Method for removing oxides on surface of nickel-based superalloy blade

Abstract

The invention provides a method for removing oxides on the surface of a nickel-based superalloy blade. The method comprises the steps of pre-corrosion, main corrosion, aftertreatment, cold water cleaning, neutralization, cold water cleaning, hot water cleaning, drying and inspection of the oxide removal effect on the surface of the blade and the surface of an inner cavity of the blade. According to the method disclosed by the invention, the oxide and the corrosive liquid are subjected to chemical reaction, so that high-efficiency removal of compact metal oxides such as hafnium, nickel, chromium and titanium on the surface of the inner cavity of the nickel-based high-temperature alloy blade and the surface of the inner cavity is realized.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy blade technology, and in particular relates to a method for removing oxides from the surface of nickel-based high-temperature alloy blades. Background Technology

[0002] In the manufacturing process of nickel-based superalloy blades, high-temperature processes such as core removal and heat treatment can cause the formation of metal oxides such as hafnium, nickel, chromium, and titanium on the outer or inner surfaces of the blades. These metal oxides have complex compositions and their presence can have several adverse effects. From a performance perspective, oxides reduce the surface smoothness of the blades, affecting their aerodynamic performance, increasing airflow turbulence, and impacting the efficiency of engines or gas turbines. From a subsequent processing perspective, oxides can interfere with subsequent processes such as blade welding and coating, affecting the mechanical properties of the blades and the adhesion of coatings, thus shortening the blade's service life.

[0003] Currently, methods for removing oxides from the surface of nickel-based superalloy blades have several shortcomings. On the one hand, existing mechanical removal methods (such as manual grinding and sandblasting) are greatly affected by human factors, easily leading to uneven blade dimensions; and the removal amount is generally only 10-100 μm, which negatively impacts blade dimensional accuracy. Furthermore, these methods rely on manual operation, and when the blade size is large or the structure is complex, a single piece can take 1-2 hours, resulting in low production efficiency. Simultaneously, due to limitations in equipment and tool accessibility, they cannot effectively remove oxides from the inner surface of blades with narrow and curved cavities. On the other hand, while chemical etching can solve some of the problems of mechanical methods, the oxides are dense and difficult to corrode due to the high-temperature and high-pressure production process, making ordinary acids ineffective in decomposing the oxides. Moreover, improper formulation of the etching solution and control of the etching method can easily lead to incomplete oxide removal or excessive corrosion of the substrate, thus affecting the dimensional accuracy and mechanical properties of the blade. Therefore, there is an urgent need for a highly efficient method that can effectively remove oxides from the surface of nickel-based superalloy blades without damaging the substrate. Summary of the Invention

[0004] In view of this, the present invention aims to overcome the defects in the prior art and proposes a method for removing oxides from the surface of nickel-based superalloy blades.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: A method for removing oxides from the surface of nickel-based superalloy blades includes the following steps: Step 1, Pre-corrosion: Immerse the blades in a low-concentration corrosive solution containing hydrochloric acid and deionized water; Step 2, Main Corrosion: Immerse the blades in a high-concentration corrosive solution, which contains acid, complexing agent and deionized water; Step 3, Post-treatment: Immerse the leaves in a complexing solution, which includes a complexing agent and deionized water; Step 4: Cold water rinsing: Soak the leaves in clean water to remove the corrosive liquid from the surface of the leaves; Step 5, Neutralization: Soak the leaves in an alkaline solution to neutralize the residual corrosive liquid on the leaf surface; Step 6: Cold water rinsing: Soak the leaves in clean water to remove any residual alkaline solution from the leaf surface; Step 7: Hot water washing: Soak the leaves in clean water to remove any residual alkaline solution from the leaf surface; Step 8: Drying: Place the leaves in a drying oven to dry; Step 9: Inspect the oxide removal effect on the surface of the blade and the inner surface of the blade cavity.

[0006] The pre-corrosion, main corrosion, and post-treatment processes described in this invention can all be used independently to remove oxides from the surface of nickel-based superalloys. In each step, mechanical stirring, ultrasonic vibration, or gas-boiling stirring can be added to improve solution fluidity and chemical reaction rate. The low-concentration corrosive solution breaks the bonding force between the oxide and the nickel-based superalloy matrix, initially loosening the oxide on the alloy surface. The high-concentration corrosive solution has strong oxidizing properties, rapidly destroying the crystal structure of the oxide through redox reactions, protonation reactions, and complexation reactions, thereby removing the oxide layer. The complexing solution can form stable complexes with metal ions, preventing the redeposition of metal ions and the formation of new oxides. The oxides that can be removed by this invention are not limited to hafnium, nickel, chromium, titanium, and other metal oxides.

[0007] Preferably, the mass concentration of hydrochloric acid in step one is 5-10%.

[0008] Preferably, in step one, the temperature of the corrosive solution is 20~30℃, and the soaking time is 2~5 minutes.

[0009] Preferably, the acid solution in step two is nitric acid.

[0010] More preferably, the mass concentration of the acid solution in step two is 20-30%.

[0011] Preferably, the complexing agent in step two comprises one or more of hydrofluoric acid, citric acid, oxalic acid, and ethylenediaminetetraacetic acid.

[0012] More preferably, the mass concentration of the complexing agent in step two is 1~10%.

[0013] Preferably, in step two, the temperature of the corrosive solution is 25~40℃, and the soaking time is 1~2 minutes.

[0014] Preferably, the complexing agent in step three is one or more of hydrofluoric acid, citric acid, oxalic acid, and ethylenediaminetetraacetic acid.

[0015] Preferably, the mass concentration of the complexing agent in step three is 1-5%.

[0016] Preferably, the temperature of the complexing solution in step three is 20~30℃, and the soaking time is 1~2 minutes.

[0017] Preferably, in step four, the water temperature is 20~30℃ and the soaking time is 3~5 minutes.

[0018] Preferably, in step five, the temperature of the alkaline solution is 20-30°C, and the soaking time is 3-5 minutes.

[0019] Preferably, the alkaline solution in step five is an aqueous solution of sodium carbonate or sodium hydroxide.

[0020] Preferably, in step six, the water temperature is 20~30℃ and the soaking time is 3~5 minutes.

[0021] Preferably, in step seven, the water temperature is 60~90℃ and the soaking time is 3~5 minutes.

[0022] Preferably, the drying temperature in step eight is 80~100℃ and the drying time is 1~2h.

[0023] Existing technologies use mechanical methods to remove oxides from the surface of high-temperature alloys: mainly relying on manual grinding and sandblasting, which is greatly affected by human factors and easily leads to uneven blade size; the removal amount is relatively large, generally 10~100μm, which can adversely affect the blade size; manual grinding or sandblasting is required, and when the blade size is large or the structure is complex, it takes 1~2 hours, resulting in low production efficiency; due to the blade structure, when the inner cavity is narrow and curved, the equipment and tools used (grinding gun, sandblasting probe, etc.) cannot enter the inner cavity, so this method cannot remove the oxides on the inner cavity surface. In contrast, this invention uses a chemical method to remove oxides through a chemical reaction between the oxides and the corrosive liquid; it is not affected by human factors, and the corrosion is uniform; due to the short reaction time, it causes almost no corrosion to the blades and has no impact on the blade size; the oxides can be completely removed by simply immersing the blades in the corrosive liquid for no more than 10 minutes, and it can be used for mass production with automated equipment, resulting in extremely high production efficiency; the blades only need to be immersed in the corrosive liquid, and the fluidity of the liquid allows them to enter the inner cavity, which is not affected by the blade structure.

[0024] Compared with the prior art, the present invention has the following advantages: (1) The method proposed in this invention achieves efficient removal of dense metal oxides such as hafnium, nickel, chromium, and titanium from the inner cavity surface and inner cavity surface of nickel-based high-temperature alloy blades by chemically reacting oxides with corrosive liquid; (2) The method proposed in this invention has uniform corrosiveness and can uniformly remove oxides from the surface and inner cavity of the blade without adversely affecting the shape of the blade. (3) The method proposed in this invention only requires immersing the blade in the corrosive solution, and the total corrosion time does not exceed 10 minutes. Due to the short chemical reaction time, it causes almost no corrosion damage to the blade substrate and has no effect on the blade size; (4) The step corrosion proposed in this invention uses both high-concentration corrosive liquid as the main corrosive liquid to remove oxides and low-concentration corrosive liquid to loosen the dense oxides. Each stage complements the other, avoiding the use of high-concentration corrosive liquid throughout the process to accelerate the corrosion of the blade substrate. (5) The method proposed in this invention can be adapted to automated equipment for operation, can achieve mass production, has high production efficiency, and can meet the needs of large-scale industrial production. (6) The method proposed in this invention allows the corrosive liquid to enter the inner cavity by utilizing the fluidity of the liquid, without being limited by the blade structure. Even in small, curved inner cavities or blind cavities, oxides can be effectively removed, making it widely applicable. Attached Figure Description

[0025] Figure 1 Comparison of the blades before and after the reaction in Examples 1-4; Figure 2 Comparative Examples 1-4: leaf comparison before and after reaction. Detailed Implementation

[0026] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] In this document, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0028] In this document, when values ​​are described as ranges, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as the specific numerical values ​​falling within that range, regardless of whether the specific numerical value or specific subrange is explicitly specified.

[0029] In this article, the terms "multiple" or "more than" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0030] In this document, the terms "preferred" and "more preferred" are used only to describe implementation methods or embodiments with better effects, and should be understood as not constituting a limitation on the scope of protection of this invention.

[0031] In this document, terms such as "further" are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0032] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0033] In this document, the term "about" means a specified value of + / - 10%, preferably + / - 5%, and more preferably + / - 1%.

[0034] In this article, the terms “include,” “including,” “have,” “contain,” etc., are all open-ended terms, meaning that they include but are not limited to.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0036] In the embodiments, blades A1, A2, A3, B1, B2, and B3 are blades of the same model and manufactured using the same process, and there are no differences between them.

[0037] The present invention will be described in detail below with reference to embodiments.

[0038] Example 1 1) Pre-corrosion: Immerse blade A1 in a low-concentration corrosive solution containing hydrochloric acid and deionized water. The hydrochloric acid concentration is 5% by mass. The temperature of the corrosive solution is 25°C, and the immersion time is 2 minutes.

[0039] 2) Main corrosion: Blade A1 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, and deionized water. The nitric acid concentration was 20% by mass, and the hydrofluoric acid concentration was 1% by mass. The temperature of the corrosive solution was 40°C, and the immersion time was 1 minute.

[0040] 3) Post-treatment: Immerse leaf A1 in a complexing solution consisting of hydrofluoric acid and deionized water, with a complexing agent concentration of 1%. The complexing solution temperature is 25℃, and the immersion time is 1 min.

[0041] 4) Cold water cleaning: Immerse blade A1 in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0042] 5) Neutralization: Immerse leaf A1 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0043] 6) Cold water rinsing: Soak leaf A1 in running water to remove residual alkaline solution on the leaf surface. Water temperature: 25℃, soaking time: 3 minutes.

[0044] 7) Hot water cleaning: Soak leaf A1 in clean water to further remove residual alkaline solution on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0045] 8) Drying: Place leaf A1 in a drying oven to dry at 80℃ for 2 hours.

[0046] 9) Inspection: Use an electronic endoscope to observe the internal condition of blade A1, test the surface roughness of the blade with a roughness tester, and check the dimensional measurement with a coordinate measuring machine.

[0047] Example 2 1) Pre-corrosion: Immerse blade A2 in a low-concentration corrosive solution containing hydrochloric acid and deionized water. The hydrochloric acid concentration is 10%. The temperature of the corrosive solution is 25°C, and the immersion time is 5 minutes.

[0048] 2) Main corrosion: Blade A2 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, and deionized water. The nitric acid concentration was 30% by mass, and the hydrofluoric acid concentration was 10% by mass. The temperature of the corrosive solution was 40°C, and the immersion time was 2 minutes.

[0049] 3) Post-treatment: Immerse leaf A2 in a complexing solution consisting of hydrofluoric acid and deionized water, with a complexing agent concentration of 5%. The complexing solution temperature is 25℃, and the immersion time is 2 minutes.

[0050] 4) Cold water cleaning: Immerse blade A2 in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0051] 5) Neutralization: Immerse leaf A2 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0052] 6) Cold water rinsing: Soak leaf A2 in running water to remove residual alkaline solution on the leaf surface. Water temperature: 25℃, soaking time: 3 minutes.

[0053] 7) Hot water cleaning: Soak leaf A2 in clean water to further remove residual alkaline solution on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0054] 8) Drying: Place leaf A2 in a drying oven and dry at 80℃ for 2 hours.

[0055] 9) Inspection: Use an electronic endoscope to observe the internal condition of blade A2, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0056] Example 3 1) Pre-corrosion: Immerse blade A3 in a low-concentration corrosive solution containing hydrochloric acid and deionized water. The hydrochloric acid concentration is 8%. The temperature of the corrosive solution is 25°C, and the immersion time is 3 minutes.

[0057] 2) Main corrosion: Blade A3 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, and deionized water. The nitric acid concentration was 25% by mass, and the hydrofluoric acid concentration was 5% by mass. The temperature of the corrosive solution was 40°C, and the immersion time was 2 minutes.

[0058] 3) Post-treatment: Immerse leaf A3 in a complexing solution consisting of hydrofluoric acid and deionized water, with a complexing agent concentration of 3%. The complexing solution temperature is 25℃, and the immersion time is 2 minutes.

[0059] 4) Cold water cleaning: Immerse blade A3 in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0060] 5) Neutralization: Immerse leaf A3 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0061] 6) Cold water rinsing: Soak leaf A3 in running water to remove residual alkaline solution on the leaf surface. Water temperature: 25℃, soaking time: 3 minutes.

[0062] 7) Hot water cleaning: Soak leaf A3 in clean water to further remove residual alkaline solution on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0063] 8) Drying: Place leaf A3 in a drying oven and dry at 80℃ for 2 hours.

[0064] 9) Inspection: Use an electronic endoscope to observe the internal condition of blade A3, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0065] Example 4 1) Pre-corrosion: Immerse blade A4 in a low-concentration corrosive solution containing hydrochloric acid and deionized water. The hydrochloric acid concentration is 8%. The temperature of the corrosive solution is 25°C, and the immersion time is 3 minutes.

[0066] 2) Main Corrosion: Blade A4 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, citric acid, and deionized water. The nitric acid concentration was 25%, the hydrofluoric acid concentration was 2%, and the citric acid concentration was 3%. The temperature of the corrosive solution was 40°C, and the immersion time was 2 minutes.

[0067] 3) Post-treatment: Immerse the A4 leaves in a complexing solution composed of hydrofluoric acid, citric acid, and deionized water. The hydrofluoric acid concentration is 1% and the citric acid concentration is 2%. The temperature of the complexing solution is 25℃, and the immersion time is 2 minutes.

[0068] 4) Cold water cleaning: Immerse the A4 blades in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃, and the soaking time is 3 minutes.

[0069] 5) Neutralization: Immerse the A4 leaf in a sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0070] 6) Cold water rinsing: Soak the A4 leaves in running water to remove the alkaline solution remaining on the leaf surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0071] 7) Hot water cleaning: Soak the A4 leaves in clean water to further remove the alkaline solution remaining on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0072] 8) Drying: Place the A4 leaf in a drying oven and dry at 80℃ for 2 hours.

[0073] 9) Inspection: Use an electronic endoscope to observe the internal condition of the blade A4 cavity, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0074] Comparative Example 1 1) Main corrosion: Blade B1 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, and deionized water. The nitric acid concentration was 25% by mass, and the hydrofluoric acid concentration was 5% by mass. The temperature of the corrosive solution was 40°C, and the immersion time was 2 minutes.

[0075] 2) Cold water cleaning: Immerse blade B1 in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0076] 3) Neutralization: Immerse leaf B1 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0077] 4) Cold water rinsing: Soak leaf B1 in running water to remove residual alkaline solution on the leaf surface. Water temperature: 25℃, soaking time: 3 minutes.

[0078] 5) Hot water cleaning: Soak leaf B1 in clean water to further remove residual alkaline solution on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0079] 6) Drying: Place leaf B1 in a drying oven to dry at 80℃ for 2 hours.

[0080] 7) Inspection: Use an electronic endoscope to observe the internal condition of blade B1, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0081] Comparative Example 2 1) Pre-corrosion: Immerse blade B2 in a low-concentration corrosive solution containing hydrochloric acid and deionized water. The hydrochloric acid concentration is 5%. The temperature of the corrosive solution is 25°C, and the immersion time is 2 minutes.

[0082] 2) Main corrosion: Blade B2 was immersed in a high-concentration corrosive solution containing nitric acid, hydrofluoric acid, and deionized water. The nitric acid concentration was 15% by mass, and the hydrofluoric acid concentration was 5% by mass. The temperature of the corrosive solution was 40°C, and the immersion time was 2 minutes.

[0083] 3) Post-treatment: Immerse leaf B2 in a complexing solution consisting of hydrofluoric acid and deionized water, with a complexing agent concentration of 5%. The complexing solution temperature is 25℃, and the immersion time is 2 minutes.

[0084] 4) Cold water cleaning: Immerse the B2 blade in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃, and the soaking time is 3 minutes.

[0085] 5) Neutralization: Immerse leaf B2 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0086] 6) Cold water rinsing: Soak the leaves of B2 in running water to remove the alkaline solution remaining on the leaf surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0087] 7) Hot water cleaning: Soak the leaves of B2 in clean water to further remove the alkaline solution remaining on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0088] 8) Drying: Place leaf B2 in a drying oven to dry at 80℃ for 2 hours.

[0089] 9) Inspection: Use an electronic endoscope to observe the internal condition of blade B1, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0090] Comparative Example 3 1) Corrosion: Immerse the blade B3 in nitric acid with a mass concentration of 25%, a corrosion solution temperature of 40℃, and an immersion time of 15 minutes.

[0091] 2) Cold water cleaning: Immerse the B3 blade in running water to remove the corrosive liquid on the blade surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0092] 3) Neutralization: Immerse leaf B3 in sodium carbonate solution to neutralize the residual corrosion liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0093] 4) Cold water rinsing: Soak the leaves of B3 in running water to remove the alkaline solution remaining on the leaf surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0094] 5) Hot water cleaning: Soak the leaves of B3 in clean water to further remove the alkaline solution remaining on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0095] 6) Drying: Place leaf B3 in a drying oven to dry at 80℃ for 2 hours.

[0096] 7) Inspection: Use an electronic endoscope to observe the internal condition of blade B1, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0097] Comparative Example 4 1) Corrosion: Immerse the B4 blade in hydrochloric acid with a mass concentration of 25%, a corrosion solution temperature of 40℃, and an immersion time of 15 minutes.

[0098] 2) Cold water cleaning: Immerse the B4 blades in running water to remove the corrosive liquid from the blade surface. The water temperature is 25℃, and the soaking time is 3 minutes.

[0099] 3) Neutralization: Immerse the leaf blades in a sodium carbonate solution to neutralize the residual corrosive liquid on the leaf surface. The solution concentration is 5%, the solution temperature is 25℃, and the immersion time is 3 minutes.

[0100] 4) Cold water rinsing: Soak the leaves of B4 in running water to remove the alkaline solution remaining on the leaf surface. The water temperature is 25℃ and the soaking time is 3 minutes.

[0101] 5) Hot water cleaning: Soak the leaves of B4 in clean water to further remove the alkaline solution remaining on the leaf surface. The water temperature is 60℃ and the soaking time is 3 minutes.

[0102] 6) Drying: Place the B4 leaf in a drying oven and dry at 80℃ for 2 hours.

[0103] 7) Inspection: Use an electronic endoscope to observe the internal condition of blade B4, use a roughness tester to test the surface roughness of the blade, and use a coordinate measuring machine to check the dimensional changes.

[0104] The detection results of Examples 1-4 and Comparative Examples 1-4 are shown in the figure. Figure 1 , Figure 2 And Table 1: Table 1. Oxide Removal Effect in the Inner Lumen The experimental data from Comparative Examples 1 and 2 show that an effective oxide removal effect can be achieved when the mass concentration of nitric acid in the main corrosion solution is 20-30% and the mass concentration of the complexing agent is 1-10%. Beyond this range, the oxide removal effect deteriorates significantly.

[0105] The experimental data from Comparative Examples 3 and 4 show that neither hydrochloric acid nor nitric acid alone can remove the oxides on the inner surface of the heat-treated nickel-based superalloy. Furthermore, the surface roughness of the blades increases after the reaction, and the acid solution causes severe corrosion to the blades.

[0106] The experimental data from Examples 1 to 4 show that the step corrosion method proposed in this invention is most effective at removing oxides from the inner surface of nickel-based superalloys, and has minimal impact on alloy corrosion.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for removing oxides from the surface of nickel-based superalloy blades, characterized in that: Includes the following steps: Step 1, Pre-corrosion: Immerse the blades in a low-concentration corrosive solution containing hydrochloric acid and deionized water; Step 2, Main Corrosion: Immerse the blades in a high-concentration corrosive solution, which contains acid, complexing agent and deionized water; Step 3, Post-treatment: Immerse the leaves in a complexing solution, which includes a complexing agent and deionized water; Step 4: Cold water rinsing: Soak the leaves in clean water to remove the corrosive liquid from the surface of the leaves; Step 5, Neutralization: Soak the leaves in an alkaline solution to neutralize the residual corrosive liquid on the leaf surface; Step 6: Cold water rinsing: Soak the leaves in clean water to remove any residual alkaline solution from the leaf surface; Step 7: Hot water washing: Soak the leaves in clean water to remove any residual alkaline solution from the leaf surface; Step 8: Drying: Place the leaves in a drying oven to dry; Step 9: Inspect the oxide removal effect on the blade surface and the inner cavity surface of the blade.

2. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step one, the mass concentration of hydrochloric acid is 5-10%; preferably, the temperature of the corrosive solution in step one is 20-30℃, and the soaking time is 2-5 minutes.

3. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: The acid solution in step two is nitric acid; More preferably, the mass concentration of the acid solution in step two is 20-30%.

4. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: The complexing agent in step two includes one or more of hydrofluoric acid, citric acid, oxalic acid, and ethylenediaminetetraacetic acid. More preferably, the mass concentration of the complexing agent in step two is 1~10%.

5. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step two, the temperature of the corrosive solution is 25~40℃, and the soaking time is 1~2 minutes.

6. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: The complexing agent in step three is one or more of hydrofluoric acid, citric acid, oxalic acid, and ethylenediaminetetraacetic acid. Preferably, the mass concentration of the complexing agent in step three is 1-5%; Preferably, the temperature of the complexing solution in step three is 20~30℃, and the soaking time is 1~2 minutes.

7. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step four, the water temperature is 20-30℃ and the soaking time is 3-5 minutes. Preferably, in step five, the temperature of the alkaline solution is 20-30°C, and the soaking time is 3-5 minutes. Preferably, the alkaline solution in step five is an aqueous solution of sodium carbonate or sodium hydroxide.

8. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step six, the water temperature is 20-30℃ and the soaking time is 3-5 minutes.

9. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step seven, the water temperature is 60-90℃ and the soaking time is 3-5 minutes.

10. The method for removing oxides from the surface of nickel-based superalloy blades according to claim 1, characterized in that: In step eight, the drying temperature is 80~100℃ and the drying time is 1~2h.

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