[0054] The present disclosure provides a method for testing the hot corrosion performance of a nickel-based single crystal superalloy. The method may include the following steps: providing a plurality of nickel-based single crystal superalloy test pieces to be tested; providing a plurality of different salt solutions, one of which Or multiple salt solutions include vanadium; each salt solution is used to deposit a layer of salt film of preset quality on the surface of each test piece, and the test pieces with the salt film are subjected to a hot corrosion test to obtain test data; Test the test data to determine the hot corrosion rate constant.
[0055] The test method for the hot corrosion performance of nickel-based single crystal superalloys provided in the present disclosure, on the one hand, supplements the salt solution containing vanadium to conduct the hot corrosion test on the test piece, and controls the test piece to fully contact the air during the hot corrosion test. Provides a test environment that is more suitable for the actual service environment of nickel-based single crystal superalloys, and improves the reliability of the test; on the other hand, a layer of salt film of preset quality is deposited on the surface of the test piece to accurately control the salt on the surface of the test piece Film content, so as to obtain accurate test data, is conducive to the quantitative analysis of hot corrosion performance, and improves the accuracy and repeatability of the test.
[0056] In step 1, a plurality of nickel-based single crystal superalloy test pieces to be tested can be provided. Wherein, the shape of each test piece may be a three-dimensional polygon, such as a cube shape. Each test piece needs to be pre-processed first, and the mass of each test piece M is measured and obtained after the processing is over 1 (mg) and surface area a 1 (cm 2 ).
[0057] In detail, the pre-treatment may include: sanding the surface of each test piece with sandpaper; cleaning the test piece, removing oil stains on the surface of the sample, and drying with a blower with cold air. Then you can use a vernier caliper (test range 0~200mm, test accuracy ±0.02mm) to measure the actual size of the sample, and calculate the surface area of the sample a 1 (cm 2 /Square centimeter); Use an analytical balance (accuracy ±0.1mg) to weigh the mass of each test piece, weighing as M 1 (mg/mg).
[0058] In step 2, a plurality of different salt solutions may be provided, and one or more of the salt solutions may include vanadium. Because the salt film formed on the surface of the test piece in the traditional test is mainly composed of NaCl and Na 2 SO 4 Two-component composition, the present invention is based on the V impurity contained in fuel gas will produce V 2 O 5 , Provides at least one salt solution containing vanadium.
[0059] In order to facilitate comparative analysis, use distilled water, Na 2 SO 4 , NaCl, V 2 O 5 Prepare three kinds of salt solutions, namely:
[0060] The first salt solution can include Na 2 SO 4 , And Na 2 SO 4 The weight ratio is 100%.
[0061] The second salt solution can include Na 2 SO 4 And NaCl, and Na 2 SO 4 The weight ratio of NaCl can be 75%, and the weight ratio of NaCl can be 25%;
[0062] The third salt solution may include Na 2 SO 4 , NaCl and V 2 O 5 , And Na 2 SO 4 The weight ratio of NaCl can be 75%, the weight ratio of NaCl can be 20%, V 2 O 5 The weight ratio can be 5%.
[0063] Among them, in the salt solution, Na 2 SO 4 , NaCl and V 2 O 5 The weight ratio of Na is not specifically limited in this disclosure. In other embodiments, Na can also be adjusted separately according to test requirements. 2 SO 4 , NaCl and V 2 O 5 Weight ratio, where V 2 O 5 The weight ratio can be 1-15%.
[0064] figure 2 Schematically show the basis provided by the present disclosure figure 1 The schematic flow chart of the test method for the hot corrosion performance of the nickel-based single crystal superalloy of an embodiment in step 3 and step 4.
[0065] Below, refer to figure 2 , Step 3 and Step 4 are described in detail.
[0066] In step 3, each salt solution can be used to deposit a layer of salt film with a preset quality on the surface of each test piece, and a hot corrosion test is performed on each test piece with the salt film to obtain test data. Specifically, it can include the following steps:
[0067] Step 31: Precisely apply salt, and form a salt film of preset quality. Specifically, put each prepared salt solution into a spray bottle, preheat each test piece to 100℃-120℃ on a clean heating plate, and divide it into three groups to spray the first salt uniformly on the sample. Solution, second salt solution, third salt solution. Due to the high temperature of the test piece during the process of spraying salt, the water in the solution attached to the surface of the test piece will evaporate at any time, and a salt film will be formed on the surface of the test piece.
[0068] What needs to be added is that since the test piece is in a cube shape with six square faces, the amount of salt film on each square face can be calculated in advance according to the salt content per square centimeter of the test piece surface and the area of each square face of the test piece. For example, according to the test requirements, the salt content per square centimeter on the surface of the test piece can be designed to be 3 mg (milligrams). Weigh the mass of the sample at any time during the spraying process. After spraying the five surfaces of the sample evenly and reaching the salt film of the preset quality, turn the sample over and spray the other surface of the sample to form the salt film of the preset quality.
[0069] Step 32, heat preservation of each test piece with salt film at a preset temperature. Before the hot corrosion test of the test piece, the corundum ceramic crucible used for the test can be dried in a box-type resistance furnace in advance to a constant weight to avoid the influence of the crucible on the hot corrosion test. In order to make all the surfaces of the test piece participate in the hot corrosion test, the test piece coated with the salt film can be tilted into a constant weight crucible. In order to avoid the influence of temperature field and other test factors, the crucibles with test pieces can be divided into three groups according to the composition of the salt film, and they can be placed in different areas of the same box-type resistance furnace in an orderly manner. The test temperature is set to 900 ℃. In some embodiments, the test temperature may be between 600°C and 1200°C.
[0070] Step 33: Desalt and measure the mass and size of the test piece. After the preset duration of heat preservation, the test pieces are taken out and the mass and size of the test pieces are measured. The test data may include the mass of each test piece and the surface area of the test piece calculated according to the size. In detail, after the current holding time reaches the preset time, the heating is stopped, and after the temperature in the resistance furnace cools, all the test pieces are taken out. In order to remove the residual salt film on the surface of the test piece, it is necessary to soak the taken test piece in boiling water for about 15 minutes, and then cool and dry it in a ventilated place, and then test the mass of the test piece after desalination. 2 (mg) and surface area a 2 (cm 2 ).
[0071] According to the test requirements, the total heat preservation time of each test piece can be set to be between 100-300h (hours); the preset time length for each heat preservation is between 10-50 hours. For example, in this exemplary embodiment, the total heat preservation time can be set to 200h (hours), and the sampling time of high temperature thermal corrosion can be set to 10h, 30h, 50h, 75h, 100h, 125h, 150h, 175h, 200h. What needs to be added is that at the beginning of the thermal corrosion, the thermal corrosion of the test piece will change significantly. Therefore, in order to more accurately capture the change of the thermal corrosion of the test piece, it can be before the start of the heat preservation time of the test piece. Within 100h, set the sampling frequency as much as possible, such as 5-8 times, and shorten the sampling interval time, such as 10-20h.
[0072] Step 34: Repeat step 31 to step 33 many times until the thermal corrosion time of the test piece reaches the total heat preservation time.
[0073] In step 4, the hot corrosion rate can be determined according to the test data of the hot corrosion test, thereby determining the hot corrosion rate constant. It can include:
[0074] Step 41: Calculate the hot corrosion rate. According to the mass of each test piece measured in each hot corrosion stage, determine the weight gain of each test piece in each hot corrosion stage ΔM=(M 2 -M 1 )(mg), combined with the surface area of each test piece before each hot corrosion stage occurs a 1 (cm 2 ) To determine the weight gain per unit area ΔW (g/cm 2 ):
[0075] ΔW=ΔM/a 1 (g/cm 2 ) (1)
[0076] Furthermore, the thermal corrosion rate of the test piece can be calculated based on the weight gain per unit area at this stage and the time ΔT(h) experienced in this stage, that is, the weight gain rate per unit area V(g/m 2 /h):
[0077] V=ΔM/a/ΔT(g/m 2 /h) (2)
[0078] Step 42, calculate the hot corrosion rate constant. Take the heating time T(h) as the abscissa, and the weight gain per unit area of the test piece ΔW(g/cm 2 ) Is the ordinate. According to the weight gain data per unit area of each test piece in each hot corrosion stage, the Origin software is used to draw the weight gain curve diagram of the alloy with the hot corrosion time; and according to the hot corrosion kinetic formula, tentative fitting The thermal corrosion kinetic curve of each test piece, and according to the correlation coefficient R of the fitted curve 2 The degree of closeness to 1 is used to judge the fit of the curve, select the best hot corrosion kinetic curve of the alloy, and then calculate the hot corrosion rate constant K of the alloy p.
[0079] Among them, the thermal corrosion kinetic formula is
[0080] △W 2 =K p ·T+C (3)
[0081] Among them △W is the weight gain per unit area of the test piece after thermal corrosion, K p Is the hot corrosion rate constant, t is the hot corrosion time, and C is the hot corrosion kinetic constant.
[0082] In the following, the method provided in the present disclosure is used to perform a test of the hot corrosion performance of a nickel-based single crystal superalloy to obtain test data, and the test data is processed and analyzed according to step 4.
[0083] Figure 3-Figure 8 The actual thermal corrosion weight gain curve and the fitted thermal corrosion dynamics of the nickel-based single crystal superalloy test piece under the salt film composition of the first salt solution, the second salt solution, and the third salt solution in an embodiment of the present disclosure are respectively shown Learning curve
[0084] Picture 9 Shows the comparison diagram of alloy hot corrosion kinetic curves fitted under the salt film composition of three salt solutions;
[0085] Figure 10-Figure 12 The surface morphology of the nickel-based single crystal superalloy test piece after 200 hours of hot corrosion under the salt film composition of the first salt solution, the second salt solution and the third salt solution in the exemplary embodiment of the present disclosure are shown. Optical microscope Figure
[0086] Table 1 to Table 3 respectively show the relevant data of the thermal corrosion kinetic curve fitted by the nickel-based single crystal superalloy test piece under the salt film composition of the first salt solution, the second salt solution, and the third salt solution.
[0087] Among them, the coordinate system in each figure uses the heating time T(h) as the abscissa, and the weight gain per unit area of the test piece ΔW(g/cm 2 ) Is the ordinate. Type-1 represents the salt film component of the first salt solution, Type-2 represents the salt film component of the second salt solution, and Type-3 represents the salt film component of the third salt solution. In addition, in order to improve the accuracy of test data, multiple test pieces can be used for parallel tests at the same time. In this test, the number of test pieces sprayed with each salt solution can be three. In each figure, dots, squares, and triangles represent the test data of one of the test pieces.
[0088] Table 1. Related data of the alloy hot corrosion kinetic curve fitted under the salt film composition of the first salt solution
[0089]
[0090] Table 2. Related data of the alloy hot corrosion kinetic curve fitted under the salt film composition of the second salt solution
[0091]
[0092] Table 3. Related data of the alloy hot corrosion kinetic curve fitted under the salt film composition of the third salt solution
[0093]
[0094] Refer to the above Figure 3-Figure 12 , Table 1-Table 3, the test conclusions are as follows:
[0095] 1), the nickel-based single crystal superalloy is at 900℃, the salt film composition Type-1, in the 0~30h stage, the hot corrosion rate constant K p =0.06816mg/(cm) 2 /h, in the incubation period of thermal corrosion; in the 50h~200h stage, the thermal corrosion rate constant K p =29.54231(mg/(cm) 2 /h) 2 , In the accelerated corrosion stage of hot corrosion.
[0096] Nickel-based single crystal superalloy is at 900℃, salt film composition Type-2, in the 0-10h stage, the hot corrosion rate constant K p =0.26938mg/(cm) 2 /h, in the incubation period of thermal corrosion; in the 50h~200h stage, the thermal corrosion rate constant K p =23.33036(mg/(cm) 2 /h) 2 , In the accelerated corrosion stage of hot corrosion.
[0097] For nickel-based single crystal superalloys at 900°C and the salt film composition Type-3, the incubation period of hot corrosion is not observed, only the accelerated corrosion period of hot corrosion. In the 0~30h stage, the hot corrosion rate constant K p =0.44295mg/(cm) 2 /h; During the 30h~200h stage, the hot corrosion rate constant K p =25.50334(mg/(cm) 2 /h) 2.
[0098] The hot corrosion rate constant of the alloy increases in the order of the three salt film components Type-1, Type-2, and Type-3, and the hot corrosion situation increases sequentially.
[0099] 2) The hot corrosion rate of the alloy under the three salt film composition changes with time shows a trend of first increasing and then decreasing. The difference is that under Type-1 salt film composition, within the first 30 hours, the alloy's hot corrosion rate is close to 0, indicating that there is almost no weight gain in the sample during this stage; while in Type-2 and Type-3 salt film There is no such trend under the composition. Combined with the analysis of the kinetic curve, the hot corrosion behavior of the sample under Type-1 salt film composition has an obvious hot corrosion incubation period; while the hot corrosion behavior of the sample under Type-2 and Type-3 salt film composition mainly shows It is an obvious accelerated period of hot corrosion, and there is no obvious hot corrosion incubation period.
[0100] 3). Compare the thermal corrosion kinetic curves fitted by the nickel-based single crystal superalloy under the salt film composition of the three salt solutions. Such as Picture 9 As shown, the alloy has a longer hot corrosion incubation period under the Type-1 salt film composition, and the alloy hot corrosion incubation period is relatively short under the Type-2 salt film composition, but not observed under the Type-3 salt film composition The hot corrosion incubation period of the alloy.
[0101] Comparing the total thermal corrosion weight gain of the samples under the three salt film compositions after 200h of thermal corrosion, it can be seen that the total thermal corrosion weight gain of the specimens under Type-1 salt film composition and the total thermal corrosion weight gain of the specimens under Type-3 salt film composition They are similar, and both are greater than the total weight gain of the samples under Type-2 salt film composition. However, the weight gain trend of the thermal corrosion kinetic curve under the Type-2 salt film composition is more similar to that of the Type-3 salt film composition.
