A silicon additive with high recovery rate and preparation method thereof

Abstract

The present invention relates to the field of alloy smelting and discloses a high-recovery silicon additive and a preparation method thereof. The silicon additive comprises the following raw materials, by mass: 85-95 parts of silicon powder, 0.5-2 parts of a surfactant, 0.1-3 parts of a flux, and aluminum powder; the silicon powder and aluminum powder are both gradient mixed, with the particle size gradient range and mass ratio being 20-25% for 100-150 mesh, 8-10% for 150-250 mesh, 25-30% for 250-350 mesh, and 25-35% for 350-500 mesh, with the remainder being ≥500 mesh. The preparation method of the silicon additive comprises the following steps: step 1, crushing and screening the raw materials, wherein the particle size of the raw materials after screening is a gradient mixture; step 2, batching and mixing; step 3, pressing: pressing the mixture into a blank; step 4, drying; and step 5, screening. The silicon additive of the present invention has a low melting temperature and a short melting time when the silicon element is melted in aluminum liquid, and has a high silicon recovery rate, which can ensure the purity of the aluminum alloy; the silicon additive prepared by the present technical solution is applied to the preparation of aluminum alloy, which can ensure the corrosion resistance, wear resistance, hardness and fatigue strength of the aluminum alloy.

Description

Technical Field

[0001] The present invention relates to the field of alloy smelting, and in particular to a silicon additive with high recovery rate and a preparation method thereof. Background Art

[0002] Aluminum alloys are the most widely used nonferrous structural materials in industry, finding extensive use in aviation, aerospace, automotive, machinery manufacturing, shipbuilding, and the chemical industry. With the continuous development of the aluminum processing and aluminum alloy industries, the research and development of aluminum alloys has been prioritized as a key technology. Common alloying elements in aluminum alloys include silicon, iron, copper, magnesium, nickel, zinc, and vanadium. Alloying is a crucial step in the aluminum alloy production process. Silicon is the most commonly used alloying element, acting as a strengthening element in aluminum alloys, significantly improving their casting properties and corrosion resistance.

[0003] In the production process of aluminum alloys, there are four main ways to add silicon: (1) Directly adding metallic silicon, specifically by placing silicon blocks at the bottom of the furnace, placing aluminum ingots on the silicon blocks, and then pouring aluminum liquid or igniting the heat to melt the silicon blocks; (2) Using an intermediate alloy, specifically by placing it at the bottom of the furnace, igniting the heat to melt it, or directly adding it to the aluminum liquid; (3) Blowing in silicon powder; (4) Adding quick-melting silicon, specifically by directly sprinkling it in when the aluminum liquid temperature in the furnace reaches above 720°C, and then waiting for the quick-melting silicon to melt completely. Currently, the first and fourth methods are the most widely used, but the inventors' team found the following problems in actual application: In order to fully and completely melt the elements and evenly disperse them in the aluminum melt, the furnace temperature needs to be above 720°C, while the melting point of aluminum is only 660°C. High temperatures will cause the aluminum melt to vaporize, resulting in burnout. At the same time, during this process, the unvaporized aluminum liquid is prone to react with the surrounding oxygen, hydrogen, water, etc. at high temperatures to form impurities that are difficult to remove, resulting in low purity of the formed aluminum alloy and its mechanical properties cannot meet the use requirements. Summary of the Invention

[0004] The present invention aims to provide a silicon additive with high recovery rate and a preparation method thereof, so as to solve the problem in the prior art that the addition of silicon during the preparation of aluminum alloy leads to low purity and unsatisfactory mechanical properties of the aluminum alloy.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical solution: a silicon additive with a high recovery rate, comprising the following raw materials, in parts by mass: 85-95 parts of silicon powder, 0.5-2 parts of a surfactant, 0.1-3 parts of a flux, and aluminum powder; the silicon powder and aluminum powder are both gradient mixed, with a particle size gradient range and mass ratio of 100-150mesh 20-25%, 150-250mesh 8-10%, 250-350mesh 25-30%, 350-500mesh 25-35%, and the remainder being ≥500mesh.

[0006] Preferably, as an improvement, the surfactant is at least one of sodium dodecylsulfate and sodium dodecylbenzenesulfonate.

[0007] Preferably, as an improvement, the surfactant is a mixture of sodium dodecylsulfate and sodium dodecylbenzenesulfonate in a mass ratio of 8:(3-5).

[0008] Preferably, as an improvement, the flux is a mixture of anhydrous magnesium chloride and fluoride.

[0009] Preferably, as an improvement, the mass ratio of anhydrous magnesium chloride to fluoride is (1-3): (65-80).

[0010] Preferably, as an improvement, the fluoride is at least one of potassium fluoroborate, potassium fluorotitanate, potassium fluorosilicate, and potassium fluoroaluminate.

[0011] Preferably, as an improvement, the fluoride is a mixture of potassium fluorotitanate and potassium fluorosilicate in a mass ratio of 1:3.

[0012] Preferably, as an improvement, a method for preparing a silicon additive with a high recovery rate comprises the following steps:

[0013] Step 1: Crushing and screening raw materials: crushing and screening silicon powder and aluminum powder. After screening, the particle size of the raw materials is a gradient mixture. The particle size gradient range and mass ratio are 100-150mesh 20-25%, 150-250mesh 8-10%, 250-350mesh 25-30%, 350-500mesh 25-35%, and the remainder is ≥500mesh.

[0014] Step 2: batching and mixing: mixing the sieved silicon powder and aluminum powder with a surfactant and a flux to obtain a mixture;

[0015] Step 3: Pressing: Pressing the mixture into a shape to obtain a blank;

[0016] Step 4: Drying: Dry the blank;

[0017] Step 5: Screening.

[0018] Preferably, as an improvement, in step 2, the mixing time is 40-60 min, and the mixing speed is 15 rpm.

[0019] Preferably, as an improvement, in step three, the pressing pressure is 25-28 MPa; in step five, the sieve is 15 mm.

[0020] The principles and advantages of this solution are as follows: In actual application, this technical solution addresses the problem of low purity and unsatisfactory mechanical properties of aluminum alloys caused by high melting temperatures when silicon additives are directly added in the prior art. By introducing an intermediate alloy, the temperature required for melting the alloying element is reduced, and the formula composition and preparation process of the silicon additive are comprehensively optimized. Among them, the addition of a flux can make the silicon additive melt quickly in the aluminum alloy, improve the melting efficiency, and evenly distribute the melted material in the aluminum alloy system; at the same time, it can reduce the melting temperature of the silicon additive to a certain extent. The addition of a surfactant can reduce the sinking speed of the silicon additive in the aluminum alloy system, thereby extending the residence time of the silicon additive in the aluminum alloy system, further ensuring that the silicon additive is fully melted and evenly dispersed. The silicon additive prepared by this technical solution has a low melting temperature and short melting time when the silicon element is melted in the aluminum liquid, and the silicon recovery rate is high (reaching over 99%), which can ensure the purity of the aluminum alloy.

[0021] During the technical research and development, the inventors discovered that the particle size of the metal powder in the metal additive has a key influence on its performance. In the traditional method of using metal powder with a single particle size, the larger the metal powder particle size, the lower the compactness of the ingredients after pressing. After it is put into the aluminum alloy system, the powdered material is very easy to fall off. And because the temperature of the aluminum alloy water is extremely high, the material that falls off will be quickly melted and burned out, resulting in a large amount of waste. The smaller the metal powder particle size, although it is pressed more tightly, its melting temperature does not decrease significantly, and the ingredients will sink to the bottom of the furnace quickly due to the excessive pressing density, resulting in the silicon additive not being completely melted and settling to the bottom of the furnace. When the silicon additive is deposited at the bottom of the furnace, it will pile up on each other, and the heating will be insufficient and uneven, making the silicon additive even more difficult to melt. After years of research and continuous experimentation, the inventors have optimized the formulation and dosage of the metal elements in the silicon additive, achieving a balance between the shedding of the powdered material and the melting temperature. Furthermore, the surfactant reduces the sinking speed, ensuring the complete melting and efficient function of the silicon additive. The silicon additive prepared using this technical solution is applied to the preparation of aluminum alloys, ensuring the alloy's corrosion resistance, wear resistance, hardness, and fatigue strength. DETAILED DESCRIPTION

[0022] The following is further described in detail through 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] Program Overview:

[0024] A silicon additive with high recovery rate comprises the following raw materials, calculated by mass percentage: 85-95% silicon powder, 0.5-2% surfactant, 0.1-3% flux, and the balance aluminum powder.

[0025] Wherein, the surfactant is at least one of sodium dodecylsulfate and sodium dodecylbenzenesulfonate.

[0026] The flux is a mixture of anhydrous magnesium chloride and fluoride in a mass ratio of (1-3): (65-80), and the fluoride is at least one of potassium fluoroborate, potassium fluorotitanate, potassium fluorosilicate and potassium fluoroaluminate.

[0027] Silicon powder and aluminum powder are mixed in a gradient manner, and the particle size gradient range and mass ratio are 100-150mesh 20-25%, 150-250mesh 8-10%, 250-350mesh 25-30%, 350-500mesh 25-35%, and the balance is ≥500mesh.

[0028] A method for preparing a silicon additive with a high recovery rate comprises the following steps:

[0029] Step 1: Crushing and screening raw materials: crushing and screening silicon powder and aluminum powder. After screening, the particle size of the raw materials is a gradient mixture. The particle size gradient range and mass ratio are 100-150mesh 20-25%, 150-250mesh 8-10%, 250-350mesh 25-30%, 350-500mesh 25-35%, and the remainder is ≥500mesh.

[0030] Step 2: batching and mixing: mixing the sieved silicon powder and aluminum powder with a surfactant and a flux for 40-60 minutes at a mixing speed of 15 rpm to obtain a mixture;

[0031] Step 3: Pressing: Press the mixture into a shape at a pressure of 25-28 MPa to obtain a blank;

[0032] Step 4: Drying: Dry the blank at a temperature of 100°C.

[0033] Step 5: Screening: Screen through a 15mm sieve.

[0034] Example 1

[0035] A silicon additive comprises the following raw materials, calculated by mass percentage: 85% silicon powder, 0.5% surfactant, 0.1% flux, and the balance (14.4%) aluminum powder.

[0036] The surfactant is a mixture of sodium dodecylsulfate and sodium dodecylbenzenesulfonate in a mass ratio of 8:3.

[0037] The flux is a mixture of anhydrous magnesium chloride and fluoride in a mass ratio of 1:65, and the fluoride is a mixture of potassium fluoroborate, potassium fluorotitanate, potassium fluorosilicate, and potassium fluoroaluminate in a mass ratio of 1:1:1:1.

[0038] Silicon powder and aluminum powder are both gradient mixed, and the particle size gradient range and mass ratio are 100-150mesh20%, 150-250mesh8%, 250-350mesh25%, 350-500mesh25%, and the balance is ≥500mesh.

[0039] A method for preparing a silicon additive comprises the following steps:

[0040] Step 1: Crushing and screening raw materials: crushing and screening silicon powder and aluminum powder. After screening, the particle size of the raw materials is a gradient mixture. The particle size gradient range and mass ratio are 100-150mesh 20%, 150-250mesh 8%, 250-350mesh 25%, 350-500mesh 25%, and the remainder is ≥500mesh.

[0041] Step 2: batching and mixing: mixing the sieved silicon powder and aluminum powder with a surfactant and a flux at a mixing time of 40 minutes and a mixing speed of 15 rpm to obtain a mixture;

[0042] Step 3: Pressing: Press the mixture into a shape at a pressure of 25 MPa to obtain a blank;

[0043] Step 4: Drying: Dry the blank at a temperature of 100°C.

[0044] Step 5: Screening: Screen through a 15mm sieve.

[0045] Examples 1 to 3 are examples of the present invention, and Comparative Examples 1 to 5 are comparative examples of the present invention. The differences between each example and comparative example and Example 1 are the selection of raw materials, the amount of addition, and the particle size gradient range. The specific design is detailed in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] Experimental Example Silicon Additive Performance Verification

[0050] The performance tests of the silicon additives prepared in the above embodiments and comparative examples were conducted. The test indicators included: silicon additive melting temperature, silicon additive melting time and silicon additive recovery rate. The silicon additive melting temperature and silicon additive melting time were recorded by traditional observation. The silicon additive recovery rate was calculated as: (recovered amount / added amount) × 100%. The test results are shown in the following table:

[0051] Table 2

[0052]

[0053]

[0054] Application Examples

[0055] The silicon additives prepared in the above embodiments and comparative examples were used to smelt aluminum alloys, and the performance of the aluminum alloys was tested. The test indicators included: corrosion resistance, wear resistance, hardness and fatigue strength. The results showed that the silicon additives prepared using this technical solution can significantly improve the corrosion resistance, wear resistance, hardness and fatigue strength of the aluminum alloy.

[0056] The above is only an embodiment of the present invention, and the common knowledge such as the specific technical solutions and / or characteristics in the solution are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the description can be used to interpret the content of the claims.

Claims

1. A silicon additive with high recovery rate, characterized by: The invention is composed of the following raw materials in the following mass percentages: 85-95% silicon powder, 0.5-2% surfactant, 0.1-3% flux, and the balance is aluminum powder; the silicon powder and aluminum powder are both gradient mixed, and the particle size gradient range and mass ratio are 20-25% for 100-150 mesh, 8-10% for 150-250 mesh, 25-30% for 250-350 mesh, 25-35% for 350-500 mesh, and the balance is ≥500 mesh; the surfactant is a mixture of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate in a mass ratio of 8:(3-5); the flux is a mixture of anhydrous magnesium chloride and fluoride.

2. A high recovery silicon additive according to claim 1, characterized in that: The mass ratio of the anhydrous magnesium chloride to the fluoride is (1-3): (65-80).

3. A high recovery silicon additive according to claim 2, characterized in that: The fluoride is at least one of potassium fluoroborate, potassium fluorotitanate, potassium fluorosilicate and potassium fluoroaluminate.

4. A silicon additive with high recovery rate according to claim 3, characterized in that: The fluoride is a mixture of potassium fluorotitanate and potassium fluorosilicate in a mass ratio of 1:

3.

5. The method for preparing a silicon additive with high recovery rate according to any one of claims 1 to 4, characterized in that: The steps include: Step 1: Crushing and screening raw materials: crushing and screening silicon powder and aluminum powder. After screening, the raw materials are mixed in a gradient size. The particle size gradient range and mass ratio are 100-150 mesh 20-25%, 150-250 mesh 8-10%, 250-350 mesh 25-30%, 350-500 mesh 25-35%, and the remainder is ≥500 mesh. Step 2: batching and mixing: mixing the sieved silicon powder and aluminum powder with a surfactant and a flux to obtain a mixture; Step 3: Pressing: Pressing the mixture into a shape to obtain a blank; Step 4: Drying: Dry the blank; Step 5: Screening.

6. The method for preparing a silicon additive with high recovery rate according to claim 5, characterized in that: In step 2, the mixing time is 40-60 min and the mixing speed is 15 rpm.

7. The method for preparing a silicon additive with high recovery rate according to claim 6, characterized in that: In step 3, the pressing pressure is 25-28 MPa; in step 5, the sieving is performed through a 15 mm sieve.

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