A sealing agent for thermal barrier coating on blade surface, its preparation method and application

Abstract

This invention relates to a sealing agent for thermal barrier coatings on blade surfaces, its preparation method, and its application. The sealing agent for thermal barrier coatings on blade surfaces provided by this invention comprises the following raw materials in parts by weight: 40-60 parts of trifluorochloroethylene-vinyl ether copolymer resin; 5-10 parts of curing agent; and 35-50 parts of diluent; wherein the total mass percentage of acidic impurities and moisture in each raw material component is ≤0.015%. This invention controls the content of acidic impurities and moisture in each raw material component in the sealing agent, ensuring that the sealing agent does not corrode the metal substrate. Furthermore, by setting the mass percentage of each raw material component, this invention obtains a sealing agent with suitable viscosity and semi-drying time, giving the sealing agent good spreadability and sufficient time to spread, and preventing accumulation around the air film pores before the sealing agent is semi-dry. This greatly improves the stability of the blade thermal barrier coating in natural environments and significantly extends its storage life in natural environments.

Description

Technical Field

[0001] This invention relates to the field of thermal protection for gas turbines, specifically to a sealing agent for a thermal barrier coating on a blade surface, its preparation method, and its application. Background Technology

[0002] Thermal barrier coatings (TBCs) are coatings that provide both thermal insulation and oxidation resistance. An oxidation-resistant metal underlayer is first prepared on the surface of the metal substrate, and then a thermally insulating ceramic toplayer is prepared on the surface of the bonding layer. Therefore, a TBC consists of a metal underlayer and a ceramic toplayer, with the ceramic toplayer primarily being YSZ (Y₂O₃-stabilized ZrO₂). TBCs can form a thermal insulation layer between the hot-end components and the exhaust gas of an aero-engine, improving the engine's thrust-to-weight ratio and extending its service life, making it one of the key technologies for aero-engines.

[0003] The YSZ layer has a volumetric porosity of 10% to 20%, with pore sizes ranging from 0.01 μm to 10 μm. It serves as a heat insulation layer, but also acts as a channel for corrosion to diffuse into the interior.

[0004] A schematic diagram of the structure of thermal barrier coatings and their surface sealing agents is shown below. Figure 1 As shown.

[0005] During subsequent water flow testing, transportation, or storage, especially under marine climate conditions, the metal substrate of the thermal barrier coating on the turbine blade surface may be corroded, leading to premature peeling and shortened lifespan of the thermal barrier coating. The causes of corrosion include the following three points: first, atmospheric acidic pollutants; second, water corrosion; and third, salt spray environment corrosion. It is necessary to use a sealing agent to seal the pores of the YSZ surface layer and block the corrosive medium from the outside of the thermal barrier coating.

[0006] Turbine blades have numerous film cooling pores on their surface, with diameters ranging from 0.3 to 2 mm. The thermal barrier coating (TBD) around these pores is porous, providing pathways for corrosive gases to diffuse into the TBD. During turbine blade operation, temperatures can reach up to 1200°C. The film cooling pores play a crucial role in heat dissipation, ensuring safe blade operation. However, existing sealing agents and their application methods often clog the film cooling pores or fail to completely cover the surrounding TBD. Clogged pores can lead to substandard water flow rates in turbine blade tests, while incomplete coverage of the TBD can cause corrosion of the metal substrate, resulting in premature TBD detachment and a shortened lifespan. Therefore, applying a sealing agent to the blade surface is a technical challenge, requiring the sealing of the TBD around the pores without blocking them. Summary of the Invention

[0007] This invention provides a sealing agent for thermal barrier coating on blade surfaces, its preparation method, and its application, in order to solve the problem that the sealing agent in the prior art cannot simultaneously satisfy the requirement of sealing the thermal barrier coating around the film pores without blocking the film pores.

[0008] In a first aspect, the present invention provides a sealing agent for a thermal barrier coating on a blade surface, comprising the following raw materials in parts by weight: 40-60 parts of trifluorochloroethylene-vinyl ether copolymer resin; 5-10 parts of curing agent; 35-50 parts of diluent; Among them, the F element in the trifluorochloroethylene-vinyl ether copolymer resin is 16-21% by mass, which can take into account both corrosion resistance and film-forming properties; The total mass percentage of acidic impurities and moisture in each raw material component is ≤0.015%; The viscosity of the sealing agent was tested using the Ford-4 cup method, and the outflow time was ≤35s under ambient temperature ≤40℃. The semi-drying time of the sealing agent is 30-120 minutes under ambient temperature conditions not exceeding 40°C.

[0009] In one optional implementation, a purifying agent is used to purify each raw material component; The purifying agent includes molecular sieves and active zinc powder; The molecular sieve is a 13X type molecular sieve.

[0010] In one optional embodiment, the molecular sieve has a pore size of 0.3 nm to 0.5 nm; And / or, the particle size of the active zinc powder is 0.2 mm to 0.5 mm; And / or, the mass ratio of the molecular sieve to the active zinc powder is 1:3-5.

[0011] In one optional embodiment, the amount of the purifying agent used in the purification process is in a mass ratio of 1:1-3 to the mass of each raw material component.

[0012] In one alternative embodiment, the curing agent comprises at least one of hexamethylene diisocyanate trimer, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, and dicyclohexyl phthalate.

[0013] In one alternative embodiment, the diluent includes at least one of n-butyl acetate, petroleum ether, butyl glycidyl ether, acetone, methyl ethyl ketone, and xylene.

[0014] Secondly, the present invention also provides a method for preparing the sealing agent described above, comprising: weighing each raw material component, adding a purifying agent to each raw material component for purification treatment, and then filtering to obtain the purified raw material component; mixing the purified trifluorochloroethylene-vinyl ether copolymer resin with the purified curing agent and aging it, and then adding the purified diluent and mixing it evenly to obtain the sealing agent.

[0015] In one optional embodiment, the purification process includes adding a purifying agent to each raw material component, thereby immersing the purifying agent in each raw material component. The purification process takes 24-30 hours.

[0016] In one optional implementation, the aging time is 30-60 minutes.

[0017] Thirdly, the present invention provides a method for sealing pores in a thermal barrier coating on a blade surface using the sealing agent described above or a sealing agent prepared by the preparation method described above, comprising the following steps: S1: Dry the leaves; S2: Fix the dried blade upright on the turntable, and spray the sealing agent onto the thermal barrier coating surface of the blade using a spray method under atmospheric conditions, and keep it upright until the sealing agent dries. The rotational speed of the turntable is 5-10 r / min; The thickness of the sealing agent after spraying and drying is 5μm-20μm.

[0018] The technical solution of this invention has the following advantages: 1. The present invention provides a sealing agent for a thermal barrier coating on a blade surface, comprising the following raw materials in parts by weight: 40-60 parts of trifluorochloroethylene-vinyl ether copolymer resin; 5-10 parts of curing agent; and 35-50 parts of diluent; wherein the total mass percentage of acidic impurities and moisture in each raw material component is ≤0.015%; the viscosity of the sealing agent is tested using the Ford-4 cup test method, and the outflow time is ≤35s under ambient temperature ≤40℃; the semi-drying time of the sealing agent is 30min-120min under ambient temperature not exceeding 40℃.

[0019] This invention controls the total mass percentage of acidic impurities and moisture in each raw material component of the sealing agent, ensuring that the sealing agent does not corrode the metal substrate. Furthermore, the sealing agent provided in this application has a uniform composition and low viscosity, exhibiting good spreadability on the surface of the blade thermal barrier coating and preventing clogging of the film pores. By setting a reasonable semi-drying time, the sealing agent has sufficient time to expand and will not accumulate around the film pores before semi-drying, providing excellent sealing of the thermal barrier coating around the film pores of the blade. This significantly improves the stability of the blade thermal barrier coating in natural environments and greatly extends its storage life under natural conditions.

[0020] 2. The blade surface thermal barrier coating sealing agent provided by the present invention contains no inorganic components, and completes combustion at the moment of engine ignition. The combustion products have no ash content and do not affect the use of the blade on the engine.

[0021] 3. The method for preparing the sealing agent for the thermal barrier coating on the blade surface provided by the present invention does not change the current material system of the thermal barrier coating, the process is simple, and it is suitable for engineering application by blade thermal barrier coating manufacturers. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the thermal barrier coating and its surface sealing agent; Figure 2 This is a schematic diagram of the device for spraying the sealing agent during the spraying process in an embodiment of the present invention; Figure 3 This is a schematic diagram of the device for spraying the sealing agent during the spraying process in an embodiment of the present invention; Figure 4 This is a schematic diagram of the blade cross-section in an embodiment of the present invention; Figure 5 This is a partial view of the blade surface after a sealant has been sprayed on it.

[0024] Explanation of reference numerals in the attached figures: 1. Concave film air hole; 2. Sealing agent spray gun; 3. Blade clamp; 4. Turntable; 5. Convex film air hole; 6. Blade. Detailed Implementation

[0025] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0026] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0027] Example 1 This embodiment provides a sealing agent for thermal barrier coating on blade surfaces, its preparation method, and its application method: The sealing agent comprises the following raw materials in parts by weight: 40 parts of trifluorochloroethylene-vinyl ether copolymer resin; 10 parts of hexamethylene diisocyanate trimer curing agent; and 50 parts of n-butyl acetate diluent. The total mass content of acidic impurities and moisture in each raw material component must be less than 0.015%.

[0028] The sealing agent is prepared by the following method: S1: Weigh each raw material component, add the purifying agent to each raw material component, and soak the purifying agent in each raw material component for 24 hours to remove the moisture and acidic impurities in each raw material component. Then filter to obtain the purified raw material components. The purifying agent includes molecular sieve and active zinc powder in a mass ratio of 1:3. The molecular sieve has a pore size of 0.3 nm, and the active zinc powder has a particle size of 0.2 mm. The mass ratio of the purifying agent to each raw material component is 1:1; S2: The purified trifluorochloroethylene-vinyl ether copolymer resin and hexamethylene diisocyanate trimer curing agent are mixed in the above mass ratio and aged at room temperature for 30 minutes. Then, n-butyl acetate diluent is added and mixed evenly to obtain the leaf surface thermal barrier coating sealing agent.

[0029] The viscosity of the sealing agent was tested using the Ford-4 cup test method, and its viscosity met the requirement that the outflow time was 27s at an ambient temperature of 40℃. The semi-drying time of the sealing agent is 30 minutes at an ambient temperature of 40℃.

[0030] The method of using the above-mentioned sealing agent includes the following steps: S1: The blades with thermal barrier coating are kept warm and dehumidified in a 60℃ oven for 4 hours; S2: Vertically fix the blade with the thermal barrier coating after drying on the turntable 4, and the rotational speed of the turntable 4 is 10 r / min; in an atmospheric atmosphere, spray the sealant on the surface of the thermal barrier coating of the blade using the spraying method. The specific scheme is as follows: As Figure 2 , Figure 3 shown in the schematic diagram, install the special fixture 3 for the blade on the three-jaw chuck of the turntable 4, and then install the blade 6 on the special fixture 3 for the blade. As Figure 4 shown, vertex a is the midpoint of the tip of the blade 6, and vertex b is the tangent point where the tangent line (i.e., Figure 4 the connection line between vertex a and vertex b in

[0031] S3: Keep the blade in a vertical state for 2 h until the sealant is completely dry, and the dry film thickness of the sealant is 5 μm.

[0032] The local appearance photo of the blade surface after spraying the sealant is as Figure 5 shown.

[0033] Example 2 This embodiment provides a sealing agent for thermal barrier coating on blade surfaces, its preparation method, and its application method: The sealing agent comprises the following raw materials in parts by weight: 60 parts of trifluorochloroethylene-vinyl ether copolymer resin; 5 parts of tert-butyl peroxybenzoate curing agent; and 35 parts of petroleum ether diluent. The total mass content of acidic impurities and moisture in each raw material component is less than 0.015%.

[0034] The sealing agent is prepared by the following method: S1: Weigh each raw material component, add the purifying agent to each raw material component, and soak the purifying agent in each raw material component for 24 hours to remove the moisture and acidic impurities in each raw material component. Then filter to obtain the purified raw material components. The purifying agent includes molecular sieve and active zinc powder in a mass ratio of 1:4. The molecular sieve has a pore size of 0.4 nm, and the active zinc powder has a particle size of 0.4 mm. The mass ratio of the purifying agent to each raw material component is 1:2; S2: The purified trifluorochloroethylene-vinyl ether copolymer resin and hexamethylene diisocyanate trimer curing agent are mixed in the above mass ratio and aged at room temperature for 30 minutes. Then, n-butyl acetate diluent is added and mixed evenly to obtain the leaf surface thermal barrier coating sealing agent.

[0035] The viscosity of the sealing agent was tested using the Ford-4 cup method, and the outflow time was 35 seconds at an ambient temperature of 20°C. The semi-drying time of the sealing agent is 120 minutes at an ambient temperature of 20℃.

[0036] The method of using the above-mentioned sealing agent includes the following steps: S1: The blades with thermal barrier coating are kept warm and dehumidified in a 60℃ oven for 4 hours; S2: The dried blade with thermal barrier coating is fixed upright on turntable 4, and the rotation speed of turntable 4 is 5 r / min; under atmospheric conditions, the sealing agent is sprayed onto the surface of the blade thermal barrier coating using a spray method. The specific plan is as follows: like Figure 2 , Figure 3 As shown in the schematic diagram, the blade-specific clamp 3 is installed onto the three-jaw chuck on the turntable 4, and then the blade 6 is mounted onto the blade-specific clamp 3. Figure 4 As shown, vertex a is the midpoint of the tip of blade 6, and vertex b is the tangent line passing through the outer edge of the concave arc of blade 6 at vertex a (i.e., Figure 4The tangent point where the line connecting vertex a and vertex b intersects the blade 6, and vertex c is the point on the convex surface of the blade 6 that is farthest from the above-mentioned tangent line. The three vertices form a triangle. Measure the interior angle at vertex a as α and the interior angle at vertex b as β. The movement trajectory of the sealant spray gun 2 is to move uniformly left and right and extend about 50 mm beyond the left and right edges of the blade projection plane in the current direction, repeat the left and right movement and gradually reduce by 5 mm until the upper and lower edges of the blade projection plane in the current direction are completely covered. During the movement, the closest distance between the nozzle of the sealant spray gun 2 and the blade 6 is maintained at about 150 mm, and the movement trajectory resembles the shape of the Chinese character "bow". Adjust the air output and the sealant spray volume of the sealant spray gun 2 to achieve a better atomization effect of the sealant. At any arbitrarily positioned horizontal rotation angle of the turntable 4, spray the sealant spray gun 2 along the concave surface of the blade 6 several times until sealant accumulation can be seen on the coating in the concave surface air film holes 1. Move the sealant spray gun 2 to the convex surface of the blade 6 and spray several times until sealant accumulation can be seen on the coating in the convex surface air film holes 5. Rotate the turntable 4 to the plane parallel to the line connecting vertex a and vertex b facing the sealant spray gun 2, zero the rotation angle of the turntable 4, and operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the line connecting vertex a and vertex b and parallel to the ground several times until a sufficient thickness of sealant adheres to the current coating surface. Rotate the turntable 4 to 180° - α, operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the line connecting vertex a and vertex c and parallel to the ground several times until a sufficient thickness of sealant adheres to the current coating surface. Rotate the turntable to 360° - β, operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the line connecting vertex b and vertex c and parallel to the ground several times until a sufficient thickness of sealant adheres to the current coating surface, and complete the spraying of the sealant on the entire coating surface of the blade 6.

[0037] S3: Keep the blade in a vertical state for 2 h until the sealant is completely dry, and the dry film thickness of the sealant is 10 μm.

[0038] Example 3 This example provides a sealant for thermal barrier coatings on the blade surface, its preparation method and usage method: The sealant includes the following raw materials in parts by weight: 50 parts of chlorotrifluoroethylene-vinyl ether copolymer resin; 10 parts of tert-butyl peroxybenzoate curing agent; 40 parts of petroleum ether diluent; Among them, the total mass content of acidic impurities and moisture in each raw material component is less than 0.015%.

[0039] The sealant is prepared by the following preparation method: S1: Weigh each raw material component, add the purifying agent to each raw material component, and soak the purifying agent in each raw material component for 24 hours to remove the moisture and acidic impurities in each raw material component. Then filter to obtain the purified raw material components. The purifying agent includes molecular sieve and active zinc powder in a mass ratio of 1:4. The molecular sieve has a pore size of 0.4 nm, and the active zinc powder has a particle size of 0.4 mm. The mass ratio of the purifying agent to each raw material component is 1:2; S2: The purified trifluorochloroethylene-vinyl ether copolymer resin and hexamethylene diisocyanate trimer curing agent are mixed in the above mass ratio and aged at room temperature for 30 minutes. Then, n-butyl acetate diluent is added and mixed evenly to obtain the leaf surface thermal barrier coating sealing agent.

[0040] The viscosity of the sealing agent was tested using the Ford-4 cup method, and the outflow time was 35 seconds at an ambient temperature of 20°C. The semi-drying time of the sealing agent is 120 minutes at an ambient temperature of 20℃.

[0041] The method of using the above-mentioned sealing agent includes the following steps: S1: The blades with thermal barrier coating are kept warm and dehumidified in a 60℃ oven for 4 hours; S2: The dried blade with thermal barrier coating is fixed upright on turntable 4, and the rotation speed of turntable 4 is 5 r / min; under atmospheric conditions, the sealing agent is sprayed onto the surface of the blade thermal barrier coating using a spray method. The specific plan is as follows: like Figure 2 , Figure 3 As shown in the schematic diagram, the blade-specific clamp 3 is installed onto the three-jaw chuck on the turntable 4, and then the blade 6 is mounted onto the blade-specific clamp 3. Figure 4 As shown, vertex a is the midpoint of the tip of blade 6, and vertex b is the tangent line passing through the outer edge of the concave arc of blade 6 at vertex a (i.e., Figure 4The tangent point where the connection line between vertex a and vertex b intersects the blade 6, and vertex c is the point on the convex surface of the blade 6 that is the farthest from the above-mentioned tangent line. The three vertices form a triangle. Measure the interior angle at vertex a as α and the interior angle at vertex b as β. The movement trajectory of the sealant spray gun 2 is to move left and right at a constant speed and extend about 50 mm beyond the left and right edges of the projection plane of the blade in the current direction. Repeat the left and right movement and gradually decrease by 5 mm until the upper and lower edges of the projection plane of the blade in the current direction are completely covered. During the movement, the closest distance between the nozzle of the sealant spray gun 2 and the blade 6 is maintained at about 150 mm, and the movement trajectory resembles the shape of the character "bow". Adjust the air output and the sealant output of the sealant spray gun 2 to achieve a better atomization effect of the sealant. At any arbitrarily positioned horizontal rotation angle of the turntable 4, spray the sealant spray gun 2 along the concave surface of the blade 6 for several times until sealant accumulation can be seen on the coating in the concave surface air film holes 1. Move the sealant spray gun 2 to the convex surface of the blade 6 and spray for several times until sealant accumulation can be seen on the coating in the convex surface air film holes 5. Rotate the turntable 4 to the plane parallel to the connection line between vertex a and vertex b facing the sealant spray gun 2, zero the rotation angle of the turntable 4, and operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the connection line between vertex a and vertex b and parallel to the ground for several times until a sufficient thickness of sealant adheres to the current coating surface. Rotate the turntable 4 to 180° - α, operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the connection line between vertex a and vertex c and parallel to the ground for several times until a sufficient thickness of sealant adheres to the current coating surface. Rotate the turntable to 360° - β, operate the sealant spray gun 2 to run along the spraying sealant movement trajectory perpendicular to the connection line between vertex b and vertex c and parallel to the ground for several times until a sufficient thickness of sealant adheres to the current coating surface, and complete the spraying of the sealant on the coating surface of the entire blade 6.

[0042] S3: Keep the blade in a vertical state for 2 h until the sealant is completely dry, and the dry film thickness of the sealant is 10 μm.

[0043] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A sealing agent for thermal barrier coating on blade surface, characterized in that, It consists of the following raw materials in parts by weight: 40-60 parts of trifluorochloroethylene-vinyl ether copolymer resin; 5-10 parts of curing agent; 35-50 parts of diluent; The total mass percentage of acidic impurities and moisture in each raw material component is ≤0.015%; The viscosity of the sealing agent was tested using the Ford-4 cup method, and the outflow time was ≤35s under ambient temperature ≤40℃. The semi-drying time of the sealing agent is 30-120 minutes under ambient temperature conditions not exceeding 40°C.

2. The blade surface thermal barrier coating sealing agent according to claim 1, characterized in that, Each raw material component is purified using a purifying agent; The purifying agent includes molecular sieves and active zinc powder.

3. The blade surface thermal barrier coating sealing agent according to claim 2, characterized in that, The molecular sieve has a pore size of 0.3 nm to 0.5 nm; And / or, the particle size of the active zinc powder is 0.2 mm to 0.5 mm; And / or, the mass ratio of the molecular sieve to the active zinc powder is 1:3-5.

4. The blade surface thermal barrier coating sealing agent according to any one of claims 2 or 3, characterized in that, The mass ratio of the purifying agent to each raw material component is 1:1-3.

5. The blade surface thermal barrier coating sealing agent according to any one of claims 1-4, characterized in that, The curing agent includes at least one of hexamethylene diisocyanate trimer, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, and dicyclohexyl phthalate.

6. The blade surface thermal barrier coating sealing agent according to any one of claims 1-5, characterized in that, The diluent includes at least one of n-butyl acetate, petroleum ether, butyl glycidyl ether, acetone, methyl ethyl ketone, and xylene.

7. A method for preparing a sealing agent for a thermal barrier coating on a blade surface as described in any one of claims 1-6, characterized in that, The process includes: weighing each raw material component, adding a purifying agent to each raw material component for purification treatment, and then filtering to obtain the purified raw material component; mixing the purified trifluorochloroethylene-vinyl ether copolymer resin with the purified curing agent and aging it, and then adding the purified diluent and mixing it evenly to obtain a sealing agent.

8. The preparation method according to claim 7, characterized in that, The purification process includes adding a purifying agent to each raw material component, allowing the purifying agent to soak into each raw material component; The purification process takes 24-30 hours.

9. The preparation method according to claim 7, characterized in that, The aging time is 30-60 minutes.

10. A method for sealing pores in a thermal barrier coating on a blade surface using the sealing agent as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Dry the leaves; S2: Fix the dried blade upright on the turntable, spray the sealing agent onto the surface of the blade thermal barrier coating under atmospheric conditions, and keep it upright until the sealing agent dries; The rotational speed of the turntable is 5-10 r / min; The thickness of the sealing agent after spraying and drying is 5μm-20μm.

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