Anti-gravity effect single crystal high-temperature alloy directional solidification growth device and application thereof

Abstract

This invention belongs to the field of directional solidification of high-temperature alloys, and provides an engineering-applicable anti-gravity effect single-crystal high-temperature alloy directional solidification growth device and its application, which reduces the formation of interdendritic segregation, avoids the formation of defects such as freckles, and meets the actual needs of high-temperature alloy directional solidification blade preparation. The device structure is as follows: a vacuum induction furnace is set at the bottom of the device, and a crucible is placed inside it. The crucible is located on a crucible lifting mechanism, and a graphite holding furnace is set above the crucible. A pulling mechanism is set at the top of the device, and a water-cooling plate is set below it. The top of the mold shell has a seed crystal mounting port for installing the seed crystal, and the bottom has an alloy liquid inlet. After the mold shell and the seed crystal are assembled, they are fixed on the water-cooling plate by a fixing clamp. The device also includes a heat insulation baffle and a vacuum system. The heat insulation baffle with through holes is set parallel to the crucible above the graphite holding furnace, and the inner diameter of the through holes of the heat insulation baffle is 10-20 mm larger than the maximum outer diameter of the mold shell.

Description

Technical Field

[0001] This invention belongs to the field of directional solidification of high-temperature alloys, and relates to the preparation of directional columnar crystals and single-crystal turbine blades in the aerospace and gas turbine industries. In particular, it provides an anti-gravity effect single-crystal high-temperature alloy directional solidification growth equipment and its application. Background Technology

[0002] Due to their excellent high-temperature performance, single-crystal and directionally solidified superalloys are widely used in gas turbines. As turbine inlet temperatures increase, superalloys are enhanced by adding large amounts of elements such as W, Mo, Ta, and Re to improve their high-temperature resistance. High-density negative segregating elements like W and Re accumulate in the dendrite centers formed early in the solidification process, while low-density positive segregating elements like Al and Ti are repelled into the residual liquid between dendrites. With increasing solid fraction, the liquid density in the mushy region decreases. Under gravity, this density contrast (heavier at the top, lighter at the bottom) makes it difficult for the liquid in the mushy region to remain stable, leading to strong tunnel-like convection, dendrite arm breakage, and ultimately the formation of fine, vertically chain-like grain defects.

[0003] Currently, the Bridgman-Stockbarger method is used for directional solidification of high-temperature alloys. This solidification technology has advantages such as simple equipment structure and stable and reliable process technology. However, the disadvantages of this process and equipment are also obvious, such as low radiative heat transfer efficiency and ineffective insulation between hot and cold zones. In particular, due to the effect of gravity and the characteristics of the alloy solidification process, the microstructure of the casting becomes very uneven and is prone to various defects.

[0004] For many years, researchers have been working to improve traditional directional solidification processes, with liquid metal cooling (LMC) and gas cooling casting (GCC) being the most well-known methods. These two methods replace radiative heat dissipation with convective heat dissipation from liquids and gases, respectively. While this generally increases the cooling rate of the casting, it also exacerbates the uneven heat dissipation across the casting. Furthermore, the effects of gravity are not eliminated, and the problem of freckle-like defects in the casting remains unresolved.

[0005] Ma Dexin invented a thin-shell lowering process (patent publication number: CN101537485A). First, a mold shell is lowered through a flexible insulation layer into the alloy molten pool inside the crucible, and the molten metal is filled into the mold shell from the bottom. A plug made of the same alloy is used at the inlet to prevent the insulation material from entering. The filled mold shell is then lifted upwards, achieving top-down directional solidification of the alloy and avoiding the influence of gravity. The problems with this process are the difficulty in controlling the process and the increased difficulty in preparing the mold shell, especially for fabricating complex thin-walled hollow blades. Summary of the Invention

[0006] The purpose of this invention is to provide an engineering-applicable anti-gravity effect single-crystal high-temperature alloy directional solidification growth device and its application, so as to reduce the formation of interdendritic segregation, avoid the formation of defects such as freckles, and meet the actual needs of high-temperature alloy directional solidification blade preparation.

[0007] The technical solution of this invention is as follows:

[0008] An anti-gravity effect single-crystal superalloy directional solidification growth device, characterized in that: the device consists of a vacuum induction furnace, a crucible lifting mechanism, a mold filling system (mold shell, seed crystal, alloy liquid inlet), a vacuum system, a graphite holding furnace, and a directional solidification pulling mechanism, as detailed below:

[0009] A vacuum induction furnace 11 is located at the bottom of the equipment, and a crucible 8 is provided inside it. The crucible 8 is located on the crucible lifting mechanism 13, and a graphite heat preservation furnace 12 is located above the crucible 8.

[0010] The pull-out mechanism 6 is located on the top of the equipment, and a water cooling plate 5 is located below it; the top of the mold shell 1 is provided with a seed crystal mounting port for installing the seed crystal 2, and the bottom is provided with an alloy liquid inlet 3; after the mold shell 1 and the seed crystal 2 are assembled, they are fixed on the water cooling plate 5 by a fixing clamp 4.

[0011] The equipment is also equipped with a heat insulation baffle 7 and a vacuum system 10. The heat insulation baffle 7 with through holes is arranged parallel to the crucible 8 above the graphite heat preservation furnace 12. The inner diameter of the through hole of the heat insulation baffle 7 is 10-20 mm larger than the maximum outer diameter of the mold shell 1.

[0012] As a preferred technical solution:

[0013] The device is also equipped with a temperature measuring thermocouple, which is a nickel-chromium-nickel-silicon or platinum-rhodium-platinum thermocouple.

[0014] Mold shell 1 is prepared using precision casting process, with 5-8 layers. The sand material is alumina sand, with the first layer being 80 mesh, the second layer being 60 mesh, the third layer being 36 mesh, and the fourth to seventh layers being 24 mesh. The final sealing layer is a surface coating.

[0015] The mold shell 1 is dried in air with an air humidity of >60% and a drying temperature of 23-35℃. The drying time for each layer is controlled at 2-4 hours. The mold shell 1 is dewaxed by steam with a steam temperature of 160-180℃, a pressure of 6-8 atmospheres, and a dewaxing time of 10-30 seconds. The mold shell 1 is fired at a temperature of 850-1050℃ for 2-5 hours and then cooled to room temperature in the furnace.

[0016] The material of seed crystal 2 is the same as that of the casting alloy, which is a nickel-based single crystal alloy. Specifically, alloys such as DD413, DD6, DD33, PWA1483, PWA1484, CMSX-4, and CMSX-6 can be selected.

[0017] Seed crystal 2 has a wedge-shaped or stepped structure to prevent it from falling off during solidification. The diameter of the large end section Φ1 of seed crystal 2 is 10-50mm and the height h2 is 5-20mm. The diameter of the small end section Φ2 is 5-20mm and the height h1 is 30-50mm.

[0018] The diameter Φ of the alloy liquid inlet 3 is 5-20mm, and the height H is 10-20mm.

[0019] The fixing fixture 4 is made of molybdenum metal.

[0020] The present invention also provides a method for preparing single-crystal high-temperature alloy blades using the aforementioned equipment, characterized by the following specific steps:

[0021] 1) After assembling the seed crystal 2 into the mold shell 1, use the fixing clamp 4 to fix the mold shell 1 onto the water cooling plate 5, and then lower the mold shell 1 into the graphite heat preservation furnace 12 so that the lowest end of the water cooling plate 5 and the lowest end of the heat insulation baffle 7 are at the same level.

[0022] 2) Fill the crucible 8 with alloy material, use the vacuum system 10 to evacuate the vacuum, and after the vacuum degree reaches a certain standard, use the vacuum induction furnace 11 to melt the alloy; at the same time, turn on the graphite heat preservation furnace 12 to preheat the mold shell 1.

[0023] 3) After the alloy melting is completed, the crucible 8 is raised by the crucible lifting mechanism 13 to ensure that the mold shell 1 with seed crystal 2 is immersed in the melt and remains in place. After the alloy liquid comes into contact with the seed crystal 2, the surface of the seed crystal 2 partially melts. After the state stabilizes, the directional solidification pulling mechanism 6 starts to pull the mold shell 1 upward. The seed crystal 2 grows epitaxially downward. The growth rate is controlled by the pulling speed.

[0024] 4) After the leaf growth is complete, remove the mold shell 1 and clean it to obtain the casting.

[0025] This invention uses a traditional precision casting process to prepare the mold shell. The bottom of the mold shell is equipped with an alloy liquid inlet, and the top of the mold shell is reserved for seed crystal installation. After the seed crystal is installed, the mold shell is lowered into the holding furnace. After the alloy liquid fills the mold shell, the mold shell is pulled upward, and the seed crystal grows downward and outward until the blade is fully grown. This avoids the influence of gravity during directional solidification and greatly reduces the generation of interdendritic segregation.

[0026] As a preferred technical solution:

[0027] Before the alloy is filled, the temperature of the alloy liquid is maintained at 1480-1520℃. The mold shell 1 needs to be kept in the graphite heat preservation furnace 12 for 10-30 minutes at a temperature of 1470-1500℃. The temperature measuring thermocouple is a nickel-chromium-nickel-silicon or platinum-rhodium-platinum thermocouple.

[0028] The vacuum level during the smelting and directional solidification process is controlled within the range of 2-8 Pa.

[0029] When filling the mold with liquid alloy, it is necessary to ensure that the seed crystal 2 does not completely melt, and the upward pulling speed of the mold shell 1 should be controlled within the range of 3-10 mm / min.

[0030] The anti-gravity effect directional solidification process of this invention has the following advantages compared with the traditional Bridgman process:

[0031] 1. The change in casting method reduces the impact of molten alloy on the mold shell, avoids the entrapment of oxide impurities, and reduces the generation of inclusion defects; the casting system is eliminated, saving raw materials and reducing costs.

[0032] 2. The anti-gravity growth method changes the solidification direction of the casting, completely avoiding defects such as surface porosity and exposed dendrites caused by insufficient feeding capacity in the gravity direction, which can significantly improve the qualification rate of castings.

[0033] 3. The anti-gravity growth method reduces the density difference at the solidification front caused by solute segregation, and the convection of the liquid will be greatly reduced. This will greatly reduce the scouring of dendrites by the melt, avoid dendrite breakage and bending, and reduce the formation of interdendritic segregation.

[0034] 4. The density distribution of the liquid in the paste-like region is lighter at the top and heavier at the bottom, which is conducive to the stability of the liquid and avoids the generation of convection, thus helping to prevent the formation of freckle defects. Attached Figure Description

[0035] Figure 1 Schematic diagram of antigravity directional solidification equipment.

[0036] Figure 2 Schematic diagram of seed crystal structure.

[0037] Figure 3 Inlet dimensions of the alloy liquid.

[0038] Figure 4 Single-crystal structures grown under anti-gravity effects.

[0039] Reference numerals: 1. Mold shell, 2. Seed crystal, 3. Alloy liquid inlet, 4. Fixing fixture, 5. Water cooling plate, 6. Pull-out mechanism, 7. Heat insulation baffle, 8. Crucible, 9. Alloy charge, 10. Vacuum system, 11. Vacuum induction furnace, 12. Graphite heat preservation furnace, 13. Crucible lifting mechanism. Detailed Implementation

[0040] like Figures 1-3 As shown, an anti-gravity effect single crystal high-temperature alloy directional solidification growth device is provided, wherein: a vacuum induction furnace 11 is set at the bottom of the device, and a crucible 8 is provided inside it. The crucible 8 is located on the crucible lifting mechanism 13, and a graphite holding furnace 12 is set above the crucible 8.

[0041] The pull-out mechanism 6 is located on the top of the equipment, and a water cooling plate 5 is provided below it; the top of the mold shell 1 is provided with a seed crystal mounting port for installing the seed crystal 2, and the bottom is provided with an alloy liquid inlet 3; after the mold shell 1 and the seed crystal 2 are assembled, they are fixed on the water cooling plate 5 by a fixing clamp 4, which is made of molybdenum metal; the pull-out mechanism 6 can drive the mold shell 1 and the like to make lifting and lowering movements.

[0042] The equipment is also equipped with a heat insulation baffle 7 and a vacuum system 10. The heat insulation baffle 7 with through holes is arranged parallel to the crucible 8 above the graphite heat preservation furnace 12. The inner diameter of the through hole of the heat insulation baffle 7 is 10-20 mm larger than the maximum outer diameter of the mold shell 1.

[0043] Example 1

[0044] The mold shell is prepared using traditional precision casting technology, with a reserved space for the alloy melt inlet and the seed crystal installation. The alloy melt inlet space and the seed crystal installation space are formed using a wax model (mounted on the integral wax model) that is identical in shape and size. The space formed after dewaxing this part of the wax model is the location of the alloy melt inlet and the installation position of the seed crystal. The alloy melt inlet has a diameter of Φ10mm and a height of H10mm. The space for installing the seed crystal has a stepped structure to prevent the seed crystal from falling off during solidification; Φ1 and Φ2 are 20mm and 10mm respectively, and h1 and h2 are 30mm and 5mm respectively.

[0045] The casting mold shell has seven layers: the first layer is 80-mesh alumina powder, the second layer is 60-mesh alumina sand, the third layer is 36-mesh alumina sand, the fourth to sixth layers are 24-mesh sand, and the seventh layer is a surface coating sealant. The casting mold shell is dried in air with a humidity >60% at a drying temperature of 30℃, and the drying time for each layer is controlled at 4 hours. The mold shell is dewaxed using steam, with the steam temperature controlled at 160℃ and the pressure controlled at 6 atmospheres, and the dewaxing time controlled at 10 seconds. The mold shell is sintered at 850℃ for 2 hours, and then furnace cooled to room temperature.

[0046] After the mold shell is prepared, the seed crystal is installed. The material of the seed crystal is the same as that of the casting alloy, which is CMSX-4 alloy; the seed crystal has a single crystal structure.

[0047] The preparation method for single-crystal castings is as follows:

[0048] 1. Lower the mold shell into the graphite insulation furnace so that the lowest end of the water cooling plate is flush with the lowest end of the heat insulation baffle. The inner diameter of the through hole of the heat insulation baffle is 10mm larger than the maximum outer diameter of the mold shell.

[0049] 2. Melting and Directional Solidification: During melting and directional solidification, the vacuum level is controlled at 5 Pa, and the alloy liquid temperature is maintained at 1520℃. Before alloy filling, the mold shell needs to be held in a graphite holding furnace for 10 minutes at a holding temperature of 1500℃. The temperature measuring thermocouple is a nickel-chromium / nickel-silicon coupler. After the alloy melting is completed, the crucible is raised, and the alloy liquid enters the mold shell. After the alloy liquid comes into contact with the seed crystal, the surface of the seed crystal partially melts. After the state stabilizes, the mold shell is pulled upwards, and the seed crystal grows epitaxially downwards. The growth rate is controlled by the pulling speed, and the upward pulling speed of the mold shell is controlled at 3 / min.

[0050] 3. After the leaf growth is complete, remove the mold shell to obtain a single-crystal casting. The microstructure of the casting is shown in the figure. Figure 4 .

[0051] Example 2

[0052] The mold shell is prepared using traditional precision casting technology, with a reserved space for the alloy melt inlet and the seed crystal installation. The alloy melt inlet space and the seed crystal installation space are formed using a wax model (mounted on the integral wax model) that is identical in shape and size to the original wax model. The space formed after dewaxing this part of the wax model is the location of the alloy melt inlet and the installation position of the seed crystal. The alloy melt inlet has a diameter of Φ5mm and a height of H20mm. The space for installing the seed crystal has a stepped structure to prevent the seed crystal from falling off during solidification; Φ1 and Φ2 are 20mm and 5mm respectively, and h1 and h2 are 50mm and 10mm respectively.

[0053] The casting mold shell has eight layers: the first layer is 80-mesh alumina powder, the second layer is 60-mesh alumina sand, the third layer is 36-mesh alumina sand, the fourth to seventh layers are 24-mesh sand, and the eighth layer is a surface coating sealant. The casting mold shell is dried in air with a humidity >60% at a drying temperature of 30℃, and the drying time for each layer is controlled at 4 hours. The mold shell is dewaxed using steam, with the steam temperature controlled at 180℃ and the pressure controlled at 6 atmospheres, and the dewaxing time controlled at 10 seconds. The mold shell is sintered at 1050℃ for 2 hours, and then furnace cooled to room temperature.

[0054] After the mold shell is prepared, the seed crystal is installed. The material of the seed crystal is the same as that of the casting alloy, which is DD6 alloy; the seed crystal has a single crystal structure.

[0055] The preparation method for single-crystal castings is as follows:

[0056] 1. Lower the mold shell into the graphite insulation furnace so that the lowest end of the water cooling plate is flush with the lowest end of the heat insulation baffle. The inner diameter of the through hole of the heat insulation baffle is 10mm larger than the maximum outer diameter of the mold shell.

[0057] 2. Melting and Directional Solidification: During melting and directional solidification, the vacuum level is controlled at 8 Pa, and the alloy liquid temperature is maintained at 1500℃. Before alloy filling, the mold shell needs to be held in a graphite holding furnace for 30 minutes at a holding temperature of 1500℃. The temperature measuring thermocouple is a platinum-rhodium-platinum coupler. After the alloy melting is completed, the crucible is raised, and the alloy liquid enters the mold shell. After the alloy liquid comes into contact with the seed crystal, the surface of the seed crystal partially melts. After the state stabilizes, the mold shell is pulled upwards, and the seed crystal grows epitaxially downwards. The growth rate is controlled by the pulling speed, and the upward pulling speed of the mold shell is controlled at 4 mm / min.

[0058] 3. After the leaf growth is complete, remove the mold shell to obtain the single crystal casting.

[0059] Example 3

[0060] The mold shell is prepared using traditional precision casting technology, with a reserved space for the alloy melt inlet and the seed crystal installation. The alloy melt inlet space and the seed crystal installation space are formed using a wax model (mounted on the integral wax model) that is identical in shape and size. The space formed after dewaxing this part of the wax model is the location of the alloy melt inlet and the installation position of the seed crystal. The alloy melt inlet has a diameter of Φ15mm and a height of H10mm. The space for installing the seed crystal has a stepped structure to prevent the seed crystal from falling off during solidification; Φ1 and Φ2 are 20mm and 8mm respectively, and h1 and h2 are 40mm and 10mm respectively.

[0061] The casting mold shell has seven layers: the first layer is 80-mesh alumina powder, the second layer is 60-mesh alumina sand, the third layer is 36-mesh alumina sand, the fourth to sixth layers are 24-mesh sand, and the seventh layer is a surface coating sealant. The mold shell is dried in air with a humidity >60% at a drying temperature of 23℃, and the drying time for each layer is controlled at 4 hours. The mold shell is dewaxed using steam, with the steam temperature controlled at 160℃ and the pressure controlled at 8 atmospheres, and the dewaxing time controlled at 10 seconds. The mold shell is fired at 850℃ for 4 hours, and then cooled in the furnace to room temperature.

[0062] After the mold shell is prepared, the seed crystal is installed. The material of the seed crystal is the same as that of the casting alloy, which is PWA1484 alloy; the seed crystal has a single crystal structure.

[0063] The preparation method for single-crystal castings is as follows:

[0064] 1. Lower the mold shell into the graphite insulation furnace so that the lowest end of the water cooling plate is flush with the lowest end of the heat insulation baffle. The inner diameter of the through hole of the heat insulation baffle is 15mm larger than the maximum outer diameter of the mold shell.

[0065] 2. Melting and Directional Solidification: During melting and directional solidification, the vacuum level is controlled at 2 Pa, and the alloy liquid temperature is maintained at 1490℃. Before alloy filling, the mold shell needs to be held in a graphite holding furnace for 10 minutes at a holding temperature of 1480℃. The temperature measuring thermocouple is a nickel-chromium / nickel-silicon coupler. After the alloy melting is completed, the crucible is raised, and the alloy liquid enters the mold shell. After the alloy liquid comes into contact with the seed crystal, the surface of the seed crystal partially melts. After the state stabilizes, the mold shell is pulled upwards, and the seed crystal grows epitaxially downwards. The growth rate is controlled by the pulling speed, and the upward pulling speed of the mold shell is controlled at 3 mm / min.

[0066] 3. After the leaf growth is complete, remove the mold shell to obtain the single crystal casting.

[0067] Example 4

[0068] The mold shell is prepared using traditional precision casting technology, with a reserved space for the alloy melt inlet and the seed crystal installation. The alloy melt inlet space and the seed crystal installation space are formed using a wax model (mounted on the integral wax model) that is identical in shape and size to the original wax model. The space formed after dewaxing this part of the wax model is the location of the alloy melt inlet and the installation position of the seed crystal. The alloy melt inlet has a diameter of Φ20mm and a height of H10mm; the space for installing the seed crystal has a wedge-shaped structure to prevent the seed crystal from falling off during solidification; Φ1 and Φ2 are 20mm and 5mm respectively, and h1 is 50mm.

[0069] The casting mold shell has six layers: the first layer is 80-mesh alumina powder, the second layer is 60-mesh alumina sand, the third layer is 36-mesh alumina sand, the fourth and fifth layers are 24-mesh sand, and the sixth layer is a surface coating sealant. The mold shell is dried in air with a humidity >60% at a drying temperature of 25℃, and the drying time for each layer is controlled at 4 hours. The mold shell is dewaxed using steam, with the steam temperature controlled at 160℃ and the pressure controlled at 6 atmospheres, and the dewaxing time controlled at 30 seconds. The mold shell is fired at 950℃ for 5 hours, and then cooled in the furnace to room temperature.

[0070] After the mold shell is prepared, the seed crystal is installed. The material of the seed crystal is the same as that of the casting alloy, which is DD413 alloy; the seed crystal has a single crystal structure.

[0071] The preparation method for single-crystal castings is as follows:

[0072] 1. Lower the mold shell into the graphite insulation furnace so that the lowest end of the water cooling plate is flush with the lowest end of the heat insulation baffle. The inner diameter of the through hole of the heat insulation baffle is 10mm larger than the maximum outer diameter of the mold shell.

[0073] 2. Melting and Directional Solidification: During melting and directional solidification, the vacuum level is controlled at 8 Pa, and the alloy liquid temperature is maintained at 1480℃. Before alloy filling, the mold shell needs to be held in a graphite holding furnace for 30 minutes at a holding temperature of 1480℃. The temperature measuring thermocouple is a nickel-chromium / nickel-silicon coupler. After the alloy melting is completed, the crucible is raised, and the alloy liquid enters the mold shell. After the alloy liquid comes into contact with the seed crystal, the surface of the seed crystal partially melts. After the state stabilizes, the mold shell is pulled upwards, and the seed crystal grows epitaxially downwards. The growth rate is controlled by the pulling speed, and the upward pulling speed of the mold shell is controlled at 6 mm / min.

[0074] 3. After the leaf growth is complete, remove the mold shell to obtain the single crystal casting.

[0075] Matters not covered in this invention are common knowledge.

[0076] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing single-crystal superalloy blades, characterized in that, The preparation is carried out using specialized equipment, the structure of which is as follows: A vacuum induction furnace (11) is located at the bottom of the equipment, and a crucible (8) is provided inside it. The crucible (8) is located on the crucible lifting mechanism (13), and a graphite heat preservation furnace (12) is located above the crucible (8). A pull-out mechanism (6) is set on the top of the equipment, and a water-cooling plate (5) is provided below it; the top of the mold shell (1) is provided with a seed crystal installation port for installing the seed crystal (2), and the bottom is provided with an alloy liquid inlet (3). The diameter Φ of the alloy liquid inlet (3) is 5-20mm and the height H is 10-20mm; after the mold shell (1) and the seed crystal (2) are assembled, they are fixed on the water-cooling plate (5) by a fixing clamp (4); the equipment is also provided with a heat insulation baffle (7) and a vacuum system (10), wherein the heat insulation baffle (7) with through holes is set parallel to the crucible (8) above the graphite heat preservation furnace (12), and the inner diameter of the through hole of the heat insulation baffle (7) is 10-20mm larger than the maximum outer diameter of the mold shell (1); The mold shell (1) is prepared by precision casting process, with a thickness of 5-8 layers. The sand material is alumina sand. The first layer is 80 mesh, the second layer is 60 mesh, the third layer is 36 mesh, the fourth to seventh layers are 24 mesh, and the eighth layer is sealed with surface coating. The fixing clamp (4) is made of molybdenum metal; The specific preparation steps are as follows: 1) After assembling the seed crystal (2) into the mold shell (1), use the fixing clamp (4) to fix the mold shell (1) onto the water cooling plate (5), and then lower the mold shell (1) into the graphite heat preservation furnace (12) so that the lowest end of the water cooling plate (5) and the lowest end of the heat insulation baffle (7) are at the same level. 2) Fill the crucible (8) with alloy material, use the vacuum system (10) to evacuate the vacuum, and after the vacuum degree reaches a certain standard, use the vacuum induction furnace (11) to melt the alloy. Before the alloy is filled into the mold, the temperature of the alloy liquid is kept at 1480-1520℃; at the same time, turn on the graphite heat preservation furnace (12) to preheat the mold shell (1). 3) After the alloy melting is completed, the crucible (8) is raised by the crucible lifting mechanism (13) to ensure that the mold shell (1) with the seed crystal (2) is immersed in the melt and remains stationary. After the alloy liquid comes into contact with the seed crystal (2), the surface of the seed crystal (2) partially melts. After the state stabilizes, the directional solidification pulling mechanism (6) starts to pull the mold shell (1) upward. The seed crystal (2) grows epitaxially downward. The growth rate is controlled by the pulling speed. The upward pulling speed of the mold shell (1) is controlled within the range of 3-10 mm / min. 4) After the leaves have grown, remove the mold shell (1) and clean it to obtain the casting.

2. The method for preparing single-crystal high-temperature alloy blades according to claim 1, characterized in that: The device is also equipped with a temperature measuring thermocouple, which is a nickel-chromium-nickel-silicon or platinum-rhodium-platinum thermocouple.

3. The method for preparing single-crystal high-temperature alloy blades according to claim 1, characterized in that: The mold shell (1) is dried in the air with an air humidity of >60% and a drying temperature of 23-35℃. The drying time for each layer is controlled at 2-4 hours. The mold shell (1) is dewaxed by steam with a steam temperature of 160-180℃, a pressure of 6-8 atmospheres, and a dewaxing time of 10-30 seconds. The mold shell (1) is baked at a temperature of 850-1050℃ for 2-5 hours and then cooled to room temperature in the furnace.

4. The method for preparing single-crystal high-temperature alloy blades according to claim 1, characterized in that: The material of the seed crystal (2) is the same as that of the casting alloy. The seed crystal (2) is a wedge-shaped structure or a stepped structure. The diameter of the large end section Φ1 of the seed crystal (2) is 10-50mm and the height h2 is 5-20mm. The diameter of the small end section Φ2 is 5-20mm and the height h1 is 30-50mm.

5. The method for preparing single-crystal high-temperature alloy blades according to claim 1, characterized in that: The mold shell (1) needs to be kept in a graphite heat preservation furnace (12) for 10-30 minutes, and the heat preservation temperature is 1470-1500℃.

6. The method for preparing single-crystal superalloy blades according to claim 1, characterized in that: The vacuum level during the smelting and directional solidification process is controlled within the range of 2-8 Pa.

7. The method for preparing single-crystal high-temperature alloy blades according to claim 1, characterized in that: When filling the alloy liquid, it is necessary to ensure that the seed crystal (2) does not completely melt.

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