Electromagnetic stirring casting method for ultra-pure aluminum alloy

Abstract

The invention provides an electromagnetic stirring casting method of an ultra-pure aluminum alloy, which comprises the following steps: (1) carrying out first smelting on an ultra-pure aluminum raw material to obtain an ultra-pure aluminum melt; (2) adding an alloy raw material into the ultra-high-purity aluminum melt, and carrying out second smelting to obtain an ultra-high-purity aluminum alloy melt; (3) the ultra-high-purity aluminum alloy melt is sequentially subjected to first degassing treatment and slagging-off, and the refined ultra-high-purity aluminum alloy melt is obtained; and (4) the refined ultra-pure aluminum alloy melt is sequentially subjected to second degassing treatment and semi-continuous casting, and the ultra-pure aluminum alloy cast ingot is obtained. According to the electromagnetic stirring casting method, an existing semi-continuous casting device is adopted for casting, an aluminum alloy melt is made to rotate spontaneously through a horizontal rotating type electromagnetic field, non-contact stirring of molten aluminum is achieved, and the purposes of grain refinement and casting crack restraining are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metal material casting, and in particular to an electromagnetic stirring casting method for an ultra-high purity aluminum alloy. Background Art

[0002] Aluminum has the characteristics of easy deposition, good etching and processing performance, high electrical conductivity, good thermal conductivity, good adhesion and bonding performance with the substrate, and low cost. It is the main interconnect material above the 90nm technology node in integrated circuit manufacturing and is also widely used in advanced packaging. As the main material for metal interconnects in integrated circuit manufacturing, the composition, microstructure, and crystal orientation of ultra-high purity aluminum alloy sputtering targets are crucial to the sputtering efficiency of the target and the quality of the deposited film during magnetron sputtering.

[0003] The purity of high-purity aluminum used in high-purity aluminum sputtering targets needs to meet 5N or above (99.999wt%), and the impurity elements in the aluminum ingot are controlled below 10ppm. The ingot grain strength is low, resulting in thermal cracks in the mushy zone during the casting process, which cannot meet production requirements. Due to the composition requirements of high-purity aluminum ingots, it is not possible to strengthen the grains by adding alloy elements or use grain refiners to refine the grains to improve strength.

[0004] CN112605352A discloses a casting method for aluminum alloy cast rods. By optimizing the chemical composition elements of the aluminum alloy cast rods and the structure of the crystallizer, when casting the aluminum alloy cast rods, a controller can be used to achieve more accurate control of the temperature regulating device, stirring speed and stirring time. While ensuring the formability of the aluminum alloy melt, the uniformity of the internal temperature of the aluminum alloy melt can also be ensured, and the breakage of the aluminum alloy dendrite arms into dendrite fragments is effectively reduced, the nucleation position is increased, and more non-uniform nucleation occurs, which significantly produces the effect of refining the grains, thereby reducing the tendency of the cast rods to crack and improving the casting smelting quality and yield rate.

[0005] CN109913711A discloses a casting aluminum alloy forming device and forming method, including: a crucible, a crucible cover and a smelting furnace, a ladle, a stirring device and a mechanical arm, a casting mold, the mechanical arm is located at a suitable position between the smelting furnace and the casting mold, and the ladle is moved from the smelting furnace to the pouring port of the casting mold by the mechanical arm; the crucible cover is provided with an inner cover and an air inlet, the air inlet is connected to the inert gas supply system, and the inner cover can be removed to allow the ladle to enter and exit the smelting furnace; a through hole is provided on the bottom wall of the ladle, and a plug rod that can seal and match the through hole is provided on the end shaft of the mechanical arm. The aluminum alloy forming method includes the steps of melting in a dry argon environment, rotary spray degassing treatment of the melt, pouring, solid solution aging treatment, etc.

[0006] However, the aluminum alloy forming device involved in the above method has a complex structure and the aluminum alloy casting cost is high.

[0007] CN208853674U discloses an aluminum alloy stirring device. Through mechanical stirring, the blade parts rotate in the aluminum alloy melt, which can continuously and quickly evenly distribute the high-temperature aluminum liquid in the core of the aluminum alloy melt to the surrounding area, forming a uniform temperature field and composition field, and solidifying and forming under near-equilibrium conditions. However, the mechanical stirring of the device is prone to air and slag entrainment, resulting in loose pores and many defects in the obtained aluminum alloy product.

[0008] Therefore, it is of great significance to develop an electromagnetic stirring casting method for ultra-high purity aluminum alloy that uses existing aluminum alloy forming equipment and ensures that the obtained aluminum alloy product has good quality, fine grains, and few casting cracks. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. After melting ultra-high purity aluminum and alloy raw materials, a horizontal rotating electromagnetic field is used in an existing semi-continuous casting device to make the aluminum alloy melt rotate spontaneously, thereby realizing contactless stirring of the aluminum liquid, and obtaining an ultra-high purity aluminum alloy ingot with refined grains and fewer casting cracks.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] The present invention provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy, the electromagnetic stirring casting method comprising the following steps:

[0012] (1) performing a first smelting of an ultra-high purity aluminum raw material to obtain an ultra-high purity aluminum melt; wherein the purity of the ultra-high purity aluminum raw material is 5N or above;

[0013] (2) adding alloy raw materials to the ultra-high purity aluminum melt to perform a second smelting to obtain an ultra-high purity aluminum alloy melt;

[0014] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and a slag removal treatment in sequence to obtain a refined ultra-high purity aluminum alloy melt;

[0015] (4) The refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting to obtain an ultra-high purity aluminum alloy ingot.

[0016] The electromagnetic stirring casting method of ultra-high purity aluminum alloy described in the present invention is simple to operate. It is to obtain an ultra-high purity aluminum alloy melt by smelting an ultra-high purity aluminum raw material and an alloy raw material; then, a first degassing treatment, slag removal, a second degassing treatment and semi-continuous casting are performed, with high production efficiency and less air entrainment, and an ultra-high purity aluminum alloy ingot with high purity, small grains, few hole defects, good surface quality and few casting cracks is obtained. During the semi-continuous casting process, the ultra-high purity aluminum alloy melt will be affected by electromagnetic force in the horizontal rotating electromagnetic field in the semi-continuous casting device. Its simple force field analysis model is shown inFigure 1 . It can be seen that the ultra-high purity aluminum alloy melt will perform horizontal rotational motion under the drive of the radial component Fc of the electromagnetic force F, and the combined force of the radial component Fr of the electromagnetic force and the reaction force F1 of the graphite ring wall on the ultra-high purity aluminum alloy melt provides the centripetal force required for rotation. The radial component Fc of the electromagnetic force F drives the liquid phase and the solid phase at the solidification front to perform relative motion, so that the solidified and unsolidified areas in the mushy zone are separated, the ultra-high purity aluminum alloy melt is replenished more timely, and the casting cracks of the ultra-high purity aluminum alloy ingot are reduced. The moving dendrites in the rotating ultra-high purity aluminum alloy melt shear and collide with each other and break into fine crystals, so that the solidification structure morphology is uniform, fine and round.

[0017] The purity of the ultra-high purity aluminum raw material described in the present invention is above 5N, for example, it can be 5N, 5.2N, 5.5N, 6N, 6.5N or 7N, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] According to common knowledge in the art, an ultra-high purity metal raw material with a purity of 5N will produce an ingot of 4N5, an ultra-high purity metal raw material with a purity of 5N5 will produce an ingot of 5N, and so on.

[0019] Preferably, the first smelting in step (1) is carried out in a graphite crucible.

[0020] Preferably, the graphite crucible is at 80°C to 245°C before use, for example, 80°C, 90°C, 100°C, 150°C, 200°C or 245°C, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable;

[0021] Preheating time is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 1.9 hours or 2 hours, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0022] Preferably, the temperature of the first smelting in step (1) is 700-750°C, for example, 700°C, 710°C, 720°C, 730°C, 740°C or 750°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the alloy raw material in step (2) includes silicon raw material or copper raw material.

[0024] Preferably, the temperature of the second smelting in step (2) is 700-750°C, for example, it can be 700°C, 710°C, 720°C, 730°C, 740°C or 750°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, during the second smelting process, a graphite stirring device is used for stirring for 10 to 50 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes or 50 minutes, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the flow rate of argon gas introduced in the first degassing treatment in step (3) is 2 to 8 m 3 / h, for example, it can be 2m 3 / h、3m 3 / h、4m 3 / h、5m 3 / h、5.5m 3 / h、6m 3 / h or 8m 3 / h, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the rotation speed adopted in the first degassing treatment is 200-550r / min, for example, it can be 200r / min, 250r / min, 300r / min, 350r / min, 400r / min, 500r / min or 550r / min, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable; preferably, it is 420-450r / min.

[0028] Preferably, the time of the first degassing treatment is 1 to 3 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 2.8 hours or 3 hours, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, the second degassing treatment in step (4) adopts an online degassing device.

[0030] Preferably, the semi-continuous casting in step (4) is carried out in a semi-continuous casting device.

[0031] The semi-continuous casting device of the present invention has pollution-free and closed conditions, light oxidation, easy to achieve stirring parameters, high production efficiency, less air entrainment, and the ultra-high purity aluminum alloy ingot finally obtained has fewer hole defects and good surface quality.

[0032] Preferably, the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator in sequence from top to bottom.

[0033] Preferably, a cooling water pipeline is provided at the lower portion of the crystallizer.

[0034] Preferably, the semi-continuous casting device further comprises a starter head arranged at the bottom. An ingot is formed on the top of the starter head, and the top of the ingot is a mushy area.

[0035] Preferably, the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device and is semi-continuously cast in a crystallizer.

[0036] Preferably, cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process.

[0037] Preferably, the liquid level height of the crystallizer is 10-35 mm, for example, it can be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm or 35 mm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the flow rate of the cooling water is 200-700 L / min, for example, it can be 200 L / min, 250 L / min, 300 L / min, 400 L / min, 600 L / min or 700 L / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the temperature of the cooling water is 10-30°C, for example, 10°C, 15°C, 20°C, 25°C, 27°C or 30°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the electromagnetic generator generates a horizontally rotating electromagnetic field.

[0041] Preferably, the current of the electromagnetic generator is 10 to 60A, for example, 10A, 15A, 20A, 30A, 50A or 60A, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable;

[0042] The frequency is 22 to 52 Hz, for example, 22 Hz, 25 Hz, 30 Hz, 40 Hz, 50 Hz or 52 Hz, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0043] The present invention preferably uses an electromagnetic generator with a current of 10 to 60 A. When the current is small, the electromagnetic tangential force generated in the melt is weak, the stirring is insufficient, and the grain refinement is small. When the current is large, the electromagnetic tangential force is too strong, the stirring is violent, turbulence is likely to occur, and the grains are coarsened.

[0044] The preferred frequency of the electromagnetic generator in the present invention is 22 to 52 Hz. When the frequency is low, the electromagnetic tangential force generated in the melt will be weak, stirring will be insufficient, and the degree of grain refinement will be low. When the frequency is high, the electromagnetic tangential force will be too strong, stirring will be violent, turbulence will easily occur, and the grains will be coarsened.

[0045] Preferably, the temperature of the semi-continuous casting in step (4) is 690-720°C, for example, it can be 690°C, 695°C, 700°C, 710°C, 715°C or 720°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] The semi-continuous casting temperature of the present invention is preferably 690-720°C to ensure that the final ultra-high purity aluminum alloy ingot has fine grains and few cracks. When the semi-continuous casting temperature is lower or higher, the final ultra-high purity aluminum alloy ingot will have coarse grains.

[0047] Preferably, the casting speed of the semi-continuous casting is 50-100 mm / min, for example, it can be 50 mm / min, 60 mm / min, 70 mm / min, 80 mm / min, 90 mm / min or 100 mm / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] The present invention preferably uses a casting speed of 50 to 100 mm / min for semi-continuous casting. When the casting speed of semi-continuous casting is slow, the aluminum liquid stays in the runner and the distribution plate for too long, which will lead to: 1. The ultra-high purity aluminum alloy melt solidifies, resulting in safety accidents; 2. The cooling intensity per unit length of the ingot is too high, resulting in cracks in the ingot. When the casting speed of semi-continuous casting is fast, it will lead to: 1. The ingot cannot be cooled and solidified quickly, aluminum is easily leaked, and safety accidents occur; 2. The cooling intensity per unit length of the ingot is too low, resulting in coarse grains.

[0049] As a preferred technical solution of the present invention, the electromagnetic stirring casting method comprises the following steps:

[0050] (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 700-750° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 5N or more; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 80° C. to 245° C. for 1 to 2 hours before use;

[0051] (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 700 to 750° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and stirring the ultra-high purity aluminum alloy melt with a graphite stirring device for 10 to 50 minutes during the second smelting process;

[0052] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 2 to 8 m 3 / h; the speed of the first degassing treatment is 200-550r / min; the time of the first degassing treatment is 1-3h;

[0053] (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 690 to 720° C. and a casting speed of 50 to 100 mm / min to obtain an ultra-high purity aluminum alloy ingot;

[0054] The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 10 to 35 mm; the flow rate of the cooling water is 200 to 700 L / min; the temperature of the cooling water is 10 to 30°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 10 to 60 A, and the frequency is 22 to 52 Hz.

[0055] Compared with the prior art, the present invention has at least the following beneficial effects:

[0056] The electromagnetic stirring casting method for ultra-high purity aluminum alloy provided by the present invention is simple to operate, adopts the existing semi-continuous casting device for casting, utilizes the horizontal rotating electromagnetic field to make the aluminum alloy melt rotate spontaneously, realizes contactless stirring of the aluminum liquid, has high production efficiency, and the obtained ultra-high purity aluminum alloy ingot has few hole defects, fine grains, and few casting cracks, and is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a simple force field analysis model diagram of ultra-high purity aluminum alloy melt subjected to electromagnetic force in a horizontal rotating electromagnetic field.

[0058] Figure 2 It is a schematic structural diagram of the semi-continuous casting device in the present invention.

[0059] In the figure: 1-crystallizer; 2-cooling water pipeline; 3-electromagnetic generator; 4-ingot; 5-paste zone; 6-graphite ring; 7-distribution plate; 8-ingot head. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0061] The structural schematic diagram of the semi-continuous casting device of the present invention is as follows Figure 2 shown.

[0062] The semi-continuous casting device is provided with a distribution plate 7, a crystallizer 1, a graphite ring 6 and an electromagnetic generator 3 in order from top to bottom. A cooling water pipeline 2 is provided at the lower part of the crystallizer 1.

[0063] The semi-continuous casting device further comprises a starter head 8 arranged at the bottom. An ingot 4 is formed on the top of the starter head 8, and the top of the ingot 4 is a mushy area 5.

[0064] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0065] Example 1

[0066] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy, and the electromagnetic stirring casting method comprises the following steps:

[0067] (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 730° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 5.2N; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 200° C. for 1.2 h before use;

[0068] (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 730° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and stirring the ultra-high purity aluminum alloy melt with a graphite stirring device for 30 minutes during the second smelting process;

[0069] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 5m 3 / h; the speed of the first degassing treatment is 300r / min; the time of the first degassing treatment is 1.3h;

[0070] (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 700° C. and a casting speed of 80 mm / min to obtain an ultra-high purity aluminum alloy ingot with a purity of 4.7N;

[0071] The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 20 mm; the flow rate of the cooling water is 500 L / min; the temperature of the cooling water is 20°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 30 A and the frequency is 40 Hz.

[0072] Example 2

[0073] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy, and the electromagnetic stirring casting method comprises the following steps:

[0074] (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 710° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 5.5N; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 100° C. for 1.7 hours before use;

[0075] (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 700° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and stirring the ultra-high purity aluminum alloy melt with a graphite stirring device for 50 minutes during the second smelting process;

[0076] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 8m 3 / h; the speed of the first degassing treatment is 550r / min; the time of the first degassing treatment is 1h;

[0077] (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 690° C. and a casting speed of 100 mm / min to obtain an ultra-high purity aluminum alloy ingot with a purity of 5N;

[0078] The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 35mm; the flow rate of the cooling water is 700L / min; the temperature of the cooling water is 10°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 60A and the frequency is 52Hz.

[0079] Example 3

[0080] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy, and the electromagnetic stirring casting method comprises the following steps:

[0081] (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 750° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 6N; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 245° C. for 1 hour before use;

[0082] (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 750° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and stirring the ultra-high purity aluminum alloy melt with a graphite stirring device for 10 minutes during the second smelting process;

[0083] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 2m 3 / h; the speed of the first degassing treatment is 200r / min; the time of the first degassing treatment is 3h;

[0084] (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 690° C. and a casting speed of 50 mm / min to obtain an ultra-high purity aluminum alloy ingot with a purity of 5.5N;

[0085] The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 10 mm; the flow rate of the cooling water is 200 L / min; the temperature of the cooling water is 10°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 15 A and the frequency is 22 Hz.

[0086] Example 4

[0087] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy, and the electromagnetic stirring casting method comprises the following steps:

[0088] (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 700° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 6.3N; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 80° C. for 2 hours before use;

[0089] (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 715° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and during the second smelting process, a graphite stirring device is used for stirring for 18 minutes;

[0090] (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 4.8 m 3 / h; the speed of the first degassing treatment is 270r / min; the time of the first degassing treatment is 1.7h;

[0091] (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 695° C. and a casting speed of 88 mm / min to obtain an ultra-high purity aluminum alloy ingot with a purity of 5.8N;

[0092] The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 32 mm; the flow rate of the cooling water is 360 L / min; the temperature of the cooling water is 25°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 55 A and the frequency is 45 Hz.

[0093] Example 5

[0094] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the current of the electromagnetic generator is 5A.

[0095] Example 6

[0096] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the current of the electromagnetic generator is 65A.

[0097] Example 7

[0098] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the frequency of the electromagnetic generator is 20 Hz.

[0099] Example 8

[0100] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the frequency of the electromagnetic generator is 55 Hz.

[0101] Example 9

[0102] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the temperature of the semi-continuous casting is 680°C.

[0103] Example 10

[0104] This embodiment provides an electromagnetic stirring casting method for ultra-high purity aluminum alloy. The electromagnetic stirring casting method is the same as that of Embodiment 1 except that the temperature of the semi-continuous casting is 730°C.

[0105] Comparative Example 1

[0106] This comparative example provides a mechanical stirring casting method for an ultra-high purity aluminum alloy. The mechanical stirring casting method is the same as Example 1 except that step (4) is replaced by the refined ultra-high purity aluminum alloy melt being subjected to a second degassing treatment and mechanical stirring casting at a temperature of 700°C in sequence, and the mechanical stirring casting is carried out in an aluminum alloy stirring device provided in the specific embodiment of CN208853674U.

[0107] The grain sizes of the ultra-high purity aluminum alloy ingots obtained in the above embodiments and comparative examples were observed using a metallographic microscope;

[0108] The cracks of the ultra-high purity aluminum alloy ingots obtained in the above embodiments and comparative examples were observed by ultrasonic flaw detection method. The results are shown in Table 1.

[0109] Table 1

[0110] Grain size (μm) Is there any crack? Example 1 80 none Example 2 120 none Example 3 69 none Example 4 100 none Example 5 90 have Example 6 131 none Example 7 86 have Example 8 108 none Example 9 97 none Example 10 91 none Comparative Example 1 96 have

[0111] From Table 1 we can see that:

[0112] (1) It can be seen from Examples 1 to 4 that the electromagnetic stirring casting method for ultra-high purity aluminum alloy provided by the present invention is simple to operate and can obtain an ultra-high purity aluminum alloy ingot with fine grains and no cracks;

[0113] (2) It can be seen from the combination of Example 1 and Examples 5 to 8 that the current of the electromagnetic generator in Example 5 is relatively small, and the frequency of the electromagnetic generator in Example 7 is relatively small, both of which will lead to weak electromagnetic tangential force generated in the melt, insufficient stirring, low degree of grain refinement, and cracks in the ultra-high purity aluminum alloy ingot; the current of the electromagnetic generator in Example 6 is relatively large, and the frequency of the electromagnetic generator in Example 8 is relatively large, both of which will lead to excessive electromagnetic tangential force, violent stirring, easy occurrence of turbulence, coarsening of grains, which are 131 μm and 108 μm respectively, and no cracks in the ultra-high purity aluminum alloy ingot;

[0114] (3) It can be seen from the combination of Example 1 and Examples 9-10 that the semi-continuous casting temperature in Example 9 is relatively low, and the semi-continuous casting temperature in Example 10 is relatively high, both of which will result in the final ultra-high purity aluminum alloy ingot having coarser grains than that in Example 1;

[0115] (4) It can be seen from the combination of Example 1 and Comparative Example 1 that the mechanical stirring casting is adopted in Comparative Example 1, and the grains of the ultra-high purity aluminum alloy ingot finally obtained are coarser than those in Example 1, and cracks are generated.

[0116] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An electromagnetic stirring casting method for ultra-high purity aluminum alloy, characterized in that: The electromagnetic stirring casting method comprises the following steps: (1) performing a first smelting of an ultra-high purity aluminum raw material to obtain an ultra-high purity aluminum melt; wherein the purity of the ultra-high purity aluminum raw material is 5N or above; (2) adding alloy raw materials to the ultra-high purity aluminum melt to perform a second smelting to obtain an ultra-high purity aluminum alloy melt; (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and a slag removal treatment in sequence to obtain a refined ultra-high purity aluminum alloy melt; (4) The refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting to obtain an ultra-high purity aluminum alloy ingot.

2. The electromagnetic stirring casting method according to claim 1, characterized in that: Step (1) The first smelting is carried out in a graphite crucible; Preferably, the graphite crucible is preheated at 80° C. to 245° C. for 1 to 2 hours before use.

3. The electromagnetic stirring casting method according to claim 1 or 2, characterized in that: Step (1) The temperature of the first smelting is 700-750°C.

4. The electromagnetic stirring casting method according to any one of claims 1 to 3, characterized in that: The alloy raw material in step (2) includes silicon raw material or copper raw material.

5. The electromagnetic stirring casting method according to any one of claims 1 to 4, characterized in that: Step (2) The temperature of the second smelting is 700-750°C. Preferably, during the second smelting process, a graphite stirring device is used for stirring for 10 to 50 minutes.

6. The electromagnetic stirring casting method according to any one of claims 1 to 5, characterized in that: Step (3) The flow rate of argon gas introduced in the first degassing treatment is 2 to 8 m 3 / h; Preferably, the first degassing treatment adopts a rotation speed of 200 to 550 r / min, preferably 420 to 450 r / min; Preferably, the first degassing treatment is performed for 1 to 3 hours.

7. The electromagnetic stirring casting method according to any one of claims 1 to 6, characterized in that: Step (4) The second degassing treatment uses an online degassing device.

8. The electromagnetic stirring casting method according to any one of claims 1 to 7, characterized in that: The semi-continuous casting in step (4) is carried out in a semi-continuous casting device; Preferably, the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator in sequence from top to bottom; Preferably, the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device and is semi-continuously cast in a crystallizer; Preferably, cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; Preferably, the liquid level of the crystallizer is 10 to 35 mm; Preferably, the flow rate of the cooling water is 200-700 L / min; Preferably, the temperature of the cooling water is 10-30°C; Preferably, the electromagnetic generator generates a horizontally rotating electromagnetic field; Preferably, the current of the electromagnetic generator is 10-60A and the frequency is 22-52Hz.

9. The electromagnetic stirring casting method according to any one of claims 1 to 8, characterized in that: The temperature of the semi-continuous casting in step (4) is 690-720° C. Preferably, the casting speed of the semi-continuous casting is 50-100 mm / min.

10. The electromagnetic stirring casting method according to any one of claims 1 to 9, characterized in that: The electromagnetic stirring casting method comprises the following steps: (1) The ultra-high purity aluminum raw material is first smelted at a temperature of 700-750° C. to obtain an ultra-high purity aluminum melt; the purity of the ultra-high purity aluminum raw material is 5N or more; the first smelting is performed in a graphite crucible; the graphite crucible is preheated at 80° C. to 245° C. for 1 to 2 hours before use; (2) adding alloy raw materials to the ultra-high purity aluminum melt, and performing a second smelting at a temperature of 700 to 750° C. to obtain an ultra-high purity aluminum alloy melt; the alloy raw materials include silicon raw materials or copper raw materials; and stirring the ultra-high purity aluminum alloy melt with a graphite stirring device for 10 to 50 minutes during the second smelting process; (3) The ultra-high purity aluminum alloy melt is subjected to a first degassing treatment and slag removal in sequence to obtain a refined ultra-high purity aluminum alloy melt; the flow rate of argon gas introduced in the first degassing treatment is 2 to 8 m 3 / h; the speed of the first degassing treatment is 200-550r / min; the time of the first degassing treatment is 1-3h; (4) the refined ultra-high purity aluminum alloy melt is sequentially subjected to a second degassing treatment and semi-continuous casting at a temperature of 690 to 720° C. and a casting speed of 50 to 100 mm / min to obtain an ultra-high purity aluminum alloy ingot; The second degassing treatment adopts an online degassing device; the semi-continuous casting is carried out in a semi-continuous casting device; the semi-continuous casting device is provided with a distribution plate, a crystallizer, a graphite ring and an electromagnetic generator from top to bottom; the ultra-high purity aluminum alloy melt after the second degassing treatment reaches the distribution plate through a filtering device, and is semi-continuously cast in the crystallizer; cooling water is introduced into the semi-continuous casting device during the semi-continuous casting process; the liquid level height of the crystallizer is 10 to 35 mm; the flow rate of the cooling water is 200 to 700 L / min; the temperature of the cooling water is 10 to 30°C; the electromagnetic generator generates a horizontal rotating electromagnetic field; the current of the electromagnetic generator is 10 to 60 A, and the frequency is 22 to 52 Hz.

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