Tenon non-penetration surface protection method for metal penetration process and aero-engine

Abstract

The application discloses a tenon non-infiltration surface protection method for a metal infiltration process and an aero-engine, and comprises the following steps: S1, a bottom layer coating is arranged to coat a turbine rotor blade first tooth and a part below the first tooth; S2, a bottom layer protective coating is applied to an under surface of a shell plate; S3, an outer layer coating is arranged to wrap the shell plate and a part below the shell plate; S4, an outer layer protective coating is applied; S5, gas phase aluminizing is carried out according to an aluminizing process to obtain a target workpiece; and S6, inspection is carried out. The protection method can provide effective protection for a high-temperature aluminized blade non-infiltration part at a temperature of 900 DEG C to 1000 DEG C, the non-aluminized surface after protection has no leakage, and the protection method is simple and fast, and special tool clamps and auxiliary equipment are not needed, so that the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation part protection methods, in particular, relates to a tenon non-permeation surface protection method for a permeation process and an aero-engine. BACKGROUND

[0002] With the increasing working temperature of new aero-engines and gas turbine systems, the turbine rotor blades widely adopt internal cavity air film cooling technology to improve the cooling capacity to meet the use requirements in high temperature, high speed and strong corrosion environment of the gas turbine. The internal and external surfaces of the gas turbine blade need to be permeated with aluminum to improve the high temperature service capability, and the internal cavity is strengthened by adopting the gas phase method. The blade tenon is subjected to high frequency and high stress alternating load for a long time, and the mechanical properties such as fatigue are required to be high. Once the tenon part is permeated with aluminum to form a brittle aluminum coating, cracks are easily generated at the position, and further expansion occurs under high stress, which has a potential safety hazard of blade fracture. Therefore, the tenon part is generally required not to have an aluminum coating. The permeation source of the gas phase permeation aluminum part is gaseous, so the protection of the non-permeation surface during the permeation process becomes an urgent problem to be solved.

[0003] At present, the protection schemes for the non-permeation part of the blade mainly include:

[0004] 1) Reserving a margin for mechanical removal

[0005] After the whole part is permeated with aluminum, the non-permeation surface part is mechanically removed by grinding to achieve the purpose of no permeation layer at the part. However, the mechanical removal of the permeation layer at the tenon part generally needs to use the blade body and other permeation surface parts of the blade for clamping and positioning, and the part will generate machining vibration during machining. The clamping part is prone to crack, and cracks or even peeling are easily formed during the milling and grinding process due to the hard and brittle permeation layer at the machining part. Therefore, the machining qualification rate of such parts is low in actual production, and the method of removing the non-permeation surface permeation layer by subsequent machining is generally not adopted.

[0006] 2) Protective coating

[0007] The protective coating is used for tenon protection, which is a common method. The patent (CN107267912B) describes an aluminum permeation protective coating, which is mainly suitable for solid powder embedding permeation of aluminum below 900 DEG C. The protective coating is configured by using metal nickel, zirconia and a binder. Natural drying is required for 6-24 hours after each coating, and the protection time is long. The protective effect is lost when the temperature exceeds 1020 DEG C, and the non-permeation surface cannot be protected by high temperature permeation of aluminum with a temperature as high as 1080 DEG C.

[0008] The protective coating disclosed in patent number CN110923621A uses metal powder and zirconium oxide as the protective coating for aluminum-chromium co-diffusion non-aluminum-diffusion surface protection, with an anti-aluminum temperature of 1025-1080℃. However, the use of a single-component, multi-layer coating makes it difficult to balance anti-aluminum effect with ease of removal in terms of component ratio. After using this method for vapor-phase aluminizing protection, some protective coating residue is difficult to remove, and it may even alloy with the substrate in some areas, affecting the performance of the parts. In addition, the protective layer has low strength after coating, making it extremely easy to be damaged during the subsequent mounting process before the parts are put into the furnace.

[0009] When using protective coatings to protect tenons with air inlets, if the coating is applied directly to the tenon, it can easily seep into the inner cavity, resulting in the absence of an aluminized layer on the required surface, or even leaving coating residue that cannot be removed, rendering the part unusable. Most patent literature on protective coatings for non-aluminized surfaces only discloses methods for preventing seepage on non-aluminized surfaces, without providing specific implementation schemes for aluminized protection of tenons with air inlets.

[0010] 3) Protective shield method

[0011] HB / Z310 recommends a metal shield protection method, using stainless steel or high-temperature alloy sheets. The gap between the shield and the part should be ≤0.1mm, which can be filled with Al2O3. However, this protection is mainly suitable for solid-phase aluminizing. During gas-phase aluminizing, the aluminizing atmosphere can easily seep in through the gap between the metal shield and the tenon, causing reactive aluminizing at the tenon. The protection method disclosed in patent CN102978565B uses a protective clamp combining alumina cotton and a metal shield, which can ensure the aluminized layer thickness at the blade tenon is 0–5μm, but it cannot achieve complete anti-seepage. Summary of the Invention

[0012] This invention provides a method for protecting the non-permeable surface of tenons during the metal infiltration process and an aero-engine, to solve the technical problem that existing protection methods cannot completely prevent permeation under high temperature conditions.

[0013] The technical solution adopted in this invention is as follows:

[0014] A method for protecting the non-porous surface of tenons during the metal infiltration process, comprising:

[0015] S1. A bottom layer covering is provided for the first tooth and the portion below the first tooth of the tenon in the direction from the slab to the tenon of the turbine rotor blade;

[0016] S2. Apply a base coat of protective coating to the entire tenon with the base layer covering, and apply the base coat of protective coating to the underside of the rafter;

[0017] S3. An outer layer is provided to cover the tenon and the area below the tenon that is coated with a base protective coating;

[0018] S4. Apply an outer protective coating to the tenon with an outer covering;

[0019] S5. Obtain the target workpiece by performing vapor phase aluminizing according to the aluminizing process;

[0020] S6. Inspection.

[0021] As a further improvement to the above technical solution, the bottom layer coating and the outer layer coating are metal foils with a thickness of 0.4-1mm.

[0022] As a further improvement to the above technical solution, the metal foil is a nickel foil.

[0023] As a further improvement to the above technical solution, the bottom protective coating is prepared by zirconium oxide and sealant in a volume ratio of 1:1.2-1.2:1; the outer protective coating is prepared by zirconium oxide and sealant in a volume ratio of 0.8:1.2-1.2:0.8.

[0024] As a further improvement to the above technical solution, step S2 also includes:

[0025] After the base protective coating is applied, allow it to cure under dry, room-temperature conditions.

[0026] Step S4 also includes:

[0027] After the outer protective coating is applied, allow it to cure under dry, room-temperature conditions.

[0028] As a further improvement to the above technical solution, the sealant is a vinyl lacquer.

[0029] As a further improvement to the above technical solution, before obtaining the target workpiece by vapor phase aluminizing according to the aluminizing process, step S5 also includes:

[0030] Inspect and clean any residual paint on the aluminized surface.

[0031] As a further improvement to the above technical solution, step S6 includes:

[0032] The parts are subjected to color treatment at a preset temperature of 500℃-650℃ for a period of time. If the non-penetrating surface of the tenon is blue after color treatment, the parts are cut for inspection.

[0033] As a further improvement to the above technical solution, before conducting the inspection, step S6 also includes:

[0034] Remove the protective layer from the tenon and clean and dry it. According to another aspect of the invention, an aircraft engine is also provided, employing any of the above-described methods for protecting the non-impregnated surface of the tenon during the metallization process.

[0035] The present invention has the following beneficial effects:

[0036] This protection method involves setting an inner layer that covers the first tooth and below of the tenon. On one hand, this physically prevents direct contact between the aluminizing atmosphere and the non-aluminizing surface. On the other hand, the inner layer preferentially reacts with the aluminizing atmosphere, reducing its activity and preventing diffusion reactions between the base metal and aluminum on the non-aluminizing surface. This consumption of the aluminizing atmosphere plays a major role in preventing seepage. Combined with the application of a base protective coating to prevent deformation under high-temperature stress, the protective effect is ensured. An outer layer further protects the rafter and the transition area to the tenon, and includes... The outer protective coating prevents the aluminizing atmosphere and fine dust from contacting the tenon, and also reacts to consume the aluminizing atmosphere, thus playing an auxiliary role in preventing seepage. Using this protective method, the non-aluminized parts of high-temperature aluminized blades can be effectively protected at temperatures of 900℃~1000℃. The protected non-aluminized surface is free of leakage, and the operation is simple and quick, without the need for specific tooling fixtures or auxiliary equipment, reducing costs. It has no impact on the tenon size, and there is no need to adjust the tenon size during subsequent machining, which can effectively avoid cracks and chips in the aluminized layer caused by clamping the aluminized layer during the tenon processing after aluminizing.

[0037] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 This is a schematic diagram of the protective structure of the tenon seepage prevention surface protection method according to a preferred embodiment of the present invention;

[0040] Figure 2 This is an appearance view of the blade before aluminizing according to a preferred embodiment of the present invention;

[0041] Figure 3 This is a metallographic image of the non-permeable surface of the tenon obtained after processing using the protection method of the preferred embodiment of the present invention;

[0042] Figure 4 This is a cross-sectional metallographic image of the aluminized surface of the blade obtained after processing using the protection method of the preferred embodiment of the present invention;

[0043] 1. Inner protective layer 2. Non-aluminized surface 3. Outer protective layer 4. Aluminizing atmosphere 5. Rafter 6. Bottom layer coating 7. Bottom layer protective coating 8. Outer layer coating 9. Outer layer protective coating 10. Side edge 11. Lower surface of rafter 13. Aluminized surface 14. Pores Detailed Implementation

[0044] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0045] Reference Figures 1 to 4 A preferred embodiment of the present invention provides a method for protecting the non-infiltrated surface of a tenon in a metal infiltration process. The tenon is a tenon of a turbine rotor blade, and the tenon includes a truss plate 5 and an air hole 14. This protection method includes:

[0046] S1. A bottom layer covering 6 is provided for the first tooth and the part below the first tooth of the tenon in the direction from the truss 5 to the tenon of the turbine rotor blade;

[0047] S2. Apply a base protective coating 7 to the entire tenon with the base cover 6, and apply the base protective coating 7 to the lower surface 11 of the rafter 5, forming an inner protective layer 1 with the base cover 6;

[0048] S3. An outer layer covering 8 is provided for the tenon 5 and the part below the tenon 5 that are coated with the base protective coating 7;

[0049] S4. Apply an outer protective coating 9 to the tenon with the outer covering 8 to form an outer protective layer 3 with the outer covering 8;

[0050] S5. Obtain the target workpiece by performing vapor phase aluminizing according to the aluminizing process;

[0051] S6. Inspection.

[0052] Understandably, this protection method, by setting an inner layer to cover the first tooth and below of the tenon, on the one hand, physically hinders the direct contact between the aluminizing atmosphere 4 and the non-aluminizing surface 2, and on the other hand, allows it to preferentially react with the aluminizing atmosphere 4, reducing the activity of the aluminizing atmosphere 4 and preventing the diffusion reaction between the base metal of the non-aluminizing surface 2 and aluminum. It consumes the aluminizing atmosphere 4, playing a major role in preventing seepage. Combined with the setting of the bottom protective coating 7, it prevents the bottom covering 6 from deforming under high temperature stress, thus ensuring the protective effect. Furthermore, an outer covering 8 is set to wrap and protect the rafter 5 and the transition area below to the tenon. An outer protective coating 9 is applied to prevent the aluminizing atmosphere 4 and fine dust from contacting the tenon. This coating also reacts to consume the aluminizing atmosphere 4, thus providing auxiliary anti-seepage protection. This protective method can effectively protect the non-aluminized parts of high-temperature aluminized blades at temperatures of 900℃~1000℃. The protected non-aluminized surface 13 is leak-free. The operation is simple and quick, requiring no specific tooling or auxiliary equipment, thus reducing costs. It has no impact on the tenon size, eliminating the need for subsequent machining adjustments. This effectively prevents cracks and chipping of the aluminized layer caused by clamping the aluminized part during tenon processing after aluminization.

[0053] In this embodiment, the bottom layer covering 6 and the outer layer covering 8 are metal foils with a thickness of 0.4-1mm. If the thickness is too low, the foil is easily broken, which affects the protective effect. If the thickness is too high, the cutting operation is difficult, and it is impossible to obtain metal foils of suitable size, making it difficult to attach the metal foils to the tenons. The metal foil attachment operation is simple, does not stick to the substrate surface, and is easy to remove. Preferably, the metal foil is nickel foil. During the vapor phase aluminizing process, it physically prevents the aluminizing atmosphere 4 from directly contacting the anti-seepage surface. Chemically, it can preferentially react with the aluminizing atmosphere 4 to reduce the aluminum activity of the aluminizing atmosphere 4, thereby avoiding the diffusion reaction between the substrate metal of the anti-seepage surface and aluminum. In this protection method, the tenon is attached with metal foil, which can effectively prevent residual paint and other waste from entering the pores 14 of the tenon to keep the inner cavity clean, thus solving the protection problem of the non-aluminized surface 13 of the tenon blade with pores 14.

[0054] Furthermore, the underlying protective coating 7 is prepared from zirconium oxide and sealant in a volume ratio of 1:1.2-1.2:1; the sealant is preferably vinyl varnish. The protective coating can, on the one hand, prevent the diffusion of the aluminizing atmosphere 4 to the non-aluminizing surface 2, and on the other hand, prevent the nickel foil from deforming due to the release of forming stress at high temperature, thus fixing the nickel foil. This allows the protective layer prepared by this method to provide effective protection for the non-aluminizing parts of the high-temperature aluminized blade at a temperature of 900℃~1000℃. If the volume ratio is lower than the above range, the fixing effect of the metal foil may not be achieved; if the volume ratio is higher than the above range, the sealing effect may be poor and the anti-permeation effect may be unsatisfactory.

[0055] The outer protective coating 9 is prepared from zirconium oxide and sealant in a volume ratio of 0.8:1.2-1.2:0.8. The sealant is preferably a vinyl ester varnish. This protective coating, on the one hand, prevents the diffusion of the aluminizing atmosphere 4 to the non-aluminized surface 2, and on the other hand, prevents the nickel foil from deforming due to the release of forming stress at high temperatures, thus fixing the nickel foil. This allows the protective layer prepared by this method to provide effective protection for the non-aluminized parts of the high-temperature aluminized blade at temperatures of 900℃ to 1000℃. Compared to the inner protective layer, the outer protective coating 9, as an auxiliary protection, has relatively more lenient requirements for the coating ratio. However, if the ratio is below the aforementioned volume ratio range, the metal foil fixation effect may not be achieved; if it is above the aforementioned volume ratio range, the sealing effect may be poor and the anti-permeation effect may be unsatisfactory.

[0056] Specifically, step S2 also includes:

[0057] After the base protective coating 7 is applied, allow it to cure under dry, room-temperature conditions;

[0058] Step S4 also includes:

[0059] After the outer protective coating 9 is applied, it should be placed in a dry room temperature environment to cure; that is, the workpiece can only be put into the furnace for aluminum infiltration after the coating has cured.

[0060] In this embodiment, before obtaining the target workpiece by vapor phase aluminizing according to the aluminizing process, step S5 further includes:

[0061] Inspect and clean any residual paint on the aluminized surface 13 to avoid affecting it.

[0062] In this embodiment, before the inspection, step S6 further includes:

[0063] Remove the protective layer outside the tenon and clean and dry it; specifically, the protective layer prepared by this method is easy to remove and clean. After aluminizing, the protective layer can be manually removed. Simple brushing can remove surface residues. After drying, the final part is obtained, and there is no paint residue on the tenon.

[0064] In this embodiment, step S6 includes:

[0065] The parts are subjected to a color treatment at a preset temperature of 500℃-650℃ for a period of time. That is, the workpiece is placed in a high-temperature air environment for heat preservation and coloring. If the non-permeable surface 2 of the tenon is blue after color treatment, the part is then cut and inspected to observe the condition of the permeable and non-permeable surfaces 2. It should be understood that the non-permeable surface 2 of the tenon should be blue after color treatment to be qualified. If it is not blue, it is unqualified. In the specific implementation of this protection method, no unqualified workpieces were found.

[0066] On the other hand, a preferred embodiment of the present invention also provides an aircraft engine that applies the above-mentioned protection method.

[0067] This protection method has been applied in the production process of vapor phase aluminizing tenon protection for a certain type of aero-engine blades; it can provide effective protection for non-aluminized parts of high-temperature aluminized blades at temperatures of 900℃~1000℃, and there is no leakage on the non-aluminized surface 13 after protection. The current protection success rate is 100%.

[0068] Example 1

[0069] The protection method in this embodiment includes:

[0070] S1. Set the bottom layer covering 6 to cover the first tooth and the part below the first tooth of the turbine rotor blade;

[0071] Specifically, a 0.6mm thick nickel foil is cut and wrapped around the first tooth and below of the tenon of a hollow turbine blade made of DZ406 material, with the nickel foil tightly attached to the tenon tooth.

[0072] S2. Apply a base protective coating 7 to the lower surface 11 of the rafter 5;

[0073] Specifically, prepare the inner protective coating: take 1 volume of vinyl varnish liquid component and 1.1 volume of zirconium oxide powder component, mix and stir for 10 minutes; apply the uniformly stirred coating to the nickel foil, ensuring the coating completely covers the nickel foil-wrapped area and extends to the lower surface 11 of the rafter 5; after coating, allow it to cure at a dry room temperature.

[0074] S3. Set an outer covering 8 to wrap the truss 5 and the area below the truss 5;

[0075] Specifically, cut the nickel foil and wrap it around the bottom of the slab 5, with the wrapped nickel foil slightly extending beyond the slab 5. The nickel foil adheres to the side 10 and the lower surface 11 of the slab 5.

[0076] S4. Apply an outer protective coating 9;

[0077] Specifically, take 1 volume of vinyl varnish liquid component and 1.1 volume of zirconium oxide powder, and mix and stir for about 10 minutes; apply the well-stirred coating to the nickel foil, ensuring the coating covers part 5 of the nickel foil-wrapped rafter but does not completely cover the entire nickel foil; after coating, allow it to cure at room temperature.

[0078] S5. Obtain the target workpiece by performing vapor phase aluminizing according to the aluminizing process;

[0079] Specifically, inspect and clean the residual coating on the aluminized surface 13, and carry out vapor phase aluminizing according to the aluminizing process, with an aluminizing temperature of 980℃ and a holding time of 4 hours.

[0080] S6. Inspection; Specifically, after aluminizing, remove the workpiece, remove the protective layer, brush the parts, and dry them; perform a color treatment at 580℃ for 1 hour on the parts. After color treatment, the tenon parts on the non-aluminized surface 2 will turn blue. Perform a cross-section inspection on the parts, such as... Figure 3 As shown, the non-aluminized surface 2 area of ​​the tenon has no aluminized layer, as... Figure 4 As shown, the other aluminized surfaces 13 have an aluminized layer, indicating that the method of protecting the non-aluminized surface 2 of the tenon in this embodiment is effective.

[0081] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for protecting the non-porous surface of tenons during the metal infiltration process, characterized in that, include: S1. A bottom layer covering (6) is provided on the first tooth and the part below the first tooth of the tenon in the direction from the slab (5) to the tenon of the turbine rotor blade; S2. Apply a base coat of protective coating (7) to the entire tenon with the base cover (6), and apply the base coat of protective coating (7) to the lower surface (11) of the rafter (5); S3. An outer layer covering (8) is provided on the tenon (5) and the part below the tenon (5) coated with the bottom protective coating (7). The bottom covering (6) and the outer covering (8) are metal foils with a thickness of 0.4-1mm. The metal foil is nickel foil. S4. Apply an outer protective coating (9) to the tenon with the outer covering (8); S5. Obtain the target workpiece by performing vapor phase aluminizing according to the aluminizing process; S6. Inspection.

2. The method for protecting the non-porous surface of tenons during the metal infiltration process according to claim 1, characterized in that, The base protective coating (7) is prepared from zirconium oxide and sealant in a volume ratio of 1:1.2-1.2:1; the outer protective coating (9) is prepared from zirconium oxide and sealant in a volume ratio of 0.8:1.2-1.2:0.

8.

3. The method for protecting the non-porous surface of tenons during the metal infiltration process according to claim 2, characterized in that, Step S2 also includes: After the base protective coating (7) is applied, allow it to cure under dry room temperature conditions; Step S4 also includes: After the outer protective coating (9) is applied, it is placed to cure under dry room temperature conditions.

4. The method for protecting the non-porous surface of tenons during the metal infiltration process according to claim 2, characterized in that, The sealant is a vinyl lacquer.

5. The method for protecting the non-porous surface of a tenon during the metal infiltration process according to claim 1, characterized in that, Before obtaining the target workpiece by vapor phase aluminizing according to the aluminizing process, step S5 also includes: Inspect and clean any residual paint on the aluminized surface (13).

6. The method for protecting the non-porous surface of tenons during the metal infiltration process according to claim 1, characterized in that, Step S6 includes: The parts are subjected to color treatment at a preset time of 500℃-650℃. If the non-permeable surface (2) of the tenon is blue after color treatment, the parts are cut and inspected.

7. The method for protecting the non-porous surface of tenons during the metal infiltration process according to claim 1, characterized in that, Before conducting the inspection, step S6 also includes: Remove the protective layer from the tenon and clean and dry it.

8. An aircraft engine, characterized in that, The method for protecting the non-porous surface of tenons during the metal infiltration process, as described in any one of claims 1-7, is applicable.

Images