A nanocomposite aluminum-based alloy for hot-dip aluminum plating and a hot-dip aluminum plating method

Abstract

The application discloses a kind of nanocomposite aluminum base alloy for hot-dip aluminizing and hot-dip aluminizing method, and it relates to hot-dip plating technical field, it uses yttrium (Y) and cerium (Ce) to form composite rare earth modifier, cooperates nanocarbide strengthening phase, and is compatible with necessary silicon (Si), iron (Fe), manganese (Mn) element, forms a set of complete aluminum base alloy formula technical means, combined with supporting in-situ reaction synthesis and ultrasonic auxiliary preparation process, reaches the effect of significantly refining interface reaction layer, substantially improves coating hardness, toughness, salt fog corrosion resistance and high temperature oxidation resistance comprehensive performance, successfully solves the key technical problems of existing hot-dip aluminizing technology, such as nanometer reinforcing body dispersion difficulty, weak interface bonding force, and traditional modification element function single, difficult to cooperatively improve coating strength and toughness and durability.

Description

Technical Field

[0001] This invention relates to the field of hot-dip plating technology, and more specifically, to a nanocomposite aluminum-based alloy for hot-dip aluminum plating and a hot-dip aluminum plating method. Background Technology

[0002] Hot-dip aluminizing is a process in which a metal substrate, such as steel, is immersed in molten aluminum. Through wetting, reaction, and diffusion, a protective coating is formed, primarily composed of aluminum and aluminum-iron intermetallic compounds. This coating combines the excellent corrosion resistance and heat resistance of aluminum with the high strength of steel, and is widely used in automotive exhaust pipes, photovoltaic brackets, heat-resistant components, and marine engineering.

[0003] Currently, hot-dip galvanizing of aluminum-silicon alloys, which involve adding a certain amount of silicon (Si) to pure aluminum, is commonly used in industry. The main purpose of adding silicon is to suppress the excessive growth of the brittle Fe2Al5 phase, thin the interfacial reaction layer, and improve the flexibility of the coating. In addition, other auxiliary elements, such as iron, manganese, and rare earth elements, are often added to the plating bath for modification to optimize the process and performance. Most improvements in existing technologies focus on optimizing and adjusting the content of these elements. Although these improvements have improved the performance of hot-dip aluminum coatings to some extent, further development of new hot-dip aluminum coating materials and processes is needed to meet the stringent requirements of high-end equipment for a better balance of strength and toughness, higher corrosion resistance, and longer heat resistance life. Summary of the Invention

[0004] The purpose of this invention is to provide a nanocomposite aluminum-based alloy for hot-dip aluminizing, which significantly improves the overall performance of the coating in terms of hardness, toughness, salt spray corrosion resistance, and high-temperature oxidation resistance while significantly refining the interfacial reaction layer.

[0005] Another objective of this invention is to provide a hot-dip aluminum plating method that uses the aforementioned nanocomposite aluminum-based alloy. This method is simple and convenient to operate, and can efficiently complete the hot-dip plating of steel substrates, thereby improving the overall performance of the product.

[0006] The embodiments of the present invention are implemented as follows: A nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 2.0%~8.0%, iron: 0.5%~3.0%, manganese: 0.2%~1.5%, nano carbide reinforcing phase: 0.2%~2.0%, composite rare earth modifier: 0.05%~0.8%, and the balance aluminum; wherein, the composite rare earth modifier is composed of yttrium and cerium.

[0007] A hot-dip aluminizing method using the above-mentioned nanocomposite aluminum-based alloy, comprising: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion, and then refined and degassed to obtain a basic melt; S2. Add titanium powder and carbon powder to the base melt and react in situ to prepare nano-carbide reinforced phase; S3. The steel substrate is pretreated on the surface and then immersed in the base melt for hot-dip galvanizing.

[0008] The beneficial effects of the embodiments of the present invention are: This invention provides a nanocomposite aluminum-based alloy for hot-dip aluminizing. It uses yttrium (Y) and cerium (Ce) as composite rare earth modifiers, synergistically with nano carbide reinforcing phases, and is combined with necessary silicon (Si), iron (Fe), and manganese (Mn) elements to form a complete aluminum-based alloy formulation. Combined with the supporting in-situ reaction synthesis and ultrasonic-assisted preparation process, it achieves the effect of significantly refining the interfacial reaction layer while greatly improving the overall performance of the coating in terms of hardness, toughness, salt spray corrosion resistance, and high-temperature oxidation resistance. It successfully solves the key technical problems in existing hot-dip aluminizing technology, such as the difficulty in dispersing nano-reinforcement, weak interfacial bonding, and the single function of traditional modifying elements, which are difficult to synergistically improve the strength, toughness, and durability of the coating. Detailed Implementation

[0009] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0010] The following is a detailed description of a nanocomposite aluminum-based alloy for hot-dip aluminizing and a method for hot-dip aluminizing according to an embodiment of the present invention.

[0011] This invention provides a nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 2.0%~8.0%, iron: 0.5%~3.0%, manganese: 0.2%~1.5%, nano carbide reinforcing phase: 0.2%~2.0%, composite rare earth modifier: 0.05%~0.8%, and the balance aluminum; wherein, the composite rare earth modifier is composed of yttrium and cerium.

[0012] In this process, silicon preferentially dissolves in the molten aluminum during hot-dip galvanizing and accumulates in the reaction zone at the iron-aluminum interface. By reducing the diffusion rate of aluminum in the Fe2Al5 phase and promoting the formation of a thinner, slightly tougher τ5 (Al-Fe-Si) ternary phase, it kinetically inhibits the excessive longitudinal growth of the brittle Fe2Al5 phase, thus achieving the effect of controlling the thickness and toughness of the interface layer.

[0013] Iron is an inherent equilibrium element in the coating. Part of it originates from the dissolution of the steel substrate. Its active addition aims to establish a Fe concentration gradient in the molten pool, thermodynamically stabilize the interfacial reaction process, improve the wettability of the aluminum melt on the steel substrate, and reduce incomplete coating. Its main function is to optimize process stability and interfacial wettability, ensuring a continuous and uniform coating.

[0014] Manganese has a high solid solubility in aluminum. It mainly dissolves in the aluminum matrix (η phase) of the coating, producing a solid solution strengthening effect. At the same time, manganese can increase the coating potential and promote the formation of a denser corrosion product film during corrosion, thereby improving the overall hardness of the coating and its corrosion resistance in certain environments.

[0015] Furthermore, this invention selects yttrium and cerium, two rare earth elements, for composite modification. Yttrium, as an element with extremely high surface activity, exhibits a strong tendency for interfacial segregation. It preferentially adsorbs onto the grain boundaries and phase boundaries of the fastest-growing Fe2Al5 phase, directly hindering the short-range diffusion channels of iron and aluminum atoms. Cerium, on the other hand, possesses excellent chemical activity; it can react with impurities such as oxygen and sulfur in molten aluminum to generate high-melting-point rare earth oxides or sulfides, which float to the surface as slag, thereby purifying the melt. Simultaneously, cerium can spheroidize brittle phases such as eutectic silicon, improving their morphology. Optionally, the mass ratio of yttrium to cerium in the composite rare earth modifier is 1:(1~3). When used in combination, not only is the interfacial segregation efficiency of yttrium maximized, but the purification effect of cerium is not weakened by the presence of yttrium, allowing both to exert their optimal effectiveness in their respective fields.

[0016] The thermodynamic stability of the nano-carbide-reinforced phase allows it to be uniformly dispersed in the coating, acting as a significant barrier to dislocation movement, forcing dislocations to bypass it and thus significantly improving the coating's strength and hardness. Nano-carbide particles can pin grain boundaries, inhibiting the growth of aluminum matrix grains and intermetallic compound grains during coating and cooling. They can also directly and physically block the interdiffusion of iron and aluminum atoms. This provides strength, hardness, and thermal stability that are difficult to achieve using traditional alloying methods. However, nano-carbides have a large specific surface area and high surface energy, making them prone to agglomeration in molten aluminum. These agglomerates act as stress concentration points, impairing the continuity and density of the coating, becoming crack initiation sites, and consequently reducing adhesion and corrosion resistance. To address this issue, the rare earth elements used in this invention can effectively solve this problem. The rare earth element cerium purifies the melt, reducing the encapsulation and agglomeration of nanoparticles by oxide impurities; simultaneously, the surface activity of rare earth elements improves the wettability of the aluminum melt on the carbide particles, solving the problem of difficult dispersion of nanoparticles. Based on this, the pinning of yttrium at the grain boundaries and the physical barrier effect of nano-carbide particles at the interface form a three-dimensional blocking network combining "points (yttrium atoms) and surfaces (nanoparticles)," which can significantly improve the inhibition effect on iron-aluminum diffusion.

[0017] Optionally, the nano-carbide is titanium carbide with a particle size of 20-100 nm. Titanium carbide has good compatibility with the aluminum matrix and extremely high thermodynamic stability. Within this particle size range, the reinforcing effect of nanoparticles can be better utilized, avoiding stress concentration caused by excessively large particles or severe agglomeration caused by excessively small particles.

[0018] The molar ratio of titanium to carbon in nano-carbide is 1:(0.95~1.05). Within this ratio range, the formation of large amounts of free titanium or free carbon can be avoided, thus preventing the generation of harmful phases and ensuring the purity and stability of the nano-reinforcing phase itself.

[0019] This invention also provides a hot-dip aluminizing method for the above-mentioned nanocomposite aluminum-based alloy, characterized in that it includes: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion, and then refined and degassed to obtain a basic melt; S2. Add titanium powder and carbon powder to the base melt and react in situ to prepare nano-carbide reinforced phase; S3. The steel substrate is pretreated on the surface and then immersed in the base melt for hot-dip galvanizing.

[0020] In this method, the nano-carbide-reinforced phase is obtained by in-situ preparation. Compared with directly adding nanoparticles, this method can effectively solve the problems of difficult dispersion and easy agglomeration of nanoparticles in aluminum liquid, and achieve better hot-dip galvanizing effect.

[0021] Optionally, surface pretreatment of the steel substrate may include degreasing, pickling and rust removal, water washing, etc., which can be selected according to actual needs. These are conventional methods in the field and will not be described in detail here.

[0022] Furthermore, in step S1, refining and degassing are carried out at 730~800℃. This temperature range ensures good melt fluidity for thorough slag and gas removal, while preventing excessive loss of rare earth elements (especially cerium) and melt oxidation due to excessively high temperatures.

[0023] Optionally, in step S2, the in-situ reaction temperature is 760–810 °C, and the reaction time is 20–50 min. Under these conditions, titanium and carbon can fully diffuse and react in the aluminum melt to generate fine, uniform nano-titanium carbide particles.

[0024] Furthermore, in step S3, the hot-dip galvanizing temperature is 720~820℃, and the galvanizing time is 3~15 min. These reaction conditions ensure good wetting of the steel substrate and moderate growth of the interfacial reaction layer while preventing excessive sedimentation or aggregation of nanoparticles. Optionally, ultrasonic vibration at a frequency of 25~35 kHz is applied during the hot-dip galvanizing process. Ultrasonic waves can further break up any potential soft agglomerates of nanoparticles and force them to distribute uniformly within the melt and the growing interfacial layer, thus maximizing their effectiveness.

[0025] Furthermore, the hot-dip plating method provided in this embodiment of the invention further includes: S4. Force-cool the hot-dip coated workpiece at a cooling rate of 15~40℃ / s.

[0026] Rapid cooling can freeze the ideal microstructure (fine grains and uniform nano-dispersed phase) formed at high temperatures, preventing the nanoparticles from coarsening and the structure from growing during slow cooling, thus preserving the high performance obtained at high temperatures to room temperature.

[0027] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0028] Example 1

[0029] This embodiment provides a nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 5.0%, iron: 1.5%, manganese: 0.5%, nano-titanium carbide: 1.0%, yttrium: 0.1%, cerium: 0.2%, and the balance aluminum; the nano-titanium carbide has a particle size of approximately 20~100nm, and the Ti:C molar ratio is 1:1.

[0030] This embodiment also provides a hot-dip galvanizing method using this nanocomposite aluminum-based alloy, including: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion at 750°C, and the temperature is maintained for refining and degassing to obtain the basic melt.

[0031] S2. Heat to 780℃, add titanium powder and carbon powder to the base melt and react in situ for 35 minutes to prepare nano-carbide reinforced phase.

[0032] S3. After surface pretreatment of the steel substrate, preheat it to 450°C, immerse the steel substrate in the base melt for hot-dip galvanizing at a temperature of 770°C for 8 minutes, while applying 30kHz ultrasound.

[0033] S4. Force-cool the hot-dip coated workpiece at a cooling rate of 25℃ / s.

[0034] Example 2

[0035] This embodiment provides a nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 3.0%, iron: 0.8%, manganese: 0.8%, nano titanium carbide: 0.5%, yttrium: 0.125%, cerium: 0.375%, and the balance aluminum; the nano titanium carbide has a particle size of approximately 20~100nm, and the Ti:C molar ratio is 1:1.

[0036] This embodiment also provides a hot-dip galvanizing method using this nanocomposite aluminum-based alloy, including: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion at 740℃, and the temperature is maintained for refining and degassing to obtain the basic melt.

[0037] S2. Heat to 765℃, add titanium powder and carbon powder to the base melt and react in situ for 45 minutes to prepare nano-carbide reinforced phase.

[0038] S3. After surface pretreatment of the steel substrate, preheat it to 450°C, immerse the steel substrate in the base melt for hot-dip galvanizing at a temperature of 750°C for 12 minutes, while applying 28kHz ultrasound.

[0039] S4. Force-cool the hot-dip coated workpiece at a cooling rate of 35℃ / s.

[0040] Example 3

[0041] This embodiment provides a nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 7.0%, iron: 2.0%, manganese: 0.3%, nano titanium carbide: 1.8%, yttrium: 0.05%, cerium: 0.05%, and the balance aluminum; the nano titanium carbide has a particle size of approximately 20~100nm, and the Ti:C molar ratio is 1:1.

[0042] This embodiment also provides a hot-dip galvanizing method using this nanocomposite aluminum-based alloy, including: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion at 790℃, and the temperature is maintained for refining and degassing to obtain the basic melt.

[0043] S2. Heat to 805℃, add titanium powder and carbon powder to the base melt and react in situ for 25 minutes to prepare nano-carbide reinforced phase.

[0044] S3. After surface pretreatment of the steel substrate, preheat it to 450°C, immerse the steel substrate in the base melt for hot-dip galvanizing at a temperature of 800°C for 5 minutes, while applying 35kHz ultrasound.

[0045] S4. Force-cool the hot-dip coated workpiece at a cooling rate of 25℃ / s.

[0046] Example 4

[0047] This embodiment provides a nanocomposite aluminum-based alloy for hot-dip aluminizing, comprising, by weight percentage: Silicon: 2.5%, Iron: 2.8%, Manganese: 1.4%, Nano-titanium carbide: 0.25%, Yttrium: 0.035%, Cerium: 0.035%, and the balance aluminum; the nano-titanium carbide has a particle size of approximately 20~100nm, and the Ti:C molar ratio is 1:1.

[0048] This embodiment also provides a hot-dip galvanizing method using this nanocomposite aluminum-based alloy, including: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion at 735°C, and the temperature is maintained for refining and degassing to obtain the basic melt.

[0049] S2. Heat to 762℃, add titanium powder and carbon powder to the base melt and react in situ for 35 minutes to prepare nano-carbide reinforced phase.

[0050] S3. After surface pretreatment of the steel substrate, preheat it to 450°C, immerse the steel substrate in the base melt for hot-dip galvanizing at a temperature of 725°C for 14 minutes.

[0051] S4. Force-cool the hot-dip coated workpiece at a cooling rate of 18℃ / s.

[0052] Comparative Example 1 This comparative example provides a nanocomposite aluminum-based alloy for hot-dip aluminizing and a hot-dip aluminizing method, which differs from Example 1 in that it does not contain nano-titanium carbide and the S2 step is omitted.

[0053] Comparative Example 2 This comparative example provides a nanocomposite aluminum-based alloy for hot-dip aluminizing and a hot-dip aluminizing method, which differs from Example 1 in that it does not contain rare earth elements.

[0054] Comparative Example 3 This comparative example provides a nanocomposite aluminum-based alloy for hot-dip aluminizing and a hot-dip aluminizing method, which differs from Example 1 in that the rare earth elements yttrium and cerium are replaced with an equal amount of lanthanum.

[0055] Comparative Example 4 This comparative example provides a nanocomposite aluminum-based alloy for hot-dip aluminizing and a hot-dip aluminizing method. The difference between this example and Example 1 is that the yttrium content is adjusted to 0.05% and the cerium content is adjusted to 0.25%.

[0056] Comparative Example 5 This comparative example provides a nanocomposite aluminum-based alloy for hot-dip aluminizing and a hot-dip aluminizing method. The difference between this example and Example 1 is that the in-situ synthesis of nano titanium carbide is replaced by the direct addition of finished titanium carbide with an average particle size of 150 nm.

[0057] Test case The hot-dip coated products provided in Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests. The test content and specific methods included: Micro Vickers hardness test: Using a micro Vickers hardness tester, apply a load of 0.3 kgf at a distance of about 50 μm from the surface of the coating cross section (avoiding the interface layer) and on the coating surface, respectively, and hold for 15 seconds. Take 10 points for each sample and average the result.

[0058] Neutral salt spray test: Place the sample in a salt spray chamber and spray continuously at 35°C using a 5% NaCl solution. Observe and record the time when the first red rust spot appears on the sample surface periodically as the corrosion resistance life.

[0059] Scratch adhesion test: A scratch tester is used to increase the vertical load at a constant loading rate while a diamond indenter scratches the coating surface. The critical loads at which the coating first cracks (LC1) and completely peels off (LC2) are determined by the abrupt changes in acoustic emission signals and frictional force.

[0060] Isothermal oxidation weight gain test: The sample was placed in a muffle furnace and oxidized at 800℃ in an air atmosphere. Every 24 hours, the sample was removed, cooled to room temperature, and weighed using a precision balance. The test was continued for 100 hours. An oxidation weight gain-time curve per unit area was plotted, and the average oxidation rate was calculated.

[0061] Four-point bending test: The coated sample is bent at four points on a universal testing machine to a predetermined deflection (50% of the coating thickness). After unloading, the number and length of cracks on the coating surface and cross-section are observed under an optical microscope or scanning electron microscope.

[0062] The test results are shown in Table 1.

[0063] Table 1. Performance Comparison Results of Hot-Dip Coating Products Test item Surface hardness (HV) Salt spray life (h) Adhesion LC2 (N) Oxidative weight gain (mg / cm 2 )]]> Bending crack density (pieces / mm) Interface layer thickness (pm) Example 1 458 2250 54.2 1.8 0.8 15.3 Example 2 385 2850 50.1 1.5 0.5 10.8 Example 3 518 1950 48.8 2.2 1.5 17.9 Example 4 428 1800 48.5 2.4 1.3 16.8 Comparative Example 1 251 1250 41.3 3.4 3.5 18.2 Comparative Example 2 298 850 36.7 4.3 5.2 26.4 Comparative Example 3 365 1320 44.5 2.6 2.8 16.8 Comparative Example 4 402 1680 45.2 2.1 1.9 14 Comparative Example 5 281 1100 43.9 3.1 4.1 19.7 As can be seen from Table 1, the hot-dip galvanized products provided in Examples 1-4 of this invention have a surface hardness of over 385 HV, a salt spray life of over 1800 h, an adhesion strength LC2 of over 48.5 N, and an oxidation weight gain of less than 2.4 mg / cm³. 2 The bending crack density is less than 1.5 cracks / mm, and the interface layer thickness is less than 17.9 μm. It exhibits excellent performance in terms of hardness, corrosion resistance, adhesion, oxidation resistance, and coating toughness. Example 1 is the optimal embodiment, showing the best overall performance parameters. Example 2 uses a high-cerium, high-manganese, and low-silicon formulation; although some strength is sacrificed, it significantly improves its corrosion and oxidation resistance.

[0064] In contrast, in Comparative Example 1, without the addition of nano-carbide, the coating substrate relied entirely on solid solution strengthening, resulting in insufficient strength. The lack of nanoparticle pinning in the interface layer led to a relatively loose structure, reducing adhesion and resistance to deformation. The most obvious results were a significant decrease in hardness (251 HV) and adhesion (41.3 N), and a high density of bending cracks (3.5 cracks / mm).

[0065] Comparative Example 2, without the addition of rare earth elements, resulted in unpurified melt and uncontrolled interfacial reactions. Oxygen and sulfur impurities in the melt led to a porous microstructure; the lack of yttrium pinning the Fe2Al5 grain boundaries resulted in rapid and disordered growth of the brittle phase, forming a thick and porous interfacial layer that became a corrosion channel and a mechanically weak area. This resulted in the thickest interfacial layer (26.4 μm) with a serrated porous structure, the weakest bonding force (36.7 N), the shortest salt spray lifetime (850 h), and the worst oxidation resistance (4.3 mg / cm³). 2 ).

[0066] Comparative Example 3 used a single rare earth element, lanthanum. Lanthanum plays a purifying role, but its surface activity in aluminum and its influence on the Fe-Al interface energy are weaker than yttrium, and it lacks the synergistic effect of cerium. Therefore, its ability to finely control the interfacial reaction layer is insufficient, and it cannot effectively pin grain boundaries like yttrium, resulting in a slightly thicker interfacial layer (16.8 μm), while its hardness and adhesion decrease.

[0067] Comparative Example 4 used more cerium and less yttrium. The excess cerium saturated the purification process, while the relatively insufficient yttrium failed to form a sufficiently dense pinning network at the interface. This resulted in a dense microstructure at the interface layer, but with poor strength-toughness matching, making it more prone to microcrack initiation under bending stress. Although the interface layer thickness (14.0 μm) was reasonably controlled, the bending crack density (1.9 cracks / mm) was significantly higher than in Example 1 (0.8 cracks / mm), leading to decreased toughness. Hardness (402 HV) and corrosion resistance (1680 h) also failed to reach their optimal levels.

[0068] Comparative Example 5 used nano-titanium carbide with excessively large particle size. The coarse particles are more likely to become crack initiation sites, severely impairing toughness. The results showed that its hardness (281 HV) was close to that of Comparative Example 1, much lower than that of Example 1, and its bending crack density (4.1 cracks / mm) was very high.

[0069] In summary, the embodiments of the present invention provide a nanocomposite aluminum-based alloy for hot-dip aluminizing. It uses yttrium (Y) and cerium (Ce) as composite rare earth modifiers, synergistically with nano carbide reinforcing phases, and is combined with necessary silicon (Si), iron (Fe), and manganese (Mn) elements to form a complete aluminum-based alloy formulation. Combined with the supporting in-situ reaction synthesis and ultrasonic-assisted preparation process, it achieves the effect of significantly refining the interfacial reaction layer while greatly improving the overall performance of the coating in terms of hardness, toughness, salt spray corrosion resistance, and high-temperature oxidation resistance. It successfully solves the key technical problems in existing hot-dip aluminizing technology, such as the difficulty in dispersing nano-reinforcement, weak interfacial bonding, and the single function of traditional modifying elements, which are difficult to synergistically improve the strength, toughness, and durability of the coating.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A nano-composite aluminum-based alloy for hot-dip aluminizing, characterized in that, By weight percentage, it includes: Silicon: 2.0%~8.0%, iron: 0.5%~3.0%, manganese: 0.2%~1.5%, nano carbide reinforcing phase: 0.2%~2.0%, composite rare earth modifier: 0.05%~0.8%, and the balance aluminum; wherein the composite rare earth modifier is composed of yttrium and cerium.

2. The nanocomposite aluminum-based alloy for hot-dip aluminizing according to claim 1, characterized in that, In the composite rare earth modifier, the mass ratio of yttrium to cerium is 1:(1~3).

3. The nanocomposite aluminum-based alloy for hot-dip aluminizing according to claim 1, characterized in that, The nanocarbide is titanium carbide, with a particle size of 20~100nm.

4. The nanocomposite aluminum-based alloy for hot-dip aluminizing according to claim 3, characterized in that, The molar ratio of titanium to carbon in the nanocarbide is 1:(0.95~1.05).

5. A hot-dip aluminizing method using a nanocomposite aluminum-based alloy as described in any one of claims 1 to 4, characterized in that, include: S1. Aluminum ingots, aluminum-silicon alloys, aluminum-iron alloys, aluminum-manganese alloys, and rare earth additives are mixed and melted in proportion, and then refined and degassed to obtain a basic melt; S2. Add titanium powder and carbon powder to the base melt and react in situ to prepare the nano-carbide reinforced phase; S3. The steel substrate is pretreated on the surface and then immersed in the base melt for hot-dip galvanizing.

6. The hot-dip aluminizing method according to claim 5, characterized in that, In step S1, refining and degassing are carried out at 730~800℃.

7. The hot-dip aluminizing method according to claim 5, characterized in that, In step S2, the in-situ reaction is carried out at a temperature of 760-810°C for a duration of 20-50 minutes.

8. The hot-dip aluminizing method according to claim 5, characterized in that, In step S3, the hot-dip plating temperature is 720~820℃ and the hot-dip plating time is 3~15min.

9. The hot-dip aluminizing method according to claim 8, characterized in that, During the hot-dip galvanizing process, ultrasonic vibrations with a frequency of 25~35 kHz are applied.

10. The hot-dip aluminizing method according to claim 5, characterized in that, Also includes: S4. Force-cool the hot-dip coated workpiece at a cooling rate of 15~40℃ / s.