Preparation method and application of shielding adhesive tape for high-temperature diffusion coating of aero-engine blade

Abstract

The invention discloses a preparation method and application of a high-temperature anti-oxidation shielding adhesive tape for an aero-engine blade coating process, and belongs to the technical field of aero-engine manufacturing. According to the method, INCONEL series or K series high-temperature alloy powder is used as an antioxidant functional filler, epoxy resin / acrylic resin is used as a binder, dibutyl phthalate / ethyl acetate is used as a flexibilizer, fumed silica is used as a thixotropic agent, and the functional filler and the organic binder are compounded through a mechanical stirring and rolling method; the shielding adhesive tape with high-temperature oxidation resistance is prepared. The adhesive tape shows excellent flexibility, self-adhesion and storage stability of more than 12 months at room temperature, can effectively block oxygen diffusion in a high-temperature environment, and realizes precise protection of local areas. During application, the protective film can be directly adhered to a to-be-protected area (such as a tenon and a blade tip) of a turbine blade, can be tightly attached to complex tenon tooth structures such as a fir-tree-shaped structure and a swallow-tail-shaped structure, realizes selective shielding in the vapor deposition or heat treatment process, avoids excessive deposition of a coating, is free of residues after treatment and does not affect the surface state of a base body. The method effectively solves the problem of local protection of complex components such as blade tenons of aero-engines in the coating process, and is suitable for the field of manufacturing and maintenance of aero-engine hot end components.

Description

Technical Field

[0001] This invention belongs to the field of surface treatment technology for aero-engine components, specifically relating to a method for preparing a masking adhesive tape for a high-temperature diffusion coating on aero-engine blades and its application. Background Technology

[0002] Aero-engine blades are core power components. To improve their high-temperature resistance, corrosion resistance, and wear resistance, high-temperature protective coatings (such as MCrAlY coatings and ceramic thermal barrier coatings) must be sprayed onto the blade airflow surfaces (blade basin and blade back). These coatings effectively isolate the turbine blade material from direct contact with the high-temperature combustion gases, reducing oxidation, corrosion, and thermal stress, thereby protecting the turbine blades from damage caused by the high-temperature environment. The blade tenon, as a key structure connecting the blade to the turbine disk (commonly fir-tree or dovetail types), requires a surface with precise fit (clearance typically at the micrometer level) and cleanliness. If the coating covers the blade tenon, it can lead to interference fit, uneven stress transmission, and even serious failures such as blade vibration and breakage. Therefore, the blade tenon must be strictly masked during the coating process. Currently, commonly used masking methods include: 1. Mechanical fixture shielding: High precision but high cost, long manufacturing cycle, and difficult to shield complex surfaces. 2. Manual application of masking paint: The process is cumbersome, the coating thickness is uneven, the edges are not clearly defined, and it is difficult to completely remove after high-temperature treatment, which can easily introduce impurities. 3. Ordinary high temperature resistant tapes: Existing commercial products either have insufficient temperature resistance (usually below 300℃), which will carbonize at high temperatures and leave residues that are difficult to remove; or they have poor flexibility and cannot adhere tightly to complex curved surfaces, resulting in "plating creep". Therefore, developing a special masking adhesive tape that can withstand high-temperature diffusion process environments, match the precision of blade tenons and other precision structures, is easy to peel off, and leaves no residue after high-temperature treatment is of great significance for improving the coating quality and production efficiency of aero-engine blades. To address the aforementioned technical bottlenecks, this invention discloses a novel high-temperature shielding material and its supporting process. This material possesses excellent high-temperature resistance (up to 1000 ℃ or higher), good flexibility and fit, enabling precise matching of the complex profile of the blade tenon area. It remains stable during high-temperature coating treatment, is easy to peel off after treatment without residue, thus ensuring the cleanliness and assembly precision of the blade tenon area, further improving the reliability and service life of aero-engines. Summary of the Invention In view of this, the purpose of this invention is to provide a high-temperature anti-oxidation masking tape for the coating process of turbine blades of aero-engines, its preparation method and application. The masking tape provided by this invention has advantages such as good flexibility, long storage period and easy removal after processing. To achieve the above objectives, the present invention provides a flexible, high-temperature resistant, and antioxidant masking tape, the masking tape being composed of two main parts: functional fillers and organic components. The functional filler is a high-temperature alloy powder from the INCONEL series and K series, specifically at least one of INCONEL 718, INCONEL 625, INCONEL 738LC, INCONEL 939, K438, K4169, K424, K640, K417, and K418. The powder has a spherical particle morphology and a particle size (D50) ranging from 10 to 100 μm. Preferably, the functional filler is at least one of INCONEL 718, K438, and K424. Preferably, the particle size (D50) of the functional filler is in the range of 30-60 μm. The organic component is composed of the following components: 70-90% adhesive, 6-10% curing agent, 2-10% toughening agent, and 2-10% thixotropic agent. The adhesive is an epoxy resin and an acrylic resin, specifically at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, butyl acrylate, and carboxylated acrylic resin. Preferably, the adhesive is at least one of bisphenol A type epoxy resin and carboxylated acrylic resin. The curing agent is an amine curing agent, specifically at least one of aliphatic amines, polyamides, or aromatic amines. Preferably, the curing agent is a fatty amine, specifically at least one of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA). The toughening agent is at least one of dibutyl phthalate or ethyl acetate. The thixotropic agent is fumed silica. This invention also provides the application of the aforementioned masking adhesive tape in the preparation process of high-temperature diffusion coatings (such as aluminized coatings) for aero-engine blades, mainly used to mask areas such as blade tenons. The application process includes surface cleaning, applying the adhesive tape, performing a high-temperature diffusion process, and peeling off and cleaning after cooling. The beneficial effects of this invention are: 1. Excellent high-temperature resistance: Based on epoxy resin or acrylic resin system, combined with metal functional filler, the adhesive tape can withstand high-temperature environments above 1000℃ for a long time without decomposition or carbonization, meeting the requirements of diffusion coating process. 2. Excellent adhesion and shielding effect: The substrate is flexible, and the initial tack of the adhesive layer is moderate, which can perfectly adhere to the complex curved surface of the leaf tenon, forming an effective seal, preventing the intrusion of the seepage agent vapor, and eliminating "climbing plating". 3. Clean peelability: After high-temperature treatment, the adhesive system is transformed into an inorganic-organic hybrid structure, still maintaining good toughness, and can be easily and completely peeled off from the metal substrate with almost no residue, eliminating the need for complex cleaning procedures. 4. Simple process and controllable cost: The preparation method is mature, easy to achieve large-scale production, and the overall cost is far lower than that of mechanical clamps. Attached image description: Figure 1 This is a schematic diagram of the high-temperature shielding adhesive tape described in this invention. Figure 2 This is a photograph of the high-temperature shielding adhesive tape described in this invention. Figure 2 a and b are the masking adhesive tapes that were just prepared. Figure 2 c and d are masking tapes stored for 12 months. Figure 3 This is a schematic diagram of the high-temperature shielding adhesive tape described in this invention applied to shielding the tenon of a turbine blade. Figure 4 The image shows the fluorescence detection results of the turbine blade tenon without the high-temperature shielding adhesive tape protection described in this invention. Figure 5 The image shows the fluorescence detection results of the turbine blade tenon protected by the high-temperature shielding adhesive tape described in this invention. Detailed Implementation Example 1 First, a mixed solvent of ethanol and water was prepared at a volume ratio of 90:10. Next, the calculated amount of KH-550 was slowly added to the ethanol-water mixture, and the pH was adjusted to 4-5 with acetic acid; this solution is denoted as Solution A. At 80°C, 1 kg of K438 (D50 of 40 μm) was added to Solution A, and the mixture was mechanically stirred for 2 hours. After filtration and washing, the resulting solid was dried at 100-120°C for 24 hours to completely solidify the coupling agent and evaporate any residual solvent, yielding modified K438, denoted as g-K438. Then, 100 g of g-K438 and 92.5 g of bisphenol A epoxy resin (E51) were thoroughly mixed under mechanical stirring. After mixing, a certain amount of triethylenetetramine, dibutyl phthalate, and fumed silica were added, and the mixture was reacted at room temperature for 4 hours. Subsequently, a flexible adhesive tape was produced using a rolling device with a 2 mm gap between the rollers. Next, apply pressure-sensitive adhesive to the surface of the adhesive tape and attach release paper. Finally, cut it to specific specifications as required. The sample structure diagram and actual product image are shown below. Figure 1 , 2 As shown. Figure 1 In the middle section, ① and ⑤ are release paper, ② and ④ are pressure-sensitive adhesive layers, and ③ is a composite material layer composed of functional fillers and organic binders. Example 2 First, a mixed solvent of ethanol and water was prepared at a volume ratio of 90:10. Next, the calculated amount of KH-560 was slowly added to the ethanol-water mixture, and the pH was adjusted to 4-5 with acetic acid; this solution is denoted as Solution A. At 80°C, 1 kg of INCONEL 718 (D50 of 56 μm) was added to Solution A, and the mixture was mechanically stirred for 2 hours. After filtration and washing, the resulting solid was dried at 100-120°C for 24 hours to completely solidify the coupling agent and evaporate any residual solvent, yielding the modified K438, denoted as g-INCONEL 718. Then, 100 g of g-INCONEL 718 and 92.5 g of bisphenol A epoxy resin (E51) were thoroughly mixed under mechanical stirring. After mixing, a certain amount of tetraethylenepentamine, ethyl acetate, and fumed silica were added, and the mixture was reacted at 60°C for 4 hours. Subsequently, a flexible adhesive tape was prepared using a rolling device with a 2 mm gap between the rollers. Then, apply pressure-sensitive adhesive to the surface of the adhesive tape and attach release paper. Example 3 First, a mixed solvent of ethanol and water was prepared at a volume ratio of 90:10. Next, the calculated amount of KH-550 was slowly added to the ethanol-water mixture, and the pH was adjusted to 4-5 with acetic acid; this solution is denoted as Solution A. At 80°C, 1 kg of K438 (D50 of 40 μm) was added to Solution A, and the mixture was mechanically stirred for 2 hours. After filtration and washing, the resulting solid was dried at 100-120°C for 2-4 hours to completely solidify the coupling agent and evaporate any residual solvent, yielding modified K438, denoted as g-K438. Then, 100 g of g-K438 and 92.5 g of carboxyacrylate resin were thoroughly mixed under mechanical stirring. Afterward, a certain amount of diethylenetriamine, ethyl acetate, and fumed silica were added, and the mixture was reacted at room temperature for 8 hours. Subsequently, a flexible adhesive tape was prepared using a rolling device with a 1.5 mm gap between the rollers. Finally, pressure-sensitive adhesive was brushed onto the surface of the tape, and release paper was attached. Finally, cut it to specific specifications as required. Example 4 First, a mixed solvent of ethanol and water was prepared at a volume ratio of 90:10. Next, the calculated amount of KH-550 was slowly added to the ethanol-water mixture, and the pH was adjusted to 4-5 with acetic acid; this solution is denoted as Solution A. At 80°C, 1 kg of INCONEL 738LC (D50 of 65 μm) was added to Solution A, and the mixture was mechanically stirred for 2 hours. After filtration and washing, the resulting solid was dried at 100-120°C for 2-4 hours to completely solidify the coupling agent and evaporate any residual solvent, yielding the modified K438, denoted as g-INCONEL 738LC. Then, 100 g of g-INCONEL 738LC and 92.5 g of carboxyacrylate resin were thoroughly mixed under mechanical stirring. After mixing, a certain amount of diethylenetriamine, dibutyl phthalate, and fumed silica were added, and the mixture was reacted at room temperature for 8 hours. Subsequently, a flexible adhesive tape was produced using a rolling device with a 1 mm gap between the rollers. Next, apply pressure-sensitive adhesive to the surface of the adhesive tape and attach release paper. Finally, cut it to the required specifications. Example 5 The masking tape prepared in Example 1 was cut into square pieces with a length and width of 100 mm, and directly attached to the tenon of the blade. It was then placed in an atmosphere furnace for the coating process, and masking performance tests were conducted according to the coating process. Comparison photos of the actual product and the fluorescence detection of the blade after protection are shown below. Figure 3 , Figure 4 and Figure 5 As shown. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A special high-temperature anti-oxidation masking adhesive tape for blade tenons used in aero-engine blade coating processes, characterized in that, By mass percentage, it consists of the following components: 215% organic components and 85% functional fillers; the masking adhesive tape is prepared by roll forming process, and after forming, it has good flexibility and can be closely fitted to the profile of the blade tenon of the aero-engine.

2. The organic component according to claim 1, characterized in that, By weight percentage, it consists of the following components: 70-90% adhesive, 6-10% curing agent, 2-10% toughening agent, and 2-10% thixotropic agent.

3. The organic component according to claim 2, characterized in that, The adhesive is at least one of epoxy resin or acrylic resin; the toughening agent is at least one of dibutyl phthalate or ethyl acetate; and the thixotropic agent is fumed silica.

4. The masking adhesive tape according to claim 1, characterized in that, The functional filler is at least one of INCONEL series and K series high-temperature alloy powder particles, with a particle size range of 10-100 μm. The functional filler particles need to undergo surface modification treatment, and the modifier is silane coupling agent KH-550 or KH-560.

5. The masking adhesive tape according to claim 1, characterized in that, The adhesive tape has a "sandwich" structure. The outer layer is a weakly tacky component with a thickness of 0.01-0.05 mm, which is a modified acrylate with a peel strength of 5-15 N / m. The inner layer is a composite material consisting of functional fillers and organic components with a thickness of 0.49-2.95 mm. The total thickness of the adhesive tape is 0.5-3 mm.

6. A method for preparing a high-temperature masking adhesive tape for blade coating process as described in any one of claims 15, characterized in that, Includes the following steps: S1: Ingredient mixing: Add the adhesive, functional filler, curing agent, toughening agent and thixotropic agent components to a high-speed mixer in proportion, and stir for 10-60 min at 25-120℃ and 500-1000 r / min to obtain a uniform premix. S2: Customized Rolling: A double-cylinder rolling device is used to press the premix obtained in S1 into shape, and the thickness of the masking tape can be adjusted by adjusting the roller spacing. S3: Curing and molding: The rolled blank is placed in a curing oven and cured at 25-150℃ for 248 hours; S4: Segmentation and Packaging: Apply pressure-sensitive adhesive to both sides of the cured masking material, then attach release paper, and divide it according to specific dimensions to obtain the final masking material.

7. The preparation method according to claim 6, characterized in that, The roller surface accuracy of the twin-cylinder rolling device in step S2 is not lower than IT4 grade, and the surface roughness Ra ≤ 0.4 μm.

8. An application of the masking adhesive tape as described in any one of claims 17, characterized in that, In plasma spraying, physical vapor deposition (PVD), or chemical vapor deposition (CVD) coating processes for aero-engine blades, the material is directly adhered to the surface of the area to be protected during masking. After the coating is completed, it is removed manually or mechanically, and then cleaned with alcohol.

9. The application according to claim 8, characterized in that, The shielding tape can withstand a maximum temperature of 1150°C during the coating process, with a single shielding duration of 8 hours, and leaves no residual material on the surface of the shielded area of ​​the blade after use.

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