Method and apparatus for making a composite structure crucible

Abstract

The application relates to a manufacturing method and device of a composite structure crucible, which comprises the following steps: fixing a treated rigid shell to a rotating motor and stably rotating in a closed chamber; putting a silica precursor into the rigid shell; using a plasma arc to heat the precursor to form a fusion layer and sufficiently melt the fusion layer to tightly adhere to the rigid shell to form an integrated composite structure crucible; in the process of heating by the plasma arc, the average volume of bubbles in the fusion layer is adjusted by controlling the pressure of a melting area or the gas content of the melting area which can be dissolved in the fusion layer or by controlling the pressure of a precursor area to control the density of the fusion layer; and the composite structure crucible is formed by using the above method through a manufacturing device. In the application, the fusion layer and the rigid shell are tightly combined to form an integrated structure, so that the problems of edge collapse, bulging and wrinkle caused by the gap between layers and the lack of tight support are avoided.

Description

Technical Field

[0001] This invention relates to the field of crucible manufacturing technology for high-temperature melts, specifically a method and apparatus for manufacturing a composite structure crucible. Background Technology

[0002] Existing high-temperature melt crucibles require the preparation of a high-temperature resistant ceramic blank, followed by sintering in an electric resistance furnace, electromagnetic induction furnace, or combustible gas furnace. Because this involves melting and bonding the edge particles of the high-temperature resistant material powder together, the finished product often contains pores that affect its strength and density. Furthermore, different materials exhibit varying high-temperature strength and thermal shock resistance, and their different coefficients of thermal expansion make it difficult to sinter materials with different performance advantages together to obtain a crucible that balances these strengths. In the current Czochralski single-crystal silicon industry, quartz crucibles are prepared using the electric arc method as containers for high-temperature molten silicon. At high temperatures, the quartz crucible softens and deforms, requiring a graphite or carbon-carbon crucible to provide support. Since both the quartz and graphite / carbon-carbon crucibles are rigid at room temperature and have machining tolerances, a gap of 3mm-10mm must be maintained between them to accommodate the quartz crucible. Under the pressure and high temperature of molten silicon, the walls of the quartz crucible gradually soften and expand outwards, adhering to the inner walls of the graphite or carbon-carbon crucible, causing vibration. At the same time, the gas generated by the chemical reaction at the junction of the quartz crucible and the graphite or carbon-carbon crucible cannot be discharged in time, resulting in bulging. The upper edge of the quartz crucible will also collapse due to gravity. The above series of problems directly affect the single crystal pulling process.

[0003] Chinese invention patent CN118326498B discloses a multilayer composite quartz crucible for monocrystalline silicon production and its preparation method, which involves coating the outer wall of the quartz crucible with a silicon carbide organic layer to suppress gas generation. However, this silicon carbide organic layer is generated by a chemical reaction during the high-temperature crystal pulling process. In the early stages of use, the high-temperature sidewalls of the quartz crucible still soften, expand, collapse, and deform due to overall collapse. Furthermore, the silicon carbide organic layer is too thin to effectively support the quartz crucible, requiring a graphite crucible to be used. Additionally, deformation of the quartz crucible can lead to cracking or fissures in the silicon carbide organic layer. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for manufacturing a composite structure crucible, solving the problems of insufficient melting of powder particles, high porosity, insufficient strength and density, and low sintering efficiency in existing ceramic material crucibles. It also addresses the problems of high-temperature deformation, cracking, bulging, edge collapse, and crystal pulling liquid surface vibration in existing quartz crucibles, improving the efficiency and quality of single crystal pulling, reducing manufacturing costs, and extending the service life of the crucible. Furthermore, by combining different materials, the crucible simultaneously possesses the superior properties of different materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for manufacturing a composite structure crucible, comprising the following steps: Step 1: An existing rigid crucible is used as the rigid outer shell. This shell maintains its rigidity throughout the fabrication and application of the composite crucible. To increase the contact area, the rigid outer shell, with a thickness of 0.3 mm to 150 mm, is formed into a randomly distributed pit structure through grinding, chemical etching, or sandblasting. The pits have a diameter of 0.01 mm to 5 mm and a depth of 0.01 mm to 5 mm, not exceeding one-third of the crucible wall thickness. This pit structure creates a "pinning" effect between the rigid outer shell and the fusion layer, strengthening the connection. "Pinning" refers to the mechanical interlocking structure formed after the fusion layer material fills the pits on the inner surface of the rigid outer shell and cools.

[0006] Step 2: Fix the processed rigid shell to the rotating motor for stable rotation; put the silica-containing precursor into the rotating rigid shell, and use a molding rod or brush to evenly attach the precursor to the inner surface of the rigid shell and keep it fixed relative to the rigid shell; due to the centrifugal force generated by the rotation of the rotating motor, the precursor and the inner surface of the rigid shell rotate together and maintain a relatively fixed position.

[0007] Step 3: Using plasma arc heating, the precursor attached to the inner surface of the rigid shell is gradually melted layer by layer from the inner surface close to the arc to form a fusion layer. The fusion layer continuously thickens and completely adheres to the inner surface of the rigid shell to form an integrated structure. The thickness of the fusion layer is 0.01 mm to 160 mm. Before the introduction of the plasma arc and during the plasma arc heating process, the density of the fusion layer is adjusted by controlling the pressure or atmosphere of the melting environment, or by controlling the pressure of the local area where the precursor is located. The ambient pressure range is 20 Pa to 10 MPa, and the pressure range of the local area where the precursor is located is 20 Pa to 0.1 MPa.

[0008] The average volume V2 of the dispersed and encapsulated bubbles in the fusion layer is adjusted by setting and controlling β, P1, and P2 using formula (1), thereby adjusting the density of the fusion layer: (1) Wherein, P1 is the pressure of the environment in which the precursor is located before melting or the pressure of a local area of ​​the precursor; P2 is the pressure of the environment in which the precursor is located after melting; V1 is the average volume of dispersed bubbles obtained by melting the precursor under certain pressure and atmosphere without soluble gases and measuring the fusion layer using an optical microscope or scanning electron microscope, and is a characteristic data of the raw material used; β is the volume content of gas in the gas in the environment in which the precursor is located before melting that can be dissolved in the fusion layer; γ is a dissolution efficiency coefficient of 0.5 to 0.95, which is the proportion of soluble gas dissolved into the target fusion layer at high temperature, and is obtained by actual measurement and calculation; V2 is the average volume of dispersed bubbles in the fusion layer under the conditions of setting and controlling β, P1, and P2.

[0009] The aforementioned precursor can be a single layer or multiple layers, each with a different material; the resulting fusion layer can be of a single composition or a multi-layer structure with different compositions for each layer; from the perspective of density, the fusion layer can be of a single density or a multi-layer structure with different densities for each layer.

[0010] Step 4: After completing the above steps, stop heating, cool, and remove to form a composite structure crucible.

[0011] The control of the pressure or atmosphere of the environment in step three above is achieved by setting the process described in step three to be carried out in a closed chamber, and adjusting the pressure or atmosphere in the closed chamber by using a vacuum pump to evacuate the closed chamber and using a gas filling mechanism to fill the closed chamber; the pressure range in the closed chamber is 200 Pa to 2 MPa, and the atmosphere includes gases that are soluble in the fusion layer and gases that are not soluble in the fusion layer. The gases that are soluble in the fusion layer include hydrogen, helium, or water vapor or a mixture of two or more of the above gases.

[0012] In step three above, controlling the pressure in the local area where the precursor is located is achieved by first melting the inner surface of the precursor to form an integral inner surface fusion layer. The upper edge of this fusion layer is connected to the upper edge of a vacuum water jacket that holds the rigid outer shell and can introduce vacuum into the precursor, forming an airtight space enclosing the precursor. A vacuum pump is used to control the pressure of the airtight space of the precursor through the vacuum water jacket. The vacuum water jacket introduces the vacuum generated by the vacuum pump into the precursor through the vent holes in its upper inner area. The pressure range of the airtight space of the precursor is 200 Pa to 0.1 MPa. The airtight space refers to the closed space enclosing the unmelted precursor formed by the tight connection between the inner surface fusion layer and the upper edge of the vacuum water jacket.

[0013] According to formula (1) in step three above, under the conditions of the absence of soluble gas and no adjustment of the local pressure of the precursor, the fusion layer prepared under relatively low pressure in the closed chamber has a high degree of density, and vice versa. This is because, during the process of the precursor gradually melting from the inner surface near the arc outwards, the pressure of the bubbles dispersed and encapsulated in the fusion layer is the same as the pressure inside the closed chamber. Therefore, when the pressure inside the closed chamber is relatively low, the pressure inside the encapsulated bubbles formed by fusion is low, and vice versa. During the subsequent continuous heating of the arc, the increased pressure in the closed chamber leads to a smaller bubble volume, resulting in an increase in the density of the fusion layer, and vice versa.

[0014] According to formula (1) in step three above, without adjusting the pressure in the sealed chamber or the local pressure of the precursor, the density of the fusion layer obtained by melting is high when the sealed chamber is filled with a high proportion of gas that can dissolve into the high-temperature fusion layer, and low when the proportion is low. Therefore, the density of the fusion layer can be adjusted by controlling the ratio of soluble and insoluble gases. The reason is that during the process of the precursor melting from the inner surface near the arc to the outside, the atmosphere in which bubbles are dispersed and wrapped in the fusion layer is the same as the atmosphere in the sealed chamber. The soluble gas in the bubbles will dissolve into the fusion layer. After dissolution, the volume of the bubbles decreases, and the density of the fusion layer increases. When there is no soluble gas in the bubbles, the density of the fusion layer does not increase.

[0015] According to formula (1) in step three above, the pressure in the sealed chamber, the pressure in the local area of ​​the precursor, and the proportion of soluble gas are simultaneously adjusted to obtain a fusion layer with higher density. First, the sealed chamber can be evacuated to negative pressure by a vacuum pump and filled with gas that can be dissolved in the fusion layer. Then, plasma arc heating is started. After the inner surface fusion layer is formed on the inner surface of the precursor, the vacuum pump of the trolley connected to the vacuum water jacket is turned on to further reduce the pressure in the precursor area. At this time, the melted product is the high-density fusion layer. Then, the trolley vacuum pump is stopped, and the gas in the sealed chamber is replaced with gas that cannot be dissolved in the fusion layer by circulating gas through the vacuum pump. The pressure in the sealed chamber is increased to a pressure higher than that when the fusion layer was formed. The remaining precursor is heated and melted to form a fusion layer with lower density. During the continued heating process, the volume of the bubbles in the high-density fusion layer will be greatly reduced due to the increase in pressure in the sealed chamber and the dissolution of soluble gas, thus increasing the density.

[0016] The above-mentioned fusion layer can be adjusted by setting and controlling β, P1, and P2 according to formula (1) to adjust the average volume of the bubbles dispersed and wrapped after different layers melt, thereby realizing a fusion layer with multiple layers of different densities.

[0017] In the above method, the pressure range in the sealed chamber is 1000 Pa to 1 MPa.

[0018] In the above method, the pressure range of the precursor airtight space is 1000 Pa to 0.1 MPa.

[0019] In step three of the above method, the plasma arc power is 15kW to 9000kW, preferably 15kW to 6000kW, and more preferably 40kW to 5000kW. The specific power is selected according to the process requirements and crucible size.

[0020] In step two of the above method, the precursor material is silicon dioxide with a mass percentage ≥ 5%, and the balance is one or more of silicon, silicon carbide, carbon fiber, graphite, silicon nitride, boron nitride, barium carbonate, barium hydroxide, tungsten carbide, platinum, and titanium, tungsten, yttrium, tantalum, cerium, scandium, germanium, cobalt, chromium, barium, zirconium, nickel, aluminum, tin, iron and their oxides and water; or the precursor material is only silicon dioxide. Preferably, it is silicon dioxide with a mass percentage ≥ 70%, and the balance is one or more of silicon, silicon carbide, carbon fiber, graphite, boron nitride, and yttrium, cerium, barium, scandium, germanium, tin, zirconium, aluminum and their oxides and water; or the precursor material is only silicon dioxide; more preferably, it is high-purity silicon dioxide with a mass percentage ≥ 99% and a purity of not less than 99.99%, and the balance is water; or the precursor material is only silicon dioxide with a purity of not less than 99.99%. One preferred physical form of the precursor that connects to the rigid shell is silica sol or silica gel, which is uniformly coated onto the inner wall of the rigid shell with a brush. Another preferred form is a precursor containing graphite powder and silica powder, because both types of precursors can generate a certain amount of finely distributed microbubbles after melting at high temperature. This structural form of the material can help release thermal stress, and it also retains a certain amount of the material's own strength.

[0021] The aforementioned precursor can be one or two or more layers. During the manufacturing process, different silica-containing precursors are layered and laid out. After melting, a structure of one or two or more fused layers is formed.

[0022] The rigid shell material mentioned above is one or more of the following: silicon, silicon carbide, carbon fiber, graphite, zirconium oxide, silicon nitride, boron nitride, tungsten, tungsten carbide, platinum, silicon dioxide, and aluminum, titanium, cobalt, chromium, nickel, iron, and their oxides. The rigid shell material may also be one or more of the following: silicon carbide ceramic, carbon-ceramic composite material containing silicon carbide and carbon fiber, mullite ceramic, graphite, and carbon-carbon composite material.

[0023] The thickness of the rigid outer shell is 1 mm to 60 mm, preferably 3 mm to 40 mm, and the thickness of the fusion layer is 1 mm to 80 mm, preferably 1 mm to 40 mm.

[0024] The present invention also provides a composite structure crucible, which is manufactured by the above method; it includes a fusion layer and a rigid outer shell that are tightly connected in sequence from the inside to the outside to form an integrated structure.

[0025] The composite crucible manufactured by this invention includes a fusion layer and a rigid outer shell that are tightly connected from the inside out. The rigid outer shell maintains its rigidity and strength during the manufacturing and use of the composite crucible. Regardless of whether it contains high-temperature liquid, the fusion layer remains tightly bonded to the rigid outer shell. The entire composite crucible can be used independently without additional support, and there will be no abnormalities such as cracking, edge collapse, overall collapse, or bulging. There will also be no phenomenon where the wall of the fusion layer continuously expands its inner diameter due to the pressure of the high-temperature liquid.

[0026] This invention also provides an apparatus for manufacturing a composite structure crucible, used to manufacture the crucible using the above method; it includes a sealed chamber, in which copper electrodes, graphite electrodes, a support, a temperature measuring component, and a rigid shell are disposed; the sealed chamber is connected to a gas supply mechanism and a vacuum pipeline; the outlet of the vacuum pipeline is connected to a vacuum pump; the gas supply mechanism is connected to the sealed chamber through the vacuum pipeline; the gas supply mechanism is used to inject one or more of hydrogen, helium, and nitrogen into the sealed chamber; the gas supply mechanism is also connected to the vacuum pump, which is used to remove the gas injected into the sealed chamber to achieve gas replacement; the flow rate of each gas in the gas filling mechanism is set by a PLC, the flow rate of each gas is controlled by an automatic valve, and the flow rates of each gas meet a preset ratio between soluble and insoluble gases. When the gas filling mechanism receives an instruction to start filling, the automatic valves of each gas open simultaneously and fill the sealed chamber according to the set flow rate, while the pressure detection device in the sealed chamber detects the pressure in real time, and stops filling when the pressure set value is reached. If the pressure deviates from the set value during operation, it is corrected by evacuating air using a vacuum pump or by opening the valve of the inflation mechanism. If the pressure is too low and inflation is required, the valves for several gases are opened simultaneously, with each gas being inflated according to its set flow rate. If the pressure is too high, the vacuum pump is activated to evacuate air until the pressure reaches the set value again. If the gas in the sealed chamber needs to be completely replaced, the gas is first evacuated using a vacuum pump to achieve a higher vacuum, and then the inflation mechanism is used to inflate the chamber according to the required pressure value. A support frame is fixedly installed inside the sealed chamber. From top to bottom, the support frame is fixed with an electrode opening and closing mechanism, a water plate lifting mechanism, a heat shield for thermal insulation, and a forming rod for leveling materials. A graphite electrode is disposed between the water plate lifting mechanism and the heat shield. One end of the graphite electrode is connected to a copper electrode, and the other end is used to generate a plasma arc. The graphite electrode is electrically connected to a high-voltage power supply through the copper electrode. The other end of the copper electrode is also movably connected to an electrode opening and closing mechanism, which is used to adjust the discharge distance between the graphite electrodes. A rigid shell is disposed below the heat shield, with the opening of the rigid shell facing the arc-emitting end of the graphite electrode. The rigid shell is connected to a gripping and flipping mechanism and a temperature measuring component. The temperature measuring component monitors a temperature range of 600℃ to 2500℃ and is used to monitor the temperature of the rigid shell in real time. The gripping and flipping mechanism is connected to the clamping mechanism, which in turn is connected to a rotary motor, which is connected to a base trolley. The gripping and flipping mechanism is used to flip the rigid shell along a vertical plane from 0° to 90° for loading. The angle is 0° when the straight wall of the rigid shell is parallel to the horizontal plane, and 90° when the straight wall of the rigid shell is perpendicular to the horizontal plane. The clamping mechanism clamps the rigid shell through the gripping and flipping mechanism. The rotary motor drives the rigid shell to rotate stably and continuously along the central axis through the clamping mechanism. The water plate lifting mechanism is used to lift the graphite electrode; after the graphite electrode descends through the gap of the heat shield into the rigid shell, it generates a plasma arc, which melts the precursor sprayed by the spraying mechanism. After melting, the graphite electrode returns to its original position.

[0027] This invention also provides an apparatus for manufacturing another composite structure crucible, used to manufacture the crucible by the above method; it includes a support, wherein an electrode opening and closing mechanism, a water plate lifting mechanism, and a heat shield for heat insulation are connected sequentially from top to bottom on the support; a graphite electrode is disposed between the water plate lifting mechanism and the heat shield; one end of the graphite electrode is connected to a copper electrode, and the other end is used to generate a plasma arc; the graphite electrode is connected to a power source through the copper electrode; the copper electrode is movably connected to the electrode opening and closing mechanism, which is used to adjust the discharge distance between the graphite electrodes; it also includes a forming rod for smoothing the precursor; A vacuum water jacket is installed below the heat shield, and a rigid outer shell is fitted inside the vacuum water jacket; the opening of the vacuum water jacket and the opening of the rigid outer shell are tightly connected; the upper inner area of ​​the vacuum water jacket, which is higher than the rigid outer shell, is also provided with a vent hole for connecting the precursor, and a filter screen is provided in the vent hole to prevent the precursor powder from leaking out of the vent hole; a push rod is provided in the space between the rigid outer shell and the vacuum water jacket, and the two ends of the push rod abut against the outer wall of the rigid outer shell and the inner wall of the vacuum water jacket, respectively, for centering and fixing the rigid outer shell inside the vacuum water jacket; the openings of the vacuum water jacket and the rigid outer shell face the arc-emitting end of the graphite electrode; A hollow central shaft is fixedly connected to the bottom center axis of the vacuum water jacket, and a rotary motor is connected to it. The rotary motor is fixedly connected to the base carriage. The gap between the rigid shell and the vacuum water jacket is connected to the carriage pipeline and the vent hole, respectively. The carriage pipeline is connected to the carriage vacuum pump. The vacuum water jacket is also connected to a water cooling mechanism through the central shaft. The rotary motor drives the vacuum water jacket and the rigid shell to rotate centrifugally through the central shaft. A precursor is laid on the inner side of the upper part of the vacuum water jacket and the inner side of the rigid shell. The entire inner surface of the precursor to be laid melts and forms an inner surface fusion layer. The upper edge of the inner surface fusion layer is tightly connected to the upper edge of the vacuum water jacket, forming an airtight space that encloses the precursor. The precursor includes an inner surface fusion layer and an unmelted layer. The unmelted layer of the precursor is evacuated by the carriage vacuum pump. A pressure sensor for measuring pressure is set near the vent hole in the airtight space. The water plate lifting mechanism is used to lift the graphite electrode; after the graphite electrode passes through the heat shield and descends to the rigid shell, it generates a plasma arc to melt the precursor. After melting is completed, the graphite electrode returns to its original position.

[0028] The beneficial effects of this invention are: (1) This invention utilizes the extremely high temperature of a plasma arc to melt high-temperature resistant materials, and adjusts the material density by controlling the melting pressure and atmosphere, thus solving the problems of insufficient melting of high-temperature resistant material powder particles, high porosity, insufficient strength and density, and low sintering efficiency during long-term sintering in existing ceramic crucibles. At the same time, the combination of multiple layers of various materials in the fusion layer solves the stress problem caused by the different thermal expansion and thermal shock properties between materials, thereby melting and combining materials with different properties to manufacture a multi-layer integrated high-temperature melt composite structure crucible that combines the superior properties of different high-temperature materials.

[0029] (2) The composite structure crucible of this invention is used to hold high-temperature molten silicon in silicon single crystal pulling. The integrated structure, with a fusion layer tightly bonded to a rigid outer shell, replaces the loose structure of traditional quartz crucibles placed in graphite or carbon-carbon crucibles. Due to the combined excellent properties of multiple materials, it effectively solves the softening and deformation problems of quartz materials, such as edge collapse, bulging, and wrinkling. In this invention, the fusion layer is difficult to deform under the support of the rigid outer shell, avoiding problems such as wire breakage during single crystal pulling caused by the strong outward expansion of the high-temperature molten silicon. This improves the efficiency and quality of single crystal pulling, extends the service life of the crucible, and further reduces costs.

[0030] (3) Due to the rigid outer shell support, the total thickness of the fusion layer of the composite structure crucible of the present invention can be significantly reduced compared with the thickness of conventional crucibles. The thickness of the crucible made for silicon single crystal pulling can be reduced to as low as 30% of the thickness of traditional quartz crucibles, which greatly reduces the amount of material used. After the composite structure crucible is used, the rigid outer shell can be recycled by removing the fusion layer, which significantly reduces the cost. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the cross-sectional structure of the crucible described in this invention. Figure 2 This is a schematic diagram illustrating the principle of vacuuming and gas filling in the sealed chamber of the device described in this invention. Figure 3 A schematic diagram illustrating the structural principle of using a forming rod to flatten the precursor; Figure 4 This is a schematic diagram of the vacuum water jacket vacuuming structure of the device described in this invention; Figure 5 for Figure 4 A schematic diagram of the enlarged cross-section of the vacuum water jacket and crucible at point A in the middle. Figure 6 This is a schematic diagram illustrating the principle of the combined structure of the sealed chamber and vacuum water jacket of the present invention; Figure 7 This is a schematic diagram of the structural principle of the vacuum hoisting mechanism in Embodiment 4 of the present invention.

[0032] In the diagram: 1—Electrode opening and closing mechanism; 2—Copper electrode; 3—Water plate lifting mechanism; 4—Graphite electrode; 5—Heat shield; 7—Bracket; 8—Temperature measuring component; 9—Rigid shell; 10—Grabbing and flipping mechanism; 11—Clamping mechanism; 12—Base carriage; 13—Rotary motor; 14—Vacuum water jacket; 15—Fusion layer; 16—Ventilation hole; 17—Precursor; 18—Forming rod; 19—Gas supply mechanism; 20—Vacuum pipe; 21—Vacuum pump; 22—Sealed chamber; 23—Central shaft; 24—Carriage pipeline; 25—Top rod; 26—Carriage vacuum pump; 27—Lifting component; 28—Vacuum suction cup; 29—Support seat; 30—Airtight space. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Example 1

[0034] refer to Figures 1 to 3 This invention relates to an apparatus for manufacturing a composite crucible, comprising a sealed chamber 22, wherein a copper electrode 2, a graphite electrode 4, a support 7, a temperature measuring component 8, and a rigid outer shell 9 are disposed within the sealed chamber 22; the sealed chamber 22 is connected to a gas supply mechanism 19 and a vacuum pipe 20; the outlet of the vacuum pipe 20 is connected to a vacuum pump 21; the gas supply mechanism 19 is connected to the sealed chamber 22; the gas supply mechanism 19 is used to inject one or more gases such as hydrogen, helium, nitrogen, argon, water vapor, and air into the sealed chamber 22; the gas supply mechanism 19 is also connected to the vacuum pump 21, which is used to remove the gas from the sealed chamber 22; A support 7 is fixedly installed inside the sealed chamber 22. From top to bottom, the support 7 is fixed with an electrode opening and closing mechanism 1, a water plate lifting mechanism 3, and a heat shield 5. The heat shield 5 is used for heat preservation and insulation, and the water plate lifting mechanism 3 is connected to a water plate for heat insulation. A graphite electrode 4 is positioned between the water plate lifting mechanism 3 and the heat shield 5. One end of the graphite electrode 4 is connected to a copper electrode 2, and the other end is used to generate a plasma arc. The graphite electrode 4 is electrically connected to a high-voltage power supply through the copper electrode 2. The other end of the copper electrode 2 is also movably connected to an electrode opening and closing mechanism 1, which is used to adjust the discharge distance between the graphite electrodes 4 to generate a high-temperature arc. The water plate lifting mechanism 3 is used to vertically lift the graphite electrode 4. A rigid shell 9 is sequentially positioned below the heat shield 5, with its opening facing the arc-emitting end of the graphite electrode 4. The rigid shell 9 is connected to a gripping and flipping mechanism 10 and a temperature measuring component 8. The temperature measuring component 8 monitors the temperature range of 600℃ to 2500℃ and monitors the temperature of the outer wall of the rigid shell 9 in real time to ensure that the precursor is fully melted and adheres to the rigid shell without undergoing a significant chemical reaction. The rigid shell 9 also serves to replace the traditional mold for forming the precursor.

[0035] The gripping and flipping mechanism 10 is connected to the clamping mechanism 11, which in turn is connected to the rotary motor 13, which is fixedly connected to the base carriage 12. The gripping and flipping mechanism 10 is used to flip the rigid shell 9 from 0° to 90° along the vertical plane for loading and unloading, and its grippers stably hold the rigid shell 9. The angle is 0° when the straight wall of the rigid shell 9 is parallel to the horizontal plane, and 90° when the straight wall of the rigid shell 9 is perpendicular to the horizontal plane. The clamping mechanism 11 clamps the rigid shell 9 by telescopically extending the gripping and flipping mechanism 10 and keeps it rotating continuously and stably in the 90° direction. The base carriage 12 serves as a foundation for fixing the rotary motor 13, which stably loads and forms the clamped rigid shell 9. The flipping function of the gripping and flipping mechanism 10 and the telescopic clamping function of the clamping mechanism 11 are used to discharge the melted composite structure crucible. The rotary motor 13 keeps the rigid shell 9 rotating along the central axis and cools the spindle, extending the service life of the spindle.

[0036] The electrode opening and closing mechanism 1 is used to drive the graphite electrode 4 through the heat shield 5 and down into the rigid shell 9. The power supply generates a plasma arc through the graphite electrode 4 connected by the copper electrode 2. The high temperature effect of the plasma arc melts the precursor. After melting, the graphite electrode 4 returns to its original position.

[0037] The heat shield 5 serves to preserve the heat of the crucible and prevent the high temperature from burning the instrument above the heat shield 5; the plasma arc emitted by the graphite electrode 4 generates a thermal effect, which heats the precursor 17 inside the rigid shell 9. The precursor 17 is heated and liquefied to form a liquid state and adheres to the inner wall of the rigid shell 9. The rigid shell 9 and the molten precursor are tightly combined into an integrated structure.

[0038] The method for fabricating a composite structure crucible using the present invention includes the following steps: Step 1: Use a rigid carbon-ceramic shell with an outer diameter of 970mm and a wall thickness of 15mm. Its main components are 80.5% silicon carbide, 7% carbon fiber, 11% silicon, and 1.5% silicon dioxide. Sandblast the inner surface of the rigid shell to create numerous pits with a depth of 1mm to 2mm and a diameter of 1mm to 2mm, with the total area of ​​the pits accounting for more than 60% of the total area of ​​the inner surface of the rigid shell. The clamping mechanism 11 rotates the gripping and flipping mechanism 10 to 0°. The rigid shell 9 is clamped onto the gripping and flipping mechanism by the horizontal extension and retraction of the clamping mechanism 11. The gripping and flipping mechanism is then rotated to 90°, and the rotational motor 13 provides the rotational speed, causing the rigid shell to rotate as a whole at 70rpm. Adjust the distance between the lower edge of the heat shield 5 and the upper edge of the rigid shell 9 to 270mm.

[0039] Step Two: A first precursor layer, 3mm thick, is formed by spreading it evenly on the inner surface of the rigid outer shell and using forming rod 18. This layer is subsequently melted to form an outer fusion layer. This thickness does not include the depth of the pits, but the pits will naturally fill with the precursor due to centrifugal force. The first precursor layer comprises 73% silica, 15% silicon carbide, 3% graphite, 4% carbon fiber, 0.007% alumina, 0.003% titanium dioxide, 4.2% silicon, and 0.79% tungsten carbide powder by weight percentage. A second precursor layer, 8mm thick, is formed by spreading it evenly on the inner surface of the first precursor layer and using forming rod. This layer is subsequently melted to form a middle fusion layer. The second precursor layer comprises 99.996% silica powder and 0.004% alumina by weight percentage. The third precursor layer, with a thickness of 5 mm, is formed by spreading it evenly on the inner surface of the second precursor layer and forming it with a forming rod. It is then melted to form an inner fusion layer. The third precursor layer is a mixed powder of 99.992% silicon dioxide, 0.0012% yttrium oxide, 0.0008% cerium oxide, 0.0016% scandium oxide, 0.0015% tin oxide, 0.0008% germanium oxide, and 0.0021% barium carbonate by mass percentage.

[0040] Step 3: The pressure and atmosphere within the sealed chamber are controlled by a vacuum pump and gas supply mechanism, and the preformed precursor is heated by a plasma arc. The input power is controlled by the copper electrode 2, the opening of the graphite electrode 4 is controlled by the electrode opening and closing mechanism 1, and the position of the graphite electrode 4 is adjusted by the water plate lifting mechanism 3. The initial position 0 is set 5mm below the heat shield plate 5 at the arc emission tip of the graphite electrode 4. Specific melting parameters are shown in the melting process reference table 1. The precursor and the powder in the pit are fully melted and tightly bonded to the outer shell. During this process, the temperature of the outer surface of the rigid outer shell 9 is much lower than the temperature inside the crucible due to the air cooling effect. The temperature of the outer surface of the rigid outer shell 9 should not exceed 1400℃; otherwise, the power should be appropriately reduced until the temperature drops below 1400℃, at which point the power is restored to normal melting until the process is complete.

[0041] Step 4: After completing the above steps, turn off the power and allow it to cool. During cooling, the clamping mechanism 11 needs to rotate continuously at 70 rpm at a 90° angle. Once the outer wall temperature of the rigid outer shell 9 drops below 100°, stop rotating and use the flipping mechanism 10 to turn it to 0°, controlling the clamping mechanism 11 to release the composite structure crucible. After air cooling to 20°C to 40°C, manually inspect the inner and outer surface defects; use high-pressure pure water to clean the surface dust, and finally heat dry and package.

[0042] Table 1 Melting process parameters

[0043] It should be noted that the pressure parameters of the sealed chamber, the start and stop status and pumping rate of the vacuum pump, the start and stop status and gas supply flow rate of the gas supply mechanism, and the flow ratio of the multi-component process gas are all automatically controlled in a closed loop by the PLC system to regulate the atmosphere and pressure of the chamber. The specific crucible melting process is as follows.

[0044] 1. Atmosphere replacement before plasma arc initiation The sealed process chamber is evacuated to a pressure of 0.03 MPa using a vacuum pump. Subsequently, a gas supply mechanism introduces a mixed process gas into the chamber at a flow rate of argon:helium of 10:90. During this process, the vacuum pump runs continuously, maintaining a constant chamber pressure of 0.03 MPa in a closed loop. The process involves continuous pressure holding, evacuation, and gas filling for 9 minutes to remove residual air from the chamber.

[0045] 2. High-density layer melting process (process stages 1-3) After the chamber atmosphere is replaced, the gas supply mechanism is shut off, the plasma arc is started, and crucible arc melting is carried out according to the process parameters of stages 1 to 3 in Table 1. The melting process adopts a dynamic closed-loop pressure stabilization strategy: when the chamber pressure is lower than 0.03 MPa, the gas supply mechanism automatically replenishes gas according to the preset argon-helium ratio; when the chamber pressure is higher than 0.03 MPa, the vacuum pump automatically starts to pump pressure to ensure stable chamber pressure conditions.

[0046] 3. Secondary atmosphere replacement (4th process stage) In the fourth melting stage, argon gas is introduced into the sealed chamber separately, and the vacuum pump continuously stabilizes the pressure at 0.03 MPa for 4.5 minutes to complete the secondary atmosphere replacement in the chamber. After the replacement process is completed, the working pressure of the chamber is increased to 0.1 MPa, and the vacuum pump and gas supply mechanism work together in a closed-loop pressure stabilization.

[0047] 4. Post-process stabilization and melting (stages 5-7) During the 5th to 7th melting process stages, the equipment system continuously maintains a constant working pressure of 0.1 MPa in the chamber in a closed loop until the entire crucible melting process is completed.

[0048] Two technical solutions can be adopted for the high-density layer melting process and the atmosphere replacement process in the fourth process stage. The specific comparison is as follows: High-vacuum purging solution: First, the sealed chamber is evacuated to a high vacuum environment of 20 Pa to 1000 Pa, and then a specified process gas is introduced to complete the atmosphere purging. This solution can reduce process gas consumption and material costs, but it has drawbacks such as long vacuum extraction cycle, high requirements for equipment sealing accuracy, low production efficiency, and high equipment maintenance costs.

[0049] Continuous pumping, filling, flushing, and replacement scheme: This is the preferred process scheme of the present invention. Considering factors such as equipment adaptability, production efficiency, and operation and maintenance costs, this technical scheme has better engineering practicality.

[0050] This invention controls the average volume of bubbles dispersed and encapsulated within the fusion layer on the inner surface of the crucible by adjusting the working pressure and process gas ratio of the sealed chamber, thereby meeting the product's density technical requirements. The process parameters are calibrated based on formula (1), with the following specific steps: 1. Preparation of comparative samples Experiment 1: Following the preparation process of Example 1, the first and second precursor layers used low-specification raw materials, while the third precursor layer used standard-specification raw materials. Under a pure argon atmosphere with a chamber pressure of 0.1 MPa, a crucible was prepared using the third-stage arc melting process in Table 1 (eliminating the original atmosphere and pressure limitations), resulting in a fusion layer on the inner surface of the crucible. Microscopic examination of the sample revealed that the average volume of the dispersed bubbles within the fusion layer was 25671 μm³.

[0051] Experiment 2: The precursor raw material specifications were consistent with those of Experiment 1; the sample was prepared using the same arc melting process under the atmospheric conditions of 0.1 MPa chamber pressure and argon to helium volume ratio of 7:3. Microscopic examination revealed that the average volume of bubbles encapsulated within the fusion layer was 18231 μm³.

[0052] 2. Substitute the two sets of test data into the calculation formula: 18231=25671×(1-3÷10×γ)×0.1÷0.1, and calculate the characteristic coefficient γ=0.966.

[0053] 3. According to the product technical standards, the average volume V2 of the dispersed bubbles in the fusion layer is limited to ≤654μm3, and the target value in this embodiment is set to 634μm3. To improve the density of the fusion layer structure, a mixed atmosphere with an argon to helium volume ratio of 1:19 is preferred; to reduce the difficulty of process control, the stable pressure P2 after the high-density fusion layer is formed is set to 0.1MPa. Substituting the parameters into formula (1): 634=25671×(1−19÷20×0.966)×P1÷0.1, the working pressure of the chamber during the high-density fusion layer melting stage is P1=0.03MPa.

[0054] 4. Process parameters for solidifying the high-density fusion layer: During the forming stage, the working pressure of the chamber is 0.03 MPa, and the volume ratio of argon to helium mixture is 1:19; after the fusion layer is formed, the chamber pressure is adjusted to 0.1 MPa, and argon is used as the pressure-replenishing protective gas. This set of process parameters corresponds to the core technical parameters recorded in Table 1, and can stably prepare composite crucible products with satisfactory density.

[0055] Through the above-described experimental calibration method, the basic characteristic parameters V1 and γ within the formula can be determined. β, P1, and P2 are customizable, adjustable process parameters. By determining any two parameters, the third parameter can be derived through the calculation formula, adapting to the density requirements and on-site process feasibility requirements of different products. Compared to the traditional trial-and-error processing method that relies on repeated adjustments to pressure and gas ratios, this quantitative calibration method effectively reduces testing costs, shortens the R&D cycle, and quickly adapts to the development needs of customized products. In conventional processing modes, repeated adjustments without quantitative formula guidance result in high randomness, low R&D efficiency, and an inability to quickly match the technical requirements of iteratively updated products.

[0056] The composite crucible prepared in this embodiment is an integrated structure consisting of a rigid outer shell and three layers of composite fusion layers. Each fusion layer uses silicon dioxide as the base material and achieves differentiated structural and mechanical properties by doping with different functional powder modifiers. The specific mechanisms of action of each layer are as follows.

[0057] The outer fusion layer modifier includes silicon carbide, graphite, carbon fiber, alumina, titanium dioxide, elemental silicon, and tungsten carbide powder. Silicon carbide and tungsten carbide balance the thermal expansion coefficient of the matrix and improve the overall structural strength. Graphite powder reacts with silica at high temperatures to generate gas, forming a porous structure within the layer and buffering thermal stress during alternating heating and cooling of the matrix. Carbon fiber enhances the tensile strength of the silica matrix. Alumina and titanium dioxide powders increase the high-temperature softening temperature of silica. Elemental silicon binds the powders together and increases strength, and reacts with graphite at high temperatures to generate silicon carbide, strengthening the interfacial bonding strength.

[0058] The intermediate fusion layer modifier is alumina powder, whose core function is to increase the high-temperature softening point of the silica matrix and improve the structural stability of the crucible under high-temperature conditions.

[0059] The inner fusion layer modifier includes yttrium oxide, cerium oxide, scandium oxide, tin oxide, and germanium oxide powders. The synergistic effect of these various rare earth oxides reduces the dissolution rate and interfacial reaction rate between the silica matrix and the high-temperature melt, while also matching the thermal expansion coefficient of the silica matrix to prevent interlayer cracking. Barium carbonate, through high-temperature arc pyrolysis to generate barium oxide, promotes the cristobalite phase transformation of silica, enhancing the structural strength and uniformity of the quartz matrix.

[0060] The finished crucible prepared in Example 1 of this invention was subjected to section microscopy examination. The results are as follows: the rigid substrate thickness of the crucible is 15 mm, and the total thickness of the composite fusion layer is 12 mm; wherein the outer fusion layer thickness is 4 mm, the middle fusion layer thickness is 5 mm, and the inner fusion layer thickness is 3 mm. The density of bubbles in the fusion layer exhibits a gradient distribution along the thickness direction, and the specific performance parameters are as follows: Extending outwards from the inner surface of the crucible for 5 mm: the structure is most compact, with an average volume of dispersed bubbles of approximately 609 μm³; extending outwards for another 1.5 mm: the average volume of bubbles within the layer gradually increases from 609 μm³ to 25593 μm³; extending outwards for another 1.5 mm: the average volume of bubbles within the layer remains stable at 25593 μm³; outer fusion layer region: affected by the high-temperature gas generation of graphite powder in the precursor, a porous structure is formed within the layer, with large dispersion and dense distribution of bubble size, making it impossible to quantitatively analyze the bubble volume parameters.

[0061] The crucible described above is used for pulling photovoltaic-grade silicon single crystals. After each use, the fusion layer inside the rigid shell is cleaned and the crucible is recycled. After 10 cycles of use using the above method, the usage of the single crystals is shown in Table 2 below.

[0062] Table 2 Comparison of performance of composite crucibles prepared in Example 1

[0063] In all ten experiments conducted, the crucible produced by this invention showed a tight bond between the fusion layer and the outer shell after use. The crucible exhibited no bulging, edge collapse, or overall sagging. The inner surface of the crucible showed no obvious wrinkles or vertical creases, and no pinholes caused by microbubble rupture. The rigid outer shell, after ten repeated uses, maintained good condition except for slight wear on the inner surface pits, allowing for continued repeated use. In contrast, of the ten conventional quartz crucibles used for crystal pulling in the comparison, one showed a slight inward bulge on the inner surface, with softening and wire-pulling phenomena between the bulge and the carbon-carbon crucible base. Another crucible showed a slight sagging of 10 cm on one side while maintaining normal height in other areas, and the entire crucible exhibited distortion. Table 2 shows that the composite structure crucible demonstrates superior performance compared to conventional crystal pulling crucibles. Example 2

[0064] The difference between this embodiment and Embodiment 1 is that: In step one: A rigid carbon-ceramic shell with an outer diameter of 460 mm and a wall thickness of 10 mm is used. Its main components are 85% silicon carbide, 5% carbon fiber, 8% silicon, 1.5% silicon dioxide, and 0.5% tungsten carbide. The inner surface of the rigid shell is sandblasted to create numerous pits with a depth of 0.5 mm to 1 mm and a diameter of 0.5 mm to 1 mm, with the total area of ​​the pits accounting for more than 70% of the total area of ​​the inner surface of the rigid shell. The rotary motor 13 drives the rigid shell 9 to rotate as a whole at a speed of 110 rpm. The lower edge of the heat shield 5 is adjusted to be 70 mm away from the upper edge of the rigid shell 9.

[0065] In step two: the first precursor layer is 1 mm thick and consists of 6% carbon fiber and 94% high-purity dry silica gel, used to form the outer fusion layer. The second precursor layer is 6 mm thick and consists of 99.998% silica and 0.002% alumina powder, used to form the middle fusion layer. The third precursor layer is 2 mm thick and uses silica powder with an impurity content of less than 100 ppb, used to form the inner fusion layer.

[0066] The specific melting parameters in step three are shown in melting process reference table 3.

[0067] Table 3. Melting process parameters for the 7 stages

[0068] In this embodiment, the porous structure of the silica gel forming the outer fusion layer, after melting, alleviates and releases stress during rapid thermal expansion and contraction, while the carbon fibers within it increase strength and toughness. The alumina powder forming the middle fusion layer increases the high-temperature softening point of silica. The extremely high-purity silica forming the inner fusion layer meets the high-purity requirements for the crucible in electronic-grade single-crystal pulling. The process parameters were calibrated using two sets of control experiments in this embodiment as follows: Experiment 1: Using a high-low mixture of layered precursor raw materials, samples were prepared under a 0.1 MPa pure nitrogen atmosphere and the third stage of the electric arc process shown in Table 3. The average volume of bubbles in the fusion layer was measured to be 14137 μm³.

[0069] Experiment 2: The precursor raw material specifications were the same as those in Experiment 1. The sample was prepared according to the third stage process in Table 3 under an atmosphere of 0.1 MPa and a nitrogen-helium volume ratio of 7:3. The average volume of the bubbles in the fusion layer was measured to be 10057 μm³.

[0070] Substituting into the formula, the characteristic coefficient γ of this embodiment is calculated to be 0.962. Based on the product standard, the target average volume of the bubble is set to 254 μm³; the preferred process atmosphere is a nitrogen-helium volume ratio of 1:25, and the post-molding stable pressure is set to 0.1 MPa. Finally, the calculated process pressure for the inner fusion layer is 0.024 MPa.

[0071] In this embodiment, the molding process involves a high-density layer melting pressure of 0.024 MPa and a nitrogen-helium ratio of 1:25. After molding, the pressure is stabilized at 0.1 MPa, and nitrogen pressure is used for protection. Corresponding to the core process parameters in Table 3, products with compliant density can be prepared.

[0072] In this embodiment, the rigid substrate of the crucible is 10 mm thick, and the average total thickness of the fusion layer is 7.3 mm (outer layer 2 mm, middle layer 4 mm, inner layer 1.3 mm). Among them, the high-purity silica layer with a purity of ≥99.998% is only 5.3 mm thick. Compared with the 10 mm thick high-purity quartz material of conventional electronic-grade quartz crucibles of the same specifications, the amount of raw materials used is greatly reduced, resulting in a significant cost advantage.

[0073] Slice analysis showed that the bubbles in the fusion layer of this embodiment exhibited a gradient distribution: the average bubble volume in the 2.8 mm region from the inner surface was approximately 232 μm³; the bubble volume increased to 14109 μm³ in the 1 mm region from the outer surface; and the bubble volume stabilized at 14109 μm³ in the 1.5 mm region from the outer surface. The outer fusion layer had a porous structure due to gas generation from the silica gel, resulting in a chaotic and dense bubble structure that could not be quantified.

[0074] The performance test data of the product manufactured in Example 2 after trial use are shown in Table 4 below.

[0075] Table 4. Performance comparison between the crucible prepared in Example 2 and a conventional electronic-grade quartz crucible.

[0076] Note: 1) In the above data, negative values ​​indicate that the composite structure crucible is lower than the comparison crucible, and positive values ​​indicate that the composite structure crucible is higher than the comparison crucible; 2) The rigid shell can be used repeatedly.

[0077] In this embodiment, in all four experiments, the fusion layer of the present invention was tightly connected to the outer shell, and the crucible did not bulge, collapse, or collapse as a whole. The inner surface of the crucible had no obvious wrinkles or vertical creases, and there were no pinholes caused by the rupture of microbubbles. Since the crucible did not have the phenomenon of the inner diameter continuously expanding outward, it showed a significant advantage in the breakage rate during electronic-grade single crystal pulling. Example 3

[0078] The difference between this embodiment and Embodiment 1 is that: In step one: Use isostatically pressed graphite with an outer diameter of 134mm and a wall thickness of 7mm as a rigid outer shell. Sandblast the inner surface of the shell to create numerous pits with a depth of 0.3mm to 0.7mm and a diameter of 0.3mm to 0.7mm. The total area of ​​these pits should account for more than 60% of the total area of ​​the inner surface of the rigid shell. Rotate motor 13 at a speed of 230rpm. Adjust the distance between the lower edge of the heat shield and the upper edge of the rigid shell to 50mm.

[0079] In step two: the first precursor layer forming the outer fusion layer has a thickness of 1.5 mm and uses 5% silica powder, 2% graphite powder, 38% silicon carbide powder, 8% carbon fiber, 22% alumina powder, and 25% chromium oxide powder; the second precursor layer forming the inner fusion layer has a thickness of 5 mm and uses a mixture of 5% silica powder, 49% boron nitride powder, 20% tungsten carbide powder, 2% yttrium oxide powder, 2% barium oxide powder, 1% germanium powder, 1% scandium powder, 7% chromium oxide powder, 7% cobalt oxide powder, and 6% nickel oxide powder.

[0080] In step three: the melting process parameters of the seven stages described in Table 5 are used for melting.

[0081] Table 5. Melting process parameters for the seven stages.

[0082] In this embodiment, the composite crucible adopts an integrated composite structure of a rigid outer shell and a double-layer fusion layer. Silicon carbide in the outer fusion layer serves as the skeleton aggregate, while carbon fiber enhances structural strength. The composite system of silicon dioxide, alumina, and chromium oxide provides adhesion across different temperature ranges. Simultaneously, silicon dioxide and graphite components form a porous structure, effectively buffering thermal stress during rapid temperature changes by leveraging the differences in thermal expansion coefficients and interfacial adhesion characteristics of the multiple components. The inner fusion layer uses boron nitride and tungsten carbide as a rigid support skeleton, yttrium oxide and barium oxide as high-temperature sintering aids, germanium and scandium oxide as grain boundary pinning agents, and silicon dioxide as the bonding matrix. Combined with high-entropy oxide components of chromium oxide, cobalt oxide, and nickel oxide, this achieves interfacial adhesion of the skeleton structure and significantly improves the high-temperature physicochemical stability of the inner fusion layer.

[0083] This embodiment completes the process parameter calibration through a single-group control experiment. The innermost 2mm thickness of the second precursor layer is fed with the required raw materials, while the rest are made with low-grade raw materials. The sample is prepared under a 0.1MPa pure argon atmosphere and the electric arc process conditions in stage 3 of Table 5. The average volume of bubbles in the fusion layer was measured to be 905μm³ by cross-section analysis.

[0084] According to product standards, V2 ≤ 198μm 3 The target average bubble volume was set at 118 μm³. To further improve the density of the inner layer, the stabilizing pressure P2 after the fusion layer was formed was set at 0.2 MPa. In this embodiment, argon was used as the protective and process gas. As an insoluble gas, the process pressure P1 during the inner fusion layer forming stage was calculated to be 0.026 MPa using the formula. The finalized parameters correspond to the process standards in Table 5, and products with satisfactory density can be stably produced.

[0085] In this embodiment, the rigid substrate of the crucible is 7 mm thick, the outer fusion layer is 2 mm thick, and the inner fusion layer is 3 mm thick. Metallographic analysis of cross-sections shows that the bubbles in the fusion layer are distributed in a gradient along the thickness: the density is optimal in the 2 mm region from the inner surface, with an average bubble volume of approximately 170 μm³; in the 0.5 mm region outwards, the average bubble volume gradually changes from 170 μm³ to 920 μm³; in the next 0.5 mm region outwards, the bubble volume stabilizes at 920 μm³; the outer fusion layer relies on the high-temperature gas generation of graphite and silica to form a porous structure, with discrete bubble sizes and dense distribution, making quantitative detection impossible.

[0086] The composite crucible prepared in this embodiment was used for YAG single crystal pulling tests with a diameter of 100 mm. Multiple furnace tests showed an average single-batch usage time of 142 hours, a pulling speed of 1.3 mm / h, and a product yield of 66.7%, performance indicators comparable to conventional pyrolytic boron nitride crucibles. Furthermore, after multiple cycles of use, the crucible showed no structural defects such as cracks, edge collapse, or bulging; its inner surface remained smooth and dense, exhibiting excellent interlayer bonding stability and good reusability and service life. Compared to traditional pyrolytic boron nitride crucible preparation processes, this invention uses an efficient electric arc heat source for melting, resulting in high preparation efficiency and low production costs. Moreover, the integrated composite structure possesses superior structural density, stability, and service life, demonstrating significant overall technical advantages. Example 4

[0087] refer to Figure 1 , Figure 4 , Figure 5 , Figure 7In this embodiment, the apparatus includes a support 7 connected from top to bottom to an electrode opening and closing mechanism 1, a water plate lifting mechanism 3, and a heat shield 5 for thermal insulation. A graphite electrode 4 is disposed between the water plate lifting mechanism 3 and the heat shield 5. One end of the graphite electrode 4 is connected to a copper electrode 2, and the other end is used to generate a plasma arc. The graphite electrode 4 is connected to a power source through the copper electrode 2. The copper electrode 2 is movably connected to the electrode opening and closing mechanism 1, which is used to adjust the discharge distance between the graphite electrodes 4. A vacuum water jacket 14 is provided below the heat shield 5, and a rigid outer shell 9 is fitted inside the vacuum water jacket 14; the opening of the vacuum water jacket 14 and the opening of the rigid outer shell 9 are tightly connected; a vent hole 16 for connecting the precursor is also provided on the inner side of the opening of the vacuum water jacket 14 that is higher than the rigid outer shell 9; a filter screen for preventing the precursor powder from leaking out of the vent hole 16 is provided in the vent hole 16; a top rod 25 is provided in the space between the rigid outer shell 9 and the vacuum water jacket 14, and the two ends of the top rod 25 are respectively connected to the rigid outer shell 9 and the vacuum water jacket 14, and the top rod 25 is used to adjust the centering and fix the rigid outer shell 9; the openings of the vacuum water jacket 14 and the rigid outer shell 9 face the arc-emitting end of the graphite electrode 4; A central shaft 23 is fixedly connected to the bottom center axis of the vacuum water jacket 14, and the central shaft 23 is connected to a rotary motor 13. The rotary motor 13 is fixedly connected to the base trolley 12. The gap between the rigid shell 9 and the vacuum water jacket 14 is connected to the trolley pipe 24 and the vent hole 16, respectively. The trolley pipe 24 is connected to the trolley vacuum pump 26. The vacuum water jacket 14 is also connected to a water cooling mechanism through the central shaft 23. The rotary motor 13 drives the vacuum water jacket 14 and the rigid shell 9 to rotate centrifugally through the central shaft 23. A precursor 17 is laid on the upper inner side of the vacuum water jacket 14 and the inner side of the rigid shell 9. The entire surface of the precursor 17 to be laid melts and forms an inner surface fusion layer. The inner surface fusion layer is tightly connected to the upper edge of the vacuum water jacket 14 to form an airtight space 30 that encloses the precursor 17. At this time, the precursor (17) includes an inner surface fusion layer and an unmelted layer. The unmelted layer of the precursor 17 is evacuated by the trolley vacuum pump 26. A pressure sensor for measuring pressure is installed in the airtight space 30.

[0088] The water plate lifting mechanism 3 is used to drive the graphite electrode 4 to rise and fall; after the graphite electrode 4 passes through the heat shield 5 and descends to the rigid shell 9, it generates a plasma arc to melt the precursor. After melting is completed, the graphite electrode 4 returns to its original position.

[0089] In addition, to facilitate the removal of the completed crucible product, a vacuum hoisting mechanism can be installed to vertically hoist the molten composite crucible out of the vacuum water jacket 14. (Reference) Figure 7The vacuum lifting mechanism includes a lifting assembly 27 and a vacuum suction cup 28. A support base 29 is provided on the inlet / outlet side of the base trolley 12. The support base 29 is movably connected to the lifting assembly 27, and the top of the lifting assembly 27 is connected to the vacuum suction cup 28. After the composite crucible is melted, the base trolley 12 moves out of the melting area and arrives below the vacuum lifting mechanism. The vacuum suction cup 28 adheres to the uppermost edge of the fusion layer 15 adjacent to the upper edge of the vacuum water jacket 14, pulling the composite crucible vertically upward and placing it down.

[0090] The rigid outer shell 9 can be a perforated crucible assembled from multiple pieces, but a one-piece, non-perforated crucible is preferred because it has a long lifespan and can also serve as a safety barrier in case of a melt-through accident in the fusion layer during product application.

[0091] The preparation method of the composite structure crucible is as follows: Step 1: Using a rigid outer shell 9 with an outer diameter of 889mm and a wall thickness of 12mm, and with identical material and processing requirements, place the rigid outer shell 9 inside the vacuum water jacket 14 and adjust its centering and fixation using the top rod 25. The rotary motor 13 drives the rigid outer shell to rotate as a whole at a speed of 80rpm. Adjust the distance between the lower edge of the heat shield 5 and the upper edge of the vacuum water jacket 14 to 260mm.

[0092] Step Two: Reference Figure 5 A first precursor layer with a thickness of 2 mm is formed by spreading it on the inner surface of the crucible-shaped structure, which is jointly formed by the rigid outer shell 9 and the inner side of the upper part of the vacuum water jacket 14, and then forming it through the forming rod 18. This precursor layer is subsequently melted to form the outer fusion layer. The first precursor layer consists of 4% carbon fiber and 96% high-purity dry silica gel by mass percentage. The second precursor layer, forming the intermediate fusion layer, has a thickness of 6 mm and consists of 99.9975% silica, 0.002% alumina powder, and 0.0005% titanium dioxide powder by mass percentage. The third precursor layer, forming the inner fusion layer, has a thickness of 4 mm and consists of high-purity silica powder with a purity of 99.9978% or higher.

[0093] Step 3: The pre-formed precursor is heated using a plasma arc, and the pressure within the airtight space 30 enclosing the precursor is controlled by the vacuum pump 26. This fully melts the powder in the pits on the inner surface of the precursor and the outer shell, causing them to adhere tightly to the outer shell. Specific melting parameters are shown in Table 6 of the melting process reference. Step 4: After completing the above steps, turn off the power and allow it to cool. Use a vacuum lifting mechanism to vertically pull the integrated composite crucible upwards and place it in the designated location for processing.

[0094] Step 5: Using an automatic cutting machine, cut off the portion of the fusion layer that protrudes above the rigid outer shell of the composite crucible. Depending on the customer's needs, it can be cut precisely to expose the top of the rigid outer shell, or a small portion of the fusion layer covering the rigid outer shell can be left. In this case, it helps to further improve the purity and hygiene of the product during use.

[0095] Table 6 Melting Process Parameters

[0096] It should be noted that the pressure in the airtight space 30, the start and stop of the trolley vacuum pump 26, and the pumping rate are automatically controlled in a closed loop by the PLC system through process settings. Five seconds after the electric arc is started, the trolley vacuum pump 26 is activated. Due to the small size of the airtight space 30, the pressure reaches the set value and is maintained approximately 20 seconds after the trolley vacuum pump 26 starts. In the fourth stage, the trolley vacuum pump 26 is shut off and the exhaust valve of the trolley pipeline 24 is opened. The pressure inside the airtight space 30 becomes 0.1 MPa until the melting process is complete.

[0097] The composite structure crucible produced in Embodiment 4 of this invention has a total fusion layer thickness of 10.5 mm within a rigid outer shell of 12 mm thickness. The outer fusion layer is 4 mm, the middle fusion layer is 4 mm, and the inner fusion layer is 2.5 mm. The fusion layer has a high degree of density within 5 mm of its inner surface, with an average bubble volume of approximately 1035 μm³.

[0098] The crucibles mentioned above are used for pulling photovoltaic-grade silicon single crystals. After each use, the fusion layer inside the rigid shell is cleaned and the crucibles are recycled 10 times. The usage of the single crystals is shown in Table 7 below.

[0099] Table 7 Comparison of Example 4 Crucible and Conventional Quartz Crucible Products

[0100] Note: The above difference data is obtained by subtracting the data of a conventional crucible from the data of a composite structure crucible.

[0101] In all 10 experiments conducted, the crucible produced by this invention showed a tight bond between the fusion layer and the outer shell after use. The crucible exhibited no bulging, edge collapse, or overall sagging. The inner surface of the crucible showed no obvious wrinkles or vertical creases, and no pinholes caused by microbubble rupture. After 10 repeated uses, the rigid outer shell, except for slight wear due to pitting on the inner surface, remained in good condition and could still be used again. In contrast, the 10 conventional quartz crucibles used for crystal pulling in the control group showed slight inward bulging of the inner surface combined with delamination and wire drawing, as well as slight edge collapse. Table 7 shows that the crucible of this invention has superior performance. Example 5

[0102] refer to Figure 1 , Figure 5 , Figure 6 and Figure 7 This embodiment combines the vacuuming, gas supply, and sealing functional components of the fabrication apparatus of embodiments one to four. Based on the fabrication apparatus of embodiment four, a copper electrode 2, a graphite electrode 4, a support 7, a temperature measuring component 8, and a rigid shell 9 are arranged inside the sealed chamber 22. The sealed chamber 22 is connected to a gas supply mechanism 19 and a vacuum pipe 20. The outlet of the vacuum pipe 20 is connected to a vacuum pump 21. The gas supply mechanism 19 is connected to the sealed chamber 22 and is used to fill the sealed chamber 22 with gas. The gas supply mechanism 19 is also connected to the vacuum pump 21, which is used to remove the gas from the sealed chamber 22. A support frame 7 is fixedly installed inside the sealed chamber 22. From top to bottom, the support frame 7 is fixed with an electrode opening and closing mechanism 1, a water plate lifting mechanism 3, and a heat shield 5. The heat shield 5 is used for heat insulation, and the water plate lifting mechanism 3 is connected to a water plate for heat insulation. A graphite electrode 4 is arranged between the water plate lifting mechanism 3 and the heat shield 5. One end of the graphite electrode 4 is connected to a copper electrode 2, and the other end is used to generate a plasma arc. The graphite electrode 4 is connected to a power source through the copper electrode 2. The copper electrode 2 is movably connected to the electrode opening and closing mechanism 1, and the electrode opening and closing mechanism 1 is used to adjust the discharge distance between the graphite electrodes 4. A vacuum water jacket 14 is provided below the heat shield 5, and a rigid outer shell 9 is fitted inside the vacuum water jacket 14; the opening of the vacuum water jacket 14 and the opening of the rigid outer shell 9 are tightly connected; a vent hole 16 for connecting the precursor is also provided on the inner side of the opening of the vacuum water jacket 14 that is higher than the rigid outer shell 9; a filter screen for preventing the precursor powder from leaking out of the vent hole 16 is provided in the vent hole 16; a top rod 25 is provided in the space between the rigid outer shell 9 and the vacuum water jacket 14, and the two ends of the top rod 25 are respectively connected to the rigid outer shell 9 and the vacuum water jacket 14, and the top rod 25 is used to adjust the centering and fix the rigid outer shell 9; the openings of the vacuum water jacket 14 and the rigid outer shell 9 face the arc-emitting end of the graphite electrode 4; A central shaft 23 is fixedly connected to the bottom center axis of the vacuum water jacket 14, and the central shaft 23 is connected to a rotary motor 13. The gap between the rigid shell 9 and the vacuum water jacket 14 is connected to a trolley pipe 24 and a vent hole 16, respectively. The trolley pipe 24 is connected to a trolley vacuum pump 26. The vacuum water jacket 14 is also connected to a water cooling mechanism through the central shaft 23. The rotary motor 13 drives the vacuum water jacket 14 and the rigid shell 9 to rotate centrifugally through the central shaft 23. A precursor body 17 is laid on the upper inner side of the vacuum water jacket 14 and the inner side of the rigid shell 9. The entire surface of the precursor body 17 to be laid is melted to form an inner surface fusion layer. The inner surface fusion layer is tightly connected to the upper edge of the vacuum water jacket 14 to form an airtight space 30 that encloses the precursor body 17. The unmelted part of the precursor body 17 is evacuated by the trolley vacuum pump 26. A pressure sensor for measuring pressure is installed in the airtight space 30.

[0103] The water plate lifting mechanism 3 is used to drive the graphite electrode 4 to rise and fall; after the graphite electrode 4 passes through the heat shield 5 and descends to the rigid shell 9, it generates a plasma arc to melt the precursor. After melting is completed, the graphite electrode 4 returns to its original position.

[0104] The present invention relates to a method for preparing a composite structure crucible, comprising the following steps: Step 1: Using the same rigid shell 9 as in Example 1 and performing the same treatment, place the rigid shell 9 inside the vacuum water jacket 14 and adjust its centering and fixation using the top rod 25. The rotary motor 13 drives the rigid shell to rotate as a whole at a speed of 70 rpm. Adjust the distance between the lower edge of the heat shield 5 and the upper edge of the vacuum water jacket 14 to 270 mm.

[0105] Step Two: Reference Figure 5 A first precursor layer, 3 mm thick, is formed by spreading it evenly on the inner surface of the crucible-shaped structure, which is composed of a rigid outer shell and the inner side of the upper part of the water jacket, and then formed by forming rod 18. This precursor layer is subsequently melted to form an outer fusion layer. The first precursor layer consists of a mixed powder of 70% silicon dioxide, 17% silicon carbide, 4% graphite, 4% carbon fiber, 0.007% alumina, 0.003% titanium dioxide, 4.2% silicon, and 0.79% tungsten carbide by weight percentage. A second precursor layer, 8 mm thick, is formed by spreading it evenly on the inner surface of the first precursor layer and then melting it through forming rod. This second precursor layer consists of 99.996% silicon dioxide, 0.001% titanium dioxide powder, and 0.003% alumina powder by weight percentage. A third precursor layer, with a thickness of 5 mm, is formed by melting and spreading it onto the inner surface of the second precursor layer and shaping it with a forming rod to form an inner fusion layer. The third precursor layer is a mixed powder of 99.992% silicon dioxide, 0.0012% yttrium oxide, 0.0008% cerium oxide, 0.0016% scandium oxide, 0.0015% tin oxide, 0.0008% germanium oxide, and 0.0021% barium carbonate by mass percentage.

[0106] Step 3: The pressure and atmosphere within the sealed chamber 22 are controlled by vacuum pump 21 and gas supply mechanism 19, and the pressure within the airtight space 30 enclosing the precursor is controlled by trolley vacuum pump 26. The formed precursor is heated by plasma arc, with specific melting parameters as shown in melting process reference table 8, to fully melt the powder in the pits on the inner surface of the precursor and the outer shell, and to form a tightly integrated structure with the outer shell.

[0107] Step 4: After completing the above steps, turn off the power and allow it to cool. During cooling, the vacuum water jacket continues to rotate at 70 rpm. When the water temperature in the water jacket drops below 50°C, stop rotating and use the vacuum lifting mechanism to pull out the crucible and place it for processing.

[0108] Table 8 Melting Process Parameters

[0109] In the initial stage of melting, air is first extracted from the sealed chamber 22 by vacuum pump 21 to stabilize the pressure in the sealed chamber 22 at 0.05 MPa. Then, gas supply mechanism 19 fills the sealed chamber 22 with argon and helium at a flow ratio of 1:19, while vacuum pump 21 continues to run, dynamically maintaining a pressure of 0.05 MPa. This replacement state is maintained for 14 minutes, completely replacing the air in the sealed chamber 22. Then, gas supply mechanism 19 is shut off, and arc melting begins, executing the first three stages in Table 8. During this stage, the sealed chamber 22 maintains a pressure of 0.05 MPa as a baseline: if the pressure is too low, gas supply mechanism 19 replenishes gas according to a predetermined ratio; if the pressure is too high, vacuum pump 21 evacuates and depressurizes, maintaining a closed-loop pressure stabilization throughout. After 10 seconds of arc melting, the trolley vacuum pump 26 automatically starts. Because the airtight space 30 has a small volume, the set pressure can be reached within 20 seconds of vacuuming, after which the trolley vacuum pump 26 enters a pressure stabilization and maintenance state.

[0110] After entering stage 4, the vacuum pump 26 of the trolley is shut down and the vacuum valve of the trolley pipeline 24 is closed. Argon gas is then introduced into the sealed chamber 22 separately, while the vacuum pump 21 maintains a pressure of 0.05 MPa for 7 minutes to stabilize and replace the gas. After replacement, the pressure of the sealed chamber 22 is adjusted to 0.1 MPa, and the gas supply mechanism 19 is filled with argon gas until the pressure reaches the target. The vacuum pump 21 and the gas supply mechanism 19 form a closed-loop pressure stabilization system. During the subsequent melting process from stage 4 to stage 7, the equipment continuously maintains a chamber pressure of 0.1 MPa in a closed loop until the melting process is completed.

[0111] Within 30 seconds of arc initiation, the entire inner surface of the precursor 17 melts and adheres, forming a thin inner surface fusion layer. The upper edge of this thin inner surface fusion layer is tightly attached to the upper edge of the vacuum water jacket 14, forming an airtight space 30 that encloses the precursor.

[0112] During the process of the precursor gradually melting from the inner surface outwards to form a fusion layer, the density of the fusion layer can be adjusted by controlling the pressure of the airtight space 30. Since the connection between the upper inner edge of the vacuum water jacket 14 and the inner surface fusion layer cannot achieve the same seal as a vacuum device, the trolley vacuum pump needs to operate continuously to maintain a relatively low pressure. Under the process conditions of Example 5, the inner surface fusion layer is an inner surface fusion layer where all the inner surfaces are melted and bonded together after the introduction of the electric arc. This layer is usually a very thin layer with a thickness of 2 to 4 times the diameter of the raw material powder particles. Since the pressure during the formation of this layer is higher than the pressure after the formation of the airtight space 30 of the precursor, the average bubble volume in this inner surface fusion layer is larger than the average bubble volume in the fusion layer formed by subsequent melting. However, this inner surface fusion layer is very thin, so during the subsequent melting process, due to its proximity to the electric arc, it will be gradually volatilized or decomposed by the high temperature of the arc, leaving a relatively dense fusion layer on the final product.

[0113] refer to Figure 1 The composite crucible fabricated in this example has a fusion layer consisting of three layers. Since the precursor material is similar to that used in Example 1, the role of different components in each layer in the product is analyzed in Example 1.

[0114] A section microscope analysis of the fusion layer of the composite crucible prepared in Embodiment 5 of the present invention revealed that within a 15mm thick rigid outer shell, the total thickness of the fusion layer is 12mm, with an outer fusion layer of 4mm, a middle fusion layer of 5mm, and an inner fusion layer of 3mm. The fusion layer 15 exhibits a high degree of density within its innermost 5mm thickness, with dispersed bubbles having an average volume of approximately 112μm³. Further outwards, within a 1.5mm thickness range, the average bubble volume transitions from 112μm³ to 25106μm³. The average bubble volume within this 1.5mm thickness range remains at 25106μm³. Beyond this is the outer fusion layer connected to the rigid outer shell 9. Due to the presence of graphite powder in the precursor 17, a porous structure is generated after melting. Because of the dense presence of numerous bubbles of varying sizes, it is difficult to quantify the bubble volume under a microscope.

[0115] The crucible described above is used for pulling photovoltaic-grade silicon single crystals. After each use, the fusion layer inside the rigid shell is cleaned and recycled. After 10 cycles of use using the above method, the usage of the single crystals is shown in Table 9 below.

[0116] Table 9 Comparison of crucibles prepared in Examples 1 and 5 with conventional quartz crucibles

[0117] In all ten experiments conducted using the crucible produced in this invention, the fusion layer remained tightly bonded to the outer shell after use. The crucible exhibited no bulging, edge collapse, or overall sagging. The inner surface of the crucible showed no obvious wrinkles or vertical creases, and no pinholes caused by microbubble rupture. The rigid outer shell, after ten repeated uses, maintained good condition except for slight wear on the inner surface pits, allowing for continued repeated use. In contrast, the ten conventional quartz crucibles used for crystal pulling exhibited slight inward bulging of the inner surface, edge collapse, and slight twisting. Table 9 shows that the composite structure crucible demonstrates superior performance compared to conventional crystal pulling crucibles.

[0118] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method of making a composite structure crucible, characterized by, Includes the following steps: Step 1: Using an existing rigid crucible as a rigid outer shell, the inner surface of the rigid outer shell is treated to form densely packed pits; the diameter of the pits is 0.01mm to 5mm, the depth is 0.01mm to 5mm and does not exceed one-third of the wall thickness of the rigid outer shell; the thickness of the rigid outer shell is 0.3mm to 150mm. Step 2: Use a centrifuge to stably rotate the treated rigid shell; put a precursor containing silica into the rotating rigid shell, and use a molding rod or brush to evenly attach the precursor to the inner surface of the rigid shell and keep it fixed relative to the rigid shell; Step 3: Using plasma arc heating, the precursor attached to the inner surface of the rigid shell is gradually melted layer by layer from the inner surface close to the arc to form a fusion layer. The fusion layer continuously thickens and completely adheres to the inner surface of the rigid shell to form an integrated structure. The thickness of the fusion layer is 0.01 mm to 160 mm. Before the introduction of the plasma arc and during the plasma arc heating process, the density of the fusion layer is adjusted by controlling the pressure or atmosphere of the melting environment, or by controlling the pressure of the local area where the precursor is located. The ambient pressure range is 20 Pa to 10 MPa, and the pressure range of the local area where the precursor is located is 20 Pa to 0.1 MPa. The average volume V2 of the dispersed and encapsulated bubbles in the fusion layer is adjusted by setting and controlling β, P1, and P2 using formula (1), thereby adjusting the density of the fusion layer: （1） Wherein, P1 is the pressure of the environment in which the precursor is located before melting or the pressure of a local area of ​​the precursor; P2 is the pressure of the environment in which the precursor is located after melting; V1 is the average volume of dispersed bubbles in the fusion layer obtained by melting the precursor under certain pressure and atmosphere without soluble gases and measuring it with an optical microscope or scanning electron microscope, and is a characteristic data of the raw material used; β is the volume content of gas in the gas in the environment in which the precursor is located before melting that can be dissolved in the fusion layer; γ is a dissolution efficiency coefficient of 0.5 to 0.95, which is the proportion of soluble gas dissolved into the target fusion layer at high temperature, and is obtained by actual measurement and calculation; V2 is the average volume of dispersed bubbles in the fusion layer under the conditions of setting and controlling β, P1, and P2. Step 4: After completing the above steps, stop heating, cool, and remove to form a composite structure crucible.

2. The method of claim 1, wherein, The control of the pressure or atmosphere of the melting environment in step three is achieved by setting the process described in step three to be carried out in a closed chamber and adjusting the pressure or atmosphere in the closed chamber by evacuation and gas filling. The pressure range in the closed chamber is 200 Pa to 2 MPa. The atmosphere includes gases that are soluble in the fusion layer and gases that are not soluble in the fusion layer. The gases that are soluble in the fusion layer include hydrogen, helium, or water vapor or a mixture of two or more of the above gases.

3. The method of claim 1, wherein In step three, the pressure control of the local area where the precursor is located is achieved by first melting the entire inner surface of the precursor to form an integral inner surface fusion layer. The upper edge of the inner surface fusion layer is connected to the upper edge of the vacuum water jacket that holds the rigid shell and can introduce vacuum into the precursor, forming an airtight space that encloses the precursor. The pressure of the airtight space of the precursor is controlled by a vacuum pump through the vacuum water jacket. The precursor is evacuated through the ventilated structure on the upper inner side of the vacuum water jacket that is higher than the area of ​​the rigid shell. The pressure range of the airtight space of the precursor is 200 Pa to 0.1 MPa.

4. The method of claim 1, wherein, The plasma arc power ranges from 15kW to 9000kW.

5. The method of claim 4, wherein, The plasma arc power ranges from 15kW to 6000kW.

6. The method of claim 1, wherein, The thickness of the rigid outer shell is 1 mm to 60 mm, and the thickness of the fusion layer is 1 mm to 80 mm.

7. The method of claim 6, wherein, The thickness of the rigid outer shell is 3mm to 40mm, and the thickness of the fusion layer is 1mm to 40mm.

8. The method of claim 1, wherein, The rigid shell is made of one or more of the following materials: silicon, silicon carbide, carbon fiber, graphite, zirconium oxide, silicon nitride, boron nitride, tungsten, tungsten carbide, platinum, aluminum, titanium, cobalt, chromium, nickel, iron and their oxides and silicon dioxide.

9. The method of claim 1, wherein, The precursor material is silicon dioxide with a mass percentage of ≥5%, and the balance is one or more of silicon, silicon carbide, carbon fiber, graphite, silicon nitride, boron nitride, barium carbonate, barium hydroxide, tungsten carbide, platinum, and titanium, tungsten, yttrium, tantalum, cerium, scandium, germanium, cobalt, chromium, barium, zirconium, nickel, aluminum, tin, iron and their oxides and water; or the precursor material is only silicon dioxide.

10. The method of claim 9, wherein, The precursor material is silicon dioxide with a mass percentage of ≥70%, and the balance is one or more of silicon, silicon carbide, carbon fiber, graphite, boron nitride, yttrium, cerium, barium, scandium, germanium, tin, zirconium, aluminum and their oxides and water; or the precursor material is only silicon dioxide.

11. The method of claim 10, wherein, The precursor material is high-purity silicon dioxide with a purity of not less than 99.99% and a mass percentage of ≥99%, with the balance being water; or the precursor material is only silicon dioxide with a purity of not less than 99.99%.

12. A composite structure crucible characterized by, It is manufactured using the method described in any one of claims 1 to 11; it includes a fusion layer and a rigid outer shell that are tightly connected in sequence from the inside to the outside to form an integrated structure.

13. An apparatus for making a composite structure crucible, comprising: The device is used to manufacture the crucible of claim 12 according to claim 2; it includes a sealed chamber (22), which is connected to a gas supply mechanism (19) and a vacuum pipe (20); the vacuum pipe (20) is connected to a vacuum pump (21); the gas supply mechanism (19) is connected to the sealed chamber (22); the gas supply mechanism (19) is used to inject gas into the sealed chamber (22); the vacuum pump (21) is used to remove the gas in the sealed chamber (22); a support (7) is fixedly installed inside the sealed chamber (22). 7) From top to bottom, the following are connected in sequence: electrode opening and closing mechanism (1), water plate lifting mechanism (3), and heat shield (5) for heat insulation; a graphite electrode (4) is provided between the water plate lifting mechanism (3) and the heat shield (5); one end of the graphite electrode (4) is connected to a copper electrode (2), and the other end is used to generate a plasma arc; the graphite electrode (4) is connected to a power source through the copper electrode (2); the copper electrode (2) is movably connected to the electrode opening and closing mechanism (1), and the electrode opening and closing mechanism (1) is used to adjust the discharge distance between at least two of the graphite electrodes (4); A rigid shell (9) is provided below the heat shield (5), with the opening of the rigid shell (9) facing the arc-emitting end of the graphite electrode (4); the rigid shell (9) is connected to the gripping and flipping mechanism (10) and the temperature measuring component (8); the gripping and flipping mechanism (10) is connected to the clamping mechanism (11), the clamping mechanism (11) is connected to the rotary motor (13), and the rotary motor (13) is fixedly connected to the base trolley (12); the gripping and flipping mechanism (10) is used to flip the rigid shell (9) for loading; the clamping mechanism (11) clamps the rigid shell (9) through the gripping and flipping mechanism (10); the rotary motor (13) drives the rigid shell (9) to rotate through the clamping mechanism (11); the water plate lifting mechanism (3) is used to drive the graphite electrode (4) to rise and fall; after the graphite electrode (4) passes through the heat shield (5) and descends to the rigid shell (9), it generates a plasma arc to melt the precursor. After melting, the graphite electrode (4) returns to its original position.

14. An apparatus for making a composite structure crucible, comprising: The device is used to manufacture the crucible of claim 12 according to claim 3; it includes a support (7), which is connected from top to bottom to an electrode opening and closing mechanism (1), a water plate lifting mechanism (3), and a heat shield (5) for heat preservation; a graphite electrode (4) is provided between the water plate lifting mechanism (3) and the heat shield (5); one end of the graphite electrode (4) is connected to a copper electrode (2), and the other end is used to generate a plasma arc; the graphite electrode (4) is connected to a power source through the copper electrode (2); the copper electrode (2) is movably connected to the electrode opening and closing mechanism (1), which is used to adjust the discharge distance between at least two of the graphite electrodes (4); a vacuum water jacket (14) is provided below the heat shield (5). 14) A rigid outer shell (9) is fitted in the middle; the opening of the vacuum water jacket (14) and the opening of the rigid outer shell (9) are tightly connected; the upper inner side of the vacuum water jacket (14) above the rigid outer shell (9) is also provided with a vent hole (16) for connecting the precursor, and a filter screen is provided in the vent hole (16) to prevent the precursor powder from leaking out of the vent hole (16); a push rod (25) is provided in the space between the rigid outer shell (9) and the vacuum water jacket (14), and the two ends of the push rod (25) abut against the outer wall of the rigid outer shell (9) and the inner wall of the vacuum water jacket (14) respectively, for centering and fixing the rigid outer shell (9) in the vacuum water jacket (14); the openings of the vacuum water jacket (14) and the rigid outer shell (9) face the arc-emitting end of the graphite electrode (4); A central shaft (23) is fixedly connected to the bottom center axis of the vacuum water jacket (14), and the central shaft (23) is connected to a rotary motor (13); the rotary motor (13) is fixedly connected to the base trolley (12); the gap between the rigid shell (9) and the vacuum water jacket (14) is respectively connected to the trolley pipe (24) and the vent hole (16); the trolley pipe (24) is connected to the trolley vacuum pump (26); the vacuum water jacket (14) is also connected to the water cooling mechanism through the central shaft (23); the rotary motor (13) drives the vacuum water jacket (14) and the rigid shell (9) to rotate centrifugally through the central shaft (23). Precursor bodies (17) are laid on the inner side of the upper part of the vacuum water jacket (14) and the inner side of the rigid shell (9). The precursor body (17) to be laid is introduced with a plasma arc to melt the entire inner surface and form an inner surface fusion layer. The inner surface fusion layer is tightly connected to the upper edge of the vacuum water jacket (14) to form an airtight space (30) that encloses the precursor body (17). At this time, the precursor body (17) includes an inner surface fusion layer and an unmelted layer. The trolley vacuum pump (26) is used to evacuate the unmelted layer of the precursor body (17). A pressure sensor for measuring pressure is set in the airtight space (30). The water plate lifting mechanism (3) is used to drive the graphite electrode (4) to rise and fall; after the graphite electrode (4) passes through the heat shield (5) and descends to the rigid shell (9), it generates a plasma arc to melt the precursor. After melting, the graphite electrode (4) returns to its original position.

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