Method for preparing a double-walled porous flame tube coating based on a volatile masking glue

Abstract

The preparation method of the volatile shielding glue-based double-wall porous flame tube coating of the present application comprises filling configured acrylic shielding glue into all air film holes, curing the acrylic shielding glue by means of ultraviolet lamp irradiation to form a shielding glue layer, depositing a thermal barrier coating system of an MCrAlY system metal bonding layer, a YSZ ceramic intermediate layer and a multi-rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer on the outer side of the flame tube, adjusting the parameters of the plasma spray gun of the spraying equipment after spraying is completed, and realizing in-situ self-cleaning by using the self-generated energy of the plasma spray gun, so that only the shielding glue can be melted without damaging the thermal barrier coating on the outer side of the flame tube, and the overall processing efficiency of the flame tube coating is improved.

Description

Technical Field

[0001] This invention belongs to the technical field of flame tube coating processing, and particularly relates to a method for preparing a double-walled porous flame tube coating based on a volatile masking adhesive. Background Technology

[0002] With the continuous rise in turbine inlet temperature of aero-engines, the combustion chamber flame tube faces severe thermal loads, making double-walled film cooling structures combined with thermal barrier coatings the mainstream technical solution. This solution achieves both heat insulation and cooling functions by machining tens of thousands of micro-film pores on the inner and outer walls and preparing a ceramic thermal barrier coating on the hot side. However, during the preparation of the thermal barrier coating, the film pores are easily blocked by the sprayed material, becoming a core process bottleneck in the industry. Existing pore-blocking technologies have significant drawbacks.

[0003] Mechanical embedding methods use rubber plugs or rigid needle plates to block holes. For micropores with a diameter of less than 0.5 mm and irregular cross-section gas film holes, insertion and removal are difficult and the edges of the hole walls are easily damaged. They are also prone to falling off and failing under the scouring of high-speed flame. Traditional filler methods use paraffin wax and water-soluble polymers. Paraffin wax has a low melting point and is easily melted and lost under the high temperature of supersonic flame or plasma spraying. Water-soluble materials cannot be dissolved and removed in a vacuum / low-pressure plasma spraying environment, and vacuum volatilization will also contaminate the furnace cavity.

[0004] In summary, the traditional method of sealing air film pores and applying a coating is inefficient. Summary of the Invention

[0005] In view of this, the method for preparing a double-walled porous flame tube coating based on volatile masking adhesive of the present invention solves the problem of low efficiency of traditional methods for coating by sealing gas film pores.

[0006] A method for preparing a double-walled porous flame tube coating based on a volatile masking adhesive, wherein the gas film pores in each layer of the flame tube are staggered, the method comprising, S1: Fill all the air film holes with the prepared acrylic masking adhesive and form a protective cap on the surface of the flame tube. The adhesiveness of the acrylic masking adhesive is adjusted automatically to ensure that it will not fall off from the air film holes. S2: Acrylic masking adhesive is cured by ultraviolet light irradiation to form a masking adhesive layer; S3: An MCrAlY-based metal bonding layer is deposited on the outer side of the flame tube. A YSZ ceramic intermediate layer and a multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are deposited sequentially on the bonding layer. The melting points of the bonding layer, the YSZ ceramic intermediate layer and the multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are all higher than those of the masking adhesive layer. S4: Adjust the parameters of the plasma spray gun in the spraying equipment so that it can only melt the masking adhesive layer. The inner side of the flame tube is axially ventilated, and the robot equipped with the spraying equipment drives the plasma spray gun to heat the outer side of the flame tube. The melted masking adhesive layer is discharged under the drive of the wind speed. Core: Utilizing the difference in physical parameters between each layer to remove the masking adhesive in the air film pores.

[0007] Preferably, S1 includes, The acrylic masking adhesive is injected in batches using a syringe device to ensure that the pores are filled tightly without any air bubbles. The acrylic masking adhesive is slightly higher than the opening of the air film pore to form a protective cap. Conventional intra-pore injection in the field does not form a protective cap and is always injected into the pore without overflowing. The protective cap can prevent the acrylic masking adhesive from being burned off prematurely, thereby effectively protecting the pore edges. This is an innovative coating concept. Use a lint-free cloth to wipe the non-air film pore areas to remove excess acrylic masking adhesive.

[0008] Preferably, S2 includes, Use a UV lamp to irradiate the masking area for 2-3 minutes at a distance of 50-150 mm.

[0009] Preferably, S3 includes, After the adhesive layer has cured, the surface of the flame tube is sandblasted to ensure that the sprayed area on the surface of the flame tube is roughened, and the residual masking adhesive is cleaned. The flame tube is mounted on the platform of the spraying equipment, which employs supersonic flame spraying or low-pressure plasma spraying processes. An MCrAlY-based metal bonding layer, with a thickness controlled between 0.1-0.15 mm, is deposited on the entire outer wall of the flame tube. This layer connects the substrate and the functional coating, providing a rough surface to increase the adhesion strength of the functional coating, alleviate thermal stress, and, at high temperatures, preferentially oxidizes Al to form a dense TGO protective film, achieving anti-oxidation and extending coating life. When low-pressure plasma spraying is used, the temperature of the flame tube surface is 250-300℃ and the vacuum degree is 150Pa. When supersonic flame is used to spray the flame tube surface, the temperature is 100-200℃. The intermediate layer mainly provides heat insulation and also makes the bottom layer and top layer transition and match. The top layer improves the coating's operating temperature and heat insulation performance, inhibits sintering and resists high-temperature corrosion. An atmospheric plasma spraying process was used to sequentially deposit a YSZ ceramic intermediate layer and a multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer on the adhesive layer, with a thickness of 0.1-0.15 mm for each layer, and the temperature was controlled at 100-200℃.

[0010] Preferably, step S4 includes adjusting the working parameters of the plasma spray gun to a high-power, non-powder-feeding flame cleaning mode, setting the robot's motion trajectory to ensure that the high-temperature plasma flame uniformly scans the outer surface of the double-walled porous flame tube. When the flame jet from the plasma spray gun raises the surface temperature of the flame tube to 350-500℃, the resin base in the masking adhesive rapidly undergoes pyrolysis and vaporization. At the same time, the inert filler particles in the masking adhesive collapse or are carried away by the airflow under thermal stress and airflow scouring, thereby achieving residue-free self-cleaning of the air film pores.

[0011] Preferably, S5 also includes using high-pressure compressed air to clean the inner and outer walls of the flame tube, and to check the air film holes and inner cavity for blockages or excess residue.

[0012] The beneficial effects of the present invention are as follows: By using liquid / paste-like colloid fillers, physical scratches and stress concentrations on the inner walls of micropores and irregularly shaped holes are avoided by mechanical pore blocking, achieving zero damage to the substrate. The acrylic-based masking adhesive can be adjusted in composition as needed, adapting to various thermal traces of processes such as supersonic flame spraying, low-pressure plasma spraying, and atmospheric plasma spraying, with strong adaptability. After the process is formed, the plasma spray gun uses its self-generated energy for in-situ self-cleaning, eliminating manual and chemical dissolution steps, resulting in high efficiency, no chemical waste, and environmental protection at low cost. This concept of non-destructive protection and cleaning of air film holes has a high degree of automation, good process repeatability, and is suitable for mass production, significantly improving the yield rate and service reliability of parts. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 is a schematic diagram of the removal of masking adhesive by plasma flame scanning according to the present invention; Figure 2 is a schematic diagram showing that the masking adhesive of the present invention is stably present in the air film pores after spraying. Figure 3 is a schematic diagram of the masking adhesive filling method of the present invention. Detailed Implementation

[0015] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0016] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure 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 disclosure. 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 disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0017] 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 disclosure, 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 other structures and / or functionalities besides one or more of the aspects set forth herein.

[0018] like Figures 1 to 3 The method shown enables efficient and non-destructive masking of air film pores, with no residue of masking material to be removed after coating deposition, thus improving coating yield and component reliability. This invention uses an acrylate-based volatile masking adhesive with staged thermal response characteristics: it remains stable in a solid state at low to medium temperature coating preparation temperatures, blocking coating particles; and it rapidly pyrolyzes and vaporizes during high-temperature cleaning processes, achieving self-cleaning. The method includes the following steps: Volatile masking adhesive filling: Fill all air film pores with the prepared acrylic masking adhesive. The adhesive will self-fix and not fall off due to its adhesiveness. The adhesive will be slightly higher than the pore opening to form a protective cap to prevent premature ablation. Wipe away excess adhesive in non-air film pore areas with a lint-free cloth. Masking adhesive curing: Use a UV lamp to irradiate the masking adhesive area at a distance of 50-150mm for 2-3 minutes to complete the curing of the masking adhesive layer. Preparation of multilayer thermal barrier coating: After curing, the surface of the flame tube is roughened by sandblasting and the residual masking adhesive is cleaned; MCrAlY-based metal bonding layer is deposited by supersonic flame spraying or low-pressure plasma spraying, and then YSZ ceramic intermediate layer and multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are deposited sequentially by atmospheric plasma spraying. The melting point of each coating is higher than that of the masking adhesive layer. High-temperature evaporation removal of masking adhesive: The plasma spray gun is switched to a high-power, non-powder flame cleaning mode. The robot drives the spray gun to evenly scan the outer surface of the flame tube. The surface of the workpiece is heated to 350-500℃. The masking adhesive resin base is pyrolyzed and vaporized. The inert filler falls off under thermal stress and airflow scouring. With the axial ventilation on the inner side of the flame tube, the removed material is discharged. Post-processing and inspection: The parts are cleaned a second time with high-pressure compressed air, and the air film holes and inner cavities are inspected to confirm that there are no blockages or foreign matter residues.

[0019] Example 1 The engineering component is a nickel-based high-temperature alloy double-walled porous flame tube, measuring Φ800mm×500mm, with a film gas vent diameter of Φ0.5mm. A thermal barrier coating is prepared on the outer wall. Specific steps are as follows: Pretreatment: Clean the parts with acetone, dry them and set them aside. Prepare the acrylic masking adhesive. Masking adhesive filling: Masking adhesive is injected in batches into all air film pores using a syringe device, filling them densely without air bubbles. The adhesive slightly protrudes from the pore opening to form a protective cap. Excess adhesive in non-pore areas is wiped away with a lintless cloth. UV curing: The UV lamp is placed 100mm away from the masking adhesive area and irradiated for 2.5 minutes until the adhesive is completely cured; Surface sandblasting: Sandblast with 60-mesh brown corundum sand until the surface roughness Ra2.5-3.0μm, and remove residual sand particles with compressed air; Coating spraying, among which, Low-pressure plasma spraying: The part is clamped onto the vacuum chamber turntable, the vacuum degree is 150Pa, and the NiCoCrAlY adhesive layer is sprayed. The surface temperature of the part is 250-300℃ and the coating thickness is 0.12mm. Atmospheric plasma spraying: YSZ ceramic intermediate layer and multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are sequentially sprayed on the adhesive layer, with the temperature controlled at 180-200℃ and the thickness of each layer being 0.12mm; Masking adhesive removal: The plasma spray gun is switched to high-power powderless flame mode, the robot trajectory scans the outer wall of the flame tube, the surface temperature rises to 400-450℃, the masking adhesive is pyrolyzed and vaporized, and axial ventilation assists in the discharge of the removed material. Post-processing inspection: The parts are thoroughly cleaned with high-pressure compressed air, and the air film holes are checked for blockages and the internal cavity is free of foreign matter. The parts are qualified.

[0020] Example 2 The adhesive layer was prepared by supersonic flame spraying, and the remaining parameters were the same as in Example 1: The masking adhesive filling, curing, and sandblasting steps are the same as in Example 1; Supersonic flame spraying of NiCoCrAlY adhesive layer, with a part surface temperature of 150-180℃ and a thickness of 0.1mm; Atmospheric plasma spraying of ceramic layer, temperature 100-150℃, thickness of intermediate layer and top layer both 0.1mm; The plasma jet cleaning temperature is controlled at 350-400℃, the masking adhesive is completely removed, and subsequent inspections are passed.

[0021] In summary, this method solves the problem of clogging in the film coating of double-walled flame tubes by utilizing the staged thermal response characteristics of volatile masking adhesive. The process is simple, low-cost, and suitable for mass production, meeting the manufacturing requirements of hot-end components for aero-engines.

[0022] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for preparing a double-walled porous flame tube coating based on a volatile masking adhesive, wherein the gas film pores in each layer of the flame tube are staggered, characterized in that, Its methods include, S1: Fill all the air film pores with the prepared acrylic masking adhesive and form a protective cap on the surface of the flame tube; S2: Acrylic masking adhesive is cured by ultraviolet light irradiation to form a masking adhesive layer; S3: An MCrAlY-based metal bonding layer is deposited on the outer side of the flame tube. A YSZ ceramic intermediate layer and a multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are deposited sequentially on the bonding layer. The melting points of the bonding layer, the YSZ ceramic intermediate layer and the multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer are all higher than those of the masking adhesive layer. S4: Adjust the parameters of the plasma spray gun in the spraying equipment so that it can only melt the masking adhesive layer. The inner side of the flame tube is axially ventilated, and the robot equipped with the spraying equipment drives the plasma spray gun to heat the outer side of the flame tube. The melted masking adhesive layer is discharged under the drive of the wind speed.

2. The method for preparing a double-walled porous flame tube coating according to claim 1, characterized in that, S1 includes, The acrylic masking adhesive is injected in batches using a syringe device, and the acrylic masking adhesive is slightly higher than the opening of the air film pore to form a protective cap; Use a lint-free cloth to wipe the non-air film pore areas to remove excess acrylic masking adhesive.

3. The method for preparing a double-walled porous flame tube coating according to claim 1, characterized in that, S2 includes, Use a UV lamp to irradiate the masking area for 2-3 minutes at a distance of 50-150 mm.

4. The method for preparing a double-walled porous flame tube coating according to claim 1, characterized in that, S3 includes, After the adhesive layer has cured, the surface of the flame tube is sandblasted to ensure that the sprayed area on the surface of the flame tube is roughened, and the residual masking adhesive is cleaned. The flame tube is installed on the platform of the spraying equipment. The spraying equipment adopts the process of supersonic flame spraying or low-pressure plasma spraying to deposit an MCrAlY-based metal bonding layer on the entire outer wall of the flame tube. The thickness is controlled between 0.1-0.15mm. During low-pressure plasma spraying, the surface temperature of the flame tube is 250-300℃ and the vacuum degree is 150Pa. During supersonic flame spraying, the surface temperature of the flame tube is 100-200℃. An atmospheric plasma spraying process was used to sequentially deposit a YSZ ceramic intermediate layer and a multi-element rare earth co-doped Gd' / Yb / Y-ZrO2 surface layer on the adhesive layer, with a thickness of 0.1-0.15 mm for each layer, and the temperature was controlled at 100-200℃.

5. The method for preparing a double-walled porous flame tube coating according to claim 1, characterized in that, S4 includes, The plasma spray gun's operating parameters were adjusted to a high-power, powder-free flame cleaning mode. The robot's motion trajectory was set to ensure the high-temperature plasma flame uniformly scans the outer surface of the double-walled porous flame tube. When the flame jet from the plasma spray gun raises the surface temperature of the flame tube to 350-500℃, the resin base in the masking adhesive rapidly undergoes pyrolysis and vaporization. At the same time, the inert filler particles in the masking adhesive collapse or are carried away by the airflow under thermal stress and airflow scouring, thereby achieving residue-free self-cleaning of the air film pores.

6. The method for preparing a double-walled porous flame tube coating according to claim 1, characterized in that, S5 also includes using high-pressure compressed air to clean the inner and outer walls of the flame tube, and to check the air film holes and inner cavity for blockages or excess residue.

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