A high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, coating and preparation method thereof

Abstract

This invention relates to the field of high-entropy alloy materials and thermal spraying surface engineering technology, specifically to a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, coating, and its preparation method. Using Al, Co, Cr, Fe, Ni, and Si elemental powders as raw materials, high-entropy alloy powder is prepared through a mechanical alloying process. Then, a high-entropy alloy coating is prepared on the surface of a metal substrate using supersonic flame spraying technology. During the mechanical alloying process, high-energy ball milling ensures thorough mixing of the multi-component powders to form a uniform solid solution structure. The powder particle size is then sieved to obtain a suitable size for thermal spraying. A dense coating is deposited on the pre-treated substrate surface to form a dense coating. The resulting high-entropy alloy coating has a relatively dense microstructure and exhibits excellent wear resistance and heat corrosion resistance in high-temperature wear and NaCl-KCl-Na2SO4 molten salt corrosion environments. This invention features a simple process and low cost, and the prepared coating is suitable for surface protection of key components such as gas turbines, boilers, and high-temperature industrial equipment.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy materials and thermal spraying surface engineering technology, specifically to a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, coating, and preparation method thereof. Background Technology

[0002] In high-end manufacturing fields such as gas turbines, power generation, and metallurgical equipment, numerous critical components, including gas turbine blades, combustion chamber components, boiler pipes, and high-temperature structural parts, require long-term service under various extreme environments, including high temperatures, intense friction, and corrosion. Under these conditions, materials not only bear high mechanical loads but also suffer from the combined effects of high-temperature wear and corrosive media erosion, leading to severe wear, oxidation, and corrosion failure on the material surface. Among these, high-temperature wear and molten salt thermal corrosion are significant factors contributing to shortened equipment service life. Particularly in sulfur- or chlorine-containing environments, molten salts such as Na₂SO₄ and NaCl formed under high-temperature conditions can chemically react on the material surface, destroying the protective oxide film and causing rapid corrosion, thereby affecting the safe operation and service life of the equipment.

[0003] To improve the durability of critical components in complex service environments, the common approach is to prepare wear-resistant and corrosion-resistant coatings on the surface of the substrate material. Ni-based alloy coatings, due to their good high-temperature stability and certain wear resistance, are widely used for surface protection of high-temperature equipment. However, under the coupled effects of high-temperature wear and molten salt corrosion, traditional Ni-based alloy coatings still have some shortcomings. For example, under long-term high-temperature conditions, the coating microstructure may coarsen or undergo phase transformation, leading to a decrease in hardness and wear resistance. Simultaneously, in molten salt corrosion environments, the oxide film formed by traditional coatings has poor stability and is easily destroyed by molten salt, resulting in a significant increase in corrosion rate. Therefore, developing novel coating materials with higher wear resistance and hot corrosion resistance has become a current research hotspot.

[0004] In recent years, high-entropy alloys (HEAs) have attracted widespread attention as a novel type of multi-principal element alloy material. HEAs are typically composed of five or more principal elements in near-equiatomic ratios, unlike traditional alloys which are designed with one or two main elements. Due to the combined effect of multiple elements, HEAs exhibit unique high-entropy effects, lattice distortion effects, hysteresis diffusion effects, and a "cocktail effect," resulting in excellent mechanical properties, wear resistance, and corrosion resistance at high temperatures.

[0005] Among numerous high-entropy alloy systems, the AlCoCrFeNi system has been extensively studied due to its excellent high-temperature stability and superior oxidation resistance. In this system, Al and Cr elements can form a stable oxide protective film under high-temperature conditions, effectively improving the material's oxidation and corrosion resistance. Furthermore, the introduction of Si elements can further enhance the material's hardness and wear resistance, and promote the formation of a more stable and dense oxide film, thereby strengthening the material's oxidation and hot corrosion resistance under high-temperature environments. Therefore, AlCoCrFeNiSi high-entropy alloys have excellent application potential in high-temperature wear resistance and corrosion resistance fields.

[0006] Currently, commonly used HEA powder manufacturing methods include gas atomization, spray granulation, and mechanical alloying. However, spray granulation produces powders that are brittle and have low density. Mechanical alloying (MA) is a powder preparation technique that utilizes high-energy ball milling to repeatedly cold-weld, fracture, and re-weld multi-component powders, thereby achieving uniform element mixing and forming a solid solution structure. This method can effectively prepare high-entropy alloy powders with uniform composition and fine microstructure, providing high-quality raw materials for subsequent thermal spraying processes. Furthermore, High Velocity Oxygen Fuel (HVOF) technology, due to its high particle velocity and moderate temperature, can form a coating structure with high density, low porosity, and high bonding strength on the substrate surface, and is therefore widely used in the preparation of wear-resistant and corrosion-resistant coatings.

[0007] Although existing research has attempted to prepare high-entropy alloy coatings using thermal spraying technology, studies on the preparation of high-entropy alloy powders of the AlCoCrFeNiSi system through mechanical alloying combined with HVOF technology to form coatings resistant to high-temperature wear and molten salt hot corrosion remain relatively limited. Therefore, developing a stable, dense AlCoCrFeNiSi high-entropy alloy coating and its preparation method, along with its excellent high-temperature wear resistance and molten salt hot corrosion resistance, has significant engineering application value for improving the service life of key components in high-temperature equipment.

[0008] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0009] The purpose of this invention is to solve the problem of high-temperature wear and thermal corrosion on the surface of key components in industries such as gas turbines, power generation, and metallurgical equipment. It provides a high-temperature wear-resistant and thermal corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, coating, and preparation method thereof.

[0010] To achieve the above objectives, this invention discloses a method for preparing high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, comprising the following steps:

[0011] S1, a mixed powder is obtained by mixing elemental powders of Al, Co, Cr, Fe, Ni and Si;

[0012] S2, the mixed powder obtained in step S1 is placed into a ball mill jar, vacuumed and argon gas is introduced, and then placed into a planetary ball mill for ball milling to obtain high entropy alloy powder.

[0013] S3. The high-entropy alloy powder obtained in step S2 is passed through a sieve to obtain AlCoCrFeNiSi high-entropy alloy powder. The sieved high-entropy alloy powder is then subjected to vacuum sintering in a vacuum heat treatment furnace.

[0014] In step S1, the molar percentages of Al, Co, Cr, Fe, Ni, and Si elemental powders are as follows: Al 17-20%, Co 17-20%, Cr 17-20%, Fe 17-20%, Ni 17-20%, and Si 0-7%. The particle size of the Al, Co, Cr, Fe, Ni, and Si elemental powders is less than 45 μm, and the purity is ≥ 99.5%. The mixing is performed using a premixer with a rotation speed of 60 r / min and a mixing time of 2 h.

[0015] In step S2, the vacuum pump pressure is set to 10 Pa and the vacuuming time is 10 min; high-purity argon gas is passed through at a pressure of 0.5 Pa for 3 min.

[0016] In step S2, stainless steel grinding balls with diameters of 15mm, 10mm, 6mm, and 5mm are selected and mixed in a ratio of 1:4:2:1. The mass ratio of grinding balls to powder is 10:1, the grinding speed is 220 rpm, and the grinding time is 40 h.

[0017] In step S3, vacuum sintering adopts a gradient heating sintering method. The powder is heated from room temperature to 300°C in 40 min, then heated to the required temperature at a rate of 10°C / min, held for 2 h, and then cooled to room temperature in the furnace.

[0018] This invention also discloses a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder prepared by the above-described method, wherein the AlCoCrFeNiSi high-entropy alloy powder is AlCoCrFeNiSi x High-entropy alloy powder, where x = 0, 0.25, 0.5, 0.75.

[0019] This invention also discloses a method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating, comprising the following steps:

[0020] A1. Before spraying, the substrate is degreased with alcohol, then the surface is roughened by sandblasting, and the roughened substrate is preheated.

[0021] A2 uses oxygen-kerosene supersonic flame spraying technology, with oxygen as the combustion aid, kerosene as the fuel, high-purity nitrogen as the powder carrier gas, and air as the cooling medium, to spray the above-mentioned AlCoCrFeNiSi high-entropy alloy powder onto the substrate surface to form an AlCoCrFeNiSi high-entropy alloy coating.

[0022] In step A1, the sandblasting material is brown corundum sand with a particle size of 60 mesh, the sandblasting pressure is 0.3~0.5 MPa, the surface roughness of the substrate after sandblasting reaches 2.5~3 μm, and the substrate preheating temperature reaches 80~120 ℃.

[0023] In step A2, the process of supersonic flame spraying technology is as follows: oxygen flow rate is 53 m³ / s. 3 The spraying parameters are: spraying speed / h, kerosene flow rate 28 L / h, spraying distance 380 mm, spraying step 3 mm, spraying speed 800 mm / s, powder feed rate 32 g / min, and barrel length 6 inches.

[0024] The present invention also discloses a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating prepared by the above preparation method. The AlCoCrFeNiSi high-entropy alloy coating has a thickness of 200~300 μm, a bonding strength between the coating and the substrate of more than 50 MPa, and a porosity of less than 1%.

[0025] This invention uses Al, Co, Cr, Fe, and Ni in a near equiatomic ratio, and constructs AlCoCrFeNiSi by adjusting the Si element content. x (x=0, 0.25, 0.5, 0.75) Multi-principal element high-entropy system. This system belongs to the typical high-entropy alloy design concept. Its core lies in achieving high-entropy effect, lattice distortion effect and hysteresis diffusion effect through the synergistic effect of multiple principal elements, thereby obtaining better comprehensive performance under high temperature service conditions.

[0026] From an elemental design perspective, existing technologies use Ti as a reinforcing element, while this application abandons Ti and introduces Si while controlling its addition amount. Ti easily forms brittle intermetallic compounds at high temperatures, which, while increasing hardness, can reduce coating toughness and increase crack susceptibility. The addition of Si not only enhances material hardness through solid solution strengthening but also promotes the formation of a SiO2 protective film during high-temperature service. Together with Al2O3 (formed by Al) and Cr2O3 (formed by Cr), Si forms a composite oxide film system, improving the stability and density of the oxide film. This significantly improves the coating's resistance to high-temperature wear and molten salt corrosion.

[0027] This invention achieves thorough mixing and solid solution formation of multiple elements in the powder stage through mechanical alloying, giving the coating material itself a more uniform and stable microstructure. This avoids the matrix dilution effect and microstructure inhomogeneity that may result from subsequent laser remelting, ensuring the stability and performance consistency of the final coating composition.

[0028] This invention achieves thorough mixing and solid solution formation of multiple elements in the powder stage through mechanical alloying, giving the coating material itself a more uniform and stable microstructure. This avoids the matrix dilution effect and microstructure inhomogeneity that may result from subsequent laser remelting, ensuring the stability and performance consistency of the final coating composition.

[0029] In the spraying process of this invention, due to the high oxidizing activity of Al and Si, oxidation easily occurs during high-temperature spraying, leading to changes in the powder's molten state, increased coating porosity, and decreased bonding strength. Therefore, it is essential to rationally control the spraying distance, oxygen flow rate, kerosene flow rate, and powder feeding rate to achieve a balance between the degree of powder melting and oxidation. This application optimizes the spraying process parameters to achieve a final coating porosity of less than 1% and a bonding strength exceeding 50 MPa, forming a relatively dense microstructure.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. This invention uses a mechanical alloying method to prepare AlCoCrFeNiSi high-entropy alloy powder. Through repeated cold welding, fracture and re-welding of the powder during high-energy ball milling, the elements are fully mixed at the microscale and form a uniform solid solution structure, thereby significantly improving the compositional uniformity and structural stability of the powder, providing high-quality raw materials for subsequent coating preparation.

[0032] 2. This invention uses supersonic flame spraying technology to prepare the coating. This process has the characteristics of high particle velocity and low oxidation degree, which can form a coating structure with high density and low porosity on the substrate surface, thereby improving the bonding strength between the coating and the substrate and the overall structural stability.

[0033] 3. The AlCoCrFeNiSi high-entropy alloy system has obvious lattice distortion effect and solid solution strengthening effect. At the same time, the addition of Si element can improve the material hardness and wear resistance. During the wear process at 700 ℃, the synergistic lubrication effect of Al2O3, Cr2O3 and SiO2 generated significantly improves the wear resistance of the coating.

[0034] 4. In the high-entropy alloy coating prepared by the supersonic flame spraying technology of this invention, elements such as Al, Cr and Si can form a stable and dense oxide film under high temperature conditions. This oxide film can effectively block the erosion of sulfur and chloride ions, thereby significantly improving the corrosion resistance of the coating in the molten salt hot corrosion environment. Attached Figure Description

[0035] Figure 1 SEM morphology of powder after different heat treatment temperatures: (a, d) 1050 ℃, (b, e) 1110 ℃, (c, f) 1160 ℃;

[0036] Figure 2 SEM morphology of powders after different heat treatment temperatures: (a) 1050 ℃, (b) 1110 ℃, (c) 1160 ℃

[0037] Figure 3 Surface morphology of HEA coatings prepared by supersonic flame spraying process: (a) AlCoCrFeNi, (b) AlCoCrFeNiSi 0.25 (c) AlCoCrFeNiSi 0.5 (d) AlCoCrFeNiSi 0.75 ;

[0038] Figure 4 Cross-sectional morphology of HEA coatings prepared by supersonic flame spraying: (a, b) AlCoCrFeNi, (c, d) AlCoCrFeNiSi 0.25 (e, f) AlCoCrFeNiSi 0.5 (g, h) AlCoCrFeNiSi 0.75 . Detailed Implementation

[0039] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0040] Example 1

[0041] An AlCoCrFeNiSi 0.5 The preparation method of HEA powder and its heat treatment includes the following steps:

[0042] (1) Weigh out Al, Co, Cr, Fe, Ni and Si elemental powders with a molar ratio of 1:1:1:1:1:0.5 according to the required total weight, place them in a premixer and mix for 2 h. After mixing, take out an appropriate amount of mixed powder and pour it into a stainless steel ball mill jar. Add stainless steel grinding balls with a mass of 10 times the mass of the powder to the ball mill jar. Select grinding balls with diameters of 15 mm, 10 mm, 6 mm and 5 mm, and configure them in a ratio of 1:4:2:1. Set the ball milling speed to 220 r / min, rotate forward for 10 min and stop for 1 min, rotate backward for 10 min and stop for 1 min, and repeat the ball milling for 40 h.

[0043] (2) After ball milling, the HEA powder and grinding balls were separated, and the resulting HEA powder was then sieved and classified. The powder was sieved using metal sieves with mesh sizes of 15 μm and 45 μm. At the same time, an ultrasonic vibrator was loaded on the edge of the small mesh sieve frame to assist in sieving the powder. The ultrasonic vibrator frequency was selected as a pulse frequency of 7 Hz. After sieving through different mesh sieves, AlCoCrFeNiSi with a particle size distribution of 15~45 μm was obtained. 0.5 HEA powder.

[0044] (3) The sieved AlCoCrFeNiSi 0.5 HEA powder was placed in an alumina crucible for vacuum sintering. The vacuum sintering program consisted of two parts: first, heating the powder from room temperature to 300 °C over 40 minutes; second, heating from 300 °C to 1050 °C over 75 minutes, holding at this temperature for 2 hours, and then cooling the powder to room temperature with the furnace. The resulting HEA powder was then sieved and classified using 15 μm and 45 μm metal sieves. An ultrasonic vibrator was attached to the edge of the smaller mesh sieve to assist in sieving. The ultrasonic vibrator used a 7 Hz pulse frequency to obtain AlCoCrFeNiSi powder with a particle size distribution of 15–45 μm after heat treatment at 1050 °C. 0.5 HEA powder.

[0045] Example 2

[0046] The only difference between this embodiment and Example 1 is that in step (3), the second procedure heats the powder from 300 °C to 1100 °C for 80 min. All other processes are the same as in Example 1, resulting in AlCoCrFeNiSi with a particle size distribution of 15~45 μm after heat treatment at 1100 °C. 0.5 HEA powder.

[0047] Example 3

[0048] The only difference between this embodiment and Embodiment 1 is that in step (3), the second procedure heats the powder from 300 °C to 1160 °C for 86 min. All other processes are the same as in Embodiment 1, resulting in AlCoCrFeNiSi with a particle size distribution of 15~45 μm after heat treatment at 1160 °C. 0.5 HEA powder.

[0049] AlCoCrFeNiSi obtained from Examples 1, 2, and 3 after heat treatment at 1050 °C 0.5 HEA powder, AlCoCrFeNiSi heat-treated at 1100 ℃ 0.5 HEA powder and AlCoCrFeNiSi heat-treated at 1160 ℃ 0.5 HEA powder and AlCoCrFeNiSi before heat treatment 0.5 The phase content of the HEA powder was tested, and the results are shown in Table 1. It can be seen that the untreated AlCoCrFeNiSi... 0.5 HEA powder contains a relatively high amount of FCC phase and a relatively low amount of BCC phase. However, after heat treatment, the BCC phase content in the HEA powder begins to increase. After heat treatment at 1100 ℃, the content of the BCC phase in AlCoCrFeNiSi... 0.5 The HEA powder contains the highest proportion of BCC phase, reaching 79%. Since the BCC phase has higher hardness than the FCC phase, while the FCC phase has better plasticity than the BCC phase, the high BCC phase content combined with a small amount of FCC phase results in excellent performance in subsequent coating preparations.

[0050] Table 1. Phase content of powder

[0051]

[0052] SEM was used to analyze AlCoCrFeNiSi prepared at different heat treatment temperatures in Examples 1, 2, and 3. 0.5 The surface and cross-section of the HEA powder were observed, such as Figure 1 and 2 As shown. By Figure 1 It can be seen that AlCoCrFeNiSi 0.5 HEA powders are mostly spherical or ellipsoidal in shape, with relatively uniform particle size. Through analysis of... Figure 2 Observation of cross-sectional SEM images shows that AlCoCrFeNiSi after heat treatment at 1100 ℃ 0.5 HEA powder has a relatively uniform distribution of elements.

[0053] In summary, the HEA powder after heat treatment at 1100 ℃ has the highest BCC phase content and the elemental distribution of the powder cross section is uniform. Therefore, the coatings with different Si contents in the subsequent embodiments were prepared according to the process parameters in Example 2.

[0054] Example 4

[0055] (1) Weigh out Al, Co, Cr, Fe, and Ni elemental powders with a molar ratio of 1:1:1:1:1 according to the required total weight, place them in a premixer and mix for 2 h. After mixing, take out an appropriate amount of mixed powder and pour it into a stainless steel ball mill jar. Add stainless steel grinding balls with a mass of 10 times the mass of the powder to the ball mill jar. Select grinding balls with diameters of 15 mm, 10 mm, 6 mm, and 5 mm, and configure them in a ratio of 1:4:2:1. Set the ball milling speed to 220 r / min, rotate forward for 10 min and stop for 1 min, rotate backward for 10 min and stop for 1 min, and repeat the ball milling for 40 h.

[0056] (2) After ball milling, the HEA powder and grinding balls were separated. The obtained HEA powder was then sieved and classified. The powder was sieved using metal sieves with mesh sizes of 15 μm and 45 μm. At the same time, an ultrasonic vibrator was loaded on the edge of the small mesh sieve frame to assist in sieving the powder. The ultrasonic vibrator frequency was selected as a pulse frequency of 7 Hz. After sieving through different mesh sieves, AlCoCrFeNi HEA powder with a particle size distribution of 15~45 μm was obtained.

[0057] (3) The sieved AlCoCrFeNi HEA powder was placed in an alumina crucible for vacuum sintering. The vacuum sintering program was set up. In the first program, the powder was heated from room temperature to 300 ℃ in 40 min. In the second program, the powder was heated from 300 ℃ to 1100 ℃ in 80 min and held at that temperature for 2 h. After heating was stopped, the powder was cooled to room temperature with the furnace. The HEA powder obtained by vacuum sintering was sieved and classified. The powder was sieved with metal sieves with mesh sizes of 15 μm and 45 μm, respectively. At the same time, an ultrasonic vibrator was loaded on the edge of the small mesh sieve frame to assist in sieving the powder. The ultrasonic vibrator frequency was selected as a pulse frequency of 7 Hz. AlCoCrFeNi HEA powder with a particle size distribution of 15~45 μm after heat treatment at 1100 ℃ was obtained.

[0058] The method for preparing the AlCoCrFeNi HEA coating for high-temperature protection of metal surfaces mainly includes the following steps:

[0059] S1: Before spraying, use alcohol to degrease the surface of the 12CrMoV substrate, and then perform sandblasting roughening treatment on the degreased surface. The sandblasting material is 60-mesh brown corundum sand (Al2O3), and the air valve is adjusted to make the sandblasting pressure reach 0.4MPa.

[0060] S2: Turn on the power, gas circuit switch, and cooling water switch of the spraying equipment. Use oxygen as the combustion aid, kerosene as fuel, high-purity nitrogen as the powder carrier gas, and air as the cooling medium. Fix the sample on the worktable. Adjust the robotic arm to achieve a spraying distance of 380 mm, a powder feed rate of 32 g / min, a spraying step distance of 3 mm, and a gun barrel length of 6 inches.

[0061] S3: Open the kerosene, oxygen, and liquid oxygen flow valves, and adjust the spray control cabinet parameters to achieve a kerosene flow rate of 28 L / h and an oxygen flow rate of 53 m³ / h. 3 Before spraying, preheat the substrate surface to 80~120 ℃, turn on the powder feeder, and maintain the powder feed rate at 32 g / min. After every 4 coats, use an air gun to cool the coating surface and use a micrometer to measure the coating thickness. Then start the spraying equipment to continue spraying, repeating the operation until the coating thickness reaches about 250 μm.

[0062] Example 5

[0063] The difference between this embodiment and embodiment 4 is that in step (1), Al, Co, Cr, Fe, Ni and Si elemental powders with a molar ratio of 1:1:1:1:1:0.25 are weighed according to the required total weight. Other process steps are the same as in embodiment 4 to obtain AlCoCrFeNiSi. 0.25 HEA coating.

[0064] Example 6

[0065] The difference between this embodiment and embodiment 4 is that in step (1), Al, Co, Cr, Fe, Ni and Si elemental powders with a molar ratio of 1:1:1:1:1:0.5 are weighed according to the required total weight. Other process steps are the same as in embodiment 4 to obtain AlCoCrFeNiSi. 0.5 HEA coating.

[0066] Example 7

[0067] The difference between this embodiment and embodiment 4 is that in step (1), Al, Co, Cr, Fe, Ni and Si elemental powders with a molar ratio of 1:1:1:1:1:0.75 are weighed according to the required total weight. The other process steps are the same as in embodiment 4, to obtain AlCoCrFeNiSi. 0.75 HEA coating.

[0068] The AlCoCrFeNi HEA coating and AlCoCrFeNiSi prepared in Examples 4, 5, 6 and 7 0.25 HEA coating, AlCoCrFeNiSi0.5 HEA and AlCoCrFeNiSi 0.75 SEM observation of the HEA coating surface and cross-section, such as Figure 3 and Figure 4 As shown, the coating cross-section is relatively dense, with no obvious cracks or voids. The performance of the HEA coating was then tested as follows:

[0069] (1) The method for testing the microhardness of the coating is as follows:

[0070] The microhardness of the coatings was tested using a Vickers hardness tester with a load of 5 N and a loading time of 10 s. Ten points were tested for each coating, and the average value was taken as the microhardness value for that coating. The test results are shown in Table 2. (This is in contrast to AlCoCrFeNi HEA coating and AlCoCrFeNiSi coating.) 0.25 HEA coating and AlCoCrFeNiSi 0.5 Compared to the HEA coating, the test results show that the AlCoCrFeNiSi prepared in Example 7... 0.75 The HEA coating exhibits high hardness, with a hardness value of 523.50 ± 20.68 HV. 0.5 This is attributed to the Si element dissolving into the crystal lattice, causing lattice distortion, which results in the highest coating hardness.

[0071] Table 2. Microhardness of the HEA coatings prepared in Examples 4, 5, 6 and 7

[0072]

[0073] (2) The test method for high-temperature wear performance of coating is as follows:

[0074] AlCoCrFeNi HEA coating, AlCoCrFeNiSi 0.25 HEA coating, AlCoCrFeNiSi 0.5 HEA and AlCoCrFeNiSi 0.75 High-temperature wear performance testing of the HEA coating was conducted on an HT-1000 high-temperature tribometer. The friction pair consisted of Al2O3 ceramic balls with a diameter of 6.35 mm. The test load was 10 N, the wear temperature was 600 ℃, the rotation speed was 360 r / min, the wear track radius was 4 mm, and the wear time was 60 min. The wear volume of the coating was calculated using a KLA P7 probe profilometer, and the wear rate was calculated using the wear rate formula.

[0075] The wear rate formula is: V (mm) 3V is the wear volume, V = A × π × D, where A is the cross-sectional area of ​​the wear track, calculated by integrating the fitted data using Origin software, P (N) is the load, L (m) is the friction distance, and D is the wear track diameter.

[0076] The test and calculation results are shown in Table 3, and are consistent with those of AlCoCrFeNi HEA coating and AlCoCrFeNiSi. 0.25 HEA coating and AlCoCrFeNiSi 0.5 Compared to the HEA coating, the test results show that the AlCoCrFeNiSi prepared in Example 7... 0.75 The HEA coating exhibited the lowest wear rate at 600 ℃, at 2.90 × 10⁻⁶. -14 m 3 ·N -1 ·m -1 It exhibits the best wear resistance. This is due to the formation of an oxide film composed of Al2O3, Cr2O3, and SiO2 on the worn surface. The oxides gradually connect to form layers, adhering to the wear surface to form a protective barrier, resulting in a lower wear rate for the coating.

[0077] Table 3. Friction coefficients and wear rates of the HEA coatings prepared in Examples 4, 5, 6, and 7.

[0078]

[0079] (3) The test method for the hot corrosion performance of the coating is as follows:

[0080] AlCoCrFeNi HEA coating, AlCoCrFeNiSi 0.25 HEA coating, AlCoCrFeNiSi 0.5 HEA and AlCoCrFeNiSi 0.75 The thermal corrosion performance of the HEA was tested in an SG-GL tube furnace under atmospheric conditions. The salt coating method was used to test the coating's resistance to NaCl-KCl-Na2SO4 composite molten salt thermal corrosion at 700 °C for 100 hours. The salt-coated samples were placed in independent Al2O3 crucibles. Before the experiment, the crucibles containing the salt-coated samples were weighed using an HZ-124 / 85S electronic balance. During the experiment, the samples were removed from the furnace and air-cooled to room temperature every 10 hours. The weight of the crucibles containing the salt-coated samples was then recorded using the electronic balance, and the samples were returned to the furnace for further testing. A total of 10 thermal corrosion cycles were completed.

[0081] The test results are shown in Table 4. (This is in contrast to the AlCoCrFeNi HEA coating and AlCoCrFeNiSi...) 0.25 HEA coating and AlCoCrFeNiSi 0.5Compared to the HEA coating, the test results show that the AlCoCrFeNi HEA coating prepared in Example 4 has the largest corrosion weight gain and corrosion weight gain kinetic constant after 100 hours of hot corrosion, which is 49.51 mg / cm³. 2 and 40.85 mg 2 / (cm 4 •h). With increasing Si content, the corrosion weight gain and corrosion weight gain kinetic constant first decrease and then increase. The AlCoCrFeNiSi prepared in Examples 5 and 7... 0.25 HEA coating and AlCoCrFeNiSi 0.75 The corrosion weight gain and corrosion weight gain kinetic constant of the HEA coating after 100 h of hot corrosion were higher than those of the AlCoCrFeNiSi prepared in Example 6. 0.5 HEA coating. AlCoCrFeNiSi prepared in Example 6 0.5 The HEA coating exhibited the lowest corrosion weight gain and corrosion weight gain kinetic constant after 100 hours of hot corrosion, at 10.45 mg / cm³. 2 and 1.729 mg 2 / (cm 4 This is because the HEA coating in Example 6 forms a stable oxide film, preventing sulfur and chloride ions from diffusing into the coating.

[0082] Table 4. Corrosion weight gain and corrosion kinetic constants of the HEA coatings prepared in Examples 4, 5, 6 and 7.

[0083]

[0084] In summary, the AlCoCrFeNiSi alloy used for high-temperature surface protection of key components prepared by this invention... 0.5 HEA coatings meet the requirements of high-temperature wear resistance and high-temperature corrosion resistance for metal surfaces. By improving methods and processes, the optimal powder and coating preparation process was obtained. A mechanical alloying process was used to prepare AlCoCrFeNiSi with a molar ratio of Al:Co:Cr:Fe:Ni:Si = 1:1:1:1:1:0.5. 0.5 HEA powder; the spraying process parameters used were an oxygen flow rate of 53 m³ / h. 3 The spraying parameters were: spraying speed / h, kerosene flow rate 28 L / h, spraying distance 380 mm, spraying step distance 3 mm, spraying speed 800 mm / s, powder feed rate 32 g / min, and barrel length 6 inches. The HEA coating prepared under these parameters exhibited good high-temperature wear resistance and excellent heat corrosion resistance.

[0085] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder, characterized in that, Includes the following steps: S1, a mixed powder is obtained by mixing elemental powders of Al, Co, Cr, Fe, Ni and Si; S2, the mixed powder obtained in step S1 is placed into a ball mill jar, vacuumed and argon gas is introduced, and then placed into a planetary ball mill for ball milling to obtain high entropy alloy powder. S3. The high-entropy alloy powder obtained in step S2 is passed through a sieve to obtain AlCoCrFeNiSi high-entropy alloy powder. The sieved high-entropy alloy powder is then subjected to vacuum sintering in a vacuum heat treatment furnace.

2. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder as described in claim 1, characterized in that, In step S1, the molar percentages of Al, Co, Cr, Fe, Ni, and Si elemental powders are as follows: Al 17-20%, Co 17-20%, Cr 17-20%, Fe 17-20%, Ni 17-20%, and Si 0-7%. The particle size of the Al, Co, Cr, Fe, Ni, and Si elemental powders is less than 45 μm, and the purity is ≥ 99.5%. The mixing is performed using a premixer with a rotation speed of 60 r / min and a mixing time of 2 h.

3. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder as described in claim 1, characterized in that, In step S2, the vacuum pump pressure is set to 10 Pa and the vacuuming time is 10 min during the evacuation process; high-purity argon gas is passed through at a pressure of 0.5 Pa for 3 min.

4. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder as described in claim 1, characterized in that, In step S2, stainless steel grinding balls with diameters of 15mm, 10mm, 6mm, and 5mm are selected and mixed in a ratio of 1:4:2:

1. The mass ratio of grinding balls to powder is 10:1, the grinding speed is 220 rpm, and the grinding time is 40 h.

5. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder as described in claim 1, characterized in that, In step S3, vacuum sintering adopts a gradient heating sintering method. The powder is heated from room temperature to 300 ℃ in 40 min, then heated to the required temperature at 10 ℃ / min, held for 2 h, and then cooled to room temperature in the furnace.

6. A high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy powder prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The AlCoCrFeNiSi high-entropy alloy powder is AlCoCrFeNiSi x High-entropy alloy powder, where x = 0, 0.25, 0.5, 0.

75.

7. A method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating, characterized in that, Includes the following steps: A1. Before spraying, the substrate is degreased with alcohol, then the surface is roughened by sandblasting, and the roughened substrate is preheated. A2, using oxygen-kerosene supersonic flame spraying technology, oxygen is used as a combustion aid, kerosene as fuel, high-purity nitrogen as a powder carrier gas, and air as a cooling medium to spray the AlCoCrFeNiSi high-entropy alloy powder as described in claim 5 onto the substrate surface to form an AlCoCrFeNiSi high-entropy alloy coating.

8. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating as described in claim 7, characterized in that, In step A1, the sandblasting material is brown corundum sand with a particle size of 60 mesh, the sandblasting pressure is 0.3~0.5MPa, the surface roughness of the substrate after sandblasting reaches 2.5~3 μm, and the substrate preheating temperature reaches 80~120 ℃.

9. The method for preparing a high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating as described in claim 7, characterized in that, In step A2, the process of supersonic flame spraying technology is as follows: oxygen flow rate is 53 m³ / s. 3 / h, kerosene flow rate is 28 L / h, spraying distance is 380 mm, spraying step is 3 mm, spraying speed is 800 mm / s, powder feed rate is 32 g / min, and barrel length is 6 inches.

10. A high-temperature wear-resistant and heat-corrosion-resistant AlCoCrFeNiSi high-entropy alloy coating prepared by the preparation method according to any one of claims 7 to 9, characterized in that, The AlCoCrFeNiSi high-entropy alloy coating has a thickness of 200~300μm, a bonding strength between the coating and the substrate exceeding 50 MPa, and a porosity of less than 1%.

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