Testing device and method for simulating hot corrosion of engine turbine blade material

Abstract

The invention belongs to the technical field of salt spray tests, and particularly relates to a test device and method for simulating hot corrosion of an engine turbine blade material, and the method comprises the following steps: after a sample is cleaned and dried, a nozzle is controlled by a mechanical arm to atomize a saturated salt solution, and the saturated salt solution is precisely sputtered to the surface of the sample preheated to 300-500 DEG C to form a uniform salt film; the sample is placed in a heating furnace at the temperature of 600-1000 DEG C to be subjected to heat preservation for 50-55 min and then cooled by compressed air for 5-10 min, and cold and hot circulation A corrosion kinetic curve is drawn based on the unit area weight increment, corrosion products are removed through a molten alkali electrolysis method, and the hot corrosion rate is calculated. The device comprises a groove type test bed with a high-temperature-resistant coating, a slit type nozzle driven by a mechanical arm, an infrared heating device and a cold and hot circulation system. According to the method, the salt film is deposited through precise position control of the mechanical arm, the cold and hot alternating working condition is simulated, the problems that a traditional salt coating method is not uniform and a salt leaching method is distorted in environment are solved by combining corrosion dynamics and microscopic characteristic analysis, and scientific evaluation of the corrosion resistance of the aero-engine blade material is achieved.

Description

Technical Field

[0001] This application belongs to the field of salt spray testing technology, and specifically relates to a device and method for simulating the hot corrosion test of engine turbine blade materials. Background Technology

[0002] The marine environment contains a large number of salt particles such as NaCl and CaCl2, and the combustion of engine fuel produces a large amount of sulfur-containing fuel gas. The interaction of these two elements deposits a mixed salt film (NaCl, CaCl2, and Na2SO4, etc.) on the surface of hot-end components such as turbine blades, causing corrosion under the influence of molten salt. This corrosion can severely damage hot-end components like turbine blades, directly affecting their operating efficiency. Localized corrosion can also lead to cracks and even fractures, significantly impacting their service life and safety. Therefore, a scientific and reasonable evaluation of the thermal corrosion resistance of turbine blade materials is crucial.

[0003] Currently, commonly used hot corrosion salt deposition methods include salt coating and salt immersion. Salt coating involves manually applying a salt film to the sample surface, but the operation is complex, the salt film coating is uneven, the thickness is difficult to control, and the experimental results have large dispersion. Salt immersion involves placing the sample and salt solution in a heating furnace, placing the sample in a molten salt environment, but oxygen is difficult to participate in the reaction process, which does not match the actual hot corrosion process of the workpiece. Main methods include:

[0004] 1. The quality of the salt film coated by the salt coating method is greatly affected by human factors, the thickness is difficult to control, and the experimental results have a large degree of dispersion.

[0005] 2. The salt immersion method involves conducting a hot corrosion test on the sample in a molten salt environment. However, oxygen is difficult to enter and participate in the reaction process, which does not match the actual hot corrosion process of the workpiece.

[0006] 3. Turbine blades are not always in a high-temperature environment during operation; they are subject to significant temperature variations. Simulating the thermal cycling effect of blade temperature has become a technical challenge.

[0007] 4. Lack of means to evaluate the corrosion resistance of materials after testing. Summary of the Invention

[0008] To address the aforementioned problems, this application provides a method for simulating the hot corrosion test of engine turbine blade materials, comprising the following steps:

[0009] Step 1: Clean and dry the surface of the sample;

[0010] Step 2: Preheat the sample to 300~500℃;

[0011] Step 3: Atomize the saturated salt solution and spray it onto the sample surface. After each spray, wait for a uniform salt film to form before continuing the next spray.

[0012] Step 4: Hold at 600℃~1000℃ for 50min~55min, then cool with air for 5min~10min after the holding period; set the 50min~55min holding period and the 5min~10min air cooling period as one corrosion cycle;

[0013] Step 5: Record the relationship between time and weight gain per unit area of ​​the sample within one corrosion cycle, and plot the thermal corrosion kinetics curve based on the relationship.

[0014] Step 6: Remove corrosion products and calculate the hot corrosion rate.

[0015] Preferably, step 6 specifically includes: removing the corrosion products of the sample by molten alkaline electrolysis, measuring the mass m1 of the sample after alkaline washing, and calculating the hot corrosion rate K=(m0-m1) / (S∙t);

[0016] Where m0 is the mass of the sample after the test, m1 is the mass of the sample after alkali washing, S is the original surface area of ​​the sample, and t is the test time.

[0017] Preferably, the saturated salt solution is a saturated salt solution of NaSO4 and NaCl.

[0018] Preferably, the alkaline washing conditions of the molten alkaline electrolysis method are...

[0019] The electrolyte contains 30-40% sodium hydroxide and 60-70% anhydrous sodium carbonate; the current density is 40-60 A / dm²; the temperature is 400-600℃; and the time is 5-10 min.

[0020] Preferably, it further includes multi-dimensional analysis of corrosion products, specifically including:

[0021] X-ray diffraction analysis of crystal structure and internal stress;

[0022] Scanning electron microscopy and energy dispersive spectroscopy analysis of surface / cross-sectional morphology and composition;

[0023] Electron probe microanalysis of elemental distribution;

[0024] Surface roughness and nanoindentation test of coated samples.

[0025] A turbine blade material hot corrosion testing apparatus is used to implement a method for simulating hot corrosion testing of engine turbine blade materials, comprising:

[0026] The test bench (1), infrared heating device (2), control device (3), sedimentation furnace (4), robotic arm (5), brine tank (6), nozzle (7), heating furnace (8), lower furnace door (9), cooling gun (10) and air pump (11) are composed of;

[0027] The sedimentation furnace (4) is located on one side of the heating furnace (8), and a robotic arm (5) is installed inside the sedimentation furnace (4). A nozzle (7) is installed on the robotic arm (5), and the nozzle (7) is connected to the brine tank (6) through a conduit.

[0028] The test bench (1) is mounted on the frame via a slide rail and is driven by the control device (3). It has translational and lifting degrees of freedom to move into the deposition furnace (4), heating furnace (8) or infrared heating device (2).

[0029] The cooling gun (10) provides air for cooling the sample via an air pump (11).

[0030] Preferably, the surface of the test bench (1) is provided with grooves (62) to accommodate different samples.

[0031] Preferably, the test bench (1) is made of high-temperature alloy GH536, GH625 or GH4169, and its surface is coated with a high-temperature corrosion resistant Al-Cr, NiCrAlY or NiCoCrAlY coating.

[0032] Preferably, the nozzle has a slit structure to ensure that the amount of salt spray deposited at all locations on the test bench is consistent.

[0033] The technical problems solved by this application include:

[0034] (1) Solve the problem that the salt coating method cannot guarantee uniform salt film coating. The atomization radius can be effectively controlled by using an air compression atomization device and a specially structured nozzle. A robotic arm is set up to control the position of the nozzle and the test piece, so as to achieve the effect of precise salt spray deposition.

[0035] (2) Solve the problem that the salt immersion method cannot simulate the actual service environment of the blade. Salt is deposited on the surface of the material by spraying and then placed in a hot and cold circulating furnace to ensure that oxygen participates in the hot corrosion reaction.

[0036] (3) Solve the problem of the thermal cycle effect on the blades. Design a heating furnace, in which heating and corrosion are carried out, and cooling gas is used to cool the material to achieve the thermal cycle effect.

[0037] (4) Address the lack of post-experiment evaluation methods for the corrosion resistance of materials. Evaluate the corrosion resistance of materials through various evaluation methods such as quantitative analysis of corrosion kinetics, qualitative analysis of microscopic characteristics, and mechanism analysis through simulation. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a turbine blade material hot corrosion test apparatus according to a preferred embodiment of this application.

[0039] Figure 2 This is a schematic diagram of a nozzle according to a preferred embodiment of this application.

[0040] Figure 3 This is a schematic diagram of the surface of the test bench according to a preferred embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0042] The corrosion testing apparatus involved in this method consists of a test bench (1), an infrared heating device (2), a control device (3), a deposition furnace (4), a robotic arm (5), a brine tank (6), a nozzle (7), a heating furnace (8), a lower furnace door (9), a cooling gun (10), and an air pump (11).

[0043] The test bench (1) is made of high-temperature alloy GH536, GH625 or GH4169, and its surface is coated with a high-temperature corrosion resistant Al-Cr, NiCrAlY or NiCoCrAlY coating. The test bench (1) can be equipped with multiple grooves (12) according to the size and shape of the test piece.

[0044] The nozzle (7) consists of a housing (71) and an atomizing port (72). The slit nozzle can ensure that the amount of salt spray deposited on the test piece at different positions in the test bench is consistent.

[0045] The distance between the nozzle (7) and the test bench (1) is controlled by the robotic arm (5) to precisely control the position of the sprayed salt film.

[0046] The test specimens were tested using the experimental setup:

[0047] (1) Clean various sheet and plate test pieces of different shapes with alcohol to remove surface oil and dry them for later use.

[0048] (2) Prepare a saturated salt solution of Na2SO4 and NaCl and put it into a brine tank for later use.

[0049] (3) The test bench containing the test piece is heated to 300~500℃ by an infrared heating device, and the test bench is sent into the deposition furnace by a control device.

[0050] (4) Control the robotic arm according to the set program, thereby controlling the position of the nozzle, atomizing the saturated salt solution in the salt tank and splashing it onto the surface of the test piece through the nozzle to achieve the effect of precise salt spraying. After each spray, wait for a uniform salt film to form on the surface before continuing the next spray.

[0051] (6) Set the furnace temperature, heating and cooling program: The preset temperature is between 600℃ and 1000℃. Heat and hold at the set temperature for 50 min to 55 min. After taking it out of the furnace, blow air to cool it for 5 min to 10 min.

[0052] (7) After the furnace temperature reaches the set temperature, the test bench containing the test piece is sent into the furnace through the control device, the lower furnace door is closed, and the hot corrosion test begins.

[0053] (8) After the heating and heat preservation process is completed, the test bench is removed from the furnace and the test piece is cooled by compressed air sprayed through the cooling gun. The heat preservation and cooling process is one test cycle. After all the tests are completed, the test piece is taken out.

[0054] (9) Plot the thermal corrosion kinetic curve with time as the horizontal axis and the weight gain per unit area of ​​the test piece as the vertical axis, based on the weight gain per unit area of ​​the test piece in each corrosion cycle.

[0055] (10) The corrosion products of the sample were removed by molten alkaline electrolysis. After alkaline washing, the sample was quickly placed in cold water, rinsed with water and dried, and the weight of the sample was measured.

[0056]

[0057] (11) Calculate the hot corrosion rate K:

[0058] K = (m0 - m1) / (S∙t);

[0059] Where K is the thermal corrosion rate of the fuel gas, in g / (m2∙h); m0 is the mass of the sample after the test, in g; m1 is the mass of the sample after alkaline washing, in grams (g); S is the original surface area of ​​the sample, in m2; and t is the test time, in h.

[0060] (12) The crystal structure and lattice parameters of the hot corrosion products were obtained by X-ray diffraction, and the content of different phase structures and internal stress in the hot corrosion products were further obtained.

[0061] (13) The surface morphology and cross-sectional morphology of the hot corrosion products were analyzed by scanning electron microscope with energy dispersive spectroscopy, and the composition of the products was analyzed.

[0062] (14) Electron probe microanalysis was used to analyze the elemental types of hot corrosion products and to perform point, line and surface scanning analysis on the micro-areas with local corrosion characteristics.

[0063] (15) For coated samples, an optical interferometer is used to measure the change in surface roughness of the sample before and after the hot corrosion test, thereby obtaining the change in the surface state and undulation of the sample.

[0064] (16) For coated samples, the hardness and Young's modulus of the samples were determined by a nanoindenter to characterize the anti-peeling ability of the coating oxide film.

[0065] This application has the following characteristics:

[0066] 1. A simple, efficient, practical and scientifically rigorous method for simulating the hot corrosion test of engine turbine blade materials is provided. An integrated hot corrosion test device is designed to effectively simulate the hot corrosion process of materials under actual working conditions.

[0067] 2. The atomized salt solution method is used to achieve a uniform salt film deposition effect. The slit nozzle effectively controls the atomization radius, and the robotic arm precisely controls the position of the sprayed salt mist.

[0068] 3. Design an integrated testing device to achieve the functions of "salt spray deposition + high temperature heating", thereby improving testing efficiency and saving costs.

[0069] 4. Design a hot and cold circulation device. The material is heated and corroded in the heating furnace, and the material is cooled down by the cooling gas, which plays a role in hot and cold circulation.

[0070] 5. Provide a comprehensive evaluation method for hot corrosion products, conduct research on evaluation techniques such as corrosion kinetics, microscopic characteristics, roughness, and microhardness, and comprehensively evaluate the corrosion resistance of materials.

[0071] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for simulating the hot corrosion test of engine turbine blade materials, characterized in that, Includes the following steps: Step 1: Clean and dry the surface of the sample; Step 2: Preheat the sample to 300~500℃; Step 3: Atomize the saturated salt solution and spray it onto the sample surface. After each spray, wait for a uniform salt film to form before continuing the next spray. Step 4: Hold at 600℃~1000℃ for 50min~55min, then cool with air for 5min~10min after the holding period; set the 50min~55min holding period and the 5min~10min air cooling period as one corrosion cycle; Step 5: Record the relationship between time and weight gain per unit area of ​​the sample within one corrosion cycle, and plot the thermal corrosion kinetics curve based on the relationship. Step 6: Remove corrosion products and calculate the hot corrosion rate.

2. The method for simulating hot corrosion testing of engine turbine blade materials according to claim 1, characterized in that, Step 6 specifically includes: removing the corrosion products of the sample by molten alkaline electrolysis, measuring the mass m1 of the sample after alkaline washing; and calculating the hot corrosion rate K=(m0-m1) / (S∙t). Where m0 is the mass of the sample after the test, m1 is the mass of the sample after alkali washing, S is the original surface area of ​​the sample, and t is the test time.

3. The method for simulating the hot corrosion test of engine turbine blade materials according to claim 1, characterized in that, The saturated salt solution is a saturated salt solution of NaSO4 and NaCl.

4. The method for simulating the hot corrosion test of engine turbine blade materials according to claim 1, characterized in that, Alkali washing conditions for molten alkaline electrolysis The electrolyte contains 30-40% sodium hydroxide and 60-70% anhydrous sodium carbonate; Current density 40~60A / dm²; Temperature 400~600℃; time 5~10min.

5. The method for simulating hot corrosion testing of engine turbine blade materials according to claim 1, characterized in that, Further analysis includes multi-dimensional analysis of corrosion products, specifically including: X-ray diffraction analysis of crystal structure and internal stress; Scanning electron microscopy and energy dispersive spectroscopy analysis of surface / cross-sectional morphology and composition; Electron probe microanalysis of elemental distribution; Surface roughness and nanoindentation test of coated samples.

6. A turbine blade material hot corrosion testing apparatus, used to implement the simulated engine turbine blade material hot corrosion testing method according to any one of claims 1-5, characterized in that, include: The test bench (1), infrared heating device (2), control device (3), sedimentation furnace (4), robotic arm (5), brine tank (6), nozzle (7), heating furnace (8), lower furnace door (9), cooling gun (10) and air pump (11) are composed of a test bench (1), infrared heating device (2), control device (3), sedimentation furnace (4), robotic arm (5), brine tank (6), nozzle (7), heating furnace (8), lower furnace door (9), cooling gun (10) and air pump (11); The sedimentation furnace (4) is located on one side of the heating furnace (8). A robotic arm (5) is installed inside the sedimentation furnace (4). A nozzle (7) is installed on the robotic arm (5). The nozzle (7) is connected to the brine tank (6) through a conduit. The test bench (1) is mounted on the frame via a slide rail and is driven by the control device (3). It has translational and lifting degrees of freedom to move into the deposition furnace (4), heating furnace (8) or infrared heating device (2). The cooling gun (10) provides air for cooling the sample via an air pump (11).

7. The turbine blade material hot corrosion testing apparatus according to claim 6, characterized in that, The test bench (1) has grooves (62) on its surface to accommodate different samples.

8. The turbine blade material hot corrosion testing apparatus according to claim 6, characterized in that, The test bench (1) is made of high-temperature alloy GH536, GH625 or GH4169, and its surface is coated with high-temperature corrosion resistant Al-Cr, NiCrAlY or NiCoCrAlY coating.

9. The turbine blade material hot corrosion testing apparatus according to claim 6, characterized in that, The nozzle has a slit structure to ensure that the amount of salt spray deposited is consistent at all locations on the test bench.

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