High-temperature wear-resistant and corrosion-resistant composite coating, and preparation method and use thereof

Abstract

The application discloses a high-temperature wear-resistant and corrosion-resistant composite coating and a preparation method and application thereof. The high-temperature wear-resistant and corrosion-resistant composite coating comprises a nickel-rich zone, a chromium-rich zone, an oxide and M x C y , wherein M is at least one of Cr and Ti, x and y satisfy the valence balance of the chemical formula, the oxide is at least one of aluminum oxide and silicon oxide, the nickel-rich zone mainly comprises nickel, and the chromium-rich zone mainly comprises chromium. The high-temperature wear-resistant and corrosion-resistant coating has good hardness and wear resistance, the microhardness and the average tensile bonding strength at room temperature are high, and compared with a substrate (material is a high-temperature alloy) without the composite coating, the average effective wear resistance at room temperature, 400 DEG C, 600 DEG C and 800 DEG C can be increased by more than 10 times.

Description

Technical Field

[0001] This invention belongs to the field of metal ceramics and their composite materials, and specifically relates to a high-temperature wear-resistant and corrosion-resistant composite coating, its preparation method and application. Background Technology

[0002] High-temperature wear-resistant and corrosion-resistant coatings are surface technologies that combine metal-ceramic composite materials with substrate materials using thermal spraying. This improves the wear resistance of parts at high temperatures, reduces wear, and extends their service life. They can be used on high-temperature, relatively rotating components in aerospace, power, and metallurgy industries.

[0003] Existing high-temperature wear-resistant and corrosion-resistant coatings often incorporate hard, high-temperature resistant ceramic particles to improve their hardness and wear resistance. However, the phase difference between ceramic materials and metals is significant, resulting in low compatibility and wettability, weak interfacial bonding, poor ceramic dispersion, and limited performance improvement.

[0004] The relevant patent (application number 201611072897.4) discloses a protective method for a high-temperature wear-resistant coating of GH4708 nickel-based high-temperature alloy. It uses heat treatment to prepare a high-temperature wear-resistant coating on the surface of the part. It discloses that after processing the part, it is aluminized, and then aged at 800℃±20℃×10~20h in air cooling. It also discloses that the aluminized package containing the part is kept at 450℃±20℃ for 2h~4h, and then heated to 900℃~950℃ in the furnace and kept at 900℃~950℃ for 5~10h for aluminization. This patent has the following defects: (1) The part needs to be aluminized at high temperature in a high-temperature furnace, which greatly limits the size of the part. It is difficult to process irregular and large-sized parts. (2) The aluminization cycle of the part is long and requires long-term heat preservation at high temperature, which is inefficient.

[0005] A related patent (application number 201310558378.9) discloses a method for preparing a high-temperature wear-resistant coating on the surface of steel parts. It discloses a method for obtaining a Fe-Al intermetallic compound and a small amount of Al2O3 composite coating through liquid aluminum immersion zinc plating and composite diffusion treatment. The process includes pretreatment (alkali washing, acid washing, fluxing), aluminum immersion plating, and diffusion treatment; aluminum immersion plating is performed in molten aluminum at 720-800℃ for 1-10 minutes; and composite diffusion annealing is carried out in a protective atmosphere or vacuum at 850-1100℃ for 1-5 hours and in air at 400-600℃ for 20-30 minutes. By adjusting the diffusion treatment temperature and time, composite wear-resistant coatings containing intermetallic compounds and a small amount of Al2O3 of different thicknesses can be obtained. This patent has the following drawbacks: the process involves many steps, and the long immersion plating time at high temperatures has a significant thermal impact on thin sheet metal parts.

[0006] Therefore, providing a high-temperature wear-resistant and corrosion-resistant composite coating and its simple preparation method, while also meeting the requirements for efficient preparation of irregularly shaped parts, is an urgent technical problem to be solved. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the present invention aims to provide a high-temperature wear-resistant and corrosion-resistant composite coating, its preparation method, and its applications. The high-temperature wear-resistant and corrosion-resistant coating of the present invention exhibits excellent hardness and wear resistance, with high microhardness and average tensile bond strength at room temperature. Compared to a substrate (made of a high-temperature alloy) without a composite coating, the average effective wear resistance at room temperature, 400℃, 600℃, and 800℃ can be increased by more than 10 times.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a high-temperature wear-resistant and corrosion-resistant composite coating, the high-temperature wear-resistant and corrosion-resistant composite coating comprising a nickel-rich region, a chromium-rich region, an oxide, and M. x C y In this formula, M is at least one of Cr and Ti, x and y satisfy the valence balance of the chemical formula, the oxide is at least one of aluminum oxide and silicon oxide, the nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium.

[0010] In this invention, "the nickel-rich region mainly includes nickel" means that more than 70% (e.g., 70%, 75%, 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 100%) of the mass composition of the region is elemental nickel, and there may also be solid solutions of some other elements.

[0011] In this invention, "chromium-rich region mainly includes chromium" means that more than 70% (e.g., 70%, 75%, 80%, 85%, 90%, 92%, 95%, 97%, 98%, or 100%) of the mass composition of the region is elemental chromium, and there may also be solid solutions of other elements.

[0012] The high-temperature wear-resistant and corrosion-resistant composite coating of the present invention is a multiphase composite coating, wherein the nickel-rich region, chromium-rich region, oxide and M are present. x C y The mutual dispersion results in excellent coating performance, dense structure, high cohesive strength, low porosity, no fine cracks or defects in the coating, and no obvious interface delamination between ceramic and metal.

[0013] The high-temperature wear-resistant and corrosion-resistant coating of this invention has good hardness and wear resistance, and good adhesion. It has high microhardness and average tensile bond strength at room temperature. Compared with the substrate without composite coating (material is nickel-based high-temperature alloy GH4169, which is a widely used high-temperature alloy in the industry), the average effective wear resistance at room temperature, 400℃, 600℃ and 800℃ can be increased by more than 10 times.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] In one implementation, M x C y The average particle size is 0.5μm to 1.5μm, for example, 0.5μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm or 1.5μm.

[0016] Preferably, the thickness of the high-temperature wear-resistant and corrosion-resistant composite coating is 150μm to 250μm, such as 150μm, 160μm, 170μm, 185μm, 190μm, 200μm, 210μm, 220μm, 230μm, 240μm or 250μm.

[0017] Preferably, the porosity of the high-temperature wear-resistant and corrosion-resistant composite coating is 0.2% to 0.5%, such as 0.2%, 0.25%, 0.3%, 0.4%, or 0.5%.

[0018] Preferably, the microhardness of the high-temperature wear-resistant and corrosion-resistant composite coating at room temperature is 600HV0.2 to 800HV0.2, for example, 600HV0.2, 605HV0.2, 610HV0.2, 620HV0.2, 630HV0.2, 640HV0.2, 650HV0.2, 665HV0.2, 680HV0.2, 690HV0.2, 700HV0.2, and 715HV0.2. 2. 730HV0.2, 740HV0.2, 750HV0.2, 765HV0.2, 785HV0.2 or 800HV0.2, etc.; the average tensile bond strength is 60MPa~70MPa, such as 60MPa, 61MPa, 62MPa, 63MPa, 64MPa, 65MPa, 68MPa or 70MPa, etc. (the general limit for tensile bond strength testing of coatings is 70MPa).

[0019] In this invention, we take 600HV0.2 as an example to explain the meaning of micro hardness. HV is the symbol for the Vickers hardness value of metal, 600 is the hardness value, and 0.2 indicates that the applied load is 0.2kg.

[0020] In this invention, room temperature refers to 20℃~30℃, such as 20℃, 22℃, 24℃, 25℃, 28℃ or 30℃, etc.

[0021] In a second aspect, the present invention provides a method for preparing a high-temperature wear-resistant and corrosion-resistant composite coating as described in the first aspect, the method comprising the following steps:

[0022] (1) Nickel powder, chromium powder and ternary layered metal ceramic M a N b C is mixed and sprayed to obtain a coating powder, wherein a and b satisfy the valence balance of the chemical formula;

[0023] (2) Using the aforementioned spray powder, a high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying it onto the substrate.

[0024] Ternary layered metal ceramic M a N b C has an irregular three-dimensional lamellar structure with poor flowability. Spray granulation can obtain spherical or near-spherical powders to improve flowability and enhance the uniformity of materials, thereby improving the subsequent coating effect.

[0025] This invention utilizes the characteristics of ternary layered MAX phases, such as the easy oxidation of A-site elements to form high-hardness oxides (taking Al as an example, which oxidizes to form high-hardness Al2O3) and the easy diffusion into other metal elements for alloying. By adding ternary layered cermet MAX phases into the material, the in-situ oxidation of the MAX phase during spraying, along with its genetic nano-strengthening and in-situ metal alloying effects, achieves the dispersed distribution of nanoscale hard ceramic particles within the coating. Simultaneously, the A-site elements (e.g., Al) of the MAX phase easily diffuse into the metal for in-situ alloying, realizing a two-phase reinforcement mechanism. These factors improve the bonding and dispersion uniformity of the interlayer interfaces within the coating.

[0026] In the method of this invention, through spray granulation and coating, nanoscale in-situ generated oxides (e.g., Al2O3) coat M. x C y The hard ceramic is a material in which M is at least one of Cr and Ti, and x and y satisfy the valence balance of the chemical formula. The hard ceramic is uniformly dispersed in the coating, and there is no obvious interfacial delamination between the ceramic and the metal, which effectively improves the bonding strength and hardness of the coating. The high-hardness coating provides better protection for the parts, thereby improving their service life at high temperatures and reducing costs.

[0027] The method of this invention does not limit the substrate; it can be a regular or irregularly shaped part with no special requirements on its shape, and can be applied to complex and special curved surfaces. Furthermore, the method of this invention involves fewer pre-treatment processes, shorter spraying time, higher preparation efficiency, and less thermal impact on the parts.

[0028] Preferably, the nickel powder, chromium powder, and ternary layered metal ceramic M mentioned in step (1) a N b The mass ratio of C is (60%–68%):(14%–18%):(18%–22%). Among them, nickel powder, chromium powder, and ternary layered metal ceramics M... a N b The total mass of C is 100%, and the nickel powder selection range is "60% to 68%", for example, 60%, 62%, 63%, 65%, 66%, or 68%, etc.; the chromium powder selection range is "14% to 18%", for example, 14%, 15%, 16%, 16.5%, 17%, or 18%, etc.; ternary layered metal ceramic M a N b The range of C is "18% to 22%", for example, it can be 18%, 19%, 20%, 21% or 22%, etc.

[0029] In one implementation, M a N b C is Cr2AlC. It is a ternary layered metal-ceramic with a typical layered structure. Its Vickers hardness is (5.5±0.4) GPa, and it has high elastic stiffness, good radiation resistance, and good thermal stability in a vacuum environment at 1450℃. In an argon atmosphere, its thermal stability temperature can reach 1500℃. Nickel (Ni) has a melting point of 1453℃, and chromium (Cr) has a melting point of 1857℃, both exhibiting good compatibility with the ternary metal-ceramic Cr2AlC.

[0030] Preferably, the particle size D90 of the sprayed powder obtained after spray granulation in step (1) is 15μm to 45μm, such as 15μm, 17μm, 20μm, 25μm, 30μm, 35μm, 40μm or 45μm. If the particle size of the sprayed powder is too large, it will lead to insufficient melting of the powder during the spraying process, poor flattening effect after impact with the substrate, resulting in weak interlayer bonding force, high porosity, poor interlayer bonding of the coating, low coating hardness, and low wear resistance. If the particle size of the sprayed powder is too small, the heated particles will melt fully, and liquefaction splashing is likely to occur during high-speed impact. Excessively fine powder will lead to severe element dissipation during spraying, severe coating oxidation, low powder application rate, high porosity, and correspondingly reduced coating bonding strength.

[0031] Preferably, the spraying is performed using a supersonic plasma spraying device.

[0032] This invention does not specifically limit the spraying equipment. It can be a commercially available supersonic plasma spraying equipment or a self-made supersonic plasma spraying equipment, such as the HEPJet supersonic plasma spraying system developed by the Army Armored Force Academy.

[0033] Preferably, the spraying current is 400A to 550A, such as 400A, 420A, 430A, 440A, 450A, 465A, 475A, 485A, 500A, 510A, 520A, 530A or 550A.

[0034] Preferably, the spraying voltage is 85V to 110V, such as 85V, 86V, 88V, 90V, 95V, 100V, 105V or 110V.

[0035] Preferably, the main air flow rate for spraying is 100L / min to 125L / min, such as 100L / min, 105L / min, 110L / min, 115L / min, 120L / min or 125L / min.

[0036] Preferably, the secondary gas flow rate for spraying is 20L / min to 35L / min, such as 20L / min, 22L / min, 24L / min, 26L / min, 28L / min, 30L / min, 32L / min, 33L / min or 35L / min.

[0037] Preferably, the spraying distance is 90mm to 110mm, such as 90mm, 95mm, 100mm, 105mm or 110mm.

[0038] Preferably, the powder feeding rate for spraying is 30g / min to 40g / min. If the powder feeding rate is too high, the powder will melt poorly due to less heat absorbed by individual particles, resulting in lower coating quality. If the powder feeding rate is too low, less powder will be produced per unit time, leading to lower coating efficiency and problems such as excessive melting and severe oxidation of particles.

[0039] In this invention, the performance of the coating can be optimized by adjusting the spraying parameters.

[0040] As a preferred embodiment of the preparation method of the present invention, the back side of the substrate is cooled during the spraying process.

[0041] In one embodiment, compressed cooling air is jetted onto the back side of the substrate to cool the coating.

[0042] In one embodiment, during cooling, the front side of the substrate is cleaned, preferably using compressed air as a cleaning air to clean the loose powder that has not adhered well to the surface.

[0043] In this invention, the compressed air is high-pressure clean air.

[0044] Preferably, the substrate is sandblasted before spraying.

[0045] Sandblasting can effectively remove oil, oxide layers and impurities from the surface. It can also effectively activate the surface. The rougher surface after sandblasting can effectively improve the mechanical interlocking between the coating and the substrate, thus increasing their bonding strength.

[0046] Preferably, the substrate surface after sandblasting should have a uniform color and no visible uneven areas. This invention does not limit the equipment used for sandblasting; commonly used sandblasting equipment in the field can be used.

[0047] Preferably, the method further includes cleaning the sandblasted surface after sandblasting to ensure that there are no residual sand particles on the surface.

[0048] Preferably, the cleaning method is: blowing with compressed air.

[0049] Alternatively, alcohol can be used to wipe away any remaining stains or dust on the substrate surface.

[0050] Thirdly, the present invention provides an application of the high-temperature wear-resistant and corrosion-resistant composite coating as described in the first aspect, wherein the high-temperature wear-resistant and corrosion-resistant composite coating is used in the aerospace, power or metallurgical fields.

[0051] The high-temperature wear-resistant and corrosion-resistant composite coating of this invention is particularly suitable for spraying onto the surface of parts subjected to friction at high temperatures, providing excellent protection. By preparing a high-temperature wear-resistant and corrosion-resistant coating on the surface of parts subjected to friction at high temperatures, it can effectively protect the parts below 800°C, effectively reducing wear at high temperatures. Compared with a substrate (made of high-temperature alloy) without the high-temperature wear-resistant and corrosion-resistant composite coating, under the same friction and wear test conditions, by comparing the maximum wear depth of the wear tracks, the hard wear-resistant coating can effectively reduce the wear depth by an order of magnitude, effectively extending its service life by more than 10 times.

[0052] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0053] Compared with existing technologies, the present invention has the following beneficial effects:

[0054] (1) The high-temperature wear-resistant and corrosion-resistant composite coating of the present invention is a multiphase composite coating in which the nickel-rich region, chromium-rich region, oxide and MxCy are dispersed in each other, resulting in excellent coating performance, dense structure, high cohesive strength, low porosity, no fine cracks or defects in the coating, and no obvious interface delamination between ceramic and metal.

[0055] (2) The high-temperature wear-resistant and corrosion-resistant coating of the present invention has good hardness and wear resistance, and good adhesion. It has high microhardness and average tensile bond strength at room temperature. Compared with the substrate (made of high-temperature alloy) without composite coating, the average effective wear resistance at room temperature, 400℃, 600℃ and 800℃ can be increased by more than 10 times.

[0056] (3) In the method of the present invention, there are fewer pretreatment processes before spraying, shorter spraying time, higher preparation efficiency, and less thermal impact on the parts. Attached Figure Description

[0057] Figure 1 This is a scanning electron microscope image of the composite powder after spray granulation.

[0058] Figure 2 , Figure 3 and Figure 4 This is a cross-sectional view of the coating provided in Embodiment 1 of the present invention, wherein, Figure 3 and Figure 4 This is a magnified view of a portion of the image. Detailed Implementation

[0059] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0060] Example 1

[0061] This embodiment provides a high-temperature wear-resistant and corrosion-resistant composite coating, which includes a nickel-rich region, a chromium-rich region, Al2O3 and Cr7C3. The nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium.

[0062] The above-mentioned high-temperature wear-resistant and corrosion-resistant composite coating is prepared by the following method, which includes the following steps:

[0063] (1) Nickel powder, chromium powder and ternary layered metal ceramic Cr2AlC are mixed in a mass ratio of 64:16:20 and sprayed to obtain a spray powder with a particle size D90 of 20μm.

[0064] (2) Pretreatment: The substrate is sandblasted. The specific steps of the sandblasting process are cleaning the substrate, sandblasting (spitting brown corundum abrasive particles, the main component of which is Al2O3), cleaning the residual abrasive particles on the substrate surface. After sandblasting, the substrate surface is required to have a uniform color and no uneven areas visible to the naked eye. After sandblasting, the sandblasted surface is cleaned by blowing with compressed air.

[0065] (3) A high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying powder onto the pretreated substrate;

[0066] The spraying is performed using a supersonic plasma spraying device, and the spraying parameters are shown in Table 1.

[0067] Table 1 Parameters for Supersonic Plasma Spraying

[0068]

[0069] During spraying, compressed cooling air is sprayed onto the back of the substrate to cool the coating; compressed air is used as a cleaning air to clean the surface of the substrate to remove loose powder that has not adhered well.

[0070] After the coating was applied, the coating thickness was measured using a micrometer, and the coating thickness was 200 μm.

[0071] Figure 1 This is a scanning electron microscope image of the composite powder after spray granulation. As can be seen from the image, the three-dimensional layered MAX phase Cr2AlC is surrounded by small particles of metallic Ni and Cr. The particle size distribution of the powder is relatively uniform, which ensures the flowability of the powder and uniform powder application.

[0072] Figure 2 , Figure 3 and Figure 4 This is a cross-sectional view of the coating provided in Embodiment 1 of the present invention, wherein... Figure 3 and Figure 4 This is a magnified view of a specific area. Figure 2 , Figure 3 and Figure 4 It can be seen that the coating has a uniform distribution of ceramic and metallic phases, no obvious crack defects, good interlayer bonding, no obvious delamination, dense structure, and excellent interfacial structure.

[0073] Example 2

[0074] This embodiment provides a high-temperature wear-resistant and corrosion-resistant composite coating, which includes a nickel-rich region, a chromium-rich region, Al2O3 and Cr7C3. The nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium.

[0075] The above-mentioned high-temperature wear-resistant and corrosion-resistant composite coating is prepared by the following method, which includes the following steps:

[0076] (1) Nickel powder, chromium powder and ternary layered metal ceramic Cr2AlC are mixed in a mass ratio of 62:16:22 and sprayed to obtain a spray powder with a particle size D90 of 15μm.

[0077] (2) Pretreatment: The substrate is sandblasted. The specific steps of the sandblasting treatment are: cleaning the substrate, sandblasting (spitting brown corundum abrasive particles, the main component of which is Al2O3), cleaning the residual abrasive particles on the substrate surface. After sandblasting, the substrate surface is required to have a uniform color and no uneven areas visible to the naked eye. After sandblasting, the sandblasted surface is cleaned by blowing with compressed air.

[0078] (3) A high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying powder onto the pretreated substrate;

[0079] The spraying is performed using a supersonic plasma spraying device, and the spraying parameters are shown in Table 2.

[0080] Table 2 Parameters for Supersonic Plasma Spraying

[0081]

[0082] During spraying, compressed cooling air is sprayed onto the back of the substrate to cool the coating; compressed air is used as a cleaning air to clean the surface of the substrate to remove loose powder that has not adhered well.

[0083] After the coating was applied, the coating thickness was measured using a micrometer, and the coating thickness was 160 μm.

[0084] Example 3

[0085] This embodiment provides a high-temperature wear-resistant and corrosion-resistant composite coating, which includes a nickel-rich region, a chromium-rich region, Al2O3 and Cr7C3. The nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium.

[0086] The above-mentioned high-temperature wear-resistant and corrosion-resistant composite coating is prepared by the following method, which includes the following steps:

[0087] (1) Nickel powder, chromium powder and ternary layered metal ceramic Cr2AlC are mixed in a mass ratio of 64:16:20 and sprayed to obtain a spray powder with a particle size D90 of 100μm.

[0088] (2) Pretreatment: The substrate is sandblasted. The specific steps of the sandblasting treatment are: cleaning the substrate, sandblasting (spitting brown corundum abrasive particles, the main component of which is Al2O3), cleaning the residual abrasive particles on the substrate surface. After sandblasting, the substrate surface is required to have a uniform color and no uneven areas visible to the naked eye. After sandblasting, the sandblasted surface is cleaned by blowing with compressed air.

[0089] (3) A high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying powder onto the pretreated substrate;

[0090] The spraying is performed using a supersonic plasma spraying device, and the spraying parameters are shown in Table 3.

[0091] Table 3 Parameters for Supersonic Plasma Spraying

[0092]

[0093] During spraying, compressed cooling air is sprayed onto the back of the substrate to cool the coating; compressed air is used as a cleaning air to clean the surface of the substrate to remove loose powder that has not adhered well.

[0094] After the coating was applied, the coating thickness was measured using a micrometer, and the coating thickness was 180 μm.

[0095] Example 4

[0096] This embodiment provides a high-temperature wear-resistant and corrosion-resistant composite coating, which includes a nickel-rich region, a chromium-rich region, Al2O3 and Cr7C3. The nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium.

[0097] The above-mentioned high-temperature wear-resistant and corrosion-resistant composite coating is prepared by the following method, which includes the following steps:

[0098] (1) Nickel powder, chromium powder and ternary layered metal ceramic Cr2AlC are mixed in a mass ratio of 64:16:20 and sprayed to obtain a spray powder with a particle size D90 of 30μm.

[0099] (2) Pretreatment: The substrate is sandblasted. The specific steps of the sandblasting treatment are: cleaning the substrate, sandblasting (spitting brown corundum abrasive particles, the main component of which is Al2O3), cleaning the residual abrasive particles on the substrate surface. After sandblasting, the substrate surface is required to have a uniform color and no uneven areas visible to the naked eye. After sandblasting, the sandblasted surface is cleaned by blowing with compressed air.

[0100] (3) A high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying powder onto the pretreated substrate;

[0101] The spraying is performed using a supersonic plasma spraying device, and the spraying parameters are shown in Table 4.

[0102] Table 4 Parameters for Supersonic Plasma Spraying

[0103]

[0104] During spraying, compressed cooling air is sprayed onto the back of the substrate to cool the coating; compressed air is used as a cleaning air to clean the surface of the substrate to remove loose powder that has not adhered well.

[0105] After the coating was applied, the coating thickness was measured with a micrometer and found to be 230 μm.

[0106] Example 5

[0107] The difference from Example 1 is that the mass ratio of nickel powder and chromium powder is kept constant, but the total mass percentage of the two is changed so that the mass percentage of the ternary layered metal ceramic Cr2AlC is 10%.

[0108] Example 6

[0109] The difference from Example 1 is that the mass ratio of nickel powder and chromium powder is kept constant, but the total mass percentage of the two is changed so that the mass percentage of the ternary layered metal ceramic Cr2AlC is 30%.

[0110] Example 7

[0111] The difference from Example 1 is that the powder feeding rate is 10g / min.

[0112] Example 8

[0113] The difference from Example 1 is that the powder feeding rate is 50g / min.

[0114] Example 9

[0115] The difference from Example 1 is that the current is 350A.

[0116] Example 10

[0117] The difference from Example 1 is that the current is 600A.

[0118] Comparative Example 1

[0119] The difference from Example 1 is that the spray granulation step was not performed; that is, the material after mixing nickel powder, chromium powder and ternary layered metal ceramic Cr2AlC was directly used for spraying.

[0120] Comparative Example 2

[0121] The difference from Example 1 is that the ternary layered metal ceramic Cr2AlC was not added.

[0122] test:

[0123] (1) Porosity test:

[0124] The porosity of the coating was measured and calculated using SEM (Scanning Electron Microscopy) observation and image processing. Specifically: First, the thermally sprayed coating was cut perpendicular to the coating-substrate interface and mounted as a sample. The cross-section of the sample was then ground and polished until scratch-free. The sample was observed under a scanning electron microscope at 500x magnification. Ten to fifteen clear microscopic images were randomly collected from different areas of the coating sample cross-section. These images were then input into ImageJ2x image processing software, and the porosity was calculated using the grayscale method, representing the porosity as the area ratio of pores and microcracks on the two-dimensional image.

[0125] (2) Bond strength test:

[0126] Following the equipment, specimens, procedures, and evaluation methods specified in the standard GB / T 8642-2002 "Thermal Spraying - Determination of Tensile Bond Strength", the coated specimen was prepared into a circular disc with a diameter of 25 mm. The back of the tensile bar and the coated specimen were roughened by sandblasting. Then, the specimen and the tensile bar were bonded together with E-7 high-strength resin adhesive and cured at 100℃ for 3 hours under load. After curing, the bonded specimen was continuously and uniformly loaded using an MTS tensile testing machine until fracture occurred. The maximum fracture load was recorded, and the bond strength was calculated. The loading speed during the tensile process did not exceed 1000 N / s ± 100 N / s. Only specimens where the coating breaks at the interface between the sprayed coating and the base metal, or where the sprayed coating itself breaks, can be used for calculation. When the fracture occurs in the adhesive layer, the specimen should not be used to calculate the average tensile bond strength; additional tests are required until three sets of valid data are obtained, and the average value is taken to obtain the average tensile bond strength.

[0127] (3) Vickers hardness test:

[0128] After grinding and polishing the 5×10mm coating sample, place it on the sample stage of the Vickers hardness testing system, apply a load of 0.2kg, hold for 15s, and then randomly test 5 points in different areas of the coating sample to calculate the average microhardness.

[0129] (4) Test method for the ratio of wear resistance improvement compared to the matrix:

[0130] A substrate (made of nickel-based high-temperature alloy GH4169) was provided as a control example. Coatings of various embodiments and comparative examples were applied to the surface of the substrate as experimental examples. The sample was a standard one-inch diameter disc (25.4 mm), which was clamped on a rotary tribometer with ball-disc contact. The grinding balls were silicon carbide ceramic balls with a diameter of 5 mm. The rotation speed was 600 r / min, the rotation diameter was 10 mm, the load was 10 N, and the heating rate was 100℃ / 10 minutes. After reaching the set test temperature, the sample was held for 10 minutes before testing. The test time was 30 minutes. Tests were conducted at three temperatures: room temperature, 400℃, 600℃, and 800℃. The friction coefficient and friction force of the grinding surface were monitored in real time during the test. After the test, the sample was ultrasonically cleaned in alcohol for 3 minutes, dried, and magnified 100 times on a three-dimensional profilometer. The morphology of the wear track was scanned and the maximum depth of the wear track was measured. The average value of the three measurements was taken. The substrate and experimental example were tested under the same test conditions. The wear depth obtained at different temperatures was recorded. The wear depth of the control example was recorded as a, and the wear depth of the experimental example was recorded as b. The wear resistance improvement factor compared with the substrate was (ab) / b.

[0131] The test results are shown in Table 2.

[0132] Table 2

[0133]

[0134]

[0135] In summary, the coating of this invention exhibits excellent performance, a dense structure, high cohesive strength, low porosity, and is free of fine cracks and defects, with no obvious interfacial delamination between the ceramic and metal. The high-temperature wear-resistant and corrosion-resistant coating of this invention possesses good hardness and wear resistance, and excellent adhesion.

[0136] A comparison of Examples 1 and 5-6 shows that there is an optimal range for the mass ratio of ternary layered metal ceramic Cr2AlC. When the mass ratio is between 18% and 22%, it is beneficial to reduce the porosity of the coating and improve its hardness, bonding strength and wear resistance.

[0137] A comparison of Examples 1 and 7-8 shows that there is an optimal range for the amount of powder fed. If the amount of powder fed is too large, the powder absorbs less heat per particle, resulting in poor melting effect and lower coating quality. If the amount of powder fed is too small, the amount of powder per unit time decreases, the coating powder application efficiency decreases, and the particles suffer from excessive melting and severe oxidation, which also reduces the quality of the coating.

[0138] A comparison of Examples 1 and 9-10 shows that adjusting the current parameters during spraying can affect the quality of the prepared coating. If the current is too high, the overall spraying power increases, and the particles are fully heated and melted. However, the degree of metal oxidation increases (not the controllable in-situ oxidation enhancement of the MAX phase), resulting in more oxide inclusions. The bonding strength and porosity of the coating will deteriorate to some extent. If the current is too low, the overall power decreases, and the energy for softening and melting of the particles during flight is insufficient, affecting the quality of their stacking. The porosity of the coating will also increase, and the density, hardness, and wear resistance of the coating will decrease to some extent.

[0139] The comparison between Example 1 and Comparative Example 1 shows that the powder prepared by spray granulation has better flowability and a more uniform particle size distribution. The distribution of ternary layered ceramics is more uniform, and the performance indicators such as coating uniformity, porosity, and bonding strength are all improved.

[0140] The comparison between Example 1 and Comparative Example 2 shows that the addition of ternary layered ceramics increases the hardness of the coating, thereby improving its wear resistance. At the same time, the oxidation genetic nano-strengthening and alloy strengthening of ternary layered ceramics reduce the porosity of the coating, further improving its performance.

[0141] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A high-temperature wear-resistant and corrosion-resistant composite coating, characterized in that, The high-temperature wear-resistant and corrosion-resistant composite coating includes nickel-rich areas, chromium-rich areas, oxides, and M. x C y Wherein, M is at least one of Cr and Ti, x and y satisfy the valence equilibrium of the chemical formula, the oxide is at least one of aluminum oxide and silicon oxide, the nickel-rich region mainly includes nickel, and the chromium-rich region mainly includes chromium; the nickel-rich region mainly includes nickel means that more than 70% of the mass composition in this region is elemental nickel, and the chromium-rich region mainly includes chromium means that more than 70% of the mass composition in this region is elemental chromium. The high-temperature wear-resistant and corrosion-resistant composite coating is prepared by the following method, which includes the following steps: (1) Nickel powder, chromium powder and ternary layered metal ceramic M a N b C is mixed and sprayed to obtain a coating powder, wherein a and b satisfy the valence balance of the chemical formula; (2) Using the aforementioned spray powder, a high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying it onto the substrate.

2. The high-temperature wear-resistant and corrosion-resistant composite coating according to claim 1, characterized in that, The thickness of the high-temperature wear-resistant and corrosion-resistant composite coating is 150μm ~ 250μm.

3. The high-temperature wear-resistant and corrosion-resistant composite coating according to claim 1, characterized in that, The porosity of the high-temperature wear-resistant and corrosion-resistant composite coating is 0.2% to 0.5%.

4. The high-temperature wear-resistant and corrosion-resistant composite coating according to claim 1, characterized in that, The high-temperature wear-resistant and corrosion-resistant composite coating has a microhardness of 600HV0.2~800HV0.2 at room temperature and an average tensile bond strength of 60MPa~80MPa.

5. A method for preparing a high-temperature wear-resistant and corrosion-resistant composite coating as described in any one of claims 1-4, characterized in that, The method includes the following steps: (1) Nickel powder, chromium powder and ternary layered metal ceramic M a N b C is mixed and sprayed to obtain a coating powder, wherein a and b satisfy the valence balance of the chemical formula; (2) Using the aforementioned spray powder, a high-temperature wear-resistant and corrosion-resistant composite coating is prepared by spraying it onto the substrate.

6. The preparation method according to claim 5, characterized in that, Step (1) involves nickel powder, chromium powder, and ternary layered metal ceramic M. a N b The mass ratio of C is (60%~68%):(14%~18%):(18%~22%).

7. The preparation method according to claim 5, characterized in that, The particle size D90 of the sprayed powder obtained after spray granulation in step (1) is 15μm ~ 45μm.

8. The preparation method according to claim 5, characterized in that, The spraying is performed using supersonic plasma spraying equipment.

9. The preparation method according to claim 5, characterized in that, The spraying current is 400A ~ 550A.

10. The preparation method according to claim 5, characterized in that, The spraying voltage is 85V~110V.

11. The preparation method according to claim 5, characterized in that, The main air flow rate for spraying is 100L / min ~ 125L / min.

12. The preparation method according to claim 5, characterized in that, The secondary gas flow rate for spraying is 20L / min to 35L / min.

13. The preparation method according to claim 5, characterized in that, The spraying distance is 90mm to 110mm.

14. The preparation method according to claim 5, characterized in that, The powder feeding rate for spraying is 30g / min to 40g / min.

15. The preparation method according to claim 5, characterized in that, During the spraying process, the back side of the substrate is cooled.

16. The preparation method according to claim 5, characterized in that, Before spraying, the substrate is sandblasted.

17. The preparation method according to claim 16, characterized in that, The method further includes cleaning the sandblasted surface after sandblasting is completed.

18. The preparation method according to claim 17, characterized in that, The cleaning method is as follows: blowing with compressed air.

19. The use of a high-temperature wear-resistant and corrosion-resistant composite coating as described in any one of claims 1-4, characterized in that, The high-temperature wear-resistant and corrosion-resistant composite coating is used in aerospace, power, or metallurgical fields.

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