Solid-liquid interface adjustable directional solidification furnace and solid-liquid interface adjusting method thereof

Abstract

The invention belongs to the field of material science and engineering, and discloses a solid-liquid interface adjustable directional solidification furnace and a solid-liquid interface adjusting method thereof.The solid-liquid interface adjustable directional solidification furnace comprises a furnace shell, a supporting frame is arranged in the furnace shell, a heat preservation assembly is arranged on the supporting frame, and a crucible and a heating assembly are arranged in the heat preservation assembly; the heat preservation assembly wraps the crucible and the heating assembly, the heating assembly comprises a plurality of sets of top heaters arranged at the top of the crucible at intervals in the axial direction, a plurality of sets of bottom heaters arranged at the bottom of the crucible at intervals in the axial direction and an end face heater, and the end face heater is located at the end, opposite to the seed crystal end, of the crucible; the left side and the right side of the bottom heater extend upwards to the left side and the right side of the crucible. Three groups of independently controlled heaters are respectively arranged at the top, the bottom and one side of a crucible. By adjusting the power distribution of the heater, the shape of the solid-liquid interface can be flexibly controlled, so that the solid-liquid interface is in a concave, convex, flat or inclined state.

Description

Technical Field

[0001] This invention relates to the field of materials science and engineering, specifically to a directional solidification furnace with adjustable solid-liquid interface and a method for adjusting the solid-liquid interface. Background Technology

[0002] In the field of materials science, directional solidification is a key material forming method widely used in the manufacture of alloys, ceramics, and crystalline materials. The core of this technology is the control of the solid-liquid interface formed during solidification. By precisely managing the temperature gradient, the microstructure and properties of the final material can be significantly influenced. Directional solidification primarily achieves the movement and morphological control of the solid-liquid interface through the adjustment of the internal temperature gradient.

[0003] In directional solidification, the axial temperature gradient directly determines the material's growth rate, thus affecting the crystal quality and grain size. The radial temperature gradient, on the other hand, significantly influences the shape of the solid-liquid interface. Different interface shapes (such as planar or uneven surfaces) have drastically different effects on the material's macroscopic properties. For example, a smooth solid-liquid interface is conducive to obtaining a uniform, fine grain structure, while an uneven interface easily leads to compositional segregation and structural defects.

[0004] Existing directional solidification furnaces typically have limitations in temperature field control, making it impossible to precisely regulate the morphology and position of the solid-liquid interface. This leads to uneven cooling and localized overcooling during material growth, affecting the uniformity and consistency of the material's microstructure and even causing crystal defects and instability in mechanical properties. Furthermore, current technologies often cannot simultaneously address the individualized needs of different materials during directional solidification, making it difficult to achieve customized control for various materials.

[0005] To improve the precise control of the solid-liquid interface morphology and position during directional solidification, an improved directional solidification device and control method are needed to overcome the limitations of existing technologies. This device can achieve precise movement and morphological control of the solid-liquid interface by adjusting the axial and radial temperature gradients, thereby optimizing the microstructure properties of the material and significantly improving its mechanical properties and service stability. This has significant application prospects for the development of novel high-performance alloys, ceramics, and high-quality crystalline materials, especially in high-end manufacturing fields such as aerospace, electronic devices, and high-temperature structural materials. Summary of the Invention

[0006] The purpose of this invention is to provide a directional solidification furnace with an adjustable solid-liquid interface and a method for adjusting the solid-liquid interface, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A directional solidification furnace with adjustable solid-liquid interface includes a furnace shell, a support frame disposed inside the furnace shell, a heat insulation component disposed on the support frame, a crucible and a heating component disposed within the heat insulation component, the heat insulation component enclosing the crucible and the heating component, the heating component including multiple sets of top heaters spaced axially at the top of the crucible, multiple sets of bottom heaters spaced axially at the bottom of the crucible, and end face heaters, the end face heaters being located at the end of the crucible facing away from the seed crystal, and the left and right sides of the bottom heaters extending upward to the left and right sides of the crucible.

[0008] Furthermore, the number of top heaters and bottom heaters is the same, and they correspond one-to-one.

[0009] Furthermore, the heat preservation assembly includes a first heat preservation module and a second heat preservation module. The first heat preservation module and the second heat preservation module are vertically sleeved on the crucible. The number of the first heat preservation modules is the same as the number of the top heater and the bottom heater. The first heat preservation module, the top heater, and the bottom heater correspond one-to-one. The first heat preservation module has a ring structure. The top heater and the bottom heater are disposed on the inner wall of the first heat preservation module. The second heat preservation module is disposed between adjacent first heat preservation modules and is in close contact with the crucible. It is used to isolate the top heater and the bottom heater distributed along the axial direction.

[0010] Furthermore, the heat preservation assembly also includes a third heat preservation module and a fourth heat preservation module. The third heat preservation module is located at the end of the crucible facing away from the seed crystal and is used to install an end face heater. The fourth heat preservation module has two sets, front and rear, located at the front and rear ends of the crucible respectively. The fourth heat preservation module at the front end of the crucible is located outside the third heat preservation module.

[0011] Furthermore, the first, second, and third insulation modules are all vertically arranged ring structures. The second and third insulation modules have the same structure and can be interchanged. The fourth insulation module is a non-hollow block structure.

[0012] Furthermore, the support frame is arranged outside the insulation component, and its axial length and width in the left and right directions can be adjusted.

[0013] Furthermore, a transmission device is also provided in the furnace shell, which is used to support and drive the support frame to move horizontally.

[0014] The present invention also provides a method for controlling the solid-liquid interface of a directional solidification furnace as described above, characterized by comprising the following steps: Step 1: Determine the thermal field: Determine the basic parameters of the thermal field, including the crucible size and shape, the shape, quantity and arrangement of the heaters, and the size of the insulation components; Step 2: Raw material preparation Arrange the processed seed crystals neatly on one side of the crucible, and then neatly spread the raw material on the remaining area of ​​the crucible; place the crucible in the heating field, ensuring that the seed crystals are far away from the end face heater; Step 3, Preheating stage: Turn on the top heater, bottom heater, and end-face heater. Heat the raw material and gradually melt it from one side of the end-face heater towards the side closer to the seed crystal, until it reaches the middle area of ​​the crucible. Maintain the solid-liquid interface stability for a certain period of time and record the output power of each heater at this time. Ensure that the radial temperature distribution of the thermal field is uniform and avoid local overheating or undercooling. At the same time, the axial temperature distribution requires that the temperature at the seed crystal end of the crucible is always the lowest. Step 4, Solid-Liquid Interface Formation Stage: Based on the output power of each heater recorded in step 3 and the shape of the target solid-liquid interface, adjust the power ratio of the top heater, bottom heater, and end face heater to ensure that the solid-liquid interface remains stable for a certain period of time. Specific adjustment methods include: Planar solid-liquid interface: Compared to the preheating stage in step 3, maintain the output power of the top heater, bottom heater and end face heater; Concave solid-liquid interface: Compared with the preheating stage in step 3, increase the output power of the end face heater and reduce the output power of the top heater and bottom heater; Convex solid-liquid interface: Compared to the preheating stage in step 3, increase the output power of the top heater and bottom heater, and decrease the output power of the end face heater; Sloping solid-liquid interface: Compared with the preheating stage in step 3, according to the required slope angle, gradually increase the power of the top heater, while gradually decrease the power of the bottom heater, and gradually decrease the power of the end heater, or gradually decrease the power of the top heater, while gradually increasing the power of the bottom heater, and gradually decreasing the power of the end heater. After the target solid-liquid interface is formed and stabilized for a certain period of time, record the output power of each heater at this time; Step 5, Interface Movement Control Stage: First, gradually increase the output power of each heater in the same proportion, control the solid-liquid interface to gradually move towards the seed crystal until the seed crystal melts, ensuring that more than two-thirds of the seed crystal is still solid, and then stabilize the solid-liquid interface for a certain period of time. Then, the output power of each heater is gradually reduced in the same proportion to control the stable movement of the solid-liquid interface, thereby completing the directional solidification and growth of the material. Step 6, Cooling Stage: After directional solidification is completed, each heater is gradually adjusted to reduce the axial and radial temperature gradients inside the thermal field, ensuring that the material is completely solidified while the temperature in each place tends to be uniform; then, the power of each heater is gradually reduced to uniformly reduce the temperature inside the crucible.

[0015] Furthermore, the power and heating / cooling rates of each heater are set according to the thermophysical parameters of different materials to ensure that different materials obtain the optimal microstructure during solidification. The temperature is monitored in real time by thermocouples installed at different positions in the crucible, and the axial and radial temperature gradients are calculated. The power of each heater is dynamically adjusted to ensure the stability and precise control of the solid-liquid interface.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention employs three independently controlled heaters, which are located at the top, bottom and side of the crucible respectively. By using different power ratios, the solid-liquid interface shape can be either concave or convex and inclined.

[0017] 2. This invention employs a tightly enclosed crucible and a partially shielded heater insulation structure design. While achieving high insulation performance, it avoids the dispersed propagation of heat radiation, effectively improving the control range of the internal axial and radial temperature gradients, thereby enabling greater control over the solid-liquid interface shape.

[0018] 3. This invention employs a modularly designed heater and insulation structure, along with a retractable thermal field fixing frame mounted on a transmission device. This facilitates the construction of thermal fields of different sizes and multiple temperature zones.

[0019] 4. This invention provides a heater power setting method, offering guidance for controlling the directional solidification preparation process and accurately controlling solid-liquid interfaces of different shapes. Attached Figure Description

[0020] Figure 1 This is one of the schematic diagrams of the internal structure of a directional solidification furnace with adjustable solid-liquid interface according to the present invention.

[0021] Figure 2 This is a second schematic diagram of the internal structure of a directional solidification furnace with adjustable solid-liquid interface according to the present invention. The furnace shell is not shown in the figure.

[0022] Figure 3 The following are simulation diagrams of different solid-liquid interfaces in this invention. In the figure, (a) represents a convex solid-liquid interface, (b) represents a planar solid-liquid interface, (c) represents a concave solid-liquid interface, and (d) and (e) represent inclined solid-liquid interfaces.

[0023] Reference numerals: 11. Top heater; 12. Bottom heater; 13. End face heater; 21. First insulation module; 22. Second insulation module; 23. Third insulation module; 24. Fourth insulation module; 3. Crucible; 4. Observation window; 5. Frame assembly; 51. Outer shell; 52. Bolt; 53. Double-ended screw; 54. Fixed base; 6. Transmission device; 61. Servo motor; 62. Bearing seat; 63. Ball screw; 64. Slide rail base; 7. Furnace shell. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see Figure 1 and Figure 2 A directional solidification furnace with adjustable solid-liquid interface includes a furnace shell 7, a support frame 5 inside the furnace shell 7, a heat insulation component on the support frame 5, a crucible 3 and a heating component within the heat insulation component, and the heat insulation component enclosing the crucible 3 and the heating component. The heating component includes multiple sets of top heaters 11 spaced axially at the top of the crucible 3, multiple sets of bottom heaters 12 spaced axially at the bottom of the crucible 3, and end-face heaters 13. The bottom heaters 12 have a U-shaped structure, with their left and right sides extending upwards to the left and right sides of the crucible 3. The arrangement of the top heaters 11 and bottom heaters 12 forms a balanced temperature field. The end-face heaters 13 are located at the end of the crucible 3 facing away from the seed crystal end, and are used to achieve radial temperature control. All heaters are made of graphite, possessing good thermal conductivity and high-temperature stability. The heaters are evenly distributed around the crucible 3, maintaining a consistent distance from it. Each heater is equipped with a thermocouple, which is fixed in place by an insulation component. The thermocouple is used to detect the temperature of the area where each heater is located. By independently adjusting the heater power, the solid-liquid interface morphology can be precisely controlled.

[0026] The heating component is fixed to the insulation component. The rear end of the crucible 3 has a pre-set seed crystal, while the front end does not. The seed crystal serves several purposes: 1) to induce consistent crystal orientation for directional solidification growth; 2) to control the initial grain size; and 3) to reduce grain boundaries and defects. The crucible 3 adopts a double-layer structure design, with a 2 mm thick quartz inner layer and a 2 mm thick graphite outer layer. This design effectively reduces heat loss and improves the structural strength of the crucible.

[0027] Continue reading Figure 1 and Figure 2The number of top heaters 11 and bottom heaters 12 is the same, and they correspond one-to-one. The heat preservation assembly includes a first heat preservation module 21 and a second heat preservation module 22. The first heat preservation module 21 and the second heat preservation module 22 are vertically sleeved on the crucible 3. The number of first heat preservation modules 21 is the same as the number of top heaters 11 and bottom heaters 12. The first heat preservation module 21, the top heater 11 and the bottom heater 12 correspond one-to-one. The first heat preservation module 21 has a ring structure. The top heaters 11 and the bottom heaters 12 are disposed on the inner wall of the first heat preservation module 21. The second heat preservation module 22 is disposed between adjacent first heat preservation modules 21 and is in close contact with the crucible 3. It is used to isolate the top heaters 11 and the bottom heaters 12 that are distributed along the axial direction.

[0028] Continue reading Figure 1 and Figure 2 The insulation component also includes a third insulation module 23 and a fourth insulation module 24. The third insulation module 23 is located at the end of the crucible 3 facing away from the seed crystal and is used to install the end face heater 13. The fourth insulation module 24 has two sets, front and rear, located at the front and rear ends of the crucible 3 respectively. The fourth insulation module 24 at the front end of the crucible 3 is located outside the third insulation module 23.

[0029] The first insulation module 21, the second insulation module 22, and the third insulation module 23 are all vertically arranged ring structures, and all are made of rigid graphite felt. The second insulation module 22 and the third insulation module 23 have the same structure and are interchangeable. The fourth insulation module 24 is a non-hollow block structure made of graphite plates. The first insulation module 21 is designed as a structure that partially encloses the heater to avoid the spread of heat radiation and improve heating efficiency. The fourth insulation module 24 is used to seal the two ends of the thermal field along the axis, reduce convective heat transfer, and improve the overall efficiency of the thermal field.

[0030] The heater and insulation module of this invention are both modularly designed, which facilitates the construction and disassembly of the thermal field according to different thermal field sizes and temperature control accuracy requirements.

[0031] Continue reading Figure 1 and Figure 2 The support frame 5 is installed around the insulation component, and its axial length and lateral width are adjustable. The support frame 5 includes a shell 51, bolts 52, double-ended screws 53, and a fixing base 54. The support frame 5 is used to fix the entire thermal field and has an adjustable telescopic function to accommodate different thermal field sizes. The main body of the support frame 5 is made of stainless steel.

[0032] The multiple outer shells 51 are connected to form a rectangular frame structure by bolts 52 and double-ended screws 53. The bolts 52 connect the horizontal part of the frame structure, and the double-ended screws 53 connect the vertical part of the frame structure. The size of the supporting frame 5 can be adjusted by adjusting the bolts 52 and double-ended screws 53. This is known technology.

[0033] Continue reading Figure 1 and Figure 2 The furnace shell 7 is also equipped with a transmission device 6, which supports the support frame 5 and drives the support frame 5 to move axially. The transmission device 6 is preferably a ball screw transmission device, whose structure is known technology, and includes a servo motor 61, a bearing housing 62, a ball screw 63, and a slide rail base 64, used to move the hot zone during installation and disassembly. The transmission device 6 can also employ cylinders, hydraulic cylinders, or other similar devices.

[0034] Continue reading Figure 1 and Figure 2 An observation window 4 is provided on the second insulation module 22 and the furnace shell 7 so that the changes at the boundary between the seed crystal and the raw material and the solid-liquid interface during the directional solidification process can be observed.

[0035] The present invention also provides a method for controlling the solid-liquid interface of the directional solidification furnace as described above, comprising the following steps: Step 1: Determine the thermal field: Determine the basic parameters of the thermal field, including the size and shape of crucible 3, the shape, number and arrangement of heaters, and the size of the insulation structure.

[0036] Step 2: Raw material preparation Arrange the processed seed crystals neatly on one side of crucible 3, ensuring they fit snugly against the crucible wall with small gaps and are level with the top of the crucible. Then, neatly spread the raw material on the remaining area of ​​the crucible. Place the crucible in the heating field, ensuring the seed crystals are far away from the end face heater 13.

[0037] Step 3, Preheating stage: Turn on the top heater 11, bottom heater 12, and end-face heater 13. The heating material gradually melts from the end-face heater 13 towards the seed crystal, reaching the middle region of crucible 3 (i.e., melting to the middle region of crucible 3 and ceasing further melting towards the seed crystal). Maintain a stable solid-liquid interface for at least 10 minutes, recording the output power of each heater during this time. Ensure uniform radial temperature distribution in the thermal field to avoid localized overheating or undercooling. Simultaneously, the axial temperature distribution requires the temperature at the seed crystal end to always be the lowest (i.e., the temperature on the seed crystal side is the lowest within the overall crucible structure), maintaining a unidirectional temperature distribution in the thermal field to promote the stable progress of the subsequent directional solidification process.

[0038] Throughout the process, the melting of the raw material is monitored in real time through the observation window to ensure that the half of the raw material away from the seed crystal is melt and the other half closer to the seed crystal is solid, with the solid-liquid interface located in the middle area of ​​the crucible.

[0039] Step 4, Solid-Liquid Interface Formation Stage: Based on the output power of each heater and the shape of the target solid-liquid interface recorded in step 3 above, adjust the power ratio of the top heater 11, bottom heater 12, and end face heater 13 to ensure that the solid-liquid interface remains stable for at least 10 minutes. Specific adjustment methods include: Planar solid-liquid interface: Compared to the preheating stage in step 3, maintain the output power of the top heater 11, bottom heater 12 and end face heater 13.

[0040] Concave solid-liquid interface: Compared with the preheating stage in step 3, the output power of the end face heater 13 is increased, while the output power of the top heater 11 and the bottom heater 12 is reduced.

[0041] Convex solid-liquid interface: Compared with the preheating stage in step 3, the output power of the top heater 11 and the bottom heater 12 is increased, while the output power of the end face heater is reduced.

[0042] Sloping solid-liquid interface: Compared with the preheating stage in step 3, according to the required slope angle, the power of the top heater 11 is gradually increased while the power of the bottom heater 12 and the power of the end heater 13 are gradually decreased, or the power of the top heater 11 is gradually decreased while the power of the bottom heater 12 is gradually increased and the power of the end heater 13 is gradually decreased.

[0043] After the target solid-liquid interface is formed and stabilized for more than 10 minutes, record the output power of each heater at this time.

[0044] Step 5, Interface Movement Control Stage: First, gradually increase the output power of each heater recorded in step 4 according to the same ratio, and control the solid-liquid interface to gradually move towards the seed crystal until the seed crystal melts, ensuring that more than two-thirds of the seed crystal is still solid. At this time, stabilize the solid-liquid interface for more than 10 minutes.

[0045] Subsequently, the output power of each heater is gradually reduced in the same proportion to control the stable movement of the solid-liquid interface, thereby completing the directional solidification growth of the material. Specifically, by simultaneously reducing the power of the top heater 11, bottom heater 12, and end-face heater 13, the temperature field changes are kept stable, preventing interface instability caused by temperature fluctuations. At the same time, the power ratio between each heater should be kept constant to maintain the stability of the interface morphology. By carefully controlling the rate of power change, the solid-liquid interface is ensured to move smoothly in the predetermined direction, ultimately achieving uniform growth of the microstructure during directional solidification.

[0046] Step 6, Cooling Stage: After directional solidification, the heaters are gradually adjusted to reduce the axial and radial temperature gradients within the thermal field, ensuring complete material solidification and uniform temperature distribution. Subsequently, the power of each heater is gradually reduced to uniformly lower the temperature within crucible 3. The cooling rate should be strictly controlled throughout the cooling process to avoid thermal stress accumulation due to excessive temperature gradients.

[0047] Specifically, the power and heating / cooling rates of each heater are set according to the thermophysical properties (such as thermal conductivity and specific heat capacity) of different materials to ensure that different materials obtain the optimal microstructure during solidification. Thermocouples installed at different positions in crucible 3 are used to monitor the temperature in real time, and then the axial and radial temperature gradients are calculated. The power of each heater is dynamically adjusted to ensure the stability and precise control of the solid-liquid interface.

[0048] In practice, different solid-liquid interface shapes can be achieved by adjusting the power ratio of each heater. The following examples illustrate several methods for realizing solid-liquid interface shapes: Convex solid-liquid interface: End face heater 13 outputs 574 watts; left bottom heater 12 outputs 580 watts, middle bottom heater 12 outputs 176 watts; left top heater 11 outputs 453 watts, middle top heater 11 outputs 77 watts; the remaining heaters have no output power. When the thermal field reaches a stable state, a convex solid-liquid interface can be formed, such as... Figure 3 As shown in (a).

[0049] Planar solid-liquid interface: End face heater 13 outputs 550 watts; left bottom heater 12 outputs 540 watts, middle bottom heater 12 outputs 200 watts, right bottom heater 12 outputs 390 watts; left top heater 11 outputs 440 watts, middle top heater 11 outputs 110 watts, and right top heater 11 outputs 275 watts. When the thermal field reaches a stable state, a planar solid-liquid interface can be formed, such as... Figure 3 As shown in (b).

[0050] Concave solid-liquid interface: The bottom right heater 12 has an output power of 540 watts, and the middle bottom heater 12 has an output power of 502 watts; the top right heater 11 has an output power of 395 watts, and the middle top heater 11 has an output power of 374 watts; the remaining heaters have no output power. After the thermal field stabilizes, a concave solid-liquid interface can be formed, such as... Figure 3 As shown in (c).

[0051] Inclined solid-liquid interface (tilted to the upper left): The left top heater 11 has an output power of 732 watts, the middle top heater 11 has an output power of 685 watts, and the right top heater 11 has an output power of 385 watts. This configuration enables a solid-liquid interface tilted to the upper left, such as... Figure 3 As shown in (d).

[0052] Inclined solid-liquid interface (tilted to the upper right): The left bottom heater 12 has an output power of 685 watts, the middle top heater 11 has an output power of 543 watts, and the right top heater 11 has an output power of 338 watts. This configuration enables a solid-liquid interface tilted to the upper right, such as... Figure 3 As shown in (e).

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A directional solidification furnace with adjustable solid-liquid interface, characterized in that: The invention comprises a furnace shell (7), a support frame (5) is arranged in the furnace shell (7), a heat-insulating component is arranged on the support frame (5), a crucible (3) and a heating component are arranged in the heat-insulating component, the heat-insulating component wraps the crucible (3) and the heating component, the heating component comprises a plurality of groups of top heaters (11) arranged at intervals along the axial direction at the top of the crucible (3), a plurality of groups of bottom heaters (12) arranged at intervals along the axial direction at the bottom of the crucible (3), and an end surface heater (13), the end surface heater (13) is located on a side of the crucible (3) facing away from the seed crystal end, and the left and right sides of the bottom heater (12) extend upward to the left and right sides of the crucible (3).

2. The directional solidification furnace with controllable solid-liquid interface according to claim 1, characterized in that: The top heaters (11) and the bottom heaters (12) are the same in number and correspond one to another.

3. The directional solidification furnace with controllable solid-liquid interface according to claim 2, characterized in that: The thermal insulation component comprises a first thermal insulation module (21) and a second thermal insulation module (22); the first thermal insulation module (21) and the second thermal insulation module (22) are sleeved on the crucible (3) in a vertical direction; the number of the first thermal insulation modules (21) is the same as the number of the top heater (11) and the bottom heater (12); the first thermal insulation module (21), the top heater (11) and the bottom heater (12) correspond to each other one by one; the first thermal insulation module (21) is an annular structure; the top heater (11) and the bottom heater (12) are arranged on the inner wall of the first thermal insulation module (21); the second thermal insulation module (22) is arranged between adjacent first thermal insulation modules (21) and is in close contact with the crucible (3); and is used to isolate the top heater (11) and the bottom heater (12) distributed along the axial direction.

4. The directional solidification furnace with controllable solid-liquid interface according to claim 3, characterized in that: The thermal insulation component further comprises a third thermal insulation module (23) and a fourth thermal insulation module (24); the third thermal insulation module (23) is located on a side of the crucible (3) facing away from the seed crystal end and is used to install an end surface heater (13); the fourth thermal insulation module (24) comprises two groups, front and rear, respectively located at the front and rear ends of the crucible (3); the fourth thermal insulation module (24) at the front end of the crucible (3) is located outside the third thermal insulation module (23).

5. The directional solidification furnace with controllable solid-liquid interface according to claim 3, characterized in that: The first thermal insulation module (21), the second thermal insulation module (22), and the third thermal insulation module (23) are all vertically arranged annular structures; the second thermal insulation module (22) and the third thermal insulation module (23) have the same structure and are interchangeable; and the fourth thermal insulation module (24) is a non-hollow block structure.

6. The directional solidification furnace with controllable solid-liquid interface according to claim 1, characterized in that: The support frame (5) is arranged outside the heat preservation component, and its axial length and width in the left-right direction are adjustable.

7. The directional solidification furnace with controllable solid-liquid interface according to claim 1, characterized in that: A transmission device (6) is also provided in the furnace shell (7), and the transmission device (6) is used to support the support frame (5) and drive the support frame (5) to move horizontally.

8. A method for controlling the solid-liquid interface of a directional solidification furnace as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1: Determine the thermal field: Determine the basic parameters of the thermal field, including the size and shape of the crucible (3), the shape, number and arrangement of the heaters, and the size of the insulation components; Step 2: Raw material preparation Arrange the processed seed crystals neatly and place them on one side of the crucible (3), and then spread the raw materials neatly on the remaining area of ​​the crucible (3); place the crucible (3) in a hot field, ensuring that the seed crystals are away from the end heater (13); Step 3: Preheating stage: Turn on the top heater (11), the bottom heater (12) and the end heater (13), heat the raw material from the end heater (13) side to gradually melt it toward the side close to the seed crystal to the middle area of ​​the crucible (3), and maintain the solid-liquid interface stable for a certain period of time, and record the output power of each heater at this time; ensure that the radial temperature distribution of the heat field is uniform to avoid local overheating or overcooling; at the same time, the axial temperature distribution requires that the temperature of the seed crystal end of the crucible (3) is always at the lowest; Step 4, solid-liquid interface formation stage: According to the output power of each heater recorded in step 3 and the shape of the target solid-liquid interface, the power ratio of the top heater (11), the bottom heater (12) and the end heater (13) is adjusted to ensure that the solid-liquid interface is kept stable for a certain period of time. The specific adjustment method includes: Planar solid-liquid interface: compared with the preheating stage in step 3, the output power of the top heater (11), the bottom heater (12) and the end heater (13) is maintained; Concave solid-liquid interface: compared with the preheating stage in step 3, the output power of the end heater (13) is increased, and the output power of the top heater (11) and the bottom heater (12) is reduced; Convex solid-liquid interface: compared with the preheating stage in step 3, the output power of the top heater (11) and the bottom heater (12) is increased, and the output power of the end heater is reduced; Inclined solid-liquid interface: Compared with the preheating stage of step 3, according to the inclined angle requirement, the power of the top heater (11) is gradually increased, while the power of the bottom heater (12) is gradually decreased, and the power of the end heater (13) is gradually decreased, or the power of the top heater (11) is gradually decreased, while the power of the bottom heater (12) is gradually increased, and the power of the end heater (13) is gradually decreased; After the target solid-liquid interface is formed and stabilized for a certain period of time, the output power of each heater is recorded; Step 5: Interface movement control stage: First, the output power of each heater is gradually increased in the same proportion, and the solid-liquid interface is controlled to gradually move toward the seed crystal until the seed crystal melts, ensuring that more than two-thirds of the seed crystal is still solid. At this time, the solid-liquid interface is stabilized for a certain period of time; Then, the output power of each heater is gradually reduced in the same proportion to control the stable movement of the solid-liquid interface, thereby completing the directional solidification growth of the material; Step 6, Cooling Phase: After the directional solidification is completed, each heater is gradually adjusted to reduce the axial and radial temperature gradients inside the heat field to ensure that the material is completely solidified while the temperature in each place tends to be consistent; then, the power of each heater is gradually reduced to evenly reduce the temperature in the crucible (3).

9. A solid-liquid interface control method according to claim 8, characterized in that: The power and heating and cooling rates of each heater are set according to the thermophysical parameters of different materials to ensure that different materials obtain the best microstructure during the solidification process; the temperature is monitored in real time by thermocouples installed at different positions of the crucible (3), and the axial and radial temperature gradients are calculated, and the power of each heater is dynamically adjusted to ensure the stability and precise control of the solid-liquid interface.

Images