Aluminum alloy surface high toughness wear-resistant corrosion-resistant composite structure coating and preparation method thereof

Abstract

The present application relates to the technical field of cermet coating, in particular to an aluminum alloy surface high-toughness wear-resistant corrosion-resistant composite structure coating and a preparation method thereof, the composite structure coating comprises, from the substrate surface outward, an AA2024 bottom layer, an AA2024-fiber Al2O3 intermediate layer, an AA2024-fiber Al2O3-multi-scale AlN sub-top layer, and an AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN top layer; a multi-layer gradient structure is constructed by introducing fiber Al2O3 and multi-scale nitride ceramics, smooth transition from the substrate to the top layer is realized, interface stress is relieved, and cracks and peeling are inhibited. By adding AlN and TiN ceramics, the hardness, wear resistance and corrosion resistance of the coating are improved. Combined with FSP, material plastic flow and recrystallization are promoted, interface bonding is improved, compactness is improved, ceramic phase distribution is more uniform, and the comprehensive performance of the coating is further enhanced.

Description

Technical Field

[0001] This invention relates to the field of metal-ceramic coating technology, specifically to a high-toughness, wear-resistant, and corrosion-resistant composite structure coating for aluminum alloy surfaces and its preparation method. Background Technology

[0002] With the rapid development of modern industry, lightweighting has become an important development direction in aerospace, rail transportation, automobile manufacturing, and marine engineering. Aluminum alloys, due to their low density, high specific strength, good formability, and excellent corrosion resistance, are widely used in various key structural components, making them one of the preferred materials for achieving lightweight equipment. However, in complex service environments, aluminum alloy components often face failure problems caused by both corrosion and wear. Traditional surface strengthening technologies such as electroplating and thermal spraying can improve the wear and corrosion resistance of aluminum alloys to some extent, but their application effects are limited by the inherent characteristics of aluminum alloys. Thermal spraying, in particular, while capable of preparing high-performance ceramic or metal-based composite coatings on metal surfaces, relies on high-temperature heating to melt and deposit the sprayed material. The high temperatures generated during this process significantly affect the low-melting-point aluminum alloy matrix, leading to thermal deformation, grain coarsening, and even melt-through, severely impacting the mechanical properties and dimensional accuracy of the substrate. Therefore, it is difficult to apply to the surface modification of aluminum alloy components.

[0003] Cold spraying technology, as an emerging solid-state additive manufacturing process, has the advantages of operating at temperatures far below the material's melting point and minimal thermal impact on the substrate. It is particularly suitable for coating easily oxidized, low-melting-point, or heat-sensitive materials, showing great potential in preparing protective coatings for aluminum alloy surfaces. However, directly depositing high-hardness, wear-resistant materials onto aluminum alloy surfaces remains a significant challenge. This is because the aluminum alloy itself has relatively low strength and hardness, failing to provide sufficient support for the high-hardness coating. Under load, it is prone to interfacial delamination or underlayer crushing, resulting in the actual wear resistance of the coating falling far short of theoretical levels. Furthermore, cold-sprayed coatings primarily rely on mechanical interlocking between particles and interfacial plastic deformation for bonding, lacking metallurgical bonding. This leads to micropores and interfacial defects between layers and particles, becoming corrosive media (such as water vapor, Cl-). - The limited penetration channels (such as those for metallurgy, corrosion, and metallurgy) into the coating restrict its long-term stable application in highly corrosive environments. Therefore, relying solely on cold spraying technology is insufficient to meet the comprehensive protection requirements of high-end equipment for aluminum alloy components, which demand both excellent wear resistance and extreme corrosion resistance. There is an urgent need to develop cold spray coating structure designs specifically for aluminum alloy substrates and explore strengthening methods to improve the metallurgical bonding of the coating.

[0004] 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

[0005] The purpose of this invention is to solve the problem that it is difficult to prepare high-quality metal-ceramic composite coatings on the surface of aluminum alloy parts with single-layer or double-layer structural designs. At the same time, it overcomes the problems of low metallurgical bonding degree of cold spray coatings and insufficient wear resistance and corrosion resistance under extreme environments. The invention provides a high-toughness, wear-resistant and corrosion-resistant composite structural coating for aluminum alloy surfaces and its preparation method.

[0006] To achieve the above objectives, the present invention discloses a high-toughness, wear-resistant, and corrosion-resistant composite structure coating for aluminum alloy surfaces. The composite structure coating comprises, from the substrate surface outwards, an AA2024 bottom layer, an AA2024-fiber Al2O3 intermediate layer, an AA2024-fiber Al2O3-multi-scale AlN sub-top layer, and an AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN top layer.

[0007] The thickness of the AA2024 bottom layer is 45-60 μm, the thickness of the AA2024-fiber Al2O3 intermediate layer is 45-80 μm, the thickness of the AA2024-fiber Al2O3-multiscale AlN sublayer is 60-80 μm, and the thickness of the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer is 100-130 μm.

[0008] The content of fiber Al2O3 in the AA2024-fiber Al2O3 interlayer is 3wt.%~5wt.%, and the average diameter of the fiber Al2O3 is 0.5-1μm.

[0009] The content of fiber Al2O3 in the AA2024-fiber Al2O3-multiscale AlN sub-top layer is 3wt.%~5wt.%, the average diameter of fiber Al2O3 is 0.5-1μm, the content of multiscale AlN in the AA2024-fiber Al2O3-multiscale AlN sub-top layer is 8wt.%~13wt.%, and the particle size of multiscale AlN is 0.05-15μm.

[0010] The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 3wt.%~5wt.% fiber Al2O3 with an average diameter of 0.5-1μm. The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 8wt.%~13wt.% multiscale AlN with a particle size of 0.05-15μm. The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 3wt.%-7wt.% multiscale TiN with a particle size of 0.05-15μm.

[0011] This invention also discloses a method for preparing the above-mentioned high-toughness, wear-resistant, and corrosion-resistant composite coating on the surface of aluminum alloy, comprising the following steps:

[0012] S1, using cold spraying technology, AA2024 base layer, AA2024-fiber Al2O3 intermediate layer, AA2024-fiber Al2O3-multiscale AlN sub-top layer, and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are sprayed sequentially from the inside to the outside on the substrate surface to obtain a composite structure coating.

[0013] S2, Grinding, polishing and ultrasonic cleaning are performed on the surface of the composite structure coating obtained in step S1;

[0014] S3. The composite structure coating after cleaning in step S2 is strengthened by friction stir processing (FSP). The rotation speed of the friction stir head is 850rpm-950rpm and the processing is performed in 2 passes.

[0015] In step S1, the cold spraying process for the composite structure coating is as follows:

[0016] S11, dry the pure AA2024, AA2024-fiber Al2O3 composite powder, AA2024-fiber Al2O3-multiscale AlN composite powder, and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder to remove excess moisture. The drying temperature is 80℃ and the time is 60min.

[0017] S12, the surface of the aluminum alloy substrate is roughened by sandblasting using 24-mesh brown corundum sand and a sandblasting carrier gas pressure of 0.1-0.3MPa. The substrate after sandblasting is cleaned with anhydrous ethanol or acetone.

[0018] S13 uses He as the accelerating gas, with the following settings: gas pressure 0.8 MPa, gas heating temperature 500℃, spraying distance 25 mm, nozzle lateral movement speed 20 mm / s, and powder feed rate 3 rpm.

[0019] S14, spray two coats of AA2024 base layer with a thickness of 45-60μm on the cleaned aluminum alloy substrate surface;

[0020] S15, spray two coats on the surface of the AA2024 base layer to obtain an AA2024-fiber Al2O3 intermediate layer with a thickness of 45-80μm;

[0021] S16, spray three passes onto the surface of the AA2024-fiber Al2O3 intermediate layer to obtain an AA2024-fiber Al2O3-multiscale AlN sub-top layer with a thickness of 60-80μm;

[0022] S17, five passes were sprayed onto the surface of the AA2024-fiber Al2O3-multiscale AlN sub-top layer to obtain an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer with a thickness of 100-130μm, and finally a composite structure coating was obtained.

[0023] In step S11, the preparation process of AA2024-fiber Al2O3 composite powder is as follows:

[0024] A1. First, weigh the AA2024 powder and fiber Al2O3 used in the mechanical alloying method of AA2024-fiber Al2O3 composite powder, and calculate the total mass of the composite powder.

[0025] A2. Weigh out AA2024 powder and Al2O3 fiber and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:1. The total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min.

[0026] A3. Place the grinding jar in an all-around planetary ball mill, set the grinding speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop. The grinding time is 12 hours.

[0027] A4, after reaching the ball milling time, AA2024-fiber Al2O3 composite powder with a particle size range of 15-45μm was sieved out.

[0028] In step S11, the preparation process of AA2024-fiber Al2O3-multiscale AlN composite powder is as follows:

[0029] B1. First, weigh the AA2024 powder, fiber Al2O3 and multi-scale AlN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN composite powder, and calculate the total mass of the composite powder.

[0030] B2. Weigh out AA2024 powder and Al2O3 fiber and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:1. The total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min.

[0031] B3. Place the grinding jar in an all-around planetary ball mill, set the ball mill speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop. The ball milling time is 12 hours.

[0032] B4. After ball milling for 12 hours, open the ball mill jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming, and argon filling treatments as described in B2. Then, continue ball milling for 6 hours according to the parameters in step B3.

[0033] B5, after reaching the ball milling time, AA2024-fiber Al2O3-multiscale AlN composite powder with a particle size range of 15-45μm was sieved out.

[0034] In step S11, the preparation process of the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder is as follows:

[0035] C1. First, weigh the AA2024 powder, fiber Al2O3, multi-scale AlN and multi-scale TiN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN composite powder, and calculate the total mass of the composite powder.

[0036] C2. Weigh out AA2024 powder and fiber Al2O3 and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:1, and the total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min.

[0037] C3, place the grinding jar in an all-around planetary ball mill, set the ball milling speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop, with a ball milling time of 12 hours;

[0038] C4. After ball milling for 12 hours, open the ball mill jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming, and argon filling treatments as in step C2. Then, continue ball milling for 6 hours according to the parameters in step C3.

[0039] C5. After ball milling for 18 hours, open the ball mill jar, add the weighed multi-scale TiN, and perform the sealing, vacuuming, and argon filling treatments as in step C2. Then, continue ball milling for 4 hours according to the parameters in step C3.

[0040] C6, after reaching the ball milling time, was sieved to obtain AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder with a particle size range of 15-45μm.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1. Cold spraying technology enables coating deposition at lower temperatures, reducing the thermal impact of the preparation process on the substrate. By introducing fibrous Al2O3 and multi-scale nitride ceramics to construct a multi-layered gradient structure, a smooth transition from the substrate to the high-hardness top layer is achieved, alleviating stress concentration at the interface caused by differences in thermal expansion coefficients and stiffness, and inhibiting crack propagation and coating peeling. The addition of corrosion-resistant AlN and TiN ceramics forms a synergistically reinforced ceramic framework structure with Al2O3 ceramics, improving the surface hardness and wear resistance of the coating while enhancing its corrosion resistance in extreme environments.

[0043] 2. FSP promotes plastic flow and dynamic recrystallization of materials in a solid-state thermoplastic state, achieving metallurgical bonding within the composite material and improving its interfacial bonding strength and overall density. However, an improper FSP process may cause component dilution and structural damage to the composite coating. Therefore, this invention optimizes key FSP process parameters to promote metallurgical bonding between coating interfaces and uniform dispersion of the ceramic phase, while ensuring the integrity of the multilayer structure. This extends FSP technology to the modification of multilayer coatings, further enhancing the overall performance of the coating. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of a composite coating structure.

[0045] Figure 2 This is a cross-sectional SEM image of the composite structure before the FSP coating;

[0046] Figure 3 OM diagram of the surface before the composite structure coating FSP;

[0047] Figure 4 This is the surface OM diagram after the composite structure is coated with FSP. Detailed Implementation

[0048] 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.

[0049] Example 1

[0050] A method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite structure coating (before FSP) on an aluminum alloy surface includes: firstly, preparing AA2024-fiber Al2O3 composite powder, AA2024-fiber Al2O3-multi-scale AlN composite powder, and AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN composite powder by mechanical alloying; cold spraying a base layer (AA2024) onto an aluminum alloy substrate; cold spraying an intermediate layer (AA2024-fiber Al2O3) onto the surface of the base layer; cold spraying a second top layer (AA2024-fiber Al2O3-multi-scale AlN) onto the surface of the intermediate layer; and cold spraying a top layer (AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN) onto the surface of the second top layer.

[0051] The mechanical alloying preparation process of the above-mentioned AA2024-fiber Al2O3 composite powder includes the following steps:

[0052] (1) First, weigh the AA2024 powder and fiber Al2O3 used in the mechanical alloying method of AA2024-fiber Al2O3 composite powder. The mass ratio is AA2024 powder: fiber Al2O3 = 0.95: 0.05. Calculate the total mass of the composite powder.

[0053] (2) Add the weighed AA2024 powder and fiber Al2O3 to the ball mill jar, add the mixed grinding balls to the ball mill jar, the size and mass ratio of the mixed grinding balls is 12mm:8mm:5mm=1:3:1, the total mass ratio of the mixed grinding balls to the total mass of the composite powder is 8:1; then seal the ball mill jar, and perform vacuuming and argon filling treatment inside the jar, the vacuum degree should be below 10Pa, the argon filling gas is high purity argon gas, the pressure is 0.2-0.3MPa, and the filling time is 15min.

[0054] (3) Place the grinding jar in an all-around planetary ball mill, set the ball milling speed to 180 rpm, and make a cycle of 10 min forward rotation, 2 min stop, 10 min reverse rotation, and 2 min stop. The ball milling time is 12 h.

[0055] (4) After reaching the ball milling time, AA2024-fiber Al2O3 composite powder with a particle size range of 15-45μm was screened out.

[0056] The mechanical alloying preparation process of the above-mentioned AA2024-fiber Al2O3-multiscale AlN composite powder includes the following steps:

[0057] (1) First, weigh the AA2024 powder, fiber Al2O3 and multi-scale AlN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN composite powder. The mass ratio is AA2024 powder: fiber Al2O3: multi-scale AlN = 0.85: 0.05: 0.1. Calculate the total mass of the composite powder.

[0058] (2) Add the weighed AA2024 powder and fiber Al2O3 to the ball mill jar, add the mixed grinding balls to the ball mill jar, the size and mass ratio of the mixed grinding balls is 12mm:8mm:5mm=1:3:1, the total mass ratio of the mixed grinding balls to the total mass of the composite powder is 8:1; then seal the ball mill jar, and perform vacuuming and argon filling treatment inside the jar, the vacuum degree should be below 10Pa, the argon filling gas is high purity argon gas, the pressure is 0.2-0.3MPa, and the filling time is 15min.

[0059] (3) Place the grinding jar in an all-around planetary ball mill, set the ball milling speed to 180 rpm, and make a cycle of 10 min forward rotation, 2 min stop, 10 min reverse rotation, and 2 min stop. The ball milling time is 12 h.

[0060] (4) After ball milling for 12 hours, open the ball milling jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming and argon filling treatments in step (2) on the ball milling jar. Then continue ball milling for 6 hours according to the parameters in step (3).

[0061] (5) After reaching the ball milling time, AA2024-fiber Al2O3-multiscale AlN composite powder with a particle size range of 15-45μm was screened out.

[0062] The mechanical alloying preparation process of the above-mentioned AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder includes the following steps:

[0063] (1) First, weigh the AA2024 powder, fiber Al2O3, multi-scale AlN and multi-scale TiN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN composite powder. The mass ratio is AA2024 powder: fiber Al2O3: multi-scale AlN: multi-scale TiN = 0.78: 0.05: 0.1: 0.07. Calculate the total mass of the composite powder.

[0064] (2) Add the weighed AA2024 powder and fiber Al2O3 into the ball mill jar, add the mixed grinding balls into the ball mill jar, the size and mass ratio of the mixed grinding balls is 12mm:8mm:5mm=1:3:1, the total mass ratio of the mixed grinding balls to the total mass of the composite powder is 8:1; then seal the ball mill jar, and perform vacuuming and argon filling treatment inside the jar, the vacuum degree should be below 10Pa, the argon filling gas is high purity argon gas, the pressure is 0.2-0.3MPa, and the filling time is 15min.

[0065] (3) Place the grinding jar in an all-around planetary ball mill, set the ball mill speed to 180 rpm, and make a cycle of 10 min forward rotation, 2 min stop, 10 min reverse rotation, and 2 min stop. The ball milling time is 12 h.

[0066] (4) After ball milling for 12 hours, open the ball milling jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming and argon filling treatments in step (2) on the ball milling jar. Then continue ball milling for 6 hours according to the parameters in step (3).

[0067] (5) After ball milling for 18 hours, open the ball milling jar, add the weighed multi-scale TiN, and perform the sealing, vacuuming and argon filling treatments in step (2) on the ball milling jar. Then continue ball milling for 4 hours according to the parameters in step (3).

[0068] (6) After reaching the ball milling time, AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder with a particle size range of 15-45μm was screened out.

[0069] The cold spraying preparation process of the above-mentioned AA2024 bottom layer, AA2024-fiber Al2O3 intermediate layer, AA2024-fiber Al2O3-multiscale AlN sub-top layer, and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer includes the following steps:

[0070] (1) Dry the pure AA2024, AA2024-fiber Al2O3 composite powder, AA2024-fiber Al2O3-multiscale AlN composite powder and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder to remove excess moisture. The drying temperature is 80℃ and the time is 60min.

[0071] (2) The surface of the aluminum alloy substrate is roughened by sandblasting. 24-mesh brown corundum sand is used and the sandblasting carrier gas pressure is 0.1-0.3MPa. The substrate after sandblasting is cleaned with anhydrous ethanol or acetone.

[0072] (3) Using He as the accelerating gas, the gas pressure is set to 0.8 MPa, the gas heating temperature is 500℃, the spraying distance is 25 mm, the nozzle lateral movement speed is 20 mm / s, and the powder feeding rate is 3 rpm.

[0073] (4) Two coats of AA2024 base coat with a thickness of 45-60μm are sprayed onto the cleaned aluminum alloy substrate.

[0074] (5) Two coats of AA2024 are sprayed onto the surface of the bottom layer to obtain an AA2024-fiber Al2O3 intermediate layer with a thickness of 45-80μm.

[0075] (6) Spray three coats onto the surface of the AA2024-fiber Al2O3 intermediate layer to obtain a AA2024-fiber Al2O3-multiscale AlN sub-top layer with a thickness of 60-80μm.

[0076] (7) Five coats were sprayed onto the surface of the AA2024-fiber Al2O3-multiscale AlN sub-top layer to obtain an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer with a thickness of 100-130 μm, finally obtaining a composite structure coating. The structure of the composite structure coating is as follows: Figure 1 As shown.

[0077] Example 2

[0078] A method for preparing an AA2024-Al2O3 interlayer includes first preparing AA2024-Al2O3 composite powder by mechanical alloying, and then preparing the AA2024-Al2O3 interlayer by cold spraying.

[0079] The mechanical alloying preparation process of the above-mentioned AA2024-Al2O3 composite powder includes the following steps:

[0080] (1) First, weigh out the AA2024 and Al2O3 powders used in the mechanical alloying method of AA2024-Al2O3 composite powder. The mass ratio is AA2024:Al2O3=0.95:0.05, and the average particle size of Al2O3 powder is 0.5-1μm.

[0081] (2) Add the weighed AA2024 powder and Al2O3 powder into the ball mill jar. The other process steps are the same as steps (2) to (4) of the mechanical alloying preparation process of AA2024-fiber Al2O3 composite powder in Example 1.

[0082] The preliminary process steps for preparing the above-mentioned cold-sprayed AA2024-Al2O3 intermediate layer are the same as steps (1) to (4) of the cold-spraying preparation process in Example 1. Subsequently, two passes are sprayed onto the surface of the AA2024 base layer to obtain an AA2024-Al2O3 intermediate layer with a thickness of 45-80 μm.

[0083] The microhardness and fracture toughness of the AA2024 bottom layer, AA2024-Al2O3 intermediate layer, AA2024-fiber Al2O3 intermediate layer, AA2024-fiber Al2O3-multiscale AlN sub-top layer and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer prepared in Examples 1 and 2 were tested, and the results are shown in Table 1.

[0084] Table 1 Microhardness and fracture toughness of the coating

[0085]

[0086] As shown in Table 1, the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer exhibits the best mechanical properties, with microhardness and fracture toughness reaching 158.64±5.06 HV, respectively. 0.3 and 6.43±0.27 This significantly enhances the coating's wear resistance and spalling resistance. Although the AA2024-fiber Al2O3 interlayer shows only a limited improvement in microhardness compared to the AA2024-Al2O3 interlayer containing ordinary Al2O3 particles, the bridging effect of the fiber Al2O3 effectively inhibits crack propagation and alleviates local stress concentration, thus greatly improving fracture toughness. Furthermore, the hardness and toughness of this interlayer lie between the AA2024 base layer and the AA2024-fiber Al2O3-multi-scale AlN sub-top layer, forming a gentle mechanical property gradient, which helps improve interface compatibility and enhance the overall service performance of the multilayer composite coating.

[0087] Example 3

[0088] The difference between this embodiment and Embodiment 1 is that: the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer is prepared directly on the aluminum alloy substrate, and the other process steps are the same as in Embodiment 1.

[0089] Example 4

[0090] The difference between this embodiment and Embodiment 1 is that an AA2024 bottom layer and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0091] Example 5

[0092] The difference between this embodiment and Embodiment 1 is that an AA2024-fiber Al2O3 intermediate layer and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0093] Example 6

[0094] The difference between this embodiment and Embodiment 1 is that AA2024-fiber Al2O3-multiscale AlN sub-top layer and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0095] Example 7

[0096] The difference between this embodiment and Embodiment 1 is that: an AA2024 bottom layer, an AA2024-fiber Al2O3 intermediate layer, and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0097] Example 8

[0098] The difference between this embodiment and Embodiment 1 is that: an AA2024 bottom layer, an AA2024-fiber Al2O3-multiscale AlN sub-top layer, and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0099] Example 9

[0100] The difference between this embodiment and Embodiment 1 is that: an AA2024-fiber Al2O3 intermediate layer, an AA2024-fiber Al2O3-multiscale AlN sub-top layer, and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are prepared on an aluminum alloy substrate, while other process steps are the same as in Embodiment 1.

[0101] The bonding strength of the single-layer, double-layer, triple-layer, and quadruple-layer coatings prepared in Examples 1 to 9 was measured using a universal tensile testing machine, and the results are shown in Table 2. The bonding strength of the single-layer top layer was only 32.23 ± 1.33 MPa. The bonding strength improved after forming a double-layer structure. The bonding strength of the double-layer structure composed of the bottom and top layers reached 41.64 ± 2.01 MPa, indicating that the bottom layer significantly enhances the interfacial bonding performance. While the double-layer combination composed of the middle layer, the second-to-top layer, and the top layer also improved the overall bonding strength, the increase was relatively limited. The bonding strength further increased after forming a triple-layer composite structure, with the combination of the bottom layer, middle layer, and top layer showing the best performance, reaching 45.09 ± 1.54 MPa. However, compared to other structures, the quadruple-layer system containing the bottom layer, middle layer, second-to-top layer, and top layer exhibited the highest bonding strength, at 48.13 ± 1.86 MPa, indicating that multi-component, multi-level collaborative design is more conducive to achieving strong interfacial bonding.

[0102] Table 2 Bond strength of different types of coatings

[0103]

[0104] Example 10

[0105] A method for strengthening aluminum alloy surfaces with a high-toughness, wear-resistant, and corrosion-resistant composite coating using FSP (Freezing Technology for Pulsed Fiber Optics), comprising the following steps:

[0106] (1) Polish the surface of the composite structure coating and thoroughly clean the polished surface with anhydrous ethanol or acetone.

[0107] (2) Fix the cleaned composite structure coating component on a rigid worktable, install the stirring head on the machining spindle, and adjust its rotational concentricity.

[0108] (3) Set the rotation speed of the stirring head to 900 rpm, press it down vertically at a uniform speed until the shoulder of the shaft is in close contact with the coating surface, and hold it for a short time to soften the local material.

[0109] (4) After the material is fully heated and softened, the stirring head moves along the predetermined path at a constant speed of 100 mm / min.

[0110] (5) When the stirring head reaches the end of the path, it stops moving and is lifted vertically to complete one FSP pass.

[0111] (6) Repeat steps (3) to (5) to complete two passes of FSP and obtain the reinforced composite structure coating.

[0112] Example 11

[0113] The difference between this embodiment and embodiment 10 is that the rotation speed of the stirring head is set to 600 rpm in step (3), while the other process steps are the same as in embodiment 10.

[0114] Example 12

[0115] The difference between this embodiment and embodiment 10 is that the rotation speed of the stirring head is set to 1200 rpm in step (3), while the other process steps are the same as in embodiment 10.

[0116] Example 13

[0117] The difference between this embodiment and embodiment 10 is that only one FSP pass is performed, while the other process steps are the same as in embodiment 10.

[0118] Example 14

[0119] The difference between this embodiment and embodiment 10 is that a total of 4 FSP processes are performed, while the other process steps are the same as in embodiment 10.

[0120] The hardness and fracture toughness of the composite coatings prepared under different process parameters after FSP strengthening in Examples 10-14 were tested, and the results are shown in Table 3. The microhardness and fracture toughness of the composite coatings after FSP were significantly improved. The mechanical properties of the composite coatings first increased and then decreased with increasing stirring head rotation speed (600 rpm~1200 rpm) and processing passes (1-4 passes). When the stirring head rotation speed was 900 rpm and the processing passes were 2, the composite coating exhibited the highest microhardness and fracture toughness, which were 172.23±8.35 HV, respectively. 0.3 and 9.34±0.63 .

[0121] Table 3 Hardness and fracture toughness of the FSP-reinforced composite coating

[0122]

[0123] The cross-section of the composite coating prepared in Example 1 was observed using SEM, such as... Figure 2 As shown. The surfaces of the pre- and post-FSP composite coatings were observed using OM, as shown. Figure 3 and Figure 4 As shown. By Figure 2It can be seen that the multilayer coating is dense and non-porous, with clear interfaces between layers and no obvious defects or inclusions at the interfaces. From the substrate outwards, it consists of an AA2024 bottom layer with a thickness of approximately 40 μm, an AA2024-fiber Al2O3 intermediate layer with a thickness of approximately 48 μm, an AA2024-fiber Al2O3-multiscale AlN sub-top layer with a thickness of approximately 62 μm, and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer with a thickness of approximately 110 μm. Compared to before FSP ( Figure 3 After the coating is treated with FSP ( Figure 4 The ceramic particles inside are more evenly distributed, the mechanical bonding interface has basically disappeared, and the metallurgical bonding degree and overall density of the coating have been improved.

[0124] Example 15

[0125] The difference between this embodiment and Embodiment 1 is that the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder is replaced by the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale AlN composite powder (used for the top layer of cold spray coating), including the following steps:

[0126] (1) First, weigh the AA2024 powder, fiber Al2O3 and multi-scale AlN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN composite powder. The mass ratio is AA2024 powder: fiber Al2O3: multi-scale AlN: =0.78:0.05:0.17. Calculate the total mass of these materials.

[0127] (2) to (5) are the same as steps (2) to (5) in the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale AlN composite powder in Example 1.

[0128] The preparation method of the top layer (AA2024-fiber Al2O3-multiscale AlN) is the same as the preparation process of the top layer (AA2024-fiber Al2O3-multiscale AlN-multiscale TiN) in Example 1.

[0129] Example 16

[0130] The difference between this embodiment and Embodiment 1 is that the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder is replaced by the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale TiN composite powder (used for the top layer of cold spray coating), including the following steps:

[0131] (1) First, weigh the AA2024 powder, fiber Al2O3 and multi-scale TiN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale TiN composite powder. The mass ratio is AA2024 powder: fiber Al2O3: multi-scale TiN = 0.78: 0.05: 0.17. Calculate the total mass of these materials.

[0132] (2) to (5) are the same as steps (2) to (5) in the mechanical alloying preparation process of AA2024-fiber Al2O3-multiscale AlN composite powder in Example 1.

[0133] The preparation method of the top layer (AA2024-fiber Al2O3-multiscale TiN) is the same as the preparation process of the top layer (AA2024-fiber Al2O3-multiscale AlN-multiscale TiN) in Example 1.

[0134] Example 17

[0135] The difference between this embodiment and Embodiment 1 is that AA2024-fiber Al2O3 composite powder is used as the raw material for the cold spray top layer to prepare a top layer (AA2024-fiber Al2O3) that does not contain AlN and TiN ceramics. Other process steps are the same as in Embodiment 1.

[0136] Performance tests were conducted on the composite coatings with different composition top layers prepared in Examples 1, 10-17, and after different FSP processes: the room temperature tribological properties of the coatings were tested using a ball-disc tribological tester; the electrochemical corrosion properties of the coatings were tested using a Princeton electrochemical workstation. The tribological test results of the coatings before and after FSP are shown in Table 4. The coefficient of friction and wear rate of the coating without nitride were 0.75 and 9.42 × 10⁻⁶, respectively. -4 Both AlN and TiN were added to improve the wear resistance of the coating, with TiN showing a more significant effect. The synergistic effect of these two nitride ceramics further reduced the coefficient of friction and wear rate of the coating to 0.61 and 4.15 × 10⁻⁶, respectively. -4 In addition, FSP can also improve the wear performance of the coating. The coating obtained by rotating at 900 rpm and processing in two passes has the lowest coefficient of friction and wear rate, which are 0.48 and 1.74 × 10⁻⁶, respectively. -4 .

[0137] Table 4. Friction coefficients and wear rates before and after FSP coating.

[0138]

[0139] The electrochemical corrosion performance test results of the FSP pre- and post-coatings are shown in Table 5. Among the fitting parameters for corrosion EIS, R... ct R is the charge transfer resistance between the corrosion solution and the working electrode. film R is the resistance of the dissolved oxide film as it diffuses through the barrier oxide film layer at the particle interface. ct and R film The larger the sum of the values, the better the corrosion resistance of the surface. Compared to ceramics without nitrides, adding either AlN or TiN can improve the corrosion resistance of the coating. However, TiN shows a more significant improvement in performance. When both types of nitride ceramics are added simultaneously, the corrosion resistance of the coating is further improved, R... ct +R film It is 4.69 Ω·cm 2 In addition, the FSP process also affects the corrosion resistance of the coating. As the rotational speed increases, the R... ct +R film Increase the speed first, then decrease it. Appropriate rotation speeds (900 rpm and 1200 rpm) significantly improve the coating's corrosion resistance. However, lower speeds (600 rpm) can actually decrease the coating's corrosion resistance. Appropriately increasing the number of machining passes helps improve the coating's corrosion resistance. However, too many machining passes (4 passes) severely damage the coating's internal structure, leading to a decrease in its corrosion resistance. Overall, the coating obtained using 900 rpm and 2 passes exhibits the best corrosion resistance, with a R0... ct +R film Reaching 10.58 Ω·cm 2 .

[0140] Table 5 Electrochemical performance of FSP before / after coating

[0141]

[0142] Based on the test results of the mechanical properties, tribological wear, and electrochemical corrosion properties of the pre- and post-FSP coatings, the following conclusions can be drawn: the above steps can produce a composite structure coating with good bonding strength, higher hardness, and fracture toughness. After FSP, the distribution of the ceramic phase inside the cold-sprayed coating is more uniform, and the interfacial bonding quality is significantly improved, thereby effectively enhancing the coating's wear resistance and corrosion resistance.

[0143] 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 high-toughness, wear-resistant, and corrosion-resistant composite coating for aluminum alloy surfaces, characterized in that, The composite structure coating comprises, from the substrate surface outwards, an AA2024 bottom layer, an AA2024-fiber Al2O3 intermediate layer, an AA2024-fiber Al2O3-multiscale AlN sub-top layer, and an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer. The content of fiber Al2O3 in the AA2024-fiber Al2O3 interlayer is 3wt.%~5wt.%, and the average diameter of the fiber Al2O3 is 0.5-1μm; The content of fiber Al2O3 in the AA2024-fiber Al2O3-multiscale AlN sub-top layer is 3wt.%~5wt.%, the average diameter of fiber Al2O3 is 0.5-1μm, the content of multiscale AlN in the AA2024-fiber Al2O3-multiscale AlN sub-top layer is 8wt.%~13wt.%, and the particle size of multiscale AlN is 0.05-15μm; The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 3wt.%~5wt.% fiber Al2O3 with an average diameter of 0.5-1μm. The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 8wt.%~13wt.% multiscale AlN with a particle size of 0.05-15μm. The AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer contains 3wt.%-7wt.% multiscale TiN with a particle size of 0.05-15μm.

2. The high-toughness, wear-resistant, and corrosion-resistant composite coating for aluminum alloy surfaces as described in claim 1, characterized in that, The thickness of the AA2024 bottom layer is 45-60 μm, the thickness of the AA2024-fiber Al2O3 intermediate layer is 45-80 μm, the thickness of the AA2024-fiber Al2O3-multiscale AlN sublayer is 60-80 μm, and the thickness of the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer is 100-130 μm.

3. A method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite coating on an aluminum alloy surface as described in claim 1 or 2, characterized in that, Includes the following steps: S1, using cold spraying technology, AA2024 base layer, AA2024-fiber Al2O3 intermediate layer, AA2024-fiber Al2O3-multiscale AlN sub-top layer, and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer are sprayed sequentially from the inside to the outside on the substrate surface to obtain a composite structure coating. S2, the surface of the composite structure coating obtained in step S1 is ground, polished and ultrasonically cleaned; S3. The composite structure coating after cleaning in step S2 is strengthened by friction stir processing. The rotation speed of the stirring head in friction stir processing is 850rpm-950rpm and the processing is performed in 2 passes.

4. The method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite coating on an aluminum alloy surface as described in claim 3, characterized in that, In step S1, the cold spraying process for the composite structure coating is as follows: S11, dry the pure AA2024, AA2024-fiber Al2O3 composite powder, AA2024-fiber Al2O3-multiscale AlN composite powder, and AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder to remove excess moisture. The drying temperature is 80℃ and the time is 60min. S12, the surface of the aluminum alloy substrate is roughened by sandblasting using 24-mesh brown corundum sand and a sandblasting carrier gas pressure of 0.1-0.3MPa. The substrate after sandblasting is cleaned with anhydrous ethanol or acetone. S13 uses He as the accelerating gas, with the following settings: gas pressure 0.8 MPa, gas heating temperature 500℃, spraying distance 25 mm, nozzle lateral movement speed 20 mm / s, and powder feed rate 3 rpm. S14, spray two coats of AA2024 base layer with a thickness of 45-60μm on the cleaned aluminum alloy substrate surface; S15, spray two coats on the surface of the AA2024 base layer to obtain an AA2024-fiber Al2O3 intermediate layer with a thickness of 45-80μm; S16, spray three passes onto the surface of the AA2024-fiber Al2O3 intermediate layer to obtain an AA2024-fiber Al2O3-multiscale AlN sub-top layer with a thickness of 60-80μm; S17, five passes were sprayed onto the surface of the AA2024-fiber Al2O3-multiscale AlN sub-top layer to obtain an AA2024-fiber Al2O3-multiscale AlN-multiscale TiN top layer with a thickness of 100-130μm, and finally a composite structure coating was obtained.

5. The method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite coating on an aluminum alloy surface as described in claim 4, characterized in that, In step S11, the preparation process of AA2024-fiber Al2O3 composite powder is as follows: A1. First, weigh the AA2024 powder and fiber Al2O3 used in the mechanical alloying method of AA2024-fiber Al2O3 composite powder, and calculate the total mass of the composite powder. A2. Weigh out AA2024 powder and Al2O3 fiber and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:

1. The total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:

1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min. A3. Place the grinding jar in an all-around planetary ball mill, set the grinding speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop. The grinding time is 12 hours. A4, after reaching the ball milling time, AA2024-fiber Al2O3 composite powder with a particle size range of 15-45μm was sieved out.

6. The method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite coating on an aluminum alloy surface as described in claim 4, characterized in that, In step S11, the preparation process of AA2024-fiber Al2O3-multiscale AlN composite powder is as follows: B1. First, weigh the AA2024 powder, fiber Al2O3 and multi-scale AlN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN composite powder, and calculate the total mass of the composite powder. B2. Weigh out AA2024 powder and Al2O3 fiber and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:

1. The total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:

1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min. B3. Place the grinding jar in an all-around planetary ball mill, set the ball mill speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop. The ball milling time is 12 hours. B4. After ball milling for 12 hours, open the ball mill jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming, and argon filling treatments as described in B2. Then, continue ball milling for 6 hours according to the parameters in step B3. B5, after reaching the ball milling time, AA2024-fiber Al2O3-multiscale AlN composite powder with a particle size range of 15-45μm was sieved out.

7. The method for preparing a high-toughness, wear-resistant, and corrosion-resistant composite coating on an aluminum alloy surface as described in claim 4, characterized in that, In step S11, the preparation process of the AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder is as follows: C1. First, weigh the AA2024 powder, fiber Al2O3, multi-scale AlN and multi-scale TiN used in the mechanical alloying method of AA2024-fiber Al2O3-multi-scale AlN-multi-scale TiN composite powder, and calculate the total mass of the composite powder. C2. Weigh out AA2024 powder and fiber Al2O3 and add them to a ball mill jar. Add mixing grinding balls to the ball mill jar. The size and mass ratio of the mixing grinding balls is 12mm:8mm:5mm = 1:3:1, and the total mass ratio of the mixing grinding balls to the total mass of the composite powder is 8:

1. Then seal the ball mill jar and evacuate and fill it with argon gas. The vacuum degree should be below 10Pa. The argon gas used should be high-purity argon gas with a pressure of 0.2-0.3MPa and a filling time of 15min. C3, place the grinding jar in an all-around planetary ball mill, set the ball milling speed to 180 rpm, and make a cycle of 10 minutes forward rotation, 2 minutes stop, 10 minutes reverse rotation, and 2 minutes stop, with a ball milling time of 12 hours; C4. After ball milling for 12 hours, open the ball mill jar, add the weighed multi-scale AlN, and perform the sealing, vacuuming, and argon filling treatments as in step C2. Then, continue ball milling for 6 hours according to the parameters in step C3. C5. After ball milling for 18 hours, open the ball mill jar, add the weighed multi-scale TiN, and perform the sealing, vacuuming, and argon filling treatments as in step C2. Then, continue ball milling for 4 hours according to the parameters in step C3. C6, after reaching the ball milling time, was sieved to obtain AA2024-fiber Al2O3-multiscale AlN-multiscale TiN composite powder with a particle size range of 15-45μm.

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