A method for detecting residual core of hollow turbine blades

Abstract

The present invention provides a method for detecting residual cores of hollow turbine blades by a chemical method, and belongs to the field of advanced aircraft engine hollow turbine blade investment casting. The present invention uses a chemical method to react the hollow turbine blades in an alkaline solution of a certain concentration, and then uses an acid solution of a certain concentration to titrate the supernatant of the solution after the reaction. If a white precipitate is produced in the supernatant after the titration, it can be determined that the hollow turbine blade contains residual cores. If no white precipitate is produced in the supernatant after the titration, it can be determined that the hollow turbine blade does not contain residual cores. The present invention is a non-destructive testing technology for hollow turbine blades. The chemical method provided by the present invention has a simple process, low cost, and accurate test results, avoiding misjudgments and missed judgments that may be caused by other detection methods.

Description

Technical Field

[0001] The present invention belongs to the technical field of investment casting, and in particular relates to a method for detecting the residual core of a hollow turbine blade, specifically a method for detecting the residual core of a hollow turbine blade by a chemical method, which is mainly used for detecting the residual core of a nickel-based high-temperature alloy hollow turbine blade prepared by using a silicon oxide-based ceramic core. Background Art

[0002] The most critical hot end component of advanced aircraft engines is the turbine blade. In order to improve the thrust-to-weight ratio of aircraft engines, the operating temperature of turbine blades continues to increase. In order to improve the cooling efficiency and further increase the temperature of the front end of the turbine blade, air cooling structure is adopted in advanced gas turbine blades. The inner cavity structure design of efficient air-cooled blades is becoming more and more complex, and the tortuous cooling channel needs to be formed by a prefabricated ceramic core with a complex shape. Since the shape of the ceramic core is very complex, the blade needs to be chemically reacted with a high-temperature and high-pressure strong alkaline solution after casting to remove the core and form a complex inner cavity structure of the blade. However, after the blade is de-cored, ceramic cores often remain in the complex inner cavity channel of the blade. During the service of the blade, these residual cores will block the cooling channel inside the blade, affect the smooth flow of cooling air, form hot spots in the local area of ​​the blade, and then locally ablate, seriously affecting the safety of the aircraft engine. Before the hollow turbine blade is put into service, it is necessary to ensure that the inner cavity of the blade is thoroughly cleaned, so the residual core detection technology of the blade is particularly important.

[0003] At present, there are five main methods for detecting residual cores of hollow turbine blades, all of which have their advantages and disadvantages. The first is the endoscopic detection method, which is simple and convenient to operate and has intuitive detection results, but it is only applicable to blades with simple cavity structures and is difficult to detect for blades with complex cavity structures; the second is the X-ray detection method, which has a fast detection speed and the detection results can directly determine the position of the residual core, but has low sensitivity and is very likely to cause misjudgment and missed detection; the third is the powder filling X-ray detection method, which has the advantage of improving the sensitivity of X-rays, but the disadvantage is that the powder in the complex cavity is difficult to fill, resulting in false detection, and at the same time, the powder in the complex cavity is difficult to remove after detection, which is bound to cause the addition of new excess materials; the fourth is the flow measurement method, which has the advantage of simple operation and intuitive results, and is particularly suitable for porous structures, but the disadvantage is that the error is large, resulting in a greater risk of misjudgment and missed detection; the fifth is the neutron detection method, which has clear and accurate results and can effectively determine the size and position of the residual core, but the neutron detection is expensive and has a long detection cycle, and is only suitable for the research and development stage. The above five detection methods are all used in my country's aero-engine factories, but none of them can achieve fast, efficient and accurate detection of the residual core of hollow turbine blades. Therefore, the development process of hollow turbine blades for aero-engines urgently needs an efficient and accurate residual core detection method. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a method for detecting the residual core of a hollow turbine blade. The method provided by the present invention can detect the residual core of a hollow turbine blade efficiently, accurately and quickly.

[0005] The present invention provides a method for detecting residual core of a hollow turbine blade, comprising:

[0006] The hollow turbine blade is immersed in an alkaline solution to obtain an immersed solution;

[0007] titrating the impregnation solution with an acidic solution;

[0008] If a white precipitate is produced in the solution after the titration, it is determined that the hollow turbine blade contains a residual core. If no white precipitate is produced in the solution after the titration, it is determined that the hollow turbine blade does not contain a residual core.

[0009] Preferably, the alkaline solution is selected from one or more of potassium hydroxide solution and sodium hydroxide solution.

[0010] Preferably, the acidic solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution.

[0011] Preferably, the dipping further comprises:

[0012] The hollow turbine blades are cleaned and dried.

[0013] Preferably, the cleaning is selected from ultrasonic cleaning or cleaning in boiling water.

[0014] Preferably, the drying temperature is 100-150°C.

[0015] Preferably, the concentration of the alkaline solution is 5 to 10 mol / L.

[0016] Preferably, the impregnation conditions include:

[0017] Heat to 100℃ and boil for 120-180min; or

[0018] Keep warm at 150-180℃ and 6-7bar for 20-40min.

[0019] Preferably, the concentration of the acidic solution is 2.5-4.5 mol / L.

[0020] Preferably, the supernatant of the impregnation solution is taken.

[0021] The present invention proposes a method for detecting the residual core of a hollow turbine blade by a chemical method, which is mainly used for detecting the residual core of a nickel-based high-temperature alloy hollow turbine blade prepared by using a silicon oxide-based ceramic core. The present invention uses a chemical method to detect the residual core of a hollow turbine blade, and the method is simple, and the detection result is intuitive and accurate. The present invention uses widely used reagents to perform reactions and titration experiments, and there is no need to change the existing hollow turbine blade manufacturing process. The detection results are accurate, there is no damage or pollution to the blade, and at the same time, it avoids misjudgment and missed judgment that may be caused by other detection methods. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The present invention provides a method for detecting residual core of a hollow turbine blade, comprising:

[0024] The hollow turbine blade is immersed in an alkaline solution to obtain an immersed solution;

[0025] titrating the impregnation solution with an acidic solution;

[0026] If a white precipitate is produced in the solution after the titration, it is determined that the hollow turbine blade contains a residual core. If no white precipitate is produced in the solution after the titration, it is determined that the hollow turbine blade does not contain a residual core.

[0027] In the present invention, the hollow turbine blade is preferably a nickel-based high-temperature alloy hollow turbine blade prepared using a silicon oxide-based ceramic core.

[0028] In the present invention, the dipping preferably further comprises:

[0029] The hollow turbine blades are cleaned and then dried.

[0030] In the present invention, the cleaning method is preferably selected from ultrasonic cleaning or boiling water cleaning.

[0031] In the present invention, the ultrasonic cleaning time is preferably 15 to 60 minutes, more preferably 20 to 50 minutes, more preferably 30 to 40 minutes, and most preferably 35 minutes; the boiling water cleaning is preferably carried out using 100°C boiling water cleaning, and the boiling water cleaning time is preferably 40 to 120 minutes, more preferably 60 to 100 minutes, and most preferably 80 minutes.

[0032] In the present invention, the drying is preferably carried out in an oven; the drying temperature is preferably 100-150°C, more preferably 110-140°C, most preferably 120°C; the drying time is preferably 1-3h, more preferably 1.5-2.5h, most preferably 2h.

[0033] In the present invention, the alkaline solution is preferably selected from one or more of potassium hydroxide solution and sodium hydroxide solution; the concentration of the alkaline solution is preferably 5-10 mol / L, more preferably 6-9 mol / L, most preferably 7-8 mol / L; the concentration is the concentration of OH- in the alkaline solution.

[0034] In the present invention, the impregnation method preferably comprises:

[0035] Heat to boiling for 120 to 180 minutes.

[0036] In the present invention, the boiling temperature is preferably 100° C.; the boiling time is preferably 130 to 170 min, more preferably 140 to 160 min, and most preferably 150 min.

[0037] In the present invention, the impregnation method preferably comprises:

[0038] Put it into the pressure autoclave at 150-180℃, 6-7bar, and keep warm.

[0039] In the present invention, the temperature in the autoclave is preferably 160-170°C, more preferably 165°C; the pressure is preferably 6.5 bar; the insulation time is preferably 20-40 min, more preferably 25-35 min, and most preferably 30 min.

[0040] In the present invention, the impregnation is preferably high temperature and high pressure impregnation, and after the impregnation, it is preferably cooled to room temperature, and after the hollow turbine blades are taken out, the remaining solution is allowed to stand, and the supernatant is taken to obtain the impregnation solution.

[0041] In the present invention, the standing time is preferably 10 to 12 hours, more preferably 11 hours; the volume of the supernatant is preferably 10 to 20 ml, more preferably 15 ml.

[0042] In the present invention, the acidic solution is preferably selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution; the concentration of the acidic solution is preferably 2.5-4.5 mol / L, more preferably 3-4 mol / L, and most preferably 3.5 mol / L; the concentration refers to the H + concentration.

[0043] In the present invention, the volume ratio of the acid solution to the impregnation solution is preferably (30-60):(10-20), more preferably (40-50):(13-17), and most preferably 45:15.

[0044] In the present invention, the method for detecting the residual core of the hollow turbine blade preferably includes:

[0045] The hollow turbine blade is subjected to a high-temperature and high-pressure immersion reaction in a certain concentration of potassium hydroxide or sodium hydroxide or a mixed solution of the two. The main component of silicon dioxide in the residual core of the hollow turbine blade will react chemically with the hydroxide solution to generate silicate ions. Then, a certain concentration of hydrochloric acid, sulfuric acid or nitric acid or a mixed solution of one or more thereof is used to titrate the supernatant of the solution after the reaction. The silicate ions react with the hydrogen ions in the acid solution to generate white precipitate silicic acid. If a white precipitate is generated in the supernatant after the titration, it can be determined that the hollow turbine blade contains a residual core. If no white precipitate is generated in the supernatant after the titration, it can be determined that the hollow turbine blade does not contain a residual core.

[0046] In the present invention, the method for detecting the residual core of the hollow turbine blade more preferably comprises the following steps:

[0047] 1) Place the hollow turbine blade in deionized water for ultrasonic cleaning for 15 to 60 minutes, or place the hollow turbine blade in 100°C boiling deionized water for cleaning for 40 to 120 minutes, take out the blade, place it in a 100°C to 150°C oven, dry it for 1 to 3 hours, and take it out for use;

[0048] 2) Prepare OH- solution: weigh KOH or NaOH or a mixture of the two powders, measure deionized water, and prepare an OH- solution with a concentration of 5 mol / L to 10 mol / L for later use;

[0049] 3) placing the dried leaves in step 1) into the OH- solution prepared in step 2), heating to 100°C and boiling for 120-180 min or placing in an autoclave at 150-180°C, 6-7 bar, and keeping warm for 20-40 min, cooling to room temperature, taking out the leaves, leaving the remaining solution to stand for 10-12 h, taking 10-20 ml of the supernatant for later use;

[0050] 4) Use HCl or HNO3 or H2SO4 or two or more to prepare H with a concentration of 2.5mol / L to 4.5mol / L. + Solution, set aside;

[0051] 5) Measure the H prepared in step 4 + Titrate 10-20 ml of the supernatant obtained in step 3 with 30-60 ml of the solution;

[0052] 6) If H + After the solution titration is completed, if a white precipitate is produced in the supernatant obtained in step 3), it can be determined that the hollow turbine blade contains a residual core;

[0053] 7) If H + After the solution titration is completed, if no white precipitate is produced in the supernatant obtained in step 3), it can be determined that the hollow turbine blade does not contain any residual core.

[0054] The present invention adopts a chemical method to detect the residual core of the hollow turbine blade, the method is simple, and the detection result is intuitive and accurate. The present invention adopts a reagent that is widely used in the market to perform reaction and titration experiments, does not need to change the existing hollow turbine blade manufacturing process, has accurate detection results, does not damage or pollute the blade, and avoids misjudgment and missed judgment that may be caused by other detection methods.

[0055] The hollow turbine blades used in the following embodiments of the present invention are single crystal blades provided by the Beijing Institute of Aeronautical Materials of China Aero Engine Corporation. The blades are nickel-based high-temperature alloy hollow turbine blades prepared using a silicon oxide-based ceramic core.

[0056] Example 1

[0057] 1) Place the hollow turbine blade in deionized water for ultrasonic cleaning for 15 minutes, take out the blade, place it in a 100°C oven, dry it for 1 hour, and take it out for use;

[0058] 2) Prepare KOH solution, weigh KOH powder and deionized water to prepare a KOH solution with a concentration of 5 mol / L, and set aside;

[0059] 3) placing the dried leaves in step 1) into the KOH solution prepared in step 2), heating to 100°C and boiling for 120 min, cooling to room temperature, taking out the leaves, letting the remaining solution stand for 10 h, taking 10 ml of the supernatant and setting aside;

[0060] 4) Prepare 2.5 mol / L HCl solution for later use;

[0061] 5) taking 30 ml of the HCl solution prepared in step 4) and titrating the 10 ml of the supernatant taken in step 3);

[0062] 6) After the titration of 30 ml of HCl solution was completed, a white precipitate appeared in the supernatant obtained in step 3), indicating that the hollow turbine blade contained residual cores.

[0063] Example 2

[0064] 1) Place the hollow turbine blade in deionized water and ultrasonically clean it for 60 minutes, take out the blade, put it in a 150°C oven, dry it for 3 hours, and take it out for use;

[0065] 2) Prepare NaOH solution: weigh NaOH powder and deionized water to prepare a NaOH solution with a concentration of 10 mol / L for later use;

[0066] 3) placing the dried leaves in step 1) into the NaOH solution prepared in step 2), heating to 100°C and boiling for 180 min, cooling to room temperature, taking out the leaves, letting the remaining solution stand for 12 h, taking 20 ml of the supernatant and setting aside;

[0067] 4) Prepare a 4.5 mol / L HNO3 solution for later use;

[0068] 5) Measure 60 ml of the HNO3 solution prepared in step 4) and titrate the 20 ml of the supernatant obtained in step 3;

[0069] 6) After the titration of 60 ml HNO3 solution was completed, a white precipitate appeared in the supernatant obtained in step 3), indicating that the hollow turbine blade contained a residual core.

[0070] Example 3

[0071] 1) Wash the hollow turbine blades in 100°C boiling deionized water for 40 minutes, take out the blades, put them in a 120°C oven, dry them for 1.5 hours, and take them out for use;

[0072] 2) Prepare a mixed solution of KOH and NaOH. Weigh KOH and NaOH powders and measure deionized water to prepare a 7 mol / L OH solution. - Solution, set aside;

[0073] 3) Place the leaves dried in step 1) into the OH solution prepared in step 2) - The solution was placed in a pressure autoclave at 150°C and 6 bar for 20 min, cooled to room temperature, the leaves were taken out, the remaining solution was allowed to stand for 11 h, and 15 ml of the supernatant was taken for later use;

[0074] 4) Prepare a mixed solution of HCl, HNO3 and H2SO4 with a concentration of 3 mol / L. + Solution, set aside;

[0075] 5) Measure the H prepared in step 4 + Titrate 15 ml of the supernatant taken in step 3 with 45 ml of solution;

[0076] 6) H + After the solution titration is completed, no white precipitate appears in the supernatant obtained in step 3, which indicates that the hollow turbine blade does not contain any residual core.

[0077] Example 4

[0078] 1) Wash the hollow turbine blades in 100°C boiling deionized water for 120 min, take out the blades, put them in a 150°C oven, dry them for 1.5 h, and take them out for use;

[0079] 2) Prepare a mixed solution of KOH and NaOH. Weigh KOH and NaOH powders and measure deionized water to prepare a 7 mol / L OH solution. - Solution, set aside;

[0080] 3) placing the dried leaves in step 1) into the OH- solution prepared in step 2), placing them in a pressure autoclave at 180°C, 7 bar, and keeping them warm for 40 minutes, cooling them to room temperature, taking out the leaves, leaving the remaining solution to stand for 12 hours, and taking 15 ml of the supernatant for later use;

[0081] 4) Prepare a mixed solution of HCl, HNO3 and H2SO4 with a concentration of 3 mol / L. + Solution, set aside;

[0082] 5) Measure the H prepared in step 4 + Titrate 15 ml of the supernatant taken in step 3 with 45 ml of solution;

[0083] 6) H + After the solution titration was completed, a white precipitate appeared in the supernatant obtained in step 3, indicating that the hollow turbine blade contained a residual core.

[0084] Performance Testing

[0085] The leaves provided in Examples 1 to 4 were dissected and analyzed by the dissection method, and the inner cavity of the dissected leaves was observed. The observation results were consistent with the detection results of Examples 1 to 4, which further verified the accuracy of the detection method provided in Examples 1 to 4. The detection results of the detection method provided by the present invention are accurate and feasible.

[0086] The present invention adopts a chemical method to detect the residual core of the hollow turbine blade, the method is simple, and the detection result is intuitive and accurate. The present invention adopts a reagent that is widely used in the market to perform reaction and titration experiments, does not need to change the existing hollow turbine blade manufacturing process, has accurate detection results, does not damage or pollute the blade, and avoids misjudgment and missed judgment that may be caused by other detection methods.

[0087] Although the present invention has been described and illustrated with reference to specific embodiments of the present invention, these descriptions and illustrations do not limit the present invention. It will be clearly understood by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention as defined by the appended claims, so that specific circumstances, materials, material compositions, materials, methods or processes are suitable for the goals, spirit and scope of the present application. All such modifications are intended to be within the scope of the appended claims. Although the methods disclosed herein have been described with reference to specific operations performed in a specific order, it should be understood that these operations may be combined, subdivided or reordered to form equivalent methods without departing from the teachings of the present invention. Therefore, unless specifically indicated herein, the order and grouping of operations are not limitations of the present application.

Claims

1. A method for detecting residual core of a hollow turbine blade, comprising: The hollow turbine blade is immersed in an alkaline solution to obtain an immersed solution; titrating the impregnation solution with an acidic solution; If a white precipitate is produced in the solution after titration, it is determined that the hollow turbine blade contains a residual core; if no white precipitate is produced in the solution after titration, it is determined that the hollow turbine blade does not contain a residual core; The hollow turbine blade is a hollow turbine blade prepared using a silicon oxide-based ceramic core; The concentration of the alkaline solution is 5-10 mol / L; The alkaline solution is selected from one or more of potassium hydroxide solution and sodium hydroxide solution.

2. The method according to claim 1, characterized in that The acidic solution is selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution.

3. The method according to claim 1, characterized in that The impregnation also includes: The hollow turbine blades are cleaned and dried.

4. The method according to claim 3, characterized in that The cleaning is selected from ultrasonic cleaning or cleaning in boiling water.

5. The method according to claim 3, characterized in that: The drying temperature is 100-150°C.

6. The method according to claim 1, characterized in that The conditions for the impregnation include: Heat to 100℃ and boil for 120~180min; or Keep warm at 150~180℃, 6~7bar for 20~40min.

7. The method according to claim 1, characterized in that The concentration of the acidic solution is 2.5-4.5 mol / L.

8. The method according to claim 1, characterized in that: The supernatant of the immersion solution is taken.