Method for preparing thermal barrier coating with high thermal shock resistance by femtosecond laser

Abstract

The application provides a method for preparing a thermal barrier coating with high thermal shock resistance by using femtosecond laser, and belongs to the technical field of thermal barrier coatings. The method specifically comprises the following steps: roughening a substrate surface, spraying a bonding layer on the roughened substrate surface, preparing an intermediate ceramic layer on the surface of the bonding layer, after completing each intermediate ceramic layer with a preset thickness, scanning and etching the surface of the intermediate ceramic layer by using femtosecond laser, and forming a micron-level structure with a preset topography on the surface of the intermediate ceramic layer; and preparing an outermost ceramic layer on the surface of the last intermediate ceramic layer. Through the processing scheme, the strain tolerance, crack stopping capacity and thermal shock resistance reliability of the thermal barrier coating are improved.

Description

Technical Field

[0001] This application relates to the field of thermal barrier coatings, and in particular to a method for preparing thermal barrier coatings with high thermal shock resistance using femtosecond laser. Background Technology

[0002] Thermal barrier coatings are a key thermal protection technology for hot-end components of aero-engines and gas turbines, effectively reducing the operating temperature of the base alloy and improving engine thermal efficiency and service reliability. Yttrium-stabilized zirconium oxide is a widely used ceramic coating material, often prepared in engineering using methods such as atmospheric plasma spraying or electron beam physical vapor deposition.

[0003] However, thermal barrier coatings prepared by traditional processes often contain randomly distributed pores and microcracks. Under severe thermal cycling loads, these defects can easily become the starting points for crack initiation and propagation. The cracks gradually expand, connect, and eventually lead to large-area peeling and failure of the coating, becoming one of the important factors limiting the life of thermal barrier coatings. Summary of the Invention

[0004] In view of this, this application provides a method for preparing thermal barrier coatings with high thermal shock resistance using femtosecond laser, which solves the problems in the prior art and improves the strain tolerance, crack arrest ability and thermal shock resistance reliability of thermal barrier coatings.

[0005] This application provides a method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser, which employs the following technical solution:

[0006] A method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser includes the following steps: The substrate surface is roughened. An adhesive layer is sprayed onto the roughened substrate surface; An intermediate ceramic layer is prepared on the surface of the adhesive layer. After each intermediate ceramic layer of a predetermined thickness is completed, a femtosecond laser is used to scan and etch the surface of the intermediate ceramic layer to form a micron-scale structure with a predetermined morphology on the surface of the intermediate ceramic layer. The outermost ceramic layer is prepared on the surface of the last intermediate ceramic layer.

[0007] Optionally, the method also includes: using a femtosecond laser to scan the surface of the outermost ceramic layer to obtain a densified protective layer of a preset thickness, wherein the thickness of the densified protective layer is 5-25 μm.

[0008] Optionally, when using a femtosecond laser to scan and etch the surface of each intermediate ceramic layer, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 10-25 μJ, the repetition frequency is 1-500 kHz, and the scanning speed is 50-200 mm / s.

[0009] Optionally, when using a femtosecond laser to scan the surface of the outermost ceramic layer, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 1-12 μJ, the repetition frequency is 80-150 kHz, the scanning speed is 50-80 mm / s, the spot overlap rate is greater than 90%, and the density of the densified protective layer is ≥97%.

[0010] Optionally, an intermediate ceramic layer can be prepared by applying ceramic layers one by one on the surface of the adhesive layer using a ceramic thermal spraying process. When applying the final layer of the intermediate ceramic layer, the femtosecond laser spot moves along the spraying path of the ceramic thermal spraying point at a preset interval behind the spraying point path.

[0011] Optionally, the micron-scale structure can be a stress-relieving structural layer and / or a thermal insulation buffer structural layer.

[0012] Optionally, the stress relief structure layer is a groove array, a pit array, or a crack network array.

[0013] Optionally, the heat insulation buffer structure layer is a connected folding channel.

[0014] Optionally, an adhesive layer is prepared on the substrate surface by atmospheric plasma spraying or supersonic flame spraying. The adhesive layer is MCrAlY alloy powder, where M is Ni, Co, or a combination of Ni and Co, and the particle size of the MCrAlY alloy powder is -140 / +325 mesh.

[0015] Optionally, the substrate surface is roughened by sandblasting, and the surface roughness Ra of the substrate surface after roughening is 3.2-12.5μm.

[0016] In summary, this application includes the following beneficial technical effects: This application introduces femtosecond laser interruption processing during the layer-by-layer growth of thermal barrier coatings and encapsulates micron-level structures inside, breaking through the limitation of the depth of action that can only modify the surface, and realizing the design and positioning of internal micron-level structures.

[0017] This application utilizes femtosecond lasers to process micron-scale structures. The ultrashort pulse characteristics of femtosecond lasers help reduce the risk of thermal impact and macroscopic cracks, and can be integrated and implemented in a modular manner in existing production lines. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 Flowchart of a method for preparing thermal barrier coatings with high thermal shock resistance for femtosecond lasers. Detailed Implementation

[0020] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0021] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0023] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0024] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0025] This application provides a method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser.

[0026] like Figure 1 As shown, a method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser includes the following steps: The substrate surface is roughened. An adhesive layer is sprayed onto the roughened substrate surface; An intermediate ceramic layer is prepared on the surface of the adhesive layer. After each intermediate ceramic layer of a predetermined thickness is completed, a femtosecond laser is used to scan and etch the surface of the intermediate ceramic layer to form a micron-scale structure with a predetermined morphology on the surface of the intermediate ceramic layer. The outermost ceramic layer is prepared on the surface of the last intermediate ceramic layer; A densified protective layer of a predetermined thickness of 5-25 μm is obtained by scanning the surface of the outermost ceramic layer using a femtosecond laser. The densified protective layer seals the micron-scale structure and reduces the penetration rate of calcium magnesium aluminum silicate / molten salt and oxygen diffusion rate.

[0027] In this application, the substrate is a nickel-based or cobalt-based high-temperature alloy. The substrate surface is roughened using a sandblasting process. The abrasive used in the sandblasting process is white or brown fused alumina with a particle size ranging from 0.2 to 0.6 mm. The sandblasting pressure is 0.4 to 0.7 MPa, and the sandblasting angle is 70 to 90°. After sandblasting, the substrate is ultrasonically cleaned with anhydrous ethanol or acetone to remove contaminants and then dried for later use. The surface roughness Ra of the roughened substrate surface is 3.2 to 12.5 μm. An adhesive layer is prepared on the substrate surface using atmospheric plasma spraying or supersonic flame spraying. The adhesive layer is MCrAlY alloy powder, where M is Ni, Co, or a combination of Ni and Co. The particle size of the MCrAlY alloy powder is -140 / +325 mesh, and the thickness of the adhesive layer ranges from 80 to 150 μm. Taking atmospheric plasma spraying as an example, the spraying process parameters are: main gas flow rate of 35-50 L / min (argon as the main gas); auxiliary gas flow rate of 8-15 L / min (hydrogen as the auxiliary gas); current of 500-650 A; voltage of 55-70 V; spraying distance of 100-150 mm; powder feed rate of 25-40 g / min; and spray gun movement speed of 300-600 mm / s. In one embodiment, the adhesive layer is NiCoCrAlY alloy powder with a thickness of 100 μm. The ceramic layer material is yttrium-stabilized zirconium oxide.

[0028] In this application, when using a femtosecond laser to perform scanning etching on the surface of each intermediate ceramic layer, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 10-25 μJ, the repetition frequency is 1-500 kHz, and the scanning speed is 50-200 mm / s.

[0029] In this application, when scanning the surface of the outermost ceramic layer using a femtosecond laser, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 1-12 μJ, the repetition frequency is 80-150 kHz, the scanning speed is 50-80 mm / s, the spot overlap rate is greater than 90%, and the density of the densified protective layer is ≥97%.

[0030] When preparing ceramic layers and micron-scale structures, after preparing an intermediate ceramic layer at the ceramic layer preparation station, the workpiece can be moved to the femtosecond laser processing station for micron-scale structure processing, and then the workpiece can be moved back to the ceramic layer preparation station.

[0031] In this application, a ceramic layer is prepared by sequentially spraying ceramic layers onto the surface of the adhesive layer using a ceramic thermal spraying process. During the final spraying of the intermediate ceramic layer, the femtosecond laser spot follows the spraying path of the ceramic thermal spraying at a predetermined interval. This application enables the preparation of the ceramic layer and the fabrication of micron-level structures without moving the substrate, achieving in-situ preparation of a thermal barrier coating on the substrate.

[0032] The micron-scale structure is a stress-relieving structural layer and / or a thermal insulation buffer structural layer. In this application, the number of intermediate ceramic layers can be 1-3, and the surface of each intermediate ceramic layer is processed with a micron-scale structure. The type of micron-scale structure of different intermediate ceramic layers can be selected and processed according to requirements. The thickness of the ceramic layer on top of the micron-scale structure is at least 1.5 times the depth of the micron-scale structure.

[0033] The stress relief structure layer is a groove array, a pit array, or a crack network array.

[0034] The trench array can consist of parallel trenches, with trenches on the same straight line being either continuous or segmented. Segmented trenches have a length of 100-800 μm and a spacing of 20-200 μm. Alternatively, it can consist of two intersecting sets of trenches, each set of trenches being parallel to each other. The trench width is 10-40 μm, the trench depth is 10-50 μm, and the spacing between adjacent trenches is 50-150 μm. The trench array disperses thermal mismatch stress and induces crack deflection / passivation through microscale opening and closing and deformation energy absorption.

[0035] The pits in the pit array have a diameter of 10-50 μm, a depth of 5-30 μm, and a spacing of 30-100 μm. The spacing can be uniform or gradually decrease along the plane from one side to the other. The pit array discretizes the continuous stress field into controllable elements and reduces local stress concentration.

[0036] The crack network array has a crack spacing of 20-150 μm and a crack depth of 10-80 μm. During thermal cycling, the crack network array preferentially releases energy through the opening and closing of microcracks, thereby improving strain tolerance and suppressing the formation of macroscopic through-cracks.

[0037] The thermal insulation buffer structure layer consists of interconnected folded channels in a labyrinthine pattern. The width of each folded channel is 5-30 μm, and the spacing between them is 50-200 μm. These interconnected channels provide an internal thermal barrier and pressure relief space, while also increasing the length and resistance of the medium's penetration path, reducing the penetration rate, and mitigating the possibility of direct crack propagation.

[0038] The thickness of a single intermediate ceramic layer can range from 50 to 450 μm. The total thickness of the ceramic layers ranges from 300 to 600 μm.

[0039] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser, characterized in that, Includes the following steps: The substrate surface is roughened. An adhesive layer is sprayed onto the roughened substrate surface; An intermediate ceramic layer is prepared on the surface of the adhesive layer. After each intermediate ceramic layer of a predetermined thickness is completed, a femtosecond laser is used to scan and etch the surface of the intermediate ceramic layer to form a micron-scale structure with a predetermined morphology on the surface of the intermediate ceramic layer. The outermost ceramic layer is prepared on the surface of the last intermediate ceramic layer.

2. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, The method also includes: using a femtosecond laser to scan the surface of the outermost ceramic layer to obtain a densified protective layer of a preset thickness, the thickness of which is 5-25 μm.

3. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, When using a femtosecond laser to scan and etch the surface of each intermediate ceramic layer, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 10-25 μJ, the repetition frequency is 1-500 kHz, and the scanning speed is 50-200 mm / s.

4. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 2, characterized in that, When scanning the surface of the outermost ceramic layer using a femtosecond laser, the pulse width of the femtosecond laser is less than 1 ps, the center wavelength is 1030 nm, the single pulse energy is 1-12 μJ, the repetition frequency is 80-150 kHz, the scanning speed is 50-80 mm / s, the spot overlap rate is greater than 90%, and the density of the densified protective layer is ≥97%.

5. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, An intermediate ceramic layer is prepared by spraying ceramic layers one by one onto the surface of the adhesive layer using a ceramic thermal spraying process. When applying the final layer of the intermediate ceramic layer, the femtosecond laser spot moves along the spraying path of the ceramic thermal spraying point at a preset interval behind the spraying point path.

6. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, The micron-scale structure is a stress-relieving structural layer and / or a thermal insulation buffer structural layer.

7. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 6, characterized in that, The stress relief structure layer is a groove array, a pit array, or a crack network array.

8. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 6, characterized in that, The heat insulation and buffer structure layer is a connected folding channel.

9. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, An adhesive layer is prepared on the substrate surface by atmospheric plasma spraying or supersonic flame spraying. The adhesive layer is MCrAlY alloy powder, where M is Ni, Co, or a combination of Ni and Co, and the particle size of the MCrAlY alloy powder is -140 / +325 mesh.

10. The method for preparing a thermal barrier coating with high thermal shock resistance using femtosecond laser according to claim 1, characterized in that, The substrate surface is roughened by sandblasting, and the surface roughness Ra of the substrate surface after roughening is 3.2-12.5μm.

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