Silicon additive with low smelting temperature and preparation method thereof

Abstract

The invention relates to the technical field of alloy additives, and discloses a low-smelting-temperature silicon additive and a preparation method thereof.The silicon additive is prepared from, by mass, 90-98 parts of silicon, 0.8-3.8 parts of surfactant, 1-2.6 parts of fluxing agent and 2-4.7 parts of chemical fluxing agent; the particle size of silicon is 28-670 meshes, the particle size of the surfactant is 35-560 meshes, the particle size of the fluxing agent is 22-480 meshes, and the particle size of the chemical fluxing agent is 42-630 meshes. The silicon additive prepared through the method can reduce the alloy smelting temperature, the recovery rate of the additive is high, when the silicon additive is applied to aluminum alloy machining, the purity of materials can be improved, energy consumption can be reduced, carbon dioxide emission can be reduced, and the outstanding advantages and effects are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy additives, and particularly relates to a silicon additive with a low melting temperature and a preparation method thereof. Background Art

[0002] Aluminum alloy is an alloy material mainly composed of aluminum and added with other elements (such as copper, magnesium, manganese, silicon, zinc, etc.). By adding different alloy elements, the mechanical properties, corrosion resistance and other characteristics of pure aluminum can be significantly improved, making it suitable for a wide range of industrial applications. Currently, common aluminum alloys on the market include 1xxx series (pure aluminum), 2xxx series (Al-Cu alloy), 3xxx series (Al-Mn alloy), 5xxx series (Al-Mg alloy), 6xxx series (Al-Mg-Si alloy), 7xxx series (Al-Zn-Mg-Cu alloy) and 8xxx series (other special-purpose alloys).

[0003] During the processing of aluminum alloy, silicon additives are usually added. The main functions of silicon additives include but are not limited to the following aspects: ①Enhancing material strength: Adding silicon to a metal alloy can improve the hardness and wear resistance of the material; ②Improving fluidity: Especially in the casting process, silicon can increase the fluidity of the molten metal, helping the formation of castings with complex shapes; ③Adjusting the coefficient of thermal expansion: The presence of silicon can help control the thermal expansion behavior of the material, reducing stress concentration caused by temperature changes; ④Enhancing corrosion resistance: In some cases, silicon can form a protective oxide layer, enhancing the antioxidant and corrosion resistance of the material; ⑤Reducing costs: Since silicon resources are abundant and the price is relatively low, appropriate addition can effectively reduce production costs. Our company found the following problems in actual application: In order to make the elements fully and completely melt and be evenly dispersed in the aluminum melt, the temperature of the furnace needs to reach above 720°C, while the melting point of aluminum is only 660°C. The high temperature will cause the aluminum melt to vaporize, resulting in burning loss. At the same time, during this process, the unvaporized aluminum liquid is prone to react with surrounding oxygen, hydrogen, water, etc. at high temperatures, forming impurities that are difficult to remove, resulting in low purity of the formed aluminum alloy and its mechanical properties not meeting the usage requirements. Summary of the Invention

[0004] The present invention aims to provide a silicon additive with a low melting temperature and a preparation method thereof to solve the problems of low purity and unsatisfactory mechanical properties of aluminum alloy caused by adding silicon in the prior art during the preparation of aluminum alloy.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A silicon additive with a low melting temperature, the raw materials are in parts by mass, including 90 - 98 parts of silicon, 0.8 - 3.8 parts of surfactant, 1 - 2.6 parts of flux, and 2 - 4.7 parts of chemical flux; the particle size of silicon is 28mm - 670 mesh, the particle size of surfactant is 35 - 560 mesh, the particle size of flux is 22 - 480 mesh, and the particle size of chemical flux is 42 - 630 mesh.

[0006] Preferably, as an improvement, the surfactant is sodium chloride.

[0007] Preferably, as an improvement, the flux is an aluminum-titanium-boron refiner.

[0008] Preferably, as an improvement, the chemical flux is ammonium fluoborate.

[0009] Preferably, as an improvement, a preparation method of a silicon additive with a low melting temperature includes the following steps:

[0010] Step 1: Raw material crushing and screening: Crush and screen the raw materials so that the particle size of silicon is 28mm - 670 mesh, the particle size of surfactant is 35 - 560 mesh, the particle size of flux is 22 - 480 mesh, and the particle size of chemical flux is 42 - 630 mesh;

[0011] Step 2: Batching and mixing: Mix the screened silicon powder, surfactant, flux, and chemical flux to obtain a mixed material;

[0012] Step 3: Pressing: Press the mixed material into a shape to obtain a blank;

[0013] Step 4: Drying: Dry the blank.

[0014] Preferably, as an improvement, in Step 2, the mixing time is 40 - 60min, and the mixing speed is 15 - 20rpm.

[0015] Preferably, as an improvement, in Step 3, the pressing pressure is 20 - 30MPa.

[0016] Preferably, as an improvement, in Step 3, the drying temperature is 95 - 100°C.

[0017] The principle and advantages of this solution are as follows: In practical applications, in this technical solution, aiming at the problems of low purity and unsatisfactory mechanical properties of aluminum alloys caused by adding silicon in the prior art during the preparation of aluminum alloys, the inventor comprehensively and integrally optimizes the formula and preparation process of the silicon additive: silicon is used as the basic raw material of the additive; the surfactant can reduce the surface tension of the melt, improve the wettability of silicon particles, enable the silicon particles to better contact with other substances during the melting process, promote the reaction, and at the same time help reduce the bubbles in the melt and improve the uniformity of the melt; the flux can reduce the melting temperature of silicon, promote the melting process of silicon, enable silicon to reach a good molten state at a lower temperature, thereby saving energy and reducing the loss of high temperature on the equipment; and the chemical flux acts synergistically with the flux to further reduce the melting temperature, and may have a positive impact on aspects such as the fluidity and stability of the melt, which helps to improve the quality and performance of the silicon additive.

[0018] In addition, for the metal additive to exert its maximum utility, it needs to melt quickly and completely in the melt and be evenly dispersed in the melt system. The inventor found that there is a very large correlation between the melting speed, dispersion degree and the particle size of the metal powder. The larger the particle size of the metal powder, the lower the compactness of the prepared mixture after pressing. After putting it into the aluminum alloy system, the powdery material is very easy to fall off. From the perspective of reaction kinetics, a smaller particle size can increase the specific surface area of the reactants, enable the flux and others to more fully contact the silicon particles, accelerate the reaction rate, and promote the melting of silicon. Based on this, this technical solution conducts gradient ratio and optimization of the particle size of the raw materials. Not only is the particle size range of the optimal main material silicon adjusted, but also the particle sizes of the surfactant, flux and chemical flux need to match the particle size of silicon to achieve good interaction between particles. When their particle sizes are within a certain range, a uniform adsorption or coating layer can be formed on the surface of the silicon particles, so as to better play the roles of reducing surface tension, promoting melting, etc.; and it can ensure that the silicon additive prepared by this technical solution can reduce the alloy melting temperature and has a high additive recovery rate. When applied in aluminum alloy processing, it can improve the mechanical properties of the material. Specific Embodiments

[0019] The following is a further detailed description 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; the materials, reagents, etc. used can all be obtained from commercial channels.

[0020] Overview of the Solution:

[0021] A silicon additive with a low melting temperature, the raw materials are in parts by mass, including 90 - 98 parts of silicon, 0.8 - 3.8 parts of surfactant, 1 - 2.6 parts of flux, and 2 - 4.7 parts of chemical flux.

[0022] Among them, the particle size of silicon is 28 mm to 670 mesh;

[0023] The surfactant is sodium chloride with a particle size of 35 to 560 mesh;

[0024] The flux is an aluminum-titanium-boron refiner with a particle size of 22 to 480 mesh;

[0025] The chemical flux is ammonium fluoborate with a particle size of 42 to 630 mesh.

[0026] A preparation method of a silicon additive with a low melting temperature includes the following steps:

[0027] Step 1, raw material crushing and screening: Crush and screen the raw materials so that the particle size of silicon is 28 mm to 670 mesh, the particle size of the surfactant is 35 to 560 mesh, the particle size of the flux is 22 to 480 mesh, and the particle size of the chemical flux is 42 to 630 mesh;

[0028] Step 2, batching and mixing: Mix the screened silicon powder, surfactant, flux and chemical flux, the mixing time is 40 - 60 min, and the mixing speed is 15 - 20 rpm to obtain a mixed material;

[0029] Step 3, pressing: Press the mixed material into a shape, and the pressing pressure is 20 - 30 MPa to obtain a blank;

[0030] Step 4, drying: Dry the blank, and the drying temperature is 95 - 100 °C.

[0031] Example 1

[0032] A silicon additive with a low melting temperature, calculated by mass of raw materials, includes 90 parts of silicon, 1 part of surfactant, 2.6 parts of flux, and 4.7 parts of chemical flux.

[0033] Among them, the particle size of silicon is 28 mm;

[0034] The surfactant is sodium chloride with a particle size of 350 mesh;

[0035] The flux is an aluminum-titanium-boron refiner with a particle size of 150 mesh;

[0036] The chemical flux is ammonium fluoborate with a particle size of 535 mesh.

[0037] A preparation method of a silicon additive with a low melting temperature includes the following steps:

[0038] Step 1, raw material crushing and screening: Crush and screen the raw materials so that the particle size of silicon is 28 mm mesh, the particle size of the surfactant is 350 mesh, the particle size of the flux is 150 mesh, and the particle size of the chemical flux is 535 mesh;

[0039] Step 2. Batching and mixing: Mix the sieved silicon powder, surfactant, flux, and chemical flux. The mixing time is 40 min and the mixing speed is 20 rpm to obtain a mixed material.

[0040] Step 3. Pressing: Press the mixed material into a shape with a pressing pressure of 30 MPa to obtain a blank.

[0041] Step 4. Drying: Dry the blank at a drying temperature of 100 °C.

[0042] Example 2

[0043] A silicon additive with a low melting temperature, the raw materials are in parts by mass, including 98 parts of silicon, 3.8 parts of surfactant, 1 part of flux, and 2 parts of chemical flux.

[0044] Among them, the particle size of silicon is 670 mesh;

[0045] The surfactant is sodium chloride with a particle size of 560 mesh;

[0046] The flux is an aluminum-titanium-boron grain refiner with a particle size of 480 mesh;

[0047] The chemical flux is ammonium fluoborate with a particle size of 630 mesh.

[0048] A preparation method of a silicon additive with a low melting temperature, comprising the following steps:

[0049] Step 1. Raw material crushing and sieving: Crush and sieve the raw materials so that the particle size of silicon is 670 mesh, the particle size of the surfactant is 560 mesh, the particle size of the flux is 480 mesh, and the particle size of the chemical flux is 630 mesh;

[0050] Step 2. Batching and mixing: Mix the sieved silicon powder, surfactant, flux, and chemical flux. The mixing time is 60 min and the mixing speed is 15 rpm to obtain a mixed material.

[0051] Step 3. Pressing: Press the mixed material into a shape with a pressing pressure of 20 MPa to obtain a blank.

[0052] Step 4. Drying: Dry the blank at a drying temperature of 95 °C.

[0053] Comparative Example 1

[0054] The difference between this comparative example and Example 1 is that: the chemical flux is not added in this comparative example.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that: the particle size of silicon is 10 mesh in this comparative example.

[0057] Comparative Example 3

[0058] The difference between this comparative example and Example 1 is that the particle size of the surfactant in this comparative example is 10 mesh.

[0059] Comparative Example 4

[0060] The difference between this comparative example and Example 1 is that the particle size of the flux in this comparative example is 10 mesh.

[0061] Comparative Example 5

[0062] The difference between this comparative example and Example 1 is that the particle size of the chemical flux in this comparative example is 10 mesh.

[0063] Comparative Example 6

[0064] The difference between this comparative example and Example 1 is that the chemical flux in this comparative example is cryolite.

[0065] Comparative Example 7

[0066] The difference between this comparative example and Example 1 is that the flux in this comparative example is calcium chloride.

[0067] Experimental Example 1 Silicon Additive Recovery Rate

[0068] The additive recovery rates of the above-mentioned examples and comparative examples were tested. The recovery rate = (recovery amount / added amount) × 100%; each group was repeated three times. The results are shown in Table 1. The results show that the recovery rate of the silicon additive prepared in the examples of the present invention is 100%. Both the raw material particle size and the type of additive in the additive have a great influence on the recovery rate of the silicon additive in this solution.

[0069] Table 1

[0070] Group Recovery rate of silicon additive % Example 1 100％ Example 2 100％ Comparative Example 1 72.5％ Comparative Example 2 80.2％ Comparative Example 3 78.6％ Comparative Example 4 75％ Comparative Example 5 76.5％ Comparative Example 6 89.3％ Comparative Example 7 88.6％

[0071] Experimental Example 2 Additive Melting Temperature and Melting Time

[0072] The melting temperature and melting time of the additives in the above-mentioned examples and comparative examples were tested. The test method was traditional observation and recording.

[0073] The test results are shown in Table 2: The results show that the melting temperature of the silicon additive prepared in the examples of the present invention is significantly reduced, and the melting time is shortened to about 6 minutes, with outstanding advantages.

[0074] Table 2

[0075] Group Melting time of silicon additive Melting temperature of silicon additive (℃) Example 1 6′05″ 685 Example 2 6′ 684 Comparative Example 1 10′18″ 726 Comparative Example 2 9′26″ 698 Comparative Example 3 9′15″ 696 Comparative Example 4 9′33″ 692 Comparative Example 5 9′46″ 689 Comparative Example 6 7′38″ 724 Comparative Example 7 8′25″ 728

[0076] Experimental Example 3 Application Experiment

[0077] The silicon additive prepared in the above Example 1 is used in the smelting and processing of aluminum alloy, and the carbon dioxide emissions, energy consumption, purity of aluminum alloy, and yield are tested. Taking the direct addition of silicon particles as a comparison, the results show that: the carbon dioxide emissions of the present invention are reduced by 33%, the energy is saved by 55%, the purity of aluminum alloy is increased by 38%, and the yield reaches 100%.

[0078] The above are only the embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail herein. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A silicon additive with a low melting temperature, characterized in that: The raw materials, by mass parts, include 90 - 98 parts of silicon, 0.8 - 3.8 parts of surfactant, 1 - 2.6 parts of flux, and 2 - 4.7 parts of chemical flux; the particle size of silicon is 28 mm - 670 mesh, the particle size of surfactant is 35 - 560 mesh, the particle size of flux is 22 - 480 mesh, and the particle size of chemical flux is 42 - 630 mesh.

2. The silicon additive with a low melting temperature according to claim 1, wherein: The surfactant is sodium chloride.

3. The silicon additive with a low melting temperature according to claim 2, characterized in that: The flux is an aluminum - titanium - boron grain refiner.

4. The silicon additive with a low melting temperature according to claim 3, characterized in that: The chemical flux is ammonium fluoborate.

5. The preparation method of a silicon additive with a low melting temperature according to any one of claims 1 to 4, characterized in that, It includes the following steps: Step 1, raw material crushing and screening: Crush and screen the raw materials to make the particle size of silicon be 28 mm - 670 mesh, the particle size of surfactant be 35 - 560 mesh, the particle size of flux be 22 - 480 mesh, and the particle size of chemical flux be 42 - 630 mesh; Step 2, batching and mixing: Mix the screened silicon powder, surfactant, flux, and chemical flux to obtain a mixed material; Step 3, pressing: Press the mixed material into a shape to obtain a blank; Step 4, drying: Dry the blank.

6. The preparation method of a silicon additive with a low melting temperature according to claim 5, characterized in that: In Step 2, the mixing time is 40 - 60 min, and the mixing speed is 15 - 20 rpm.

7. The preparation method of a silicon additive with a low melting temperature according to claim 6, characterized in that: In Step 3, the pressing pressure is 20 - 30 MPa.

8. The preparation method of a silicon additive with a low melting temperature according to claim 7, characterized in that: In Step 3, the drying temperature is 95 - 100 °C.