High-wear-resistance chromium-based composite additive adaptive to high-temperature working condition and application of high-wear-resistance chromium-based composite additive in aluminum alloy

Abstract

The invention relates to the field of metal additives, and discloses a high-wear-resistance chromium-based composite additive adaptive to a high-temperature working condition and application of the high-wear-resistance chromium-based composite additive in an aluminum alloy. Comprising 25-35 parts of nano chromium powder, 5-10 parts of cerium oxide, 4-8 parts of tungsten carbide nanoparticles, 3-6 parts of vanadium boride, 20-30 parts of aluminum magnesium alloy powder, 2-5 parts of a dispersing aid and 1-4 parts of a high-temperature stabilizing aid. According to the invention, the problem of uneven dispersion is solved through modification of the nano chromium powder and synergistic compounding of the dispersion aid, the performance of the aluminum alloy under the high-temperature working condition is synergistically improved through a process closed loop of modification, coating, dispersion and strengthening in the preparation process, the strict requirements of aerospace and high-end equipment are completely met, and the preparation method has important significance in the industry.

Description

Technical Field

[0001] This invention relates to the field of metal additives, specifically to a high wear-resistant chromium-based composite additive suitable for high-temperature working conditions and its application in aluminum alloys. Background Technology

[0002] Aluminum alloys are widely used in aerospace, automotive, and high-end equipment industries due to their low density, good thermal conductivity, and excellent machinability. However, pure aluminum alloys and conventional alloys have low hardness and poor wear resistance, especially under high-temperature conditions (300-500℃), where their mechanical properties degrade significantly, limiting their application in harsh environments. Chromium additives, as key auxiliary materials for aluminum alloy modification, can improve the hardness and wear resistance of aluminum alloys through solid solution strengthening and second-phase precipitation strengthening, thus becoming a focus of industry research.

[0003] However, the application of existing chromium additives in aluminum alloys has significant technical defects and differs markedly from the technical solutions disclosed in patents and literature, as follows: 1. Severe performance degradation at high temperatures: Most existing chromium additives are elemental chromium powder or Cr-Al alloy powder, which are prone to forming coarse CrAl7 phase during aluminum alloy smelting. At high temperatures, this phase is prone to embrittlement and shedding, resulting in a decrease in hardness of aluminum alloys of more than 30% at working conditions above 300℃, and a sharp decline in wear resistance, making it unsuitable for high-temperature scenarios. 2. Poor dispersibility and uneven strengthening effect: Chromium powder density (7.19 g / cm³) 3 ) and the melt density of aluminum alloy (2.3-2.8 g / cm³) 3 The large differences lead to uneven distribution of chromium, resulting in significant differences in the wear resistance of aluminum alloys in different areas, and components are prone to local wear failure. 3. Corrosion resistance is not improved in tandem: Most existing technologies only focus on improving hardness and wear resistance, without considering corrosion under high-temperature conditions. The salt spray corrosion resistance of aluminum alloys is improved by less than 10% after the addition, which cannot meet the needs of marine and humid environments. Therefore, there is an urgent need to develop a chromium-based composite additive that is significantly different from existing technologies and has high dispersibility, high-temperature wear resistance and stability, and corrosion resistance synergistic effect. This would solve the industry pain points of poor high-temperature performance, rapid wear and severe corrosion of aluminum alloys caused by existing technologies, and fill the technological gap in the modification of cast aluminum alloys under high-temperature conditions. Summary of the Invention

[0004] The present invention aims to provide a high wear-resistant chromium-based composite additive suitable for high-temperature working conditions and its application in aluminum alloys, so as to solve the problems of uneven dispersion, high-temperature performance degradation and insufficient corrosion resistance of existing chromium additives in aluminum alloys.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a high wear-resistant chromium-based composite additive suitable for high-temperature working conditions, comprising, by weight, 25-35 parts of nano-chromium powder, 5-10 parts of cerium oxide, 4-8 parts of tungsten carbide nanoparticles, 3-6 parts of vanadium boride, 20-30 parts of aluminum-magnesium alloy powder, 2-5 parts of dispersing agent, and 1-4 parts of high-temperature stabilizing agent.

[0006] Preferably, as an improvement, the nano-chromium powder is modified with silane coupling agent KH560 and its surface is grafted with epoxy groups.

[0007] Preferably, as an improvement, the nano-chromium powder has a particle size of 50-100 nm and a purity of ≥99.7%.

[0008] Preferably, as an improvement, the cerium oxide has a particle size of 80-150 nm and a purity of ≥99.5%.

[0009] Preferably, as an improvement, the tungsten carbide nanoparticles have a particle size of 30-80 nm and a hardness ≥2600 HV; the vanadium boride nanoparticles have a particle size of 100-200 nm.

[0010] Preferably, as an improvement, the dispersing agent is a compound of sodium citrate and polyethylene glycol 400 in a mass ratio of 3:2.

[0011] Preferably, as an improvement, the high-temperature stabilizing agent is titanium nitride nanoparticles with a particle size of 50-120 nm.

[0012] Preferably, as an improvement, a method for preparing a high-wear-resistant chromium-based composite additive suitable for high-temperature operating conditions includes the following steps: S1. Chromium powder modification treatment: Add nano-chromium powder to ethanol solution, stir and disperse, then add silane coupling agent KH560, heat and stir and dry to obtain modified nano-chromium powder. S2. Premixing of composite components: Weigh out cerium oxide, tungsten carbide nanoparticles, vanadium boride, and high-temperature stabilizing agent according to the ratio, and mix them to obtain the premixed components; S3. Melt coating modification: After heating and melting aluminum-magnesium alloy powder, premixed components and dispersants are added to form aluminum-magnesium alloy coated composite powder; S4. Molding process: Cool the coated powder to room temperature, crush it, sieve it, and vacuum dry it to obtain a high wear-resistant chromium-based composite additive.

[0013] Preferably, as an improvement, in step one, the amount of silane coupling agent KH560 added is 3-5% of the mass of chromium powder.

[0014] Preferably, as an improvement, the application of a high wear-resistant chromium-based composite additive adapted to high-temperature working conditions in aluminum alloys involves melting aluminum alloy ingots to obtain a melt, wherein the amount of chromium-based composite additive added is 1.5-3.0% of the mass of the aluminum alloy melt.

[0015] The principle and advantages of this solution are as follows: In practical applications, this technical solution comprehensively upgrades the composition and preparation process of chromium additives to address the problems existing in the prior art. Through multi-dimensional synergy including nano-modification, dispersion control, and particle size adaptation, it simultaneously solves the problems of high-temperature performance degradation, uneven dispersion, and insufficient corrosion resistance, achieving a balance of high hardness, high wear resistance, and high corrosion resistance. The density of chromium powder differs greatly from that of molten aluminum alloy, making direct addition prone to sedimentation and agglomeration; furthermore, pure chromium powder has high surface activity, making it easily oxidized or forming coarse CrAl7 phases, leading to high-temperature embrittlement. Based on this, this technical solution uses silane coupling agent KH560 for modification. Through the reaction of "ethanol solution dispersion + grafting epoxy groups", an organic-inorganic composite film is formed on the surface of chromium powder. On the one hand, the epoxy groups improve the wettability of chromium powder and aluminum alloy melt, changing the chromium powder from "hydrophobic and easily agglomerated" to "hydrophilic and easily dispersed", reducing surface tension. On the other hand, the apparent density of chromium powder is significantly reduced after modification, narrowing the density difference with aluminum alloy melt, thus alleviating the sedimentation problem at its source. At the same time, surface modification can also inhibit the formation of harmful phases: the surface modification layer can prevent the rapid reaction of chromium powder and aluminum to form coarse CrAl7 phase, laying the foundation for subsequent synergistic strengthening.

[0016] During the modification stage, the amount of KH560 added has a crucial impact on performance. Excessive addition of KH560 can lead to an overly thick surface coating, affecting the strengthening effect; insufficient addition results in inadequate modification. Furthermore, this technical solution optimizes and upgrades the dispersant, as a single dispersant cannot simultaneously solve both sedimentation and agglomeration problems. Sodium citrate alone provides insufficient dispersibility, while polyethylene glycol 400 alone can easily lead to abnormal system viscosity. This technical solution utilizes the combined use of sodium citrate and polyethylene glycol. Sodium citrate, an anionic dispersant, can adsorb onto the surface of chromium powder, breaking the van der Waals forces between particles through electrostatic repulsion and preventing agglomeration. Polyethylene glycol 400, a nonionic dispersant, can create a steric hindrance effect, further hindering particle collision and aggregation, while simultaneously reducing the interfacial tension between chromium powder and the melt, improving dispersion uniformity. In the optimization of dispersants, the compounding ratio of the two is one of the key points of the research and development of this technical solution. The 3:2 ratio balances the electrostatic repulsion and steric hindrance. If the proportion of sodium citrate is too high, it will easily lead to an excessively high electrolyte concentration in the system, which will cause flocculation. If the proportion of polyethylene glycol 400 is too high, it will increase the melt viscosity and affect the fluidity.

[0017] Furthermore, in this technical solution, the particle size of the raw materials also has a crucial impact on the performance of the chromium additives. Nano-chromium powder (50-100nm): Particles that are too small (<50nm) are prone to agglomeration and oxidation, while those that are too large (>100nm) are difficult to disperse uniformly. A particle size of 50-100nm can balance dispersibility and strengthening effect, improving the matrix hardness through solid solution strengthening. Tungsten carbide nanoparticles (30-80nm): With a hardness ≥2600HV and a particle size smaller than chromium powder, they can fill the gaps between chromium powder particles, forming a "chromium-tungsten" dual strengthening phase. A particle size of 30-80nm ensures synergistic effect with chromium powder, avoiding uneven distribution of the strengthening phase due to excessive particle size differences. Cerium oxide (80-150nm): With a particle size slightly larger than chromium powder, it can refine the aluminum alloy grains while inhibiting the coarsening of the CrAl7 phase. The particle size ensures slow diffusion in the melt, fully leveraging the dual effects of grain refinement and corrosion resistance; Vanadium boride (100-200nm): melting point ≥2800℃, larger particle size can improve high-temperature stability and inhibit second-phase decomposition, 100-200nm particle size can avoid excessive dissolution at high temperatures, ensuring continuous stability under 300-500℃ conditions; Titanium nitride (50-120nm): matching the particle size of chromium powder, can be uniformly distributed at grain boundaries, improving the structural stability at high temperatures and preventing grain growth.

[0018] The principle and beneficial effects of this technical solution are as follows: 1. Breakthrough in high-temperature performance: Hardness retention rate at 400℃ is ≥84%, which is more than 40% higher than the existing technology (50-60%), solving the problem of high-temperature embrittlement.

[0019] 2. Synergistic performance improvement: Simultaneously achieve room temperature hardness ≥120HB, wear amount ≤0.03g / 1000r, and salt spray corrosion resistant area ≤5%, breaking the limitations of single performance optimization in existing technologies.

[0020] 3. Technological and cost advantages: Using conventional equipment, production efficiency is significantly improved and costs are significantly reduced. The coefficient of variation of chromium element distribution is ≤0.12, with no sedimentation or agglomeration, and it can be mass-produced industrially.

[0021] 4. Strong adaptability to various scenarios: Specifically designed for high-temperature operating conditions of 300-500℃, it is compatible with various cast aluminum alloys such as A356 and A380, covering the core component needs of aerospace and high-end equipment. Detailed Implementation

[0022] The following detailed description provides further details on specific embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; and the materials, reagents, etc. used are all commercially available.

[0023] Overview of the plan: A high-wear-resistant chromium-based composite additive suitable for high-temperature working conditions, comprising, by weight, 25-35 parts of nano-chromium powder, 5-10 parts of cerium oxide (CeO2), 4-8 parts of tungsten carbide (WC) nanoparticles, 3-6 parts of vanadium boride (VB2), 20-30 parts of aluminum-magnesium alloy powder, 2-5 parts of dispersing agent, and 1-4 parts of high-temperature stabilizing agent.

[0024] The nano-chromium powder has a particle size of 50-100nm and a purity of ≥99.7%. It is modified with silane coupling agent KH560 and has epoxy groups grafted onto its surface to reduce the density difference with the aluminum alloy melt and improve its dispersibility.

[0025] Cerium oxide has a particle size of 80-150nm and a purity of ≥99.5%. It can refine the grains of aluminum alloys, suppress the coarsening of the CrAl7 phase at high temperatures, and improve corrosion resistance.

[0026] Tungsten carbide nanoparticles have a particle size of 30-80nm and a hardness of ≥2600HV. They synergistically form a "chromium-tungsten" dual-strengthening phase with chromium, which improves high-temperature wear resistance.

[0027] Vanadium boride has a particle size of 100-200 nm and a melting point of ≥2800℃, which can improve the high-temperature stability of additives and inhibit the decomposition of the second phase at high temperatures.

[0028] The dispersing agent is a compound of sodium citrate and polyethylene glycol 400 in a mass ratio of 3:2, which reduces the surface tension of chromium powder and prevents sedimentation and agglomeration.

[0029] The high-temperature stabilizing agent is titanium nitride (TiN) nanoparticles with a particle size of 50-120nm. It has excellent thermal stability and can improve the microstructure stability of aluminum alloys at high temperatures.

[0030] A method for preparing a high-wear-resistant chromium-based composite additive suitable for high-temperature operating conditions includes the following steps: S1. Chromium powder modification treatment: Add nano chromium powder to ethanol solution, stir and disperse, then add silane coupling agent KH560 (the amount added is 3-5% of the mass of chromium powder), stir at a constant temperature of 60-70℃ for 2-3 hours, and vacuum dry (120-150℃, ≤-0.09MPa) to obtain modified nano chromium powder. S2. Premixing of composite components: Weigh out cerium oxide, tungsten carbide nanoparticles, vanadium boride, and high-temperature stabilizing agent according to the ratio, add them to a high-speed mixer, stir at room temperature and speed of 500-600 r / min for 30-40 min to obtain the premixed components; S3. Melt coating modification: Heat aluminum-magnesium alloy powder to 650-700℃ to melt, add premixed components and dispersants, stir at 300-400 r / min, keep warm and stir for 1-1.5 h to form aluminum-magnesium alloy coated composite powder; S4. Molding process: Cool the coated powder to room temperature, pulverize it and pass it through a 100-120 mesh sieve. Then, vacuum dry it at 180-200℃ for 2-3 hours to obtain a high wear-resistant chromium-based composite additive.

[0031] The application of a high-wear-resistant chromium-based composite additive suitable for high-temperature working conditions in aluminum alloys includes the following steps: Step 1: Aluminum alloy melting: Add aluminum alloy ingots (A356 aluminum alloy) to a medium frequency induction furnace, heat to 720-760℃ to melt, hold for 30 minutes, and remove impurities and gases from the melt; Step 2, Additive addition: Add the above-mentioned chromium-based composite additive to the melt at 1.5-3.0% of the mass of the aluminum alloy melt, and disperse it by mechanical stirring (200-250 r / min) + argon purging (8-12 L / min) for 20-30 min to ensure uniform dispersion of the additive. Step 3: Casting and molding: Let the uniformly mixed aluminum alloy melt stand for 10-15 minutes, pour it into a mold preheated to 200-250℃, and let it cool naturally to room temperature to obtain the cast aluminum alloy component. Step 4, Post-treatment: Place the cast components in an electric resistance furnace for T6 heat treatment (solution treatment at 520-540℃ for 2 hours, followed by water cooling to room temperature; aging treatment at 170-190℃ for 4 hours) to further improve mechanical properties and wear resistance.

[0032] Example 1 A high-wear-resistant chromium-based composite additive suitable for high-temperature working conditions comprises, by weight, 30 parts modified nano-chromium powder (particle size 80nm, purity 99.7%), 7 parts cerium oxide (particle size 120nm), 6 parts tungsten carbide nanoparticles (particle size 50nm), 4.5 parts vanadium boride (particle size 150nm), 25 parts aluminum-magnesium alloy powder, 3.5 parts dispersant (sodium citrate 2.1 parts + polyethylene glycol 400 1.4 parts), and 4 parts high-temperature stabilizing agent (titanium nitride nanoparticles, particle size 80nm).

[0033] A method for preparing a high-wear-resistant chromium-based composite additive suitable for high-temperature operating conditions includes the following steps: S1. Chromium powder modification treatment: Add nano chromium powder to ethanol solution, stir and disperse, then add silane coupling agent KH560 (addition amount is 5% of the mass of chromium powder), stir at 65℃ for 2.5h, and vacuum dry (130℃, ≤-0.09MPa) to obtain modified nano chromium powder. S2. Premixing of composite components: Weigh cerium oxide, tungsten carbide nanoparticles, vanadium boride, and high-temperature stabilizing agent according to the formula, add them to a high-speed mixer, stir for 35 minutes at room temperature and 550 r / min to obtain the premixed components; S3. Melt coating modification: Heat aluminum-magnesium alloy powder to 680℃ to melt, add premixed components and dispersing agents, stir at 350 r / min, keep warm and stir for 1.2 h to form aluminum-magnesium alloy coated composite powder; S4. Molding process: Cool the coated powder to room temperature, pulverize it and pass it through a 110-mesh sieve. Then, vacuum dry it at 190°C for 2.5 hours to obtain a high wear-resistant chromium-based composite additive.

[0034] The application of a high-wear-resistant chromium-based composite additive suitable for high-temperature working conditions in aluminum alloys includes the following steps: Step 1: Aluminum alloy melting: Add aluminum alloy ingots (A356 aluminum alloy) to a medium frequency induction furnace, heat to 740℃ to melt, hold for 30 minutes, and remove impurities and gases from the melt; Step 2, Additive addition: Add the above-mentioned chromium-based composite additive to the melt at 2.0% of the mass of the aluminum alloy melt, and disperse it by mechanical stirring (220 r / min) + argon purging (10 L / min) for 25 min to ensure uniform dispersion of the additive; Step 3: Casting and molding: Let the uniformly mixed aluminum alloy melt stand for 12 minutes, pour it into a mold preheated to 220°C, and let it cool naturally to room temperature to obtain the cast aluminum alloy component. Step 4, Post-processing: Place the cast component in an electric resistance furnace for T6 heat treatment (solution treatment at 530℃ for 2 hours, followed by water cooling to room temperature; aging treatment at 180℃ for 4 hours).

[0035] Example 2 The difference between this embodiment and Embodiment 1 is that: in this embodiment, a high wear-resistant chromium-based composite additive suitable for high-temperature working conditions includes, by weight, 32 parts of modified nano-chromium powder (particle size 70nm), 8 parts of cerium oxide (particle size 100nm), 7 parts of tungsten carbide nanoparticles (particle size 60nm), 5 parts of vanadium boride (particle size 120nm), 23 parts of aluminum-magnesium alloy powder, 4 parts of dispersing agent (2.4 parts of sodium citrate + 1.6 parts of polyethylene glycol 400), and 3 parts of high-temperature stabilizing agent (titanium nitride nanoparticles, particle size 70nm).

[0036] The preparation process is the same as in Example 1, except that in this example, the chromium powder modification temperature is adjusted to 68°C, the melt coating temperature to 690°C, and the drying temperature to 195°C.

[0037] Its application in aluminum alloys includes the following steps: Step 1: Melting: Melt A380 aluminum alloy ingots at 750℃ and hold for 30 minutes; Step 2, Addition: Add additive at 2.5% of the melt mass, stir at 240 r / min + purge with argon gas at 11 L / min, stir for 28 min; Step 3, Casting: Let stand for 14 minutes, then pour into a 240℃ mold and allow to cool naturally; Step 4, heat treatment: solution treatment at 535℃ for 2 hours (water cooling), followed by aging at 185℃ for 4 hours.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that the additive components in this comparative example are: 30 parts of elemental chromium powder (unmodified, particle size 80 nm) and 25 parts of aluminum-magnesium alloy powder, with no other modifying components. The preparation process is the same as in Example 1, except that the chromium powder modification and melt coating steps are removed, and the powder is added directly after mixing.

[0039] Comparative Example 2 The difference between this comparative example and Example 1 is that the additive components in this comparative example are: 30 parts modified nano-chromium powder, 7 parts cerium oxide, 25 parts aluminum-magnesium alloy powder, 3.5 parts dispersant, and 4 parts high-temperature stabilizing agent. The preparation and application steps are the same as in Example 1.

[0040] Comparative Example 3 The difference between this comparative example and Example 1 is that in this comparative example, during the nano-chromium powder modification stage, the amount of KH560 added is 2% of the mass of the chromium powder.

[0041] Comparative Example 4 The difference between this comparative example and Example 1 is that in this comparative example, during the nano-chromium powder modification stage, the amount of KH560 added is 6% of the mass of the chromium powder.

[0042] Comparative Example 5 The difference between this comparative example and Example 1 is that the dispersant in this comparative example is sodium citrate.

[0043] Comparative Example 6 The difference between this comparative example and Example 1 is that the dispersant in this comparative example is polyethylene glycol.

[0044] Comparative Example 7 The difference between this comparative example and Example 1 is that the mass ratio of sodium citrate to polyethylene glycol in this comparative example is 1:1.

[0045] Experimental Performance Testing The aluminum alloys prepared in the above embodiments and comparative examples were subjected to performance tests, with each group undergoing three repeated tests. The test indicators and results are shown in Table 1: Room temperature hardness test method: GB / T 231.1-2018; High-temperature hardness test method: GB / T 4340.3-2012; Wear test method: GB / T 231.1-2018, wear test conditions (load 50N, speed 200r / min, time 60min). Corrosion area test method: GB / T 231.1-2018, salt spray corrosion test, test time 48h; The coefficient of variation test method is GB / T 231.1-2018, which characterizes the uniformity of chromium distribution.

[0046] Table 1

[0047] As shown in Table 1, Examples 1 and 2, containing a complete synergistic system of nano-chromium powder, tungsten carbide, vanadium boride, and cerium oxide, achieved a room temperature hardness of 128-132 HB, a high-temperature hardness retention rate of 84.3-84.8%, and a wear rate of only 0.022-0.025 g / 1000 r. Comparative Example 1, lacking the composite component and consisting only of elemental chromium powder, resulted in a sharp drop in high-temperature hardness (retention rate of 54.7%), and a significant increase in wear rate and corrosion area. Comparative Example 2, lacking tungsten carbide and vanadium boride, showed a significant decline in high-temperature hardness and wear resistance. The properties of Comparative Example 3 (2% KH560 addition, insufficient modification) and Comparative Example 4 (6% KH560 addition, excessive coating) were inferior to those of the Examples. The coefficients of variation (0.24-0.26) of Comparative Examples 5 (single sodium citrate) and 6 (single polyethylene glycol 400) were much higher than those of Examples (0.10-0.12), and the wear and corrosion area were also worse. Although Comparative Example 7 (compound ratio 1:1) was better than a single dispersant, its performance was still not as good as the 3:2 ratio of Examples.

[0048] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A high-wear-resistant chromium-based composite additive suitable for high-temperature operating conditions, characterized in that: By weight, it includes 25-35 parts of nano-chromium powder, 5-10 parts of cerium oxide, 4-8 parts of tungsten carbide nanoparticles, 3-6 parts of vanadium boride, 20-30 parts of aluminum-magnesium alloy powder, 2-5 parts of dispersing agent, and 1-4 parts of high-temperature stabilizing agent.

2. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 1, characterized in that: The nano-chromium powder is modified with silane coupling agent KH560 and has epoxy groups grafted onto its surface.

3. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 2, characterized in that: The nano-chromium powder has a particle size of 50-100 nm and a purity of ≥99.7%.

4. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 3, characterized in that: The cerium oxide has a particle size of 80-150 nm and a purity of ≥99.5%.

5. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 4, characterized in that: The tungsten carbide nanoparticles have a particle size of 30-80 nm and a hardness ≥2600 HV; the vanadium boride nanoparticles have a particle size of 100-200 nm.

6. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 5, characterized in that: The dispersing agent is a compound of sodium citrate and polyethylene glycol 400 in a mass ratio of 3:

2.

7. The high wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 6, characterized in that: The high-temperature stabilizing agent is titanium nitride nanoparticles with a particle size of 50-120 nm.

8. A method for preparing a high-wear-resistant chromium-based composite additive suitable for high-temperature operating conditions according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Chromium powder modification treatment: Add nano-chromium powder to ethanol solution, stir and disperse, then add silane coupling agent KH560, heat and stir and dry to obtain modified nano-chromium powder. S2. Premixing of composite components: Weigh out cerium oxide, tungsten carbide nanoparticles, vanadium boride, and high-temperature stabilizing agent according to the ratio, and mix them to obtain the premixed components; S3. Melt coating modification: After heating and melting aluminum-magnesium alloy powder, premixed components and dispersants are added to form aluminum-magnesium alloy coated composite powder; S4. Molding process: Cool the coated powder to room temperature, crush it, sieve it, and vacuum dry it to obtain a high wear-resistant chromium-based composite additive.

9. The method for preparing a high-wear-resistant chromium-based composite additive suitable for high-temperature working conditions according to claim 8, characterized in that: In step one, the amount of silane coupling agent KH560 added is 3-5% of the mass of chromium powder.

10. The application of a high-wear-resistant chromium-based composite additive adapted to high-temperature working conditions in aluminum alloys according to any one of claims 1 to 7, characterized in that: The aluminum alloy ingot is melted to obtain a melt, and the amount of chromium-based composite additive added is 1.5-3.0% of the mass of the aluminum alloy melt.

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