Rotary lifting device for improving grain boundary form of high-purity aluminum through directional solidification

Abstract

The utility model relates to the technical field of metal aluminum purification, in particular to a rotary lifting device for improving the grain boundary form of high-purity aluminum through directional solidification, which is characterized in that a furnace body is arranged above a cabinet body, a heating device is arranged in an inner cavity, a cooling device is arranged below the heating device, and a base at the lower end of a corundum crucible of the heating device is fixedly connected with the upper end of a directional solidification rod; the directional solidification rod penetrates through the gallium-indium alloy cooling pool and then is connected with the lifting device and the rotating device, the lifting device is fixed to the left side of the mounting frame, and the rotating device is fixed to the bottommost end of the directional solidification rod. The utility model designs the directional solidification equipment which is supported by double motors and can rotate and lift in the crystal pulling process, and the ceramic gasket with better heat insulation performance is used for keeping the temperature difference between the two intervals as high as possible, so that the liquid-phase temperature gradient at the front edge of an interface can be effectively increased to be relatively stable; and the thermal field distribution is optimized to control the temperature gradient in the solidification process, so that the grain boundary form and migration behavior are remarkably improved, and finally the purification efficiency and purity of the high-purity aluminum are greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of metal aluminum purification, specifically to a rotating lifting device for directional solidification to improve high-purity aluminum grain boundary morphology. BACKGROUND

[0002] High-purity aluminum (purity ≥ 99.99%, 4N level and above) is a high-tech, high-value material, which is mainly used in some high-tech fields and scientific research, such as integrated circuit wires and target materials in the electronic industry, electrolytic capacitors, lithium battery current collectors in energy and optics, laser equipment mirrors, lightweight structural components in aerospace, etc. On a single crystal silicon substrate, epitaxial growth of single crystal aluminum thin film can obtain extremely low resistivity and excellent anti-electromigration ability, thereby improving the integration, speed and reliability of chips. For high-purity aluminum sputtering targets used in the manufacture of semiconductor chips, if they are single crystal or super-large grains, the particle spatter during sputtering can be reduced, and the uniformity and quality of the thin film can be improved. At present, there are more studies on the purification effect and research of high-purity aluminum, but there are fewer studies on the improvement of grain boundary morphology and even single crystal effect of high-purity aluminum.

[0003] At present, the main preparation methods of high-purity aluminum are chemical methods based on electrolysis and pure physical segregation purification methods. Among them, the electrolysis method is mainly three-layer liquid electrolytic refining method; the segregation method mainly includes vacuum volatilization method, step crystallization method, directional solidification method and zone melting method. For directional solidification purification technology, it is necessary to strengthen segregation, which can be achieved by increasing the temperature gradient, reducing the growth rate to ensure the growth of crystal flat interface or cell crystal, increasing the diameter of cell crystal, reducing the number of grain boundaries, and controlling the liquid flow at the interface front to improve the purification efficiency. In the purification process, forced stirring can reduce the solute concentration at the solid-liquid interface front, promote the diffusion of solute elements into the liquid phase, and improve the purification effect.

[0004] According to the principle of segregation method, Dai Fei, Yu Yang, etc. respectively made a rotating segregation device, and found that the crystallization process of aluminum is equivalent to the directional solidification process. It was found that with the increase of stirring intensity, the relative speed of solidified aluminum and melt was increased, and the impurities in the crystallized aluminum that had not completely solidified would be thrown back into the melt under the action of centrifugal force. At the same time, stirring makes the melt produce forced convection, which speeds up the transmission speed of impurities in solid aluminum to liquid phase, so that the purification effect is significantly increased. [1] Dai Fei. Research on continuous rotating segregation purification process of electrolytic aluminum [J]. Aluminum processing, 2019(4):9-12. [2] Yu Yang, Hu Zhiqiang, Wang Haiquan, et al. Purification process of primary aluminum by rotating segregation method [J]. Journal of Dalian University of Technology, 2015, 34(4):282-285.

[0005] A method, device and high-purity aluminum for directional solidification extraction of high-purity aluminum are invented by Chalco Zhengzhou Nonferrous Metals Research Institute. The aluminum to be purified is placed in an inert protective gas and heated to obtain an aluminum liquid melt with a set temperature. The aluminum liquid melt is stirred, and air cooling is applied above the upper surface of the aluminum liquid melt to cause the upper surface of the aluminum liquid melt to partially solidify and produce suspended pure aluminum crystals. The remaining portion of the aluminum liquid melt is cooled layer by layer from bottom to top to cause the aluminum in the aluminum liquid melt to directionally crystallize and separate from the melt layer by layer to obtain an ingot. Thus, grain refinement and equiaxed crystal structure formation are achieved while the purification efficiency is improved. According to the research, it can be found that during the purification process, forced stirring can reduce the solute concentration at the front of the solid-liquid interface, promote the diffusion of solute elements into the liquid phase, and improve the purification effect. Chalco Zhengzhou Nonferrous Metals Research Institute Co., Ltd. A method, device and high-purity aluminum for directional solidification extraction of high-purity aluminum. CN202410842619.0[P], 2024.10.25.

[0006] From the development process of directional solidification technology, it can be seen that obtaining high temperature gradient is still the future development trend. In the CN202320686778.7 patent, by setting heating element A and heating element B in the directional solidification furnace body, the temperature gradient of the ingot in the pulling and descending process of the alloy melt can be controlled; at the same time, the heating temperature is controlled in multiple sections, which can realize the regulation of the temperature gradient of the ingot in the directional solidification process. The double-zone heating assisted by side and bottom strong cooling can obtain stable and higher temperature gradient, ensure that the crystal maintains a flat interface during growth, and is beneficial to the removal of impurity elements.[4] Panzhihua College. High-temperature alloy directional solidification temperature gradient control device. CN202320686778.7[P], 2023.11.07.

[0007] An Shaoyun studied the structure characteristics of cellular crystal boundaries in the directional solidification process of high-purity aluminum by using a self-made directional solidification device for high-purity aluminum. The results showed that there are microscopic elevations and wrinkles at the edges of the cellular crystal boundaries of high-purity aluminum, which are caused by uneven micro-solute distribution. The solute concentration at the crystal boundary is related to the crystal boundary structure parameters, the solute concentration at the front of the liquid-solid interface, and the directional solidification speed.[5] An Shaoyun, Zhang Jiao. Research on crystal boundary structure and solute distribution characteristics in directional solidification of high-purity aluminum [J]. Foundry Technology, 2014, 35(5):1013-1018.

[0008] The directional solidification method for purifying high-purity aluminum described in the above patents and papers shows that the solute concentration at the solid-liquid interface front can be reduced by forced stirring to improve the purification effect, and the temperature of the melt near the interface front can be increased by using a heater to increase the temperature gradient of the liquid phase at the interface front, but a part of the heat will be dissipated during the crystal pulling and solidification process of the aluminum ingot, and the temperature gradient of the liquid phase at the interface front cannot be kept relatively stable, and the directional solidification rate and precision cannot be controlled. Content of the utility model

[0009] In view of the above problems, the utility model provides a rotary lifting device for directional solidification to improve the grain boundary morphology of high-purity aluminum, which adopts an existing high-precision, high-efficiency and high-rigidity ball screw device, and designs a directional solidification equipment capable of rotating and lifting during the crystal pulling process, uses ceramic gaskets with good heat insulation performance to maintain a high temperature difference between the two zones as much as possible, effectively increases the liquid phase temperature gradient at the interface front, makes the liquid phase temperature gradient at the interface front relatively stable, optimizes the thermal field distribution to control the temperature gradient of the solidification process, thereby significantly improves the grain boundary morphology and migration behavior, and finally greatly improves the purification efficiency and purity of high-purity aluminum.

[0010] To achieve the above object, the technical scheme of the utility model is as follows:

[0011] A rotary lifting device for directional solidification to improve the grain boundary morphology of high-purity aluminum, the furnace body is installed above the cabinet body, the inner cavity of the closed structure furnace body is provided with a heating device, the heating device is an induction coil heating, the inner side of the induction coil is provided with a heat preservation layer, the heat preservation layer surrounds the corundum crucible, and the aluminum melt is in the corundum crucible;Cooling device is arranged below the heating device, the cooling device is gallium-indium alloy cooling pool and is arranged below the induction coil, the gallium-indium alloy cooling pool is filled with gallium-indium alloy cooling liquid;The base at the lower end of the corundum crucible is fixedly connected with the upper end of the directional solidification rod;The directional solidification rod is connected with the lifting device and the rotating device after passing through the gallium-indium alloy cooling pool, the lifting device is fixed on the left side of the mounting frame, the rotating device is fixed at the bottom end of the directional solidification rod, and the directional solidification rod is driven to rotate or lift by the rotating device and the lifting device.

[0012] The furnace body is designed as a horizontal cylindrical multilayer shell structure, the outer shell and the inner lining are made of stainless steel, and the middle interlayer is made of heat preservation material. The furnace shell designed in this way mainly ensures that the temperature of the outer shell does not exceed 60 DEG C, and avoids the conduction of the temperature in the furnace to the outside of the furnace.

[0013] The induction coil is a medium-frequency induction heating, the induction coil is spirally wound by copper pipe and led out from the furnace body, and the induction coil can suspend the heat preservation layer and the corundum crucible as a whole. The heat preservation layer arranged on the inner side of the induction coil is composed of graphite and graphite sleeve, and a temperature field is formed in the heat preservation layer after heating, so that the temperature after heating is not easy to dissipate, and the heat preservation effect is better.

[0014] The corundum crucible is cylindrical, hollow, and open at both ends, with an inner diameter of Φ12-20mm. The inner wall of the bottom of the corundum crucible is embedded in the outer wall of the upper part of the base, the bottom end of the base is provided with a threaded hole to engage with the external threads of the upper end of the directional solidification rod for threaded connection, the outer threads of the sidewall of the base are engaged with the inner wall of the fixing ring for threaded connection, the upper part of the fixing ring is provided with a plurality of clamping pieces to clamp the outer wall of the corundum crucible, and the upper end surface of the base is placed with a plurality of ceramic gaskets. The assembled crucible has the advantages that: after the purification is completed, the corundum crucible is separated from the fixing ring, and the high-purity aluminum ingot in the corundum crucible can be easily ejected with a tool.

[0015] The ceramic gaskets placed at the bottom of the corundum crucible are heat insulation gaskets, located between the corundum crucible and the cold zone. The core function of the heat insulation gasket is to increase the total thermal resistance (i.e. total heat insulation capacity, the thermal resistance formula is R=d / λ, R is the thermal resistance, d: total thickness of the heat insulation material / m, λ is the thermal conductivity of the material) by stacking the number, so as to reduce the heat flux q from the graphite crucible to the cold zone. According to Fourier's law: q=λ 总 •ΔT / d 总 , wherein λ 总 is the total thermal conductivity, d 总 is the total thickness, the more gaskets, the smaller λ 总 , the larger d 总 , and the lower q. The heat flux q directly determines two key parameters: temperature gradient and solidification speed. When the number of gaskets increases to a certain extent, q decreases, which leads to a decrease in the temperature gradient in the system (especially the gradient near the solid-liquid interface), and q decreases, which leads to a decrease in the heat loss of the aluminum melt and a decrease in the solidification speed. The increase in the number of gaskets leads to a non-monotonic change in the ratio of temperature gradient to solidification speed, which is the core criterion for component supercooling, and finally affects the crystal growth morphology. The ceramic gasket specifically adopts a 99 alumina heat insulation gasket, each with a thickness of 1mm and a thermal conductivity of 24W / (m•K).

[0016] The directional solidification rod and the base are made of pure tungsten, which has a melting point of 3410℃, which can ensure that the aluminum ingot is completely melted and that the base and the directional solidification rod remain intact and stable during high-temperature processes.

[0017] The lifting device includes a lifting motor, a ball screw, a ball screw mounting base, a ball screw nut, angle iron one, angle iron two, and a clamping block. Both ends of the ball screw are fixed inside the ball screw mounting base, which is vertically fixed to the left side of the mounting frame. The ball screw nut is fitted onto the ball screw. Angle iron one is mounted on the right side, and angle iron two is mounted above angle iron one in the opposite direction. A clamping block is mounted on the right side of angle iron two, clamping the lower middle part of the directional solidification rod. The lifting motor is connected to the bottom end of the ball screw and fixed to the left side of the mounting frame. The ball screw nut is slidably mounted on a vertical guide rail on the left side. The lifting motor drives the ball screw to rotate, causing the ball screw nut to move up and down linearly, thereby indirectly driving the corundum crucible to move up and down. The lifting device is controlled by a stepper motor. Due to the high precision, high efficiency, and high rigidity of the ball screw, the stepper motor, combined with a PLC and touch screen, can precisely control the lifting stroke and speed of the corundum crucible, thus precisely controlling the directional solidification rate.

[0018] The rotary motor of the rotating device is installed below the angle iron and connected to the bottom of the directional solidification rod. The rotary motor directly drives the directional solidification rod to rotate, indirectly driving the alumina crucible to rotate, thereby causing the molten aluminum inside the alumina crucible to rotate and thus achieving a stirring effect. The rotary motor is a rotary stepper motor, which, combined with a PLC and touch screen, allows for precise control of the rotation speed of the alumina crucible.

[0019] The gallium-indium alloy cooling pool has a double-layer shell with a sandwich layer through which cold air can be introduced. The cold air is introduced through the inlet pipe and the hot air is discharged through the outlet pipe. The inlet pipe is connected to a water chiller, which improves the water cooling effect. Furthermore, the use of gallium-indium alloy coolant as the cooling medium has many advantages, such as not affecting the vacuum level of the cavity, fast heat transfer, and non-volatile properties.

[0020] The steps of this invention for purifying high-purity aluminum are as follows:

[0021] S1. Use an electrical discharge cutting device to cut irregular raw aluminum ingots into regular aluminum ingots with the same size as the inner cavity of the corundum crucible, and fit them into the corundum crucible.

[0022] S2. Use an angle grinder to grind away the oxide layer and oily cutting fluid remaining from the wire cutting process on the surface of the aluminum ingot to be purified. Then use an ultrasonic cleaner to ultrasonically clean the aluminum chips on the ground aluminum ingot for 20 minutes. Then put the cleaned aluminum ingot into a vacuum drying oven to dry for later use.

[0023] S3. Connect the corundum crucible to the base, and put 2-8 ceramic pads and the aluminum ingots processed in the second step into the corundum crucible in sequence. Then, put the whole thing into the directional solidification furnace through the connection between the base and the directional solidification rod.

[0024] S4. First, purge the directional solidification furnace three times with argon gas, then use a vacuum pump to evacuate the directional solidification furnace to a high vacuum state (vacuum degree ≤ 10). -3Pa), and then argon gas is introduced to balance the internal pressure of the directional solidification furnace with the outside; the corundum crucible is heated to a temperature of 750 DEG C to completely melt the aluminum ingot, and the temperature is kept for 1 hour; during the temperature keeping, the rotating motor is started to rotate and stir the aluminum liquid in the corundum crucible; the rotating and stirring makes the impurities in the aluminum liquid uniformly distributed; the height of the aluminum liquid is about 60-100mm; and the rotating speed is 6 rad / s;

[0025] S5, the rotating motor is turned off to stop the rotating crucible, the lifting motor is started after the solid-liquid interface is kept static, the pulling crystal speed is kept at 20mm / h, the part of the descending crucible is cooled by the cooling device arranged at the bottom, and then directional solidification segregation is carried out, so that the aluminum liquid is solidified in the direction opposite to the heat flow; in the process that the aluminum liquid is gradually solidified from bottom to top, the impurities in the aluminum liquid gradually move to the upper end and are finally gathered in the upper aluminum liquid (tail aluminum);

[0026] S6, after the crucible is descended for 3-5h, the corundum crucible is reset by reversing the lifting motor, the furnace door is opened, the corundum crucible is taken out from the base, and the purified aluminum ingot is taken out; the purified high-purity aluminum ingot has a diameter range of 12-20mm and a height range of 60-100mm; the tail aluminum at the upper end of the aluminum ingot is cut off to a height of 20-30mm; and the remaining aluminum ingot is high-purity aluminum; the obtained high-purity aluminum ingot is cut along the longitudinal section, polished and polished, and the influence of ceramic gaskets with different thicknesses on the grain size and grain boundary number of the refined aluminum is observed.

[0027] Advantages of the utility model:

[0028] 1, the utility model discloses a high-precision, high-efficiency, high-rigidity ball screw device, and a directional solidification equipment capable of rotating and lifting in the pulling crystal process is designed to optimize the heat field distribution to control the solidification process temperature gradient, thereby improving the grain boundary morphology and migration behavior, and finally greatly improving the purification efficiency and purity of high-purity aluminum.

[0029] 2,The utility model discloses a ceramic gasket with good heat insulation performance to keep the temperature difference between two areas as high as possible, which can effectively increase the liquid phase temperature gradient of the interface front, make the liquid phase temperature gradient of the interface front relatively stable, and the huge temperature gradient has a decisive influence on the nucleation and growth mode of the crystal grain. Increasing the liquid phase temperature gradient of the interface front promotes the growth of columnar crystals and reduces the transverse grain boundary. Experimental results show that increasing the ceramic gasket can avoid the uneven heating of the bottom of the aluminum ingot caused by the temperature gradient formed on the bottom during the heating process, and avoid the formation of circular holes and other obvious defects. The bottom of the purified aluminum ingot is smooth and flat, and the obtained sample has extremely high density. On the macro level, there is no sponge-like loose area, and the purity can reach 99.9995%.

[0030] 3,The gallium-indium alloy cooling pool is designed as a double-shell structure, the interlayer between the shells can pass cold air, the gallium-indium alloy cooling liquid can keep a lower heating rate in a working state for a long time, and the cooling effect is better. Faster cooling speed means better purification effect, and using the gallium-indium alloy cooling liquid as a cooling medium has many advantages, such as not affecting the vacuum degree of the cavity, fast heat transfer, and non-volatility. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a structural schematic view of the utility model;

[0032] Figure 2 It is Figure 1 It is an enlarged structural view of I in the middle;

[0033] Figure 3 It is a corundum crucible decomposition structural schematic view;

[0034] Figure 4 It is a corundum crucible combination structural schematic view;

[0035] The serial number and the component name in the drawing are as follows: 1-furnace body; 2-directional solidification rod; 3-cabinet; 4-mounting frame; 5-base; 6-lifting motor; 7-ceramic gasket; 8-rotary motor; 9-corundum crucible; 10-ball screw; 11-ball screw mounting seat; 12-aluminum melt; 13-ball screw nut; 14-angle iron one; 15-gallium-indium alloy cooling pool; 16-angle iron two; 17-heat preservation layer; 18-induction coil; 19-clamping block; 20-fixing ring; 21-air inlet pipe; 22-exhaust pipe. DETAILED DESCRIPTION

[0036] In order to introduce the utility model more in detail, the utility model will be further described below in combination with examples and drawings.

[0037] Example 1

[0038] For example, Figure 1As shown, a rotating lifting device for directional solidification improves the grain boundary morphology of high purity aluminum, the furnace body 1 is installed above the cabinet body 3, the inner cavity of the closed structure furnace body 1 is provided with a heating device, the heating device is an induction coil 18 heating, the inner side of the induction coil 18 is provided with a heat preservation layer 17, the heat preservation layer 17 surrounds the corundum crucible 9 around, the corundum crucible 9 is aluminum melt 12; The cooling device is provided below the heating device, the cooling device is a gallium-indium alloy cooling pool 15 and is arranged directly below the induction coil 18, the gallium-indium alloy cooling pool 15 is filled with gallium-indium alloy cooling liquid; The base 5 at the lower end of the corundum crucible 9 is fixedly connected with the upper end of the directional solidification rod 2; The directional solidification rod 2 passes through the gallium-indium alloy cooling pool 15 and is connected with the lifting device and the rotating device, the lifting device is fixed on the left side of the mounting frame 4, the rotating device is fixed on the bottom end of the directional solidification rod 2, the directional solidification rod 2 is driven to rotate or lift by the rotating device and the lifting device.

[0039] As shown in the figure, Figures 2-4 The corundum crucible 9 is cylindrical, hollow, open at both ends, the inner diameter is between Φ12-20mm, the inner wall of the bottom of the corundum crucible 9 is embedded in the outer wall of the upper part of the base 5, the bottom end of the base 5 is provided with a threaded hole and the outer thread of the upper end of the directional solidification rod 2 is engaged and threadedly connected, the outer thread of the sidewall of the base 5 is engaged and connected with the inner wall of the fixing ring 20, the upper part of the fixing ring 20 is provided with a plurality of clamping pieces clamping the outer wall of the corundum crucible 9, and a plurality of ceramic gaskets 7 are placed on the upper end surface of the base 5.

[0040] The lifting device includes a lifting motor 6, a ball screw 10, a ball screw mounting seat 11, a ball screw nut 13, an angle iron one 14, an angle iron two 16, and a clamping block 19. The two ends of the ball screw 10 are fixed in the ball screw mounting seat 11, the ball screw mounting seat 11 is vertically fixed on the left side of the mounting frame 4, the ball screw nut 13 is sleeved on the ball screw 10, the angle iron one 14 is installed on the right side, the angle iron two 16 is reversely installed above the angle iron one 14, the clamping block 19 is installed on the right side of the angle iron two 16, the clamping block 19 clamps the middle and lower part of the directional solidification rod 2, the lifting motor 6 is connected with the bottom end of the ball screw 10 and is fixed on the left side of the mounting frame 4, the ball screw nut 13 is slidably installed on the vertical guide rail on the left side, the lifting motor 6 drives the ball screw 10 to rotate and drives the ball screw nut 13 to move up and down, thereby indirectly driving the corundum crucible 9 to lift up and down.

[0041] The rotating motor 8 of the rotating device is installed below the angle iron one 14, the rotating motor 8 is connected with the bottom of the directional solidification rod 2, the rotating motor 8 directly drives the directional solidification rod 2 to rotate, indirectly drives the corundum crucible 9 to rotate, and further makes the aluminum melt 12 in the corundum crucible 9 rotate to play a stirring role.

[0042] The pool wall of the gallium-indium alloy cooling pool 15 is a double-layer shell, the interlayer can be filled with cold air, the cold air is filled by the air inlet pipe 21, the hot air is discharged by the air outlet pipe 22, the air inlet pipe 21 is connected with the water cooling machine.

[0043] The method for purifying high-purity aluminum in the embodiment has the following steps:

[0044] S1, use the electric spark cutting equipment to cut the irregular raw aluminum ingot into a regular aluminum ingot with the same size as the corundum crucible, and fit the regular aluminum ingot with the corundum crucible;

[0045] S2, polish the surface oxide layer and the residual oily cutting fluid in the cutting process of the wire cutting machine of the refined aluminum to be purified, then further clean the aluminum scraps on the polished aluminum ingot by using the ultrasonic cleaning instrument for 20 minutes, and then put the cleaned aluminum ingot into the vacuum drying box for drying for standby;

[0046] S3, connect the corundum crucible with the base, put 2-8 ceramic gaskets and the aluminum ingot treated in the second step into the corundum crucible in sequence, and then put the whole into the directional solidification furnace through the connection of the base and the directional solidification rod;

[0047] S4, first wash the directional solidification furnace with argon for three times, then use the vacuum pump to draw the directional solidification furnace into a high vacuum state (vacuum degree ≤10 -3 Pa), and then introduce argon to balance the internal pressure in the directional solidification furnace with the outside. Heat the corundum crucible, and increase the temperature to 750℃ to completely melt the aluminum ingot, and keep the temperature for 1 hour. At the same time of keeping the temperature, start the rotating motor to make the aluminum liquid in the corundum crucible rotate and stir. The rotating and stirring makes the impurities in the aluminum liquid uniformly distributed. The height of the aluminum liquid is about 60-100mm, and the rotating speed is 6 rad / s;

[0048] S5, stop the rotating crucible by closing the rotating motor, and then start the lifting motor after the solid-liquid interface keeps still. The pulling crystal speed is kept at 20mm / h. The part of the descending crucible is cooled by the cooling device installed at the bottom, and then directional solidification segregation is carried out. The aluminum liquid is solidified in the direction opposite to the heat flow. In the process of the aluminum liquid gradually solidifying from bottom to top, the impurity solute in the aluminum liquid gradually moves to the upper end and finally gathers in the upper aluminum liquid (tail aluminum);

[0049] S6, after the crucible is lowered for 3-5h, the lifting motor is reversed to make the corundum crucible rise and reset. The corundum crucible is taken out from the base, the purified aluminum ingot is taken out, the diameter of the purified high-purity aluminum ingot is Φ12-20mm, the height is 60-100mm, the tail aluminum at the upper end of the aluminum ingot is cut off for 20-30mm in height, and the remaining aluminum ingot is the high-purity aluminum. The obtained high-purity aluminum ingot is cut, polished and polished along the longitudinal section, and the influence of the ceramic gaskets with different thicknesses on the grain size and the number of grain boundaries of the refined aluminum is observed.

[0050] The high-purity aluminum purified in the embodiment has a purity ranging from 99.9985% to 99.9995%, which is relatively high.

Claims

1. A rotary lifting device for improving the grain boundary morphology of high-purity aluminum through directional solidification, characterized in that: The furnace body (1) is installed above the cabinet (3). The inner cavity of the closed furnace body (1) is equipped with a heating device, which is an induction coil (18) for heating. The inner side of the induction coil (18) is equipped with a heat insulation layer (17), which surrounds the corundum crucible (9). The corundum crucible (9) contains aluminum melt (12). A cooling device is provided below the heating device. The cooling device is a gallium indium alloy cooling pool (15) and is located directly below the induction coil (18). The gallium indium alloy cooling pool (15) is filled with gallium indium alloy coolant. The base (5) at the lower end of the corundum crucible (9) is fixedly connected to the upper end of the directional solidification rod (2). The directional solidification rod (2) passes through the gallium indium alloy cooling pool (15) and is connected to the lifting device and the rotating device. The lifting device is fixed on the left side of the mounting frame (4), and the rotating device is fixed at the bottom of the directional solidification rod (2). The directional solidification rod (2) is driven by the rotating device and the lifting device to rotate or lift.

2. The rotary lifting device for improving the grain boundary morphology of high-purity aluminum through directional solidification according to claim 1, characterized in that: The corundum crucible (9) is cylindrical, hollow, and open at both ends. The inner wall of the bottom of the corundum crucible (9) is embedded and sleeved on the outer wall of the upper part of the base (5). The bottom end of the base (5) is provided with a threaded hole that meshes with the external thread of the upper end of the directional solidification rod (2). The external thread of the side wall of the base (5) meshes with the inner thread of the fixing ring (20). Several clamping pieces are provided around the upper part of the fixing ring (20) to clamp the outer wall of the corundum crucible (9). Several ceramic pads (7) are placed on the upper surface of the base (5).

3. The rotary lifting device for improving the grain boundary morphology of high-purity aluminum through directional solidification according to claim 1, characterized in that: The lifting device includes a lifting motor (6), a ball screw (10), a ball screw mounting seat (11), a ball screw nut (13), angle iron one (14), angle iron two (16), and a clamping block (19). The two ends of the ball screw (10) are fixed inside the ball screw mounting seat (11). The ball screw mounting seat (11) is vertically fixed on the left side of the mounting frame (4). The ball screw nut (13) is sleeved on the ball screw (10). Angle iron one (14) is installed on the right side. Angle iron 2 (16) is installed in both directions. A clamping block (19) is installed on the right side of angle iron 2 (16). The clamping block (19) clamps the lower part of the directional solidification rod (2). The lifting motor (6) is connected to the bottom end of the ball screw (10) and fixed on the left side of the mounting frame (4). The ball screw nut (13) is slidably installed on the left side of the vertical guide rail. The lifting motor (6) drives the ball screw (10) to rotate, which drives the ball screw nut (13) to make up-down linear motion, thereby indirectly driving the corundum crucible (9) to move up and down.

4. The rotary lifting device for improving the grain boundary morphology of high-purity aluminum through directional solidification according to claim 1, characterized in that: The rotating motor (8) of the rotating device is installed below the angle iron (14). The rotating motor (8) is connected to the bottom of the directional solidification rod (2). The rotating motor (8) directly drives the directional solidification rod (2) to rotate, and indirectly drives the corundum crucible (9) to rotate, thereby causing the aluminum melt (12) in the corundum crucible (9) to rotate and play a stirring role.

5. The rotary lifting device for improving the grain boundary morphology of high-purity aluminum through directional solidification according to claim 1, characterized in that: The gallium-indium alloy cooling pool (15) has a double-layer shell wall with a sandwich layer through which cold air can be introduced. The cold air is introduced through the air inlet pipe (21), and the hot air is discharged through the exhaust pipe (22). The air inlet pipe (21) is connected to the water chiller.

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