A method for evaluating the effectiveness of a coating chemical removal solvent

Abstract

This invention provides a method for evaluating the effectiveness of chemical solvent removal from coatings, belonging to the technical field of aero-engine turbine blade coating modification. The method includes: S1: preparing multiple sets of solvent removal solutions; S2: preparing multiple samples with the same coating; S3: setting identical protective areas on the surfaces of all samples; S4: conducting the coating removal reaction and starting timing; S5: stopping the removal when the reaction ends, denoted as T; S6: removing the samples, cleaning, removing the protective coating, preparing metallographic samples, and performing metallographic testing; S7: obtaining the removal area of ​​each sample using metallographic image analysis software, denoted as S; S8: judging the coating removal effect of the solvent based on time T and area S. This method can quantitatively compare the removal effects of different formulations, thereby achieving an evaluation of the effectiveness of the solvent removal agent and solving the problem of strong subjectivity in the manual evaluation of the removal effect of solvent removal agents in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine turbine blade coating modification technology, specifically relating to a method for evaluating the effectiveness of chemical solvent removal from coatings. Background Technology

[0002] Aero-engine turbine blades operate in high-temperature, high-pressure, and high-speed environments, and their surfaces typically require protective coatings, such as aluminide coatings. During regular engine maintenance, coatings on blade surfaces that do not meet standards need to be removed and reapplied. The main methods for removing blade coatings are physical and chemical methods. Physical methods, including sandblasting and mechanical grinding, are time-consuming, inefficient, and can damage the blade substrate. Therefore, chemical methods remain the primary method for removing aluminide coatings.

[0003] When using chemical methods to remove aluminide coatings, the key technology lies in the chemical formulation. The removal agent formulation needs to be designed based on the coating and substrate composition, and then optimized based on the removal effect. The removal effect is generally judged using weighing and visual methods. Visual observation of the removed surface relies heavily on human judgment of the removal agent's effectiveness, making it highly subjective; different inspectors may produce biased results. Weighing, on the other hand, requires measuring the amount removed. Given the small amount removed, the error from weighing has a significant impact, and it cannot accurately determine whether corrosion products have been completely removed, making it difficult to accurately assess the removal effect.

[0004] In summary, the lack of a scientific method for evaluating the effectiveness of chemical removal agents for aluminide coatings makes it difficult to assess the reaction effects of multiple removal agent formulations, which hinders formulation development and optimization. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that the evaluation of the effectiveness of chemical coating removers in the prior art is highly subjective and it is difficult to accurately evaluate the effect of the removers.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for evaluating the effectiveness of chemical solvent removal from coatings, comprising: S1: Prepare multiple sets of solvent removal solutions; S2: Prepare multiple samples with the same coating; S3: Set up the same protective area on all sample surfaces, perform protective operations on the protective area, and perform wet sandblasting on the surface of the non-protected area; S4: Place the samples into the removal solvent to carry out the coating removal reaction and start timing; S5: Stop the removal process when the coating removal reaction is complete, and record the removal time as T; S6: Take out the sample, clean it, remove the protective coating, prepare a metallographic sample, and conduct a metallographic test. S7: The area removed from each sample is obtained using metallographic image analysis software and denoted as S; S8: Determine the solvent coating removal effect based on time T and area S.

[0007] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the following technical features: in step S2, multiple samples are samples prepared in the same batch with the same substrate material, the same size, and the same batch. The sample size is not less than 10mm × 10mm × 3mm, and the number of samples is not less than the number of groups that remove solvent.

[0008] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the technical feature that the protected area occupies 1 / 3 of the area of ​​the sample coating.

[0009] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the following technical feature: the protective operation of the protected area in S3 includes masking and protection using chemically removed protective tape or protective paint.

[0010] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the following technical features: in step S3, the pressure of wet sandblasting on the coating surface is 0.1-0.3 MPa, and the distance is 100-250 mm.

[0011] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by the present invention also has the technical feature that stirring is continuously performed during coating removal in step S4.

[0012] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the following technical features: the post-cleaning removal of protection in step S6 further includes drying the sample after cleaning and polishing it during the preparation of the metallographic sample.

[0013] The method for evaluating the effectiveness of chemical solvent removal from coatings provided by this invention also has the following technical features: the determination of the solvent removal effect of the coating based on time T and area S in step S8 includes: determining the removal effect based on the coating reaction rate r, where r = S / T.

[0014] Beneficial effects: The evaluation method provided in this application uses metallographic image analysis software to obtain the coating removal area, and then divides it by the removal time to obtain the coating removal rate of different removal agents. This allows for a quantitative comparison of the removal effects of different formulations, thereby enabling the evaluation of the effectiveness of the removal agent and solving the problem of strong subjectivity in the manual evaluation of the removal effect of the removal agent in the prior art. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a statistical chart of the area removed in the method provided in the embodiments of the present invention; Figure 2 This is a schematic diagram of the chemical removal process of the coating. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent changes or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0018] In the description of the embodiments of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the invention.

[0019] Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] The terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art will understand the specific meaning of these terms in this invention based on the specific circumstances.

[0021] This invention provides a method for evaluating the effectiveness of chemical solvent removal from coatings, comprising: S1: preparing multiple sets of solvent removal solutions; S2: Prepare multiple samples with the same coating; S3: Set up the same protective area on all sample surfaces, perform protective operations on the protective area, and perform wet sandblasting on the surface of the non-protected area; S4: Place the samples into the removal solvent to carry out the coating removal reaction and start timing; S5: Stop the removal process when the coating removal reaction is complete, and record the removal time as T; S6: Take out the sample, clean it, remove the protective coating, prepare a metallographic sample, and conduct a metallographic test. S7: The area removed from each sample is obtained using metallographic image analysis software and denoted as S; S8: Determine the solvent coating removal effect based on time T and area S.

[0022] In some embodiments, in step S2, multiple samples are samples prepared in the same batch with the same matrix material, the same size, and the same batch. The sample size is not less than 10mm×10mm×3mm, and the number of samples is not less than the number of groups that have had the solvent removed.

[0023] In some embodiments, the protected area occupies one-third of the area of ​​the sample coating. The location and size of the protected area are the same for each sample.

[0024] In some embodiments, the protective operation in S3 includes using chemically removed protective tape or protective paint to mask the area. This protective operation ensures that the un-sandblasted area is not corroded. In some embodiments, the pressure for wet sandblasting the coating surface in step S3 is 0.1-0.3 MPa, and the distance is 100-250 mm.

[0025] In some embodiments, stirring continues during coating removal in step S4.

[0026] In some embodiments, the removal of protection after cleaning in S6 also includes drying the sample after cleaning and polishing during the preparation of the metallographic sample.

[0027] In some embodiments, the determination of the solvent coating removal effect based on time T and area S in step S8 includes: determining the removal effect based on the coating reaction rate r, where r = S / T.

[0028] The technical principle of the method provided in any of the above embodiments is as follows: Regardless of the type of removal agent, the removal of the aluminide coating involves the following process: Figure 2The process is illustrated. Initially, pitting occurs on the coating surface. As the removal process progresses, these pits develop in two directions: Path 1: Pittings grow laterally and connect, gradually flattening the surface, reducing the number of pits and their cross-sectional area; or new pits connect, resulting in a flattened surface and a smaller area. Path 2: Pittings grow vertically and connect, reducing the number of pits but increasing their area. Finally, all pits merge, resulting in a relatively smooth substrate surface. Based on the coating removal process, the area S (mm²) of the coating removed can be obtained using metallographic image analysis software. 2 Divide the coating reaction rate r (mm) by the removal time T (min), and obtain the coating reaction rate r (mm). 2 The larger the value of V (per min), the faster the removal rate and the more effective the solution; conversely, the smaller the value of V, the more effective the removal agent. This allows for a quantitative assessment of the effectiveness of the removal agent.

[0029] like Figure 1 As shown, based on the method provided in the above embodiments, the chemical removal formulation for AlSiY coatings on aero-engine turbine blades was optimized: (1) Prepare four groups of removal agent solutions to verify the removal effectiveness, and label them as A, B, C and D in order; (2) Prepare four coating samples made of the same substrate material and in the same batch. The sample size is 10mm×20mm×5mm. (3) Protect 1 / 3 of the coating surface of the coating sample with tape, and wet blow sandblast the remaining coating surface with a pressure of 0.2 MPa and a distance of 150 mm; (4) All un-sandblasted areas of the samples were re-masked with tape to ensure that the un-sandblasted areas would not be corroded; (5) Place the sample into the removal agent solution, one sample per solution group; start timing, and keep the solution stirred during the removal process; (6) Observe the reaction of each group of solutions, and record the time after the reaction stops to obtain the reaction time of each group of solutions. =23min =25min =19min =20 minutes; (7) Remove the sample that has stopped being removed from the solution, rinse it with water to remove the masking material, clean it thoroughly and blow it dry; (8) Prepare metallographic specimens from the coated specimens and polish them according to relevant procedures for testing; (9) The samples were cut along the centerline of each test group, and the area of ​​coating removal on the cut surface was analyzed using metallographic image analysis software. The area of ​​coating removal for each sample was calculated statistically. See [link to relevant documentation]. Figure 1 Dashed line area. Area S (μm) removed from groups A, B, C, and D. 2), respectively =2165μm 2 , =1764μm 2 , =2081μm 2 , =2294μm 2 ; (10) Calculate the reaction rate r respectively. =94.13μm 2 / min、 =70.56μm 2 / min、 =109.53μm 2 / min、 =114.7μm 2 / min, after comparison > > > Based on the comparison results of the size of r, The higher the value, the better the removal effect and the higher the effectiveness of the D-formula. The lowest value indicates that remover B is the least effective and has low efficiency.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. 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 technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method of evaluating the effectiveness of a coating chemical removal solvent, characterized by, include: S1: Prepare multiple sets of solvent removal solutions; S2: Prepare multiple samples with the same coating; S3: Set up the same protective area on all sample surfaces, perform protective operations on the protective area, and perform wet sandblasting on the surface of the non-protected area; S4: Place the samples into the removal solvent to carry out the coating removal reaction and start timing; S5: Stop the coating removal reaction when it ends, and record the removal time as T; S6: Take out the sample, clean it, remove the protective coating, prepare a metallographic sample, and conduct a metallographic test. S7: The area removed from each sample is obtained using metallographic image analysis software and denoted as S; S8: Determine the solvent coating removal effect based on time T and area S.

2. The method of evaluating the effectiveness of a coating chemical removal solvent according to claim 1, wherein, In S2, multiple samples are samples prepared in the same batch with the same matrix material, the same size, and the same batch. The sample size is not less than 10mm×10mm×3mm, and the number of samples is not less than the number of groups that have had the solvent removed.

3. The method of evaluating the effectiveness of a coating chemical removal solvent according to claim 1, wherein, The protected area occupies 1 / 3 to 1 / 2 of the area of ​​the sample coating.

4. The method of evaluating the effectiveness of a coating chemical removal solvent according to claim 1, wherein The protective operation in S3 includes using chemically removed protective tape or protective paint to mask and protect the area.

5. The method of evaluating the effectiveness of a coating chemical removal solvent according to claim 1, wherein, In step S3, the pressure for wet sandblasting of the coating surface is 0.1-0.3 MPa, and the distance is 100-250 mm.

6. The method for evaluating the effectiveness of chemical solvent removal from coatings according to claim 1, characterized in that, Stirring continues during the coating removal process in step S4.

7. The method for evaluating the effectiveness of chemical solvent removal from coatings according to claim 1, characterized in that, The removal of protection after cleaning in S6 also includes drying the sample after cleaning and polishing it during the preparation of the metallographic sample.

8. The method for evaluating the effectiveness of chemical solvent removal from coatings according to claim 1, characterized in that, The determination of the solvent coating removal effect based on time T and area S in S8 includes: determining the removal effect based on the coating reaction rate r, where r = S / T.

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