An apparatus and method for cerium silicide synthesis and isolation

Abstract

The application discloses a device and method for synthesizing and separating cerium silicide, and belongs to the technical field of crystal growth. The device for synthesizing and separating cerium silicide comprises a crucible main body, an inner cavity of the crucible main body being a circular truncated cone cavity with a cross-sectional size gradually decreasing from top to bottom, an ejection rod arranged at the bottom of the inner cavity of the crucible main body, and a base used for bearing the crucible main body and provided with a through hole through which the ejection rod passes, wherein the ejection rod is configured to be driven through the through hole to eject the solidified cerium silicide ingot in the inner cavity of the crucible main body in the axial direction. The application can realize lossless and efficient taking out of the synthesized product of cerium silicide by designing the crucible main body with the circular truncated cone cavity and integrating the ejection mechanism, and radial separation force is generated in the ejection process.

Description

Technical Field

[0001] This invention relates to the field of crystal growth technology, and in particular to an apparatus and method for the synthesis and separation of cerium silicide. Background Technology

[0002] The information disclosed in the background section of this invention is intended only to enhance the understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Silicon carbide (SiC), as a key third-generation semiconductor material, directly determines the performance of downstream devices through its crystal quality. When growing SiC crystals using the physical vapor transport (PVT) method, cerium (Ce) is typically introduced as a crystal form stabilizer to suppress polytype defects, a process often achieved by adding cerium silicide. However, during the high-temperature synthesis of cerium silicide, molten cerium silicide wets commonly used crucible materials such as graphite, tungsten, and boron nitride, leading to severe mechanical embedding and chemical adhesion between the cooled product and the crucible wall, making the product difficult to remove.

[0004] Regarding the difficulty in removing the aforementioned product, in practice, strong external forces such as hammering are usually required, which is not only inefficient but also prone to damaging the crucible. Secondly, cerium silicide itself is brittle, and violent mechanical separation can easily cause the ingot to crack or even break, resulting in a decrease in product yield. More seriously, the rough removal process may introduce metallic or non-metallic impurities, which may contaminate the cerium silicide product and eventually enter the crystal lattice during subsequent silicon carbide crystal growth, damaging crystal quality. Furthermore, the above operations also involve high labor intensity and high safety risks.

[0005] Currently, crucible separation techniques for other material systems (such as ordinary metal ingots), such as methods utilizing thermal expansion differences or applying ultrasonic vibration, have limited effectiveness or are not applicable in solving the adhesion problem between cerium silicide and graphite crucibles. For example, methods based on the principle of thermal expansion have little deformation effect on crucible materials with low coefficients of thermal expansion; while methods such as ultrasonic vibration have limitations such as complex process flows and the difficulty in separating tightly adhered cerium silicide. Therefore, there is an urgent need in this field to develop a dedicated device and method specifically designed for the synthesis characteristics of cerium silicide that can effectively avoid or solve the problem of product adhesion to crucibles. Summary of the Invention

[0006] In view of this, the present invention provides an apparatus and method for the synthesis and separation of cerium silicide. The present invention designs a crucible body with a frustum-shaped cavity and integrates an ejection mechanism to generate radial separation force during the ejection process, thereby achieving non-destructive and efficient extraction of cerium silicide synthesis products.

[0007] In a first aspect, the present invention provides an apparatus for the synthesis and separation of cerium silicide, comprising: The crucible body has an inner cavity that is a frustum-shaped cavity with a cross-sectional dimension that gradually decreases from top to bottom; An ejector rod is located at the bottom of the inner cavity of the crucible body; A base for supporting the crucible body and having a through hole for the ejector rod to pass through; The ejector rod is configured to be driven through the through hole to eject the solidified cerium silicide ingot from the inner cavity of the crucible body axially.

[0008] Preferably, the cone angle of the frustum-shaped cavity is 1~3°.

[0009] Preferably, the crucible body is made of graphite.

[0010] Preferably, the inner wall of the crucible body is coated with an insulating coating.

[0011] Furthermore, the material of the isolation coating is selected from one or more of tantalum carbide, tantalum diboride, hafnium carbide, or zirconium carbide, and the thickness of the isolation coating is 4~8 μm.

[0012] Preferably, the base is further provided with a limiting step for supporting the ejector rod.

[0013] Preferably, an isolation foil is provided between the bottom of the inner cavity and the top of the ejector rod, and the material of the isolation foil is graphite or tantalum; the thickness of the isolation foil is 1~5μm.

[0014] Preferably, the top diameter of the ejector rod is smaller than the inner diameter of the bottom of the inner cavity.

[0015] Secondly, the present invention provides a method for the synthesis and separation of cerium silicide, based on the above-mentioned apparatus for the synthesis and separation of cerium silicide, comprising the following steps: The cerium-containing raw material and the silicon raw material are loaded into the inner cavity of the crucible body of the device; Under a protective atmosphere, the raw materials are heated to the cerium silicide synthesis temperature to react and form a melt; The melt is cooled to solidify and form cerium silicide ingots. A mechanical ejection force is applied to the ejector rod to eject and separate the cerium silicide ingot from the inner cavity.

[0016] Preferably, after the cooling step and before the mechanical ejection step, a pre-separation step is further included: inverting the device and letting it stand for 1 to 20 hours.

[0017] Preferably, the ratio of the loose volume of the cerium-containing raw material and the silicon raw material before melting to the volume of the inner cavity is 1:(2.5~5).

[0018] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) This invention changes the way the separation force works by designing the inner cavity of the crucible as a frustum shape with a cross-section decreasing from top to bottom and cooperating with the bottom ejector rod. During the ejection process, the conical structure effectively converts the axial ejection force into a radial component force that separates the cerium silicide ingot from the inner wall of the crucible, thereby actively destroying the mechanical interlocking and chemical adhesion interface between the two, thus transforming the traditional axial frictional peeling into a separation mode that guides the ingot to detach radially, fundamentally reducing the separation resistance.

[0019] (2) This invention constructs a multi-layered chemical and physical barrier system by coating the inner wall with a high-temperature stable isolation coating such as tantalum carbide and setting a graphite foil or tantalum foil as an additional physical isolation layer at the bottom. This system can effectively suppress side reactions and element diffusion between high-temperature molten cerium silicide and the graphite crucible substrate, reducing chemical adhesion from the source and creating favorable conditions for subsequent mechanical separation.

[0020] (3) This invention integrates the synthesis reaction vessel and the separation actuator into a compact system, and through coordinated process steps such as inverted static pre-separation and smooth ejection, the entire operation process is coherent and controllable. This significantly reduces the risk of product cracking or the introduction of impurities due to repeated and rough operation. While ensuring the integrity and purity of cerium silicide ingots, it also greatly improves the safety and efficiency of the separation operation, protects the crucible itself, and extends its service life. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0022] Figure 1 This is a schematic diagram of the apparatus for the synthesis and separation of cerium silicide provided by the present invention; Figure 2 This is a top view of the apparatus for the synthesis and separation of cerium silicide provided by the present invention; Figure 3 This is a schematic diagram of the cone angle α of the apparatus for the synthesis and separation of cerium silicide provided by the present invention; Figure 4 This is a schematic diagram of the structure of the apparatus for the synthesis and separation of cerium silicide provided by the present invention when the ejector rod is a cylindrical rod of equal diameter; Figure 5This is the X-ray diffraction (XRD) pattern of the cerium silicide ingot prepared in Example 1 of this invention; In the figure, 1. Crucible lid; 2. Side wall; 3. Inner cavity; 4. Base; 5. Ejector rod; 6. Ejector rod head; 7. Ejector rod body; 8. Isolation coating; 9. Limiting step; 10. Through hole; 11. Isolation foil. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] This invention addresses the technical challenge of severe adhesion between cerium silicide and the inner wall of the crucible after high-temperature synthesis, making it difficult to remove without damage. It proposes a device for the synthesis and separation of cerium silicide. (See attached document.) Figures 1 to 2 , Figure 1 This is a schematic diagram of the apparatus for the synthesis and separation of cerium silicide according to the present invention. Figure 2 This is a top view of the apparatus for the synthesis and separation of cerium silicide according to the present invention. The apparatus includes a crucible body, an ejector rod 5, and a base 4, which together constitute an integrated system combining synthesis and separation functions.

[0025] The crucible body is the core reaction vessel of the entire device. The crucible body consists of a movable crucible lid 1 and sidewalls 2 with a specific internal cavity 3 structure. The internal cavity 3 is designed as a frustum-shaped cavity with a cross-sectional dimension gradually decreasing from top to bottom, i.e., it presents an inverted frustum shape with a cone angle α. A schematic diagram of the cone angle α for the frustum-shaped cavity is shown below. Figure 3 As shown, it satisfies the following formula: (Top inner diameter - Bottom inner diameter) / (2 × height) = tan(α).

[0026] This cone angle design is key to the invention. Its working principle is as follows: when the cerium silicide ingot is ejected from the bottom, the contact surface between the ingot and the conical inner wall generates a reaction force perpendicular to the wall. This force can be decomposed into axial and radial components, with the radial component pointing towards the center of the cavity. This effectively promotes the separation of the ingot from the crucible's inner wall, thus overcoming mechanical interlocking. Extensive experimental verification has shown that the cone angle α is preferably between 1° and 3°. Within this range, sufficient radial separation force is generated without causing a significant increase in contact pressure due to an excessively large cone angle, which could lead to mechanical interlocking. More preferably, the cone angle α is between 1.5° and 2.5°. The crucible body is preferably made of high-purity, high-density isostatically pressed graphite to meet the requirements for high-temperature strength and purity.

[0027] To address the chemical reactivity of molten cerium silicide at high temperatures, an isolation coating 8 is further applied to the inner wall of the crucible body. This isolation coating 8 effectively isolates the graphite matrix from the reactants, preventing side reactions and element diffusion, and fundamentally reducing chemical adhesion. The material of the isolation coating 8 is selected from ceramic materials with good high-temperature stability and poor wettability with cerium silicide, such as one or more of tantalum carbide (TaC), tantalum diboride (TaB2), hafnium carbide (HfC), or zirconium carbide (ZrC). The thickness of the isolation coating 8 is preferably controlled at 4~8 μm to ensure its density, integrity, and ability to withstand thermal stress.

[0028] The ejector rod 5 is located at the bottom of the inner cavity 3 of the crucible body and is a key driving component for performing the separation action. The ejector rod 5 can be designed as a cylindrical rod of uniform diameter, such as... Figure 4 As shown. In a preferred embodiment, the ejector rod 5 has a one-piece molded structure, such as... Figure 1 As shown, it includes a relatively large-diameter ejector rod head 6 and a relatively small-diameter ejector rod body 7; this design provides a larger support surface for the cerium silicide ingot, making the force transmission more uniform and stable during the ejection process, and avoiding stress concentration. The diameter of the ejector rod head 6 needs to be slightly smaller than the inner diameter of the bottom of the inner cavity 3 of the crucible body, for example, by 0.5~1 mm, to reserve necessary movement clearance during the ejection process and prevent jamming.

[0029] To prevent the ejector rod 5 from falling off during non-working states such as loading and handling, and to reliably support its weight during high-temperature synthesis, a limiting step 9 is provided on the base 4. The limiting step 9 is located below the head 6 of the ejector rod and is used to limit and support the axial position of the ejector rod 5.

[0030] The structural form of the limiting step 9 is not limited, as long as it can effectively support the ejector rod 5. In one embodiment, the limiting step 9 is a continuous annular boss surrounding the bottom of the inner cavity 3. In a preferred embodiment, the limiting step 9 is a plurality of independent bosses evenly distributed circumferentially along the bottom of the inner cavity 3. When multiple independent bosses are used, the number is preferably three to six, more preferably four, such as... Figure 2 As shown. The radial width (i.e., protrusion dimension) and vertical height of the limiting step 9 can be designed according to the crucible size and the weight of the ejector rod 5 to ensure stable support. For example, its radial width can be 15-25 mm and its vertical height can be 5 mm. When an independent boss is used, its tangential length can be 15-25 mm. The rod body 7 of the ejector rod 5 must have sufficient mechanical strength to withstand the axial thrust required to eject the cerium silicide ingot.

[0031] The base 4 is used to stably support the crucible body. A through hole 10 is provided at the center of the base 4, corresponding to the position of the ejector rod 7. A cavity is formed circumferentially around the through hole 10, the size of which is larger than the minimum operating space required for the rod. This design provides a smooth operating channel for external force-applying tools (such as the push rod of a hydraulic press or jack) to drive the ejector rod 5 to move towards the top of the crucible body; on the other hand, the larger cavity structure also reduces the material used in the base 4, achieving material savings and overall weight reduction.

[0032] The device also includes a separating foil 11, which, as a preferred additional component, is disposed between the bottom of the crucible cavity 3 and the ejector rod head 6. This separating foil 11 prevents the melt from adhering to the bottom structure. The separating foil 11 can be made of high-purity graphite foil or tantalum foil, with a preferred thickness of 3-5 μm and a diameter that precisely matches the inner diameter of the crucible bottom (preferably with a difference of less than 0.5 mm). One or more layers of the separating foil 11 can be placed.

[0033] Based on the above-described apparatus, the present invention also provides a method for the synthesis and separation of cerium silicide, which mainly includes the following steps: Loading: First, place a separating foil 11 at the bottom of the crucible cavity 3, then accurately weigh and uniformly mix cerium-containing raw material (e.g., CeO2) and silicon raw material (Si) into the cavity 3. The molar ratio of the raw materials (in Ce:Si) is preferably 1:(2.5~5), more preferably 1:(3~4). The loose volume (V) of the raw materials before melting is... 反 ) and the volume of the crucible cavity 3 (V 坩埚 The ratio of reactants to ferrous metals is 1:(2.5~5), more preferably 1:(3~4). This ratio ensures that the reactants have adequate space to expand after melting, avoids excessive compression of the inner wall, and ensures a complete reaction.

[0034] Synthesis reaction: Cover the crucible with lid 1 and place the entire apparatus in a high-temperature furnace. Under an inert protective atmosphere (such as high-purity argon), heat the raw materials to the cerium silicide synthesis temperature (e.g., 1500~1600℃) and hold for a sufficient time (e.g., 7~20 hours, depending on the amount of material fed) to allow the raw materials to react fully and melt completely to form a melt.

[0035] Cooling and solidification: After the reaction is complete, stop heating and allow the furnace to cool slowly (e.g., 6-10 hours) to allow the cerium silicide melt to solidify completely and form a dense cerium silicide ingot.

[0036] Pre-separation treatment: The cooled device is removed from the furnace and inverted to stand for a period of time, such as 1 to 20 hours, more preferably 10 to 20 hours. This step aims to use the gravity of the cerium silicide ingot itself to create a slight pre-separation between it and the ejector head 6 below, thereby significantly reducing the initial ejection resistance.

[0037] Ejection Separation: With the device upright, apply a smooth, continuous, and slow mechanical ejection force to the ejector rod 7 through the through hole 10 of the base 4. The ejector rod head 6 transmits the force upward, pushing the cerium silicide ingot axially. During this process, due to the conical design of the crucible cavity 3, the cerium silicide ingot is subjected to a continuous radial inward force, causing it to gradually detach from the inner wall. Typically, only a small distance (e.g., 3-10 mm) needs to be lifted for the cerium silicide ingot to allow it to fall smoothly from the crucible under its own weight due to complete detachment, achieving non-destructive separation.

[0038] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0039] Example 1 This embodiment provides an apparatus for the synthesis and separation of cerium silicide, such as... Figure 1 As shown, the inner cavity 3 of the crucible body has a height of 100 mm, a top inner diameter of 145.5 mm, a bottom inner diameter of 135 mm, and a calculated cone angle of approximately 3.0°. The inner wall is coated with a 4 μm thick TaC insulating coating 8. A layer of high-purity graphite foil with a diameter of 134.5 mm and a thickness of 4 μm is used as the insulating foil 11. The diameter of the ejector rod head 6 is 0.5 mm smaller than the bottom inner diameter. The limiting step 9 consists of four independent bosses with dimensions (length × width × height) of 15 mm × 15 mm × 5 mm.

[0040] This embodiment provides a method for the synthesis and separation of cerium silicide based on the above-described apparatus, comprising the following steps: (1) Loading: A high-purity graphite foil with a diameter of 134.5 mm and a thickness of 4 μm is placed at the bottom of the inner cavity 3 of the crucible as a separating foil 11. Then, a mixed raw material with a total mass of 500 g is loaded into the inner cavity 3. The mixed raw material is prepared by mixing cerium dioxide (CeO2) and silicon powder (Si) at a molar ratio of cerium to silicon of 1:4. After loading, the ratio of the loose volume of the raw material before melting to the volume of the inner cavity 3 of the crucible (V 反 / V 坩埚 The ratio is approximately 1:3.

[0041] (2) Synthesis reaction: Cover the crucible with lid 1 and move the entire apparatus into the high-temperature furnace. Evacuate the furnace and fill it with high-purity argon gas to a pressure of 20 mbar to form a protective atmosphere. Then, heat the raw materials to a synthesis temperature of 1550°C and hold the reaction at this temperature for 7 hours to allow the raw materials to react fully and melt completely.

[0042] (3) Cooling and solidification: After the reaction is completed, stop heating and allow the system to cool slowly with the furnace for 10 hours. The cerium silicide melt will completely solidify to form a solid cerium silicide ingot.

[0043] (4) Pre-separation treatment: Take the cooled device out of the furnace, invert it as a whole, and let it stand at room temperature for 12 hours.

[0044] (5) Ejection and separation: Reset the device to its upright position, and apply a steady upward mechanical ejection force to the ejector rod 7 through the through hole 10 of the base 4. After the cerium silicide ingot is steadily lifted about 5 mm, it completely separates from the inner wall of the crucible and falls off by its own weight, thus completing the separation.

[0045] Verification of Results: The cerium silicide ingots obtained in this embodiment are uniformly silvery-gray and have a dense structure. X-ray diffraction (XRD) pattern (see...) Figure 5 Analysis confirmed that the product was a cerium-silicon compound. After separation and inspection, the TaC coating on the inner wall of the crucible was intact, without peeling or breakage, and the crucible body could be reused after cleaning.

[0046] Example 2 This embodiment provides an apparatus for the synthesis and separation of cerium silicide, such as... Figure 1 As shown, the inner cavity 3 of the crucible body has a height of 150 mm, a top inner diameter of 180.5 mm, a bottom inner diameter of 170 mm, and a calculated cone angle of approximately 2.0°. The inner wall is coated with a 5 μm thick TaC isolation coating 8. A layer of high-purity graphite foil with a diameter of 169.8 mm and a thickness of 4 μm is used. The diameter of the ejector rod head 6 is 1 mm smaller than the bottom inner diameter. The limiting step 9 consists of four independent bosses with dimensions (length × width × height) of 15 mm × 15 mm × 5 mm.

[0047] This embodiment provides a method for the synthesis and separation of cerium silicide based on the above-described apparatus, comprising the following steps: (1) Loading: A high-purity graphite foil with a diameter of 169.8 mm and a thickness of 4 μm is placed at the bottom of the inner cavity 3 of the crucible as a separating foil 11. Then, a mixed raw material with a total mass of 1000 g is loaded into the inner cavity 3. The mixed raw material is prepared by mixing cerium dioxide (CeO2) and silicon powder (Si) at a molar ratio of cerium to silicon of 1:4. After loading, the ratio of the loose volume of the raw material before melting to the volume of the inner cavity 3 of the crucible (V 反 / V 坩埚 The ratio is approximately 1:3.5.

[0048] (2) Synthesis reaction: Cover the crucible with lid 1 and move the entire apparatus into the high-temperature furnace. Evacuate the furnace and fill it with high-purity argon gas to a pressure of 20 mbar to form a protective atmosphere. Then, heat the raw materials to a synthesis temperature of 1550℃ and keep the reaction at this temperature for 12 hours to allow the raw materials to react fully and melt completely.

[0049] (3) Cooling and solidification: After the reaction is completed, stop heating and allow the system to cool slowly with the furnace for 10 hours. The cerium silicide melt will completely solidify to form a solid cerium silicide ingot.

[0050] (4) Pre-separation treatment: Take the cooled device out of the furnace, invert it as a whole, and let it stand at room temperature for 12 hours.

[0051] (5) Ejection and separation: Reset the device to its upright position, and apply a steady upward mechanical ejection force to the ejector rod 7 through the through hole 10 of the base 4. The separation process is extremely smooth, and the ejection operation is completed in one go. The cerium silicide ingot is smoothly debonded and falls off by its own weight, achieving non-destructive separation.

[0052] Verification of Results: The cerium silicide ingot obtained in this embodiment was intact, uniformly silvery-gray, with a dense structure and homogeneous composition. Upon inspection after separation, the TaC coating on the inner wall of the crucible remained intact, indicating that the crucible body is reusable.

[0053] Example 3 This embodiment provides an apparatus for the synthesis and separation of cerium silicide, such as... Figure 1 As shown, the inner cavity 3 of the crucible body has a height of 200 mm, a top inner diameter of 277 mm, a bottom inner diameter of 270 mm, and a calculated cone angle of approximately 1.0°. The inner wall is coated with an 8 μm thick TaC insulating coating 8. A layer of high-purity graphite foil with a diameter of 269.7 mm and a thickness of 4 μm is used. The limiting step 9 consists of four independent bosses with dimensions (length × width × height) of 15 mm × 15 mm × 5 mm.

[0054] This embodiment provides a method for the synthesis and separation of cerium silicide based on the above-described apparatus, comprising the following steps: (1) Loading: A high-purity graphite foil with a diameter of 269.7 mm and a thickness of 4 μm is placed at the bottom of the inner cavity 3 of the crucible as a separating foil 11. Then, a mixed raw material with a total mass of 3000 g is loaded into the inner cavity 3. The mixed raw material is prepared by mixing cerium dioxide (CeO2) and silicon powder (Si) at a molar ratio of cerium to silicon of 1:4. After loading, the ratio of the loose volume of the raw material before melting to the volume of the inner cavity 3 of the crucible (V 反 / V 坩埚 The ratio is approximately 1:4.

[0055] (2) Synthesis reaction: Cover the crucible with lid 1 and move the entire apparatus into the high-temperature furnace. Evacuate the furnace and fill it with high-purity argon gas to a pressure of 20 mbar to form a protective atmosphere. Then, heat the raw materials to a synthesis temperature of 1550℃ and maintain the reaction at this temperature for 20 hours to allow the raw materials to react fully and melt completely.

[0056] (3) Cooling and solidification: After the reaction is completed, stop heating and allow the system to cool slowly with the furnace for 10 hours. The cerium silicide melt will completely solidify to form a solid cerium silicide ingot.

[0057] (4) Pre-separation treatment: Take the cooled device out of the furnace, invert it as a whole, and let it stand at room temperature for 12 hours.

[0058] (5) Ejection and separation: Reset the device to its upright position, and apply a steady upward mechanical ejection force to the ejector rod 7 through the through hole 10 of the base 4. The separation process is smooth, and the cerium silicide ingot is steadily lifted and completely removed without damage.

[0059] Results Verification: In this embodiment, a large-sized cerium silicide ingot was successfully extracted. The product was in close contact with the inner wall of the crucible, but no difficult-to-separate chemical bonds or severe mechanical embedding were formed. It was also in close contact with the isolation foil 11 and did not leak downwards from the isolation foil 11. There were no adhesion marks to the ejector rod. The product synthesized by ejection had a uniform composition and a uniform silver-gray color.

[0060] Examples 4-9 The parameters and specific separation effects are detailed in Table 1. Any parts not listed are consistent with the conditions and parameters of Example 1.

[0061] Comparative Example 1 The difference between this comparative example and Example 1 is that the inner cavity 3 of the crucible body in this comparative example is a cylinder without a cone angle, that is, the inner diameter of the top and bottom is 135 mm.

[0062] After reacting and cooling under the same process conditions, an attempt was made to eject the product. Due to the lack of radial separation force, the cerium silicide ingot and the crucible wall were subjected to pure frictional compression. Even after about 40 attempts to eject the product, it still cracked severely, with the edge portion remaining in the gap between the inner wall of the crucible and the limiting step 9, making complete and damage-free separation impossible.

[0063] Comparative Example 2 The difference between this comparative example and Example 1 is that the inner cone angle of the crucible body in this comparative example is designed to be approximately 4.0° (top inner diameter 203 mm, bottom inner diameter 182 mm, height 150 mm).

[0064] Although a large cone angle helps generate radial force, an excessively large cone angle significantly increases the contact area and normal pressure between the ingot and the crucible wall after solidification, leading to an enhanced "mechanical interlocking" effect. The initial resistance during ejection is enormous, and after dozens of forceful ejections, the cerium silicide ingot eventually breaks, with only about two-thirds collected, proving that a cone angle exceeding 3° is actually detrimental to non-destructive separation.

[0065] Comparative Examples 3-6 The parameters and specific separation effects are detailed in Table 1. Any parts not listed are consistent with the conditions and parameters of Example 1.

[0066] Table 1. Parameters and specific separation effects of Examples 4-9 and Comparative Examples 3-6

[0067] Note: The evaluation criteria for separation effect are as follows: - Easy: Smooth ejection, completed in one operation, product intact and undamaged; - Relatively easy: Smooth ejection, intact product, no damage; - Medium: Requires adjustment of top output force; product is basically intact. - Challenges: Requires multiple attempts; product is slightly damaged. - Extremely difficult: Cannot be completely removed; product is severely damaged.

[0068] The experimental data shown in Table 1 further validated the influence of the key parameters. The results indicate that at cone angles of 1°–3° and V… 反 / V 坩埚 When the ratio is 1:3 to 1:4 and graphite foil of appropriate thickness (3~5μm) is used, the separation effect can be "relatively easy" or "easy". However, when there is no cone angle or the cone angle is too large (≥3.5°), the separation becomes "difficult" or "extremely difficult".

[0069] In summary, this invention, through the device design of "conical cavity + ejection mechanism" combined with specific process methods including "inverted pre-separation", systematically solves the problem of adhesion removal in cerium silicide synthesis, and achieves dual protection for the synthesis product and the crucible.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An apparatus for the synthesis and separation of cerium silicide, characterized in that, include: The crucible body has an inner cavity that is a frustum-shaped cavity with a cross-sectional dimension that gradually decreases from top to bottom; the cone angle of the frustum-shaped cavity is 1~3°; the inner wall of the crucible body is coated with an isolation coating; and an isolation foil is also provided between the bottom of the inner cavity and the top of the ejector rod. An ejector rod is located at the bottom of the inner cavity of the crucible body; A base for supporting the crucible body and having a through hole for the ejector rod to pass through; The ejector rod is configured to be driven through the through hole to eject the solidified cerium silicide ingot from the inner cavity of the crucible body axially.

2. The apparatus for the synthesis and separation of cerium silicide as described in claim 1, characterized in that, The material of the isolation coating is selected from one or more of tantalum carbide, tantalum diboride, hafnium carbide or zirconium carbide, and the thickness of the isolation coating is 4~8μm.

3. The apparatus for the synthesis and separation of cerium silicide as described in claim 1, characterized in that, The crucible body is made of graphite; the base is also provided with a limiting step for supporting the ejector rod.

4. The apparatus for the synthesis and separation of cerium silicide as described in claim 1, characterized in that, The material of the insulating foil is graphite or tantalum; the thickness of the insulating foil is 1~5μm.

5. The apparatus for the synthesis and separation of cerium silicide as described in claim 1, characterized in that, The top diameter of the ejector rod is smaller than the inner diameter of the bottom of the inner cavity.

6. A method for the synthesis and separation of cerium silicide, characterized in that, The apparatus for the synthesis and separation of cerium silicide according to any one of claims 1 to 5 comprises the following steps: The cerium-containing raw material and the silicon raw material are loaded into the inner cavity of the crucible body of the device; Under a protective atmosphere, the raw materials are heated to the cerium silicide synthesis temperature to react and form a melt; The melt is cooled to solidify and form cerium silicide ingots. A mechanical ejection force is applied to the ejector rod to eject and separate the cerium silicide ingot from the inner cavity; After the cooling step and before the mechanical ejection step, a pre-separation step is also included: the device is inverted and left to stand for 1 to 20 hours.

7. The method as described in claim 6, characterized in that, The ratio of the loose volume of the cerium-containing raw material and the silicon raw material before melting to the volume of the inner cavity is 1:(2.5~5).

Images