High-dispersion silicon additive adaptive to low-temperature smelting and application of high-dispersion silicon additive in aluminum alloy

Abstract

The invention relates to the field of metal additives, and discloses a high-dispersion silicon additive suitable for low-temperature smelting and application of the high-dispersion silicon additive in aluminum alloy, the additive comprises the following raw materials in parts by mass: 85-92 parts of silicon powder, 2-5 parts of a coating agent, 3-6 parts of a composite fluxing agent and 1-3 parts of a modifier; the surface of the silicon powder is subjected to plasma activation treatment. According to the invention, a raw material formula is optimized, plasma activated silicon powder is taken as a core, and a sodium alginate modified chitosan coating agent, a specific composite fluxing agent and a nano titanate modifier are matched; the technology parameters are optimized, low-temperature smelting at the temperature of 700-750 DEG C is achieved, the silicon dispersity and recovery rate are improved, energy consumption and the impurity content are reduced, the pain point of a traditional technology is solved, and the high-end aluminum-silicon alloy production requirement is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal additives, in particular to a high-dispersion silicon additive suitable for low-temperature smelting and its application in aluminum alloys. BACKGROUND

[0002] Under the upgrading trend of lightweight materials, aluminum-silicon alloys have become the core materials in high-end fields such as automotive lightweight parts and aerospace structural parts due to their low density, high specific strength and good casting performance, and the market application demand continues to rise. However, the traditional aluminum-silicon alloy smelting process has long relied on high-temperature silicon addition mode, with a smelting temperature as high as about 950℃, which not only causes huge energy consumption, but also causes serious silicon element volatilization loss due to high-temperature environment, resulting in low silicon recovery rate, and easily causing alloy composition segregation, coarse grain and other problems, which directly affects the mechanical property stability of the product. In addition, the existing silicon additive mainly uses single silicon-based components, which needs to be used with fluoride flux, and this system easily induces severe oxidation of aluminum liquid, resulting in an increase in the content of oxide impurities in the alloy, and the adaptability of the flux to different aluminum matrixes and different smelting processes is poor, especially it cannot meet the current industry's low-temperature smelting energy-saving demand, which has become a key bottleneck restricting the high-quality development of the aluminum-silicon alloy industry.

[0003] Therefore, it is urgent to develop a silicon additive suitable for low-temperature smelting, with good silicon dispersibility, high recovery rate and strong environmental protection, to solve the energy consumption, quality and pollution problems of the existing technology. SUMMARY

[0004] The present application aims to provide a high-dispersion silicon additive suitable for low-temperature smelting and its application in aluminum alloys, to solve the problems of high melting temperature and poor dispersibility of the existing silicon additive.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solution: a high-dispersion silicon additive suitable for low-temperature smelting, comprising the following raw materials in mass parts: 85-92 parts of silicon powder, 2-5 parts of coating agent, 3-6 parts of composite flux, and 1-3 parts of modifier; the surface of the silicon powder is subjected to plasma activation treatment. Preferably, as an improvement, the coating agent is sodium alginate modified chitosan, and the particle size of the coating agent is 100-300 mesh.

[0006] Preferably, as an improvement, the composite flux comprises the following raw materials: 2-4 parts of modified bentonite, 0.5-1 part of cerium oxide, and 0.5-1 part of calcium fluoride.

[0007] Preferably, as an improvement, the modified bentonite is subjected to calcination and activation treatment at 1000-1200℃.

[0008] Preferably, as an improvement, the modifier is nano titanate.

[0009] Preferably, as an improvement, the particle size of the silicon powder is 50-200 mesh, and the purity of the silicon powder is ≥99.5%.

[0010] Preferably, as an improvement, a method for preparing a highly dispersed silicon additive adapted to low-temperature melting includes the following steps: Step 1: Plasma treatment of silicon powder; Step 2: Weigh out the coating agent, composite flux, and modifier according to the formula, and mix them together. Step 3: Add the silicon powder treated in Step 1, continue stirring, and then dry at a temperature of 120-150℃ to obtain a highly dispersed silicon additive.

[0011] Preferably, as an improvement, in step one, the plasma treatment is carried out in an argon atmosphere for 10-15 minutes, and the treatment power is 400-600W.

[0012] Preferably, as an improvement, in step two, the stirring temperature is 60-80℃, the stirring time is 20-30min, and the stirring speed is 300-500r / min.

[0013] Preferably, as an improvement, a highly dispersed silicon additive adapted to low-temperature melting is used in aluminum alloys, wherein the amount of silicon additive added is 1.5-3% of the mass of the aluminum liquid, and the aluminum liquid is obtained by removing impurities after melting aluminum ingots.

[0014] The principle and advantages of this solution are as follows: In practical applications, addressing the problems of high melting temperature and poor dispersibility of silicon additives in existing technologies, this technical solution focuses on adapting to low-temperature melting and high-dispersion silicon additives. Through raw material formulation optimization and precise design of process parameters, the melting temperature of silicon additives is reduced while ensuring their dispersibility. Specifically, this technical solution utilizes plasma activation treatment of silicon powder. High-energy plasma can break through the inert oxide layer on the surface of silicon powder, forming a large number of active sites on the silicon powder surface, while increasing the specific surface area of ​​silicon powder. This process breaks through the inert barrier of the traditional silicon powder surface, making silicon powder easier to wet and fuse with molten aluminum, solving the problems of poor dispersibility and easy agglomeration of silicon powder at low temperatures. In addition, through synergistic optimization of silicon powder particle size and coating machine particle size, a particle size gradient of coarse silicon powder + fine coating agent is formed. The fine coating agent can be uniformly attached to the silicon powder surface, avoiding direct contact and agglomeration between silicon powder particles, and can also decompose rapidly during melting, providing a space buffer for silicon powder dispersion and further enhancing the dispersion effect. In this technical solution, sodium alginate-modified chitosan is used as a coating agent. Its polymer chain structure can form a flexible coating layer on the surface of silicon powder. On the one hand, it isolates air during storage and pretreatment to prevent silicon powder oxidation; on the other hand, during low-temperature melting (700-750℃), the coating layer slowly decomposes (avoiding violent reactions), gradually releasing silicon powder and ensuring that the silicon powder is evenly distributed in the aluminum melt, rather than concentrated floating or sinking. In addition, this technical solution creatively optimizes the formulation of the composite flux: after bentonite is calcined and activated at 1000-1200℃, it forms a porous structure inside, which can act as a "flux carrier" to evenly disperse and transport cerium oxide and calcium fluoride to the interface between silicon powder and aluminum melt, reducing the silicon-aluminum interfacial tension and lowering the melting temperature of silicon from the traditional 950℃ or above to 700-750℃, which is suitable for low-temperature melting requirements. Cerium oxide serves two main purposes: first, it acts as a grain refiner, forming a nanoscale CeAl3 phase in molten aluminum to inhibit grain growth in aluminum-silicon alloys and improve compositional segregation; second, it acts as a deoxidizer, preferentially combining with O in molten aluminum to form CeO2, reducing the formation of Al2O3 impurities caused by traditional fluoride fluxes and lowering the alloy oxide content. Calcium fluoride, in synergy with modified bentonite and cerium oxide, further lowers the eutectic temperature of the silicon-aluminum system while promoting melt fluidity and avoiding uneven silicon dispersion caused by the viscosity of molten aluminum at low temperatures. Furthermore, in this technical solution, nano-titanium ester acts as a modifier. Its alkoxy groups in its molecular structure can bind to the active sites on the silicon powder surface, while the metalophilic groups at the other end can form chemical bonds with molten aluminum, essentially building a "molecular bridge" between the silicon powder and molten aluminum, improving the wettability and stability of silicon powder in molten aluminum, and reducing silicon volatilization loss.

[0015] The beneficial effects of this technical solution are as follows: 1. Significantly reduced energy consumption: It is suitable for low-temperature melting at 700-750℃, which significantly reduces energy consumption compared to the traditional high-temperature process at 950℃, thus greatly saving production costs; 2. Improved silicon utilization: Through the synergistic effect of coating agents and composite fluxes, the silicon recovery rate is increased from 75-80% in the existing technology to 90-95%, reducing silicon resource waste; 3. Alloy performance optimization: The tensile strength and elongation of the aluminum alloy are significantly improved, and the impurity content (Fe and Si oxides) is significantly reduced, meeting the needs of high-end applications; 4. Improved environmental friendliness: The fluoride content in the composite flux is reduced by more than 50% compared with the existing technology, reducing environmental pollution and improving the production environment. Detailed Implementation

[0016] 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 and reagents used are all commercially available.

[0017] A highly dispersed silicon additive suitable for low-temperature melting, comprising, by weight, the following raw materials: 85-92 parts silicon powder, 2-5 parts coating agent, 3-6 parts composite flux, and 1-3 parts modifier.

[0018] The silicon powder has a particle size of 50-200 mesh, and the surface of the silicon powder is treated with plasma activation, resulting in a purity of ≥99.5%.

[0019] The coating agent is sodium alginate modified chitosan, and the particle size of the coating agent is 100-300 mesh.

[0020] The composite flux consists of 2-4 parts modified bentonite, 0.5-1 parts cerium oxide, and 0.5-1 parts calcium fluoride; wherein the modified bentonite is activated by calcination at 1000-1200℃.

[0021] The modifier is nano-titanium ester.

[0022] A method for preparing a highly dispersed silicon additive suitable for low-temperature melting includes the following steps: Step 1: Place the silicon powder in a plasma treatment device and treat it under an argon atmosphere for 10-15 minutes. The plasma treatment power is 400-600W. Step 2: Weigh the coating agent, composite flux, and modifier according to the formula, add them to a high-speed mixer, and stir at 60-80℃ for 20-30 minutes at a stirring speed of 300-500 r / min. Step 3: Add the activated silicon powder from Step 1, continue stirring for 15-20 minutes, and then dry at 120-150℃ for 2-3 hours to obtain a highly dispersed silicon additive.

[0023] The application of a highly dispersed silicon additive suitable for low-temperature melting in aluminum alloys includes the following steps: (1) Heat the aluminum ingot to 700-750℃ to melt it into molten aluminum, stir to remove impurities, and ensure that the impurity content in the molten aluminum is ≤0.2%; (2) Add silicon additive at a ratio of 1.5-3% of the aluminum liquid mass and stir at a speed of 200-300 r / min for 10-15 min; (3) After heat preservation for 20-30 minutes, the aluminum-silicon alloy is cast and molded, and nitrogen atmosphere protection is used during the heat preservation process.

[0024] Example 1 A highly dispersed silicon additive suitable for low-temperature melting, comprising the following raw materials by weight: 88 parts silicon powder (particle size 100 mesh, purity 99.6%), 3 parts sodium alginate modified chitosan (particle size 200 mesh), 4 parts composite flux (2.5 parts modified bentonite + 0.8 parts cerium oxide + 0.7 parts calcium fluoride), and 2 parts nano titanate.

[0025] A method for preparing a highly dispersed silicon additive suitable for low-temperature melting includes the following steps: Step 1: Place the silicon powder in a plasma treatment device and treat it under an argon atmosphere for 12 minutes. The plasma treatment power is 500W. Step 2: Weigh the coating agent, composite flux, and modifier according to the formula, add them to a high-speed mixer, and stir at 70°C for 25 minutes at a stirring speed of 400 r / min. Step 3: Add the activated silicon powder from Step 1, continue stirring for 18 minutes, and then dry at 130°C for 2.5 hours to obtain a highly dispersed silicon additive.

[0026] The application of a highly dispersed silicon additive suitable for low-temperature melting in aluminum alloys includes the following steps: (1) Heat the aluminum ingot to 720℃ to melt it into molten aluminum, stir to remove impurities, and ensure that the impurity content in the molten aluminum is ≤0.2%; (2) Add silicon additive at a ratio of 2% of the mass of aluminum liquid and stir at a speed of 250 r / min for 12 min; (3) After heat preservation for 25 min, the aluminum-silicon alloy is cast and molded, and nitrogen atmosphere protection is used during the heat preservation process.

[0027] Example 2 A highly dispersed silicon additive suitable for low-temperature melting, comprising the following raw materials by weight: 90 parts silicon powder (particle size 50 mesh, purity 99.8%), 2 parts sodium alginate modified chitosan, 3.5 parts composite flux (2 parts modified bentonite + 1 part cerium oxide + 0.5 parts calcium fluoride), and 1.5 parts nano titanate.

[0028] A method for preparing a highly dispersed silicon additive suitable for low-temperature melting includes the following steps: Step 1: Place the silicon powder in a plasma treatment device and treat it under an argon atmosphere for 15 minutes. The plasma treatment power is 400W. Step 2: Weigh the coating agent, composite flux, and modifier according to the formula, add them to a high-speed mixer, stir at 80°C for 20 minutes, and stir at a speed of 500 r / min. Step 3: Add the activated silicon powder from Step 1, continue stirring for 20 minutes, and then dry at 120°C for 3 hours to obtain a highly dispersed silicon additive.

[0029] The application of a highly dispersed silicon additive suitable for low-temperature melting in aluminum alloys includes the following steps: (1) Heat the aluminum ingot to 750℃ to melt it into molten aluminum, stir to remove impurities, and ensure that the impurity content in the molten aluminum is ≤0.2%; (2) Add silicon additive at a ratio of 2.5% of the mass of aluminum liquid and stir at 300 r / min for 10 min; (3) After heat preservation for 30 min, the aluminum-silicon alloy is cast and molded, and nitrogen atmosphere protection is used during the heat preservation process.

[0030] Example 3 The difference between this embodiment and Embodiment 1 is that: in this embodiment, a method for preparing a highly dispersed silicon additive suitable for low-temperature melting includes the following steps: Step 1: Place the silicon powder in a plasma treatment device and treat it under an argon atmosphere for 15 minutes. The plasma treatment power is 400W. Step 2: Weigh the coating agent, composite flux, and modifier according to the formula, add them to a high-speed mixer, and stir at 60 ℃ for 30 min at a stirring speed of 450 r / min; Step 3: Add the activated silicon powder from Step 1, continue stirring for 20 minutes, and then dry at 150°C for 2 hours to obtain a highly dispersed silicon additive.

[0031] The application of a highly dispersed silicon additive suitable for low-temperature melting in aluminum alloys includes the following steps: (1) Heat the aluminum ingot to 700℃ to melt it into molten aluminum, stir to remove impurities, and ensure that the impurity content in the molten aluminum is ≤0.2%; (2) Add silicon additive at a ratio of 3% of the mass of aluminum liquid and stir at a speed of 200 r / min for 15 min; (3) After heat preservation for 30 minutes, the aluminum-silicon alloy is cast and molded, and nitrogen atmosphere protection is used during the heat preservation process.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that the silicon powder in this comparative example was not subjected to plasma treatment.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that the chitosan in this comparative example was not modified with sodium alginate.

[0034] Comparative Example 3 The difference between this comparative example and Example 1 is that the bentonite in the flux in this comparative example is not modified.

[0035] Comparative Example 4 The difference between this comparative example and Example 1 is that the flux used in this comparative example is only modified bentonite.

[0036] Comparative Example 5 The difference between this comparative example and Example 1 is that in this comparative example, the mass ratio of modified bentonite, cerium oxide, and calcium fluoride in the flux is 1:1:1.

[0037] Experimental Performance Testing The aluminum alloys and silicon additives prepared in the above embodiments and comparative examples were subjected to performance tests. The test indicators included: melting temperature, silicon additive recovery rate, tensile strength of aluminum alloy, elongation, and impurity content. The tensile strength of aluminum alloy was tested in accordance with GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test at room temperature". Each group was tested three times repeatedly. The test results are shown in Table 1. Table 1

[0038] As shown in Table 1, the melting temperature of the embodiments of the present invention is significantly lower than that of the comparative example, and the silicon recovery rate is above 90% in all cases. Furthermore, regarding mechanical properties, the tensile strength (310-340 MPa) and elongation (7.8%-9.2%) of the embodiments are superior to those of the comparative example (tensile strength 255-290 MPa, elongation 4.9%-6.3%), thanks to the uniform silicon dispersion, refined grains, and reduced impurities. The impurity content of the embodiments (0.11%-0.15%) is lower than that of the comparative example (0.21%-0.31%), indicating that the deoxidizing effect of cerium oxide and the low-fluorine formulation of the composite flux effectively reduce oxide impurities.

[0039] 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 highly dispersed silicon additive suitable for low-temperature melting, characterized in that: The product comprises the following raw materials by weight: 85-92 parts silicon powder, 2-5 parts coating agent, 3-6 parts composite flux, and 1-3 parts modifier; the surface of the silicon powder is subjected to plasma activation treatment.

2. The highly dispersed silicon additive adapted for low-temperature melting according to claim 1, characterized in that: The coating agent is sodium alginate modified chitosan, and the particle size of the coating agent is 100-300 mesh.

3. The highly dispersed silicon additive adapted for low-temperature melting according to claim 2, characterized in that: The composite flux comprises the following raw materials: 2-4 parts modified bentonite, 0.5-1 parts cerium oxide, and 0.5-1 parts calcium fluoride.

4. The highly dispersed silicon additive adapted for low-temperature melting according to claim 3, characterized in that: The modified bentonite was activated by calcination at 1000-1200℃.

5. The highly dispersed silicon additive adapted for low-temperature melting according to claim 4, characterized in that: The modifier is nano-titanium ester.

6. The highly dispersed silicon additive adapted for low-temperature melting according to claim 5, characterized in that: The silicon powder has a particle size of 50-200 mesh and a purity of ≥99.5%.

7. A method for preparing a highly dispersed silicon additive suitable for low-temperature melting according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Plasma treatment of silicon powder; Step 2: Weigh out the coating agent, composite flux, and modifier according to the formula, and mix them together. Step 3: Add the silicon powder treated in Step 1, continue stirring, and then dry at a temperature of 120-150℃ to obtain a highly dispersed silicon additive.

8. The method for preparing a highly dispersed silicon additive suitable for low-temperature melting according to claim 7, characterized in that: In step one, the plasma treatment is carried out in an argon atmosphere for 10-15 minutes at a power of 400-600W.

9. The method for preparing a highly dispersed silicon additive suitable for low-temperature melting according to claim 8, characterized in that: In step two, the stirring temperature is 60-80℃, the stirring time is 20-30 minutes, and the stirring speed is 300-500 r / min.

10. The application of a highly dispersed silicon additive adapted for low-temperature melting according to any one of claims 1 to 6 in aluminum alloys, characterized in that: The amount of silicon additive added is 1.5-3% of the mass of the molten aluminum, which is obtained by removing impurities from melted aluminum ingots.

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