Smelting process for improving purity of magnesium alloy

Abstract

The smelting process for improving the purity of the magnesium alloy has the advantages that the steps of the smelting process for improving the purity of the magnesium alloy are simple and exquisite, the control is easy, and each step is carefully fine. The protective gas is used in the whole magnesium alloy preparation process, a large number of oxides are prevented from being generated in the preparation process, and therefore the purity of the magnesium alloy obtained through the smelting process for improving the purity of the magnesium alloy is improved. In the whole magnesium alloy preparation process, multiple times of physical deslagging are adopted, so that the purity of the magnesium alloy is further improved. And on the other hand, in the magnesium alloy preparation process, no extra refining agent or other additives are added, and the high purity of the magnesium alloy obtained through the smelting technology for improving the purity of the magnesium alloy is guaranteed. In the magnesium alloy forging and pressing treatment step, the first-stage magnesium alloy block is subjected to inert forging and pressing treatment at different high temperatures, the density and structural strength of the magnesium alloy block are improved, and the stress in the magnesium alloy block is reduced.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloy smelting and manufacturing, and in particular to a smelting process for improving the purity of magnesium alloys. Background Technology

[0002] Magnesium alloys are alloys composed of magnesium as a base and other elements. Magnesium alloys are characterized by: low density, high strength, high elastic modulus, good heat dissipation, good shock absorption, greater impact load capacity than aluminum alloys, and good resistance to corrosion from organic matter and alkalis. The main alloying elements in magnesium alloys include aluminum, zinc, manganese, cerium, thorium, and small amounts of zirconium or cadmium. The most widely used are magnesium-aluminum alloys, followed by magnesium-manganese alloys and magnesium-zinc-zirconium alloys. They are mainly used in aerospace, transportation, chemical, and rocket industries. Magnesium alloys have a significant advantage in heat dissipation compared to aluminum alloys. For heat sinks of the same volume and shape, magnesium alloys transfer heat from the base to the top of the heat sink more quickly than aluminum alloys, resulting in a higher temperature at the top. In other words, the temperature difference between the base and top of an aluminum alloy heat sink is smaller than that of a magnesium alloy heat sink. This means that the temperature difference between the base and top of the air in a magnesium alloy heat sink is greater than that in an aluminum alloy heat sink, thus accelerating the diffusion and convection of air inside the heat sink and improving heat dissipation efficiency.

[0003] However, traditional magnesium alloy smelting processes, such as the technical solutions disclosed in the patent application number CN201711320248.6 entitled "Corrosion-resistant Magnesium Alloy and its Preparation Method", result in magnesium alloys with low purity, which cannot meet the requirements for high purity magnesium alloys. Summary of the Invention

[0004] Therefore, it is necessary to address the technical problem that traditional magnesium alloy smelting processes result in magnesium alloys with low purity, which cannot meet the requirements for high purity magnesium alloys, and to provide a smelting process that improves the purity of magnesium alloys.

[0005] A smelting process for improving the purity of magnesium alloys, the process comprising the following steps: Preheating steps for pure magnesium ingots: The pure magnesium ingots are preheated in a preheating furnace to 400 to 500 degrees Celsius under the protection of a protective gas. Pure magnesium ingot melting steps: Place the preheated pure magnesium ingot into a melting furnace and heat it to 680 to 700 degrees Celsius under the protection of a protective gas, so that the pure magnesium ingot melts into molten magnesium. Alloy preheating step: Preheat pure aluminum ingots and pure zinc ingots to 350 degrees Celsius to 450 degrees Celsius under the protection of a protective gas. Alloy mixing steps: First, put the preheated pure aluminum ingot into the magnesium liquid and heat it to 720 degrees Celsius to 750 degrees Celsius; after the pure aluminum ingot is completely melted, put the preheated pure zinc ingot into the magnesium-aluminum alloy liquid and heat it to 700 degrees Celsius to 730 degrees Celsius; after the pure zinc ingot is completely melted, mix and stir evenly to obtain the magnesium alloy melt. Magnesium alloy refining steps: Heat the molten magnesium alloy to 750 to 780 degrees Celsius and refining it for 5 to 10 minutes by blowing in argon gas; Magnesium alloy casting steps: Magnesium alloy is cast using a low-pressure casting process under the protection of a protective gas. After cooling and demolding, the first-grade magnesium alloy ingot is obtained. Magnesium alloy forging process steps: Under the protection of a protective gas, the first-stage magnesium alloy block is held at 450°C to 520°C for 2 to 4 hours, and then subjected to multi-directional forging; under the protection of a protective gas, the first-stage magnesium alloy block is then cooled to 370°C to 420°C and held for 1 to 3 hours, and then subjected to multi-directional forging; finally, under the protection of a protective gas, the first-stage magnesium alloy block is cooled to 300°C to 350°C and held for 1 to 2 hours, and then subjected to multi-directional forging to obtain the second-stage magnesium alloy block; Magnesium alloy block finishing steps: Remove burrs and risers from the surface of magnesium alloy ingots, and perform preliminary grinding on the surface of magnesium alloy ingots to obtain high-purity magnesium alloy castings.

[0006] In one embodiment, during the preheating step of the pure magnesium ingot, the heating rate is 10 degrees Celsius per minute to 20 degrees Celsius per minute.

[0007] In one embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, wherein the volume ratio of SF6 gas to nitrogen gas is 1:5 to 4:5.

[0008] In one embodiment, during the pure magnesium ingot melting step, the slag on top of the molten magnesium is cleaned off.

[0009] In one embodiment, during the alloy mixing step, slag on the magnesium-aluminum alloy melt and the magnesium alloy melt is removed respectively.

[0010] In one embodiment, during the alloy mixing step, pure aluminum ingots and pure zinc ingots are added to the magnesium melt according to the required content of AZ31 magnesium alloy.

[0011] In one embodiment, during the magnesium alloy refining step, slag on the molten magnesium alloy is removed after refining.

[0012] In one embodiment, during the magnesium alloy casting step, a release agent is applied to the mold cavity before casting.

[0013] In one embodiment, the release agent comprises the following components in parts by weight: 20 to 30 parts of high-temperature resistant filler, 4 to 8 parts of fluorinated graphite, 2 to 4 parts of sodium polyphosphate, 10 to 20 parts of rosin, 3 to 6 parts of tetraethyl orthosilicate, 3 to 6 parts of succinic acid, 10 to 20 parts of liquid paraffin, 4 to 8 parts of polyvinyl alcohol, and 100 to 200 parts of water.

[0014] In one embodiment, the high-temperature resistant filler comprises the following components in parts by weight: 8 to 18 parts Tween, 6 to 20 parts vermiculite powder, 10 to 16 parts sodium alginate, 10 to 15 parts alumina powder, 5 to 14 parts Span, 15 to 25 parts silicon nitride powder, 8 to 15 parts kaolin, and 7 to 15 parts titanium dioxide.

[0015] The aforementioned smelting process for improving magnesium alloy purity is concise, sophisticated, and easy to control, with each step requiring meticulous attention. Protective gas is used throughout the magnesium alloy preparation process to prevent the generation of large amounts of oxides, thereby increasing the purity of the magnesium alloy obtained through this smelting process. Multiple physical slag removal processes are employed throughout the magnesium alloy preparation process to further enhance its purity. Furthermore, no additional refining agents or other additives are added during the magnesium alloy preparation process, ensuring the high purity of the magnesium alloy obtained through this smelting process. The magnesium alloy forging process involves inert forging the first-stage magnesium alloy block at different high temperatures, increasing the density and structural strength of the magnesium alloy block while reducing internal stress. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a smelting process for improving the purity of magnesium alloys in one embodiment. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0019] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0021] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0022] Please see Figure 1 This invention provides a smelting process for improving the purity of magnesium alloys, the process comprising the following steps: Step 101: Preheating of pure magnesium ingots: The pure magnesium ingots are preheated in a preheating furnace to 400 to 500 degrees Celsius under the protection of a protective gas.

[0023] In this embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:5.

[0024] Specifically, the pure magnesium ingots are preheated in a preheating furnace to 400 to 500 degrees Celsius under the protection of a protective gas. The heating rate is 10 to 20 degrees Celsius per minute.

[0025] Step 102: Pure magnesium ingot melting step: Place the preheated pure magnesium ingot into the melting furnace and heat it to 680 to 700 degrees Celsius under the protection of protective gas, so that the pure magnesium ingot melts into magnesium liquid.

[0026] In this embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:5.

[0027] Specifically, the preheated pure magnesium ingots are placed in a melting furnace and heated to 680 to 700 degrees Celsius under a protective gas atmosphere, melting the ingots into molten magnesium. The heating rate is 10 to 20 degrees Celsius per minute. The scum on top of the molten magnesium is then removed to further improve its purity.

[0028] Step 103: Alloy preheating step: Preheat pure aluminum ingots and pure zinc ingots to 350 degrees Celsius to 450 degrees Celsius respectively under the protection of protective gas.

[0029] In this embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:5.

[0030] Specifically, pure aluminum ingots and pure zinc ingots are preheated to 350°C to 450°C under a protective gas atmosphere. The heating rate is 10°C to 20°C per minute.

[0031] Step 104: Alloy Mixing Step: First, place the preheated pure aluminum ingots into the molten magnesium and heat to 720°C to 750°C. After the pure aluminum ingots are completely melted, place the preheated pure zinc ingots into the molten magnesium-aluminum alloy and heat to 700°C to 730°C. After the pure zinc ingots are completely melted, mix and stir evenly to obtain the molten magnesium alloy.

[0032] In this embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:5.

[0033] Specifically, preheated pure aluminum ingots are first placed into molten magnesium and heated to 720-750 degrees Celsius. After the pure aluminum ingots are completely melted, preheated pure zinc ingots are then placed into the molten magnesium-aluminum alloy and heated to 700-730 degrees Celsius. After the pure zinc ingots are completely melted, the mixture is stirred evenly to obtain a molten magnesium alloy. During this process, scum on the surface of both the molten magnesium-aluminum alloy and the molten magnesium alloy is removed to further improve the purity of the magnesium alloy. The heating rate is 10-20 degrees Celsius per minute. In this embodiment, pure aluminum and pure zinc ingots are added to the molten magnesium according to the required content of AZ31 magnesium alloy.

[0034] Step 105: Magnesium alloy refining step: Heat the magnesium alloy melt to 750 to 780 degrees Celsius and blow in argon gas to refine for 5 to 10 minutes.

[0035] Specifically, the molten magnesium alloy is heated to 750 to 780 degrees Celsius and refined for 5 to 10 minutes by blowing in argon gas. The heating rate is 10 to 20 degrees Celsius per minute. After refining, the slag on the molten magnesium alloy is removed.

[0036] Step 106: Magnesium alloy casting process: Magnesium alloy is cast using a low-pressure casting process under the protection of a protective gas. After cooling and demolding, the first-grade magnesium alloy ingot is obtained.

[0037] In this embodiment, the protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:5.

[0038] Specifically, a low-pressure casting process is used to cast magnesium alloy under the protection of a protective gas. After cooling and demolding, the first-stage magnesium alloy ingot is obtained.

[0039] Step 107: Magnesium Alloy Forging Process: Under a protective gas atmosphere, the first-stage magnesium alloy block is held at 450°C to 520°C for 2 to 4 hours, followed by multi-directional forging. Then, under the same protective gas atmosphere, the first-stage magnesium alloy block is cooled to 370°C to 420°C and held for 1 to 3 hours, followed by multi-directional forging. Finally, under a protective gas atmosphere, the first-stage magnesium alloy block is cooled to 300°C to 350°C and held for 1 to 2 hours, followed by multi-directional forging to obtain the second-stage magnesium alloy block.

[0040] Step 108: Magnesium alloy block finishing steps: Remove burrs and risers from the surface of the magnesium alloy ingot, and perform preliminary grinding on the surface of the magnesium alloy ingot to obtain a high-purity magnesium alloy casting.

[0041] To facilitate the demolding of the first-stage magnesium alloy ingot, in one embodiment, a release agent is applied to the mold cavity before casting in the magnesium alloy casting step. In one embodiment, the release agent comprises the following components in parts by weight: 20 to 30 parts of high-temperature resistant filler, 4 to 8 parts of fluorinated graphite, 2 to 4 parts of sodium polyphosphate, 10 to 20 parts of rosin, 3 to 6 parts of tetraethyl orthosilicate, 3 to 6 parts of succinic acid, 10 to 20 parts of liquid paraffin, 4 to 8 parts of polyvinyl alcohol, and 100 to 200 parts of water. The release agent composed of the above components facilitates the smooth demolding of the first-stage magnesium alloy ingot from the mold during the magnesium alloy casting step.

[0042] To enhance the high-temperature resistance of the release agent, in one embodiment, the high-temperature resistant filler comprises the following components in parts by weight: 8 to 18 parts Tween, 6 to 20 parts vermiculite powder, 10 to 16 parts sodium alginate, 10 to 15 parts alumina powder, 5 to 14 parts Span, 15 to 25 parts silicon nitride powder, 8 to 15 parts kaolin, and 7 to 15 parts titanium dioxide. The high-temperature resistant filler composed of the above components can effectively increase the high-temperature resistance of the release agent.

[0043] To enhance the oxidation resistance of high-purity magnesium alloy ingots, in one embodiment, a surface treatment step is included after the magnesium alloy ingot trimming step: the high-purity magnesium alloy ingot is immersed in a surface protective liquid, then removed and air-dried. The surface protective liquid comprises the following components in parts by weight: 4 to 10 parts sodium silicate, 2 to 10 parts nano-silica, 2 to 4 parts polyacrylic acid, 2 to 4 parts ethylene glycol, 1 to 2 parts polyethylene polyamine, 20 to 40 parts epoxy resin, 30 to 40 parts imidazolidinone, and 80 to 150 parts water. The surface protective liquid composed of the above components can form a protective film on the surface of the high-purity magnesium alloy ingot, increasing its oxidation resistance. The aforementioned smelting process for improving magnesium alloy purity is concise, sophisticated, and easy to control, with each step requiring meticulous attention. Protective gas is used throughout the magnesium alloy preparation process to prevent the generation of large amounts of oxides, thereby increasing the purity of the magnesium alloy obtained through this smelting process. Multiple physical slag removal processes are employed throughout the magnesium alloy preparation process to further enhance its purity. Furthermore, no additional refining agents or other additives are added during the magnesium alloy preparation process, ensuring the high purity of the magnesium alloy obtained through this smelting process. The magnesium alloy forging process involves inert forging the first-stage magnesium alloy block at different high temperatures, increasing the density and structural strength of the magnesium alloy block while reducing internal stress. The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A smelting process for improving the purity of magnesium alloys, characterized in that, The process includes the following steps: Preheating steps for pure magnesium ingots: The pure magnesium ingots are preheated in a preheating furnace to 400 to 500 degrees Celsius under the protection of a protective gas. Pure magnesium ingot melting steps: Place the preheated pure magnesium ingot into a melting furnace and heat it to 680 to 700 degrees Celsius under the protection of a protective gas, so that the pure magnesium ingot melts into molten magnesium. Alloy preheating step: Preheat pure aluminum ingots and pure zinc ingots to 350 degrees Celsius to 450 degrees Celsius under the protection of a protective gas. Alloy mixing steps: First, put the preheated pure aluminum ingot into the magnesium liquid and heat it to 720 degrees Celsius to 750 degrees Celsius; after the pure aluminum ingot is completely melted, put the preheated pure zinc ingot into the magnesium-aluminum alloy liquid and heat it to 700 degrees Celsius to 730 degrees Celsius; after the pure zinc ingot is completely melted, mix and stir evenly to obtain the magnesium alloy melt. Magnesium alloy refining steps: Heat the molten magnesium alloy to 750 to 780 degrees Celsius and refining it for 5 to 10 minutes by blowing in argon gas; Magnesium alloy casting steps: Magnesium alloy is cast using a low-pressure casting process under the protection of a protective gas. After cooling and demolding, the first-grade magnesium alloy ingot is obtained. Magnesium alloy forging process steps: Under the protection of a protective gas, the first-stage magnesium alloy block is held at 450°C to 520°C for 2 to 4 hours, and then subjected to multi-directional forging; under the protection of a protective gas, the first-stage magnesium alloy block is then cooled to 370°C to 420°C and held for 1 to 3 hours, and then subjected to multi-directional forging; finally, under the protection of a protective gas, the first-stage magnesium alloy block is cooled to 300°C to 350°C and held for 1 to 2 hours, and then subjected to multi-directional forging to obtain the second-stage magnesium alloy block; Magnesium alloy block finishing steps: Remove burrs and risers from the surface of magnesium alloy ingots, and perform preliminary grinding on the surface of magnesium alloy ingots to obtain high-purity magnesium alloy castings.

2. The process according to claim 1, characterized in that, In the preheating step of the pure magnesium ingot, the heating rate is 10 degrees Celsius per minute to 20 degrees Celsius per minute.

3. The process according to claim 1, characterized in that, The protective gas is a mixture of SF6 gas and nitrogen gas, with a volume ratio of SF6 gas to nitrogen gas of 1:5 to 4:

5.

4. The process according to claim 1, characterized in that, In the pure magnesium ingot melting step, the slag on the surface of the magnesium liquid is cleaned off.

5. The process according to claim 1, characterized in that, In the alloy mixing step, the slag on the magnesium-aluminum alloy liquid and the magnesium alloy melt is removed.

6. The process according to claim 1, characterized in that, In the alloy mixing step, pure aluminum ingots and pure zinc ingots are added to the magnesium liquid according to the AZ31 magnesium alloy content requirements.

7. The process according to claim 1, characterized in that, In the magnesium alloy refining step, after refining is completed, the slag on the magnesium alloy melt is removed.

8. The process according to claim 1, characterized in that, In the magnesium alloy casting step, a release agent is applied to the mold cavity before casting.

9. The process according to claim 8, characterized in that, The release agent comprises the following components in parts by weight: 20 to 30 parts of high-temperature resistant filler, 4 to 8 parts of fluorinated graphite, 2 to 4 parts of sodium polyphosphate, 10 to 20 parts of rosin, 3 to 6 parts of tetraethyl orthosilicate, 3 to 6 parts of succinic acid, 10 to 20 parts of liquid paraffin, 4 to 8 parts of polyvinyl alcohol, and 100 to 200 parts of water.

10. The process according to claim 1, characterized in that, The high-temperature resistant filler comprises the following components in parts by weight: 8 to 18 parts Tween, 6 to 20 parts vermiculite powder, 10 to 16 parts sodium alginate, 10 to 15 parts alumina powder, 5 to 14 parts Span, 15 to 25 parts silicon nitride powder, 8 to 15 parts kaolin, and 7 to 15 parts titanium dioxide.

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