining a metal substrate layer using electrodes), the discharge gap relationship is: initial stage > perforation stage > intermediate stage. To prevent direct contact between the electrode and the workpiece surface due to unevenness, which could damage the electrode or cause a short circuit, the discharge gap is larger in the initial stage. During the perforation stage, the current density increases, concentrating the discharge energy and effectively penetrating the workpiece. During the intermediate stage, the discharge process is stable and efficient, with concentrated energy and uniform and continuous material removal, resulting in the smallest discharge gap.

[0107] In some embodiments, 0.05 mm≦the first discharge gap, the second discharge gap, and the third discharge gap≦0.3 mm.

[0108] According to one embodiment of the present invention, the preset distance between the outer wall and the inner wall of the turbine blade is: 0 mm < preset distance ≤ 0.8 mm.

[0109] In this embodiment, a preset distance range is provided between the outer wall and the inner wall of the turbine blade.

[0110] Preferably, 0.6 mm ≤ the preset spacing ≤ 0.8 mm.

[0111] According to one embodiment of the present invention, the first aperture of the preset air film hole is 0.3-3.0 mm, and the difference between the target film aperture of the target air film hole and the first aperture of the preset air film hole is ±0.05 mm.

[0112] In this embodiment, by setting a preset film pore diameter and a preset remelting layer thickness, the processing of the air film hole is facilitated while ensuring the quality of the target air film hole.

[0113] According to one embodiment of the present invention, the laser comprises an ultrafast laser, a short pulse laser, or a long pulse laser;

[0114] The ultrafast laser includes a picosecond laser or a femtosecond laser; the short pulse laser includes a nanosecond laser; and the long pulse laser includes a millisecond laser.

[0115] In this embodiment, some selectable laser examples are provided.

[0116] In some embodiments, the electrode is a tubular copper wire with a diameter of 1.4 mm, and the preset air film aperture is 1.5 mm.

[0117] In some embodiments, when the picosecond laser is used, the picosecond laser processing method is circular cutting and punching, the scanning path of the picosecond laser does not exceed 1.5 mm, and the interval between the concentric circles processed by the picosecond laser does not exceed 0.01 mm.

[0118] According to one embodiment of the present invention, the laser processing parameters during the picosecond laser processing include a single pulse energy of 30 to 50 μJ, a scanning speed of 250 to 450 mm / s, and a repetition frequency of 84 to 500 kHz.

[0119] In this embodiment, reasonable laser processing parameters are set to ensure the processing quality of the air film hole.

[0120] Preferably, the single pulse energy is 40 μJ, the scanning speed is 300 mm / s, and the repetition frequency is 500 kHz.

[0121] In some embodiments, the number of laser processing times is obtained according to the thickness of the ceramic layer. When the thickness of the ceramic layer is 0.03 to 0.15 mm, the number of processing times is 16 to 20 times. The number of processing times mainly affects the depth of the hole and has little effect on the entrance aperture. Therefore, the number of processing times usually depends on the thickness of the ceramic layer. The preferred number of processing times is 16 times.

[0122] According to one embodiment of the present invention, the electrode comprises tubular brass, and electrode processing parameters during brass processing include a peak current of 1 to 2.35 A and a pulse width of 5 to 12 μs.

[0123] In this embodiment, the processing quality of the air film hole is further guaranteed by setting reasonable electrode processing parameters.

[0124] Preferably, the peak current is 2.03-2.35 A, the pulse width is 5-6 μs, the pulse time is 25 μs, and the pulse peak voltage is 80 V, so that the thickness of the remelted layer generated by the electrode processing the inner wall is ≤0.03 mm.

[0125] More preferably, the peak current is 2.03 A and the pulse width is 5 μs.

[0126] Examples 1-4

[0127] 1.1 Equipment

[0128] Picosecond fiber laser, with an output wavelength of 1064nm, a Gaussian beam with a pulse width of 10-15ps, a repetition rate range of 1Hz-1000kHz, an average output power of 35W, and a maximum single pulse energy of 135μJ.

[0129] The EDM equipment has a voltage of 380V, an XY stroke of 500×400mm, and a tool electrode made of tubular brass. During machining, the workpiece is positive and the electrode is negative.

[0130] A nickel-based superalloy thermal barrier coating (TBC) was used to simulate a gas turbine blade. The test specimens were circular specimens approximately 30 mm in diameter. The metal substrate layer consisted of a nickel-based single-crystal superalloy IC10, approximately 1 to 2 mm thick. An 8YSZ ceramic layer, approximately 0.03 to 0.15 mm thick, was used. The metal bonding layer, a NiCrAlYSi alloy, was approximately 0.015 to 0.06 mm thick, and was deposited using electron beam physical vapor deposition (EB-PVD).

[0131] 1.2 Forming φ1.5mm air film holes on double-wall turbine blades

[0132] The non-conductive ceramic layer is etched away at room temperature and pressure using a picosecond laser. Circular cutting and punching are used as the processing method. The scanning path is set to a concentric circle with a maximum diameter of 1.5 mm and an interval of 0.01 mm to obtain the first air film hole. The diameter of the first air film hole in the embodiment has an error range of ±0.05 mm from φ1.5 mm, that is, the diameter range of the processed first air film hole is φ1.45-1.55 mm.

[0133] The electrode is inserted into the first air film hole to process the conductive layer to obtain the second air film hole. The processing method of filling the electrode with cold water during the electric spark machining process and the electric spark machining principle are existing technologies, so they will not be repeated in this article.

[0134] The picosecond laser processing parameters of Examples 1-4 are shown in Table 1 below. Each example is divided into three groups:

[0135] Table 1 Picosecond laser processing parameters of Examples 1-4

[0136]

[0137] The EDM parameters of Examples 1-4 are shown in Table 2 below:

[0138] Table 2 EDM parameters of Examples 1-4

[0139]

[0140] Example 1-4 The air film holes before and after electric sparking are as follows Figure 3 As shown, the initial state is the surface morphology of the ceramic layer after picosecond laser beam processing (i.e., the state before EDM), and the final state is the surface morphology of the ceramic layer after EDM perforation. Figure (a) shows the surface morphology of the ceramic layer after EDM perforation. Figure 3 Figure (b) shows the surface morphology of the hole before and after EDM at different single pulse energies. Figure (c) shows the surface morphology of the hole before and after EDM at different scanning speeds. Figure (d) shows the surface morphology of the hole before and after EDM at different repetition frequencies. After picosecond laser processing, no heat-affected zone (HAZ) or ablation was observed on the ceramic layer. The surface integrity of the ceramic layer after EDM in Examples 1c, 2c, and 3c was maintained, with pore diameters of 1.486 mm, 1.499 mm, and 1.488 mm, respectively, within the tolerance range of ±0.05 mm. The surfaces of the ceramic layers in Examples 1 (a, b), 2 (a, b), and 3 (a, b) showed some degree of damage to the surface integrity during EDM. Therefore, minimizing surface damage during EDM is crucial. Excessive or insufficient spark discharge energy will lead to thickening of the remelting layer and reduced machining accuracy. If the erosion products are not discharged in time and adhere to the surface, they will affect the surface morphology of the hole and the integrity of the hole mouth.

[0141] The thickness of the remelted layer on the wall of the air film holes obtained by processing in Examples 1-4 is shown in Table 3.

[0142] Table 3 Thickness of the remelted layer on the wall of the air film holes obtained by processing in Examples 1-4

[0143]

[0144] The thickness of the remelted layer is one of the important technical indicators for measuring the quality of film hole processing. If it does not meet the processing requirements, it is very easy to break and directly shorten the fatigue life of the material. As shown in Table 3, the maximum thickness of the remelted layer is 0.06mm and the minimum thickness is 0mm.

[0145] Examples 5-6

[0146] The difference between Example 5-6 and Example 1c lies in the different EDM parameters. The EDM parameters of Example 5-6 are shown in Table 4.

[0147] Table 4 EDM parameters of Examples 5-6

[0148]

[0149] Example 5: Gas turbine blades are formed with air film holes such as Figure 4 As shown in Figure 1, under a metallographic microscope, Figure (a) shows the surface morphology of the entrance hole of the film hole after EDM. The average entrance diameter of the eroded holes in the ceramic layer measured by the metallographic microscope is 1.483 mm. This figure shows that the eroded holes are minimally affected by EDM and maintain a complete hole shape. Figure (b) is a schematic diagram of the bonding layer on the hole wall under EDM conditions in Example 5. The ceramic layer machined by the picosecond laser beam exhibits no noticeable microcracks on the sidewalls, and no obvious erosion products adhere to the inner wall of the hole. No significant interface delamination is observed between the ceramic and bonding layers, indicating a high bond density. The coating exhibits no flaking or melt-etching. There are virtually no microcracks or significant delamination between the ceramic and bonding layers, or between the bonding layer and the metal substrate. Figures (c) and (d) show the remelted layer thickness of the initial section of the EDM metal substrate layer. The average remelted layer thickness is 0.026 mm on the left and 0.03 mm on the right, demonstrating that the film holes produced by this method have a low remelted layer thickness and good film hole quality.

[0150] Example 6 The gas turbine blade is formed with air film holes such as Figure 5 As shown, Figure (a) shows the surface morphology of the entrance hole of the air film hole after EDM. The average entrance diameter of the eroded holes in the ceramic layer measured by the metallographic microscope is 1.534 mm. After EDM, traces of ablation appear on the surface of the ceramic layer, likely representing accumulation of mixed oxidation products between the ceramic layer and the metal substrate. The peak current (2.35 A) and pulse width (6 μs) of Example 6 are both greater than those of Example 5 (peak current 2.03 A, pulse width 5 μs), indicating that the greater discharge energy produces ablation. Figure (b) shows a schematic diagram of the bonding layer on the hole wall under these experimental conditions. Microcracks are virtually absent on the ceramic layer surface, and no significant delamination is observed between the thermal barrier coating and the metal substrate. Figures (c) and (d) show the thickness of the remelted layer at the entrance of the EDM metal substrate. The average remelted layer thickness on the left is 0.02 mm, and on the right is 0.011 mm. The remelted layer is thin. Except for the slight flaws of ablation marks on the surface of the ceramic layer, Example 6 still has a good processing effect in terms of interface stratification and remelted layer.

[0151] By comparing the surface morphologies of the thermal barrier coatings obtained by processing in Examples 1-4, Example 5 and Example 6, it can be seen that inappropriate electric spark parameters result in excessive discharge energy, severe ablation damage, and the erosion products are not ejected in time, resulting in their eventual attachment to the hole surface, thereby affecting the hole surface morphology.

[0152] For the production of holes in metal substrates coated with ceramic coatings, this invention proposes a combined picosecond laser and electrospark machining method. The ceramic layer is first machined using a picosecond laser beam, and then the conductive layer is machined using electrospark after the metal bonding layer is exposed. The feasibility of combined picosecond laser and electrospark machining of metal-based ceramic coating materials is demonstrated by analyzing the surface morphology of the ceramic layer, a schematic diagram of the longitudinal section of the hole wall, and the thickness of the remelted layer on the metal substrate hole wall. This method addresses the problems of electrospark machining of film holes with thermal barrier coatings, the tendency of laser machining to damage the back wall, interface delamination, and taper, and provides data support and a theoretical basis for the subsequent composite machining of film holes in double-walled turbine blades. This method has important scientific significance and application value.

[0153] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present disclosure, and that in actual applications, various changes may be made thereto in form and detail without departing from the scope of the present disclosure.

Claims

1. A method for forming film holes in a double-wall turbine blade with a thermal barrier coating, characterized in that: The steps include: Obtaining a first distance between an outer wall and an inner wall of the turbine blade; According to the first distance being less than or equal to the preset distance between the outer wall and the inner wall of the turbine blade, the following steps are performed: Obtaining a second depth of the first air film hole obtained by machining the laser beam on the outer wall according to the first spacing, the first thickness of the outer wall, the first depth of the preset air film hole, and the first laser energy of the laser beam, wherein the second depth is less than the first depth; According to the first spacing, the first thickness, the first depth, and the second depth, a first stroke of the electrode is obtained when the electrode is processed along the first air film hole on the outer wall until the electrode punches the outer wall to form a second air film hole, wherein a second spacing is provided between the electrode and the inner wall, and 0<second spacing≤first spacing; A target air film hole is obtained according to the electrode punching a hole in the outer wall and the sum of the second depth and the third depth of the second air film hole being consistent with the first depth; The outer wall includes a thermal barrier coating section and a metal substrate section, the thermal barrier coating section includes a ceramic layer and a bonding layer, the ceramic layer is a non-conductive layer, and the bonding layer and the metal substrate section are conductive layers; The method for processing the outer wall with a laser beam comprises the following steps: Obtaining a first aperture of the preset air film hole; The laser beam processes the non-conductive layer to form the first air film hole, the second aperture of the first air film hole is within the first aperture range, the first air film hole has a fourth depth, and the bottom of the first air film hole is at least partially located in the bonding layer; The laser beam processes the first air film hole in the conductive layer to obtain a third aperture and a fifth depth of the second air film hole, wherein the third aperture is smaller than the second aperture, and the fifth depth is smaller than the third depth; The second air film hole obtained by machining the electrode along the laser beam is machined on the conductive layer to obtain a fourth aperture and a sixth depth of the second air film hole, wherein the fourth aperture is greater than the third aperture, the sixth depth is greater than the fifth depth, or the sixth depth is less than the fifth depth; According to the electrode being perforated in the conductive layer, the fourth aperture being within the first aperture range, and the sum of the fourth depth, the fifth depth, and the sixth depth being consistent with the first depth, a target air film hole is obtained; The electrode processing along the second air film hole on the outer wall includes at least three electrode processing stages; The three electrode processing stages include an electrode initial processing stage, an electrode intermediate processing stage and an electrode perforation stage which are performed in sequence; When in the initial processing stage of the electrode, the electrode has a first discharge gap; When in the intermediate processing stage of the electrode, the electrode has a second discharge gap; When in the electrode perforation stage, the electrode has a third discharge gap; The first discharge gap is greater than the second discharge gap, the third discharge gap is greater than the second discharge gap, and the first discharge gap is greater than or equal to the third discharge gap.

2. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: According to the first spacing, the first thickness of the outer wall, the second thickness of the non-conductive layer, the first depth of the preset air film hole and the first laser energy of the laser beam, the second depth of the first air film hole processed by the laser beam in the non-conductive layer is obtained, wherein the second depth is less than the first depth, and the second thickness of the non-conductive layer is ≤ the second depth of the first air film hole ≤ the sum of the second thickness of the non-conductive layer and the third thickness of the conductive layer.

3. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 2, characterized in that: The method for processing the first air film hole in the non-conductive layer with a laser beam comprises the following steps: The laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular manner from the first axis to approach the first outer diameter of the preset air film hole until the movement trajectory of the laser beam coincides with the first outer diameter, and the laser beam processes the non-conductive layer to obtain the first air film hole; Alternatively, the laser beam moves along the first outer diameter of the preset air film hole around the first central axis of the preset air film hole, and the laser beam moves in a circular manner from the first outer diameter to the first central axis until the laser beam is located at the first axis of the preset air film hole, and the laser beam processes the non-conductive layer to obtain the first air film hole; Alternatively, the laser beam revolves around the first central axis of the preset air film hole along the first axis of the preset air film hole, and the laser beam moves in a circular motion from the first axis to approach the first outer diameter of the preset air film hole until the moving trajectory of the laser beam coincides with the second outer diameter of the preset air film hole. Thereafter, the laser beam revolves around the first central axis of the preset air film hole along the first outer diameter of the preset air film hole, and the laser beam moves in a circular motion from the first outer diameter to approach the first central axis until the moving trajectory of the laser beam coincides with the second outer diameter. The laser beam processes the first air film hole in the non-conductive layer, wherein the second outer diameter is less than the first outer diameter.

4. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: Obtaining the electrode having a third outer diameter according to the first aperture of the preset air film hole, wherein the electrode has a hollow cooling water channel; Obtaining the third aperture of the second air film hole according to the second diameter of the cooling water channel in the electrode; The second diameter is less than the third outer diameter and the third aperture is less than the first aperture.

5. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: When the bottom of the first air film hole is close to the conductive layer, the first laser energy is reduced to the second laser energy.

6. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: The preset distance between the outer wall and the inner wall of the turbine blade is: 0≤preset distance≤0.8mm.

7. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: The first aperture of the preset air film hole is 0.3-3.0 mm, and the difference between the target film aperture of the target air film hole and the first aperture of the preset air film hole is ±0.05 mm.

8. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: The laser includes an ultrafast laser, a short pulse laser or a long pulse laser; The ultrafast laser includes a picosecond laser or a femtosecond laser; the short pulse laser includes a nanosecond laser; and the long pulse laser includes a millisecond laser.

9. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 8, characterized in that: The laser processing parameters during the picosecond laser processing include a single pulse energy of 30 to 50 μJ, a scanning speed of 250 to 450 mm / s, and a repetition frequency of 84 to 500 kHz.

10. The method for forming film holes in a double-wall turbine blade with a thermal barrier coating according to claim 1, characterized in that: The electrode comprises tubular brass, and electrode processing parameters during brass processing include a peak current of 1 to 2.35 A and a pulse width of 5 to 12 μs.

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