Thermal field component for SiC crystal growth and preparation method thereof

Abstract

The invention belongs to the technical field of SiC crystal growth, and particularly relates to a thermal field component for SiC crystal growth and a preparation method of the thermal field component. The thermal field component comprises a thermal field component body, and the thermal field component body is made of a porous tantalum carbide material. The thermal field component can efficiently filter carbon particles, has corrosion resistance and long service life, and can remarkably reduce the production cost.

Description

Technical Field

[0001] This application belongs to the field of SiC crystal growth technology, specifically relating to a thermal field component for SiC crystal growth and its preparation method. Background Technology

[0002] During the PVT growth of SiC crystals, SiC sublimates at high temperatures, producing gaseous components including Si, C2, Si2C, and SiC2. These gaseous components are transported to the seed crystal region under the influence of temperature differences, where they deposit and grow into SiC single crystals on the seed crystal surface. As the reaction proceeds, gaseous C2 and gaseous SiC2 easily deposit in low-temperature regions such as the edge of the thermal field, forming free carbon particles. These carbon particles, after entering the crystal growth surface, form carbon inclusions, which in turn cause defects in the SiC crystal, thus reducing the quality of the SiC crystal. Related technologies use a porous tantalum carbide coating to filter carbon particles on the surface of graphite components. However, the tantalum carbide coating exhibits failure phenomena such as peeling, cracking, and bulging under high-temperature and vapor-phase corrosion environments, causing the graphite component to lose its filtering ability and become unusable, and the coating process is complex. Therefore, there is a need to develop a thermal field component with a long service life that can effectively filter carbon particles and its preparation method. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, this invention proposes a thermal field component for SiC crystal growth, its preparation method, and the thermal field itself. This thermal field component can efficiently filter carbon particles, is corrosion-resistant, has a long service life, and can significantly reduce production costs.

[0004] The first aspect of this application provides a thermal field component for SiC crystal growth, characterized in that the thermal field component includes a thermal field component body, which is made of porous tantalum carbide material.

[0005] This application replaces the graphite component body in the hot zone with an integral porous tantalum carbide material. On the one hand, porous tantalum carbide has uniform pore size and porosity, which can efficiently and stably filter free carbon particles of different sizes, significantly improving the filtration efficiency of carbon particles, thereby improving the quality and yield of SiC crystals. On the other hand, porous tantalum carbide material has excellent corrosion resistance and high hardness, and its service life can be extended to 20 times, greatly reducing the replacement frequency of hot zone components, thereby reducing production costs.

[0006] According to embodiments of this application, at least one of the following conditions is met: the pore size of the porous tantalum carbide material is 10 μm-20 μm, specifically 10 μm; and the porosity of the porous tantalum carbide material is 40%-60%. Thus, within the aforementioned pore size and porosity range, sufficient transport channels for gaseous components can be provided to meet the raw material supply requirements for SiC crystal growth.

[0007] According to embodiments of this application, the thermal field component includes at least one of the following in a SiC crystal growth apparatus: a crucible, a crucible cover, a seed crystal rod, an insulation layer, and a tooling mold assembly. Therefore, porous tantalum carbide material has wide applicability and can meet the needs of different thermal field components in SiC crystal growth apparatuses.

[0008] A second aspect of this application provides a method for fabricating a thermal field component for SiC crystal growth, characterized by comprising:

[0009] The raw material mixture is sintered in a mold to obtain porous tantalum carbide material;

[0010] The raw material mixture is composed of a carbon source and a tantalum source;

[0011] The tantalum source includes at least one of tantalum pentoxide and tantalum particles;

[0012] The carbon source includes at least one of carbon particles and carbon powder.

[0013] Therefore, this method is simple to operate and easy to implement, reducing complex process steps and thus improving production efficiency.

[0014] According to an embodiment of this application, the tantalum source comprises tantalum pentoxide, and the method further includes:

[0015] The tantalum pentoxide and the carbon source are stirred and mixed to obtain the raw material mixture. This facilitates the uniform distribution of the two raw materials in the mixture, ensuring simultaneous and complete reaction in all regions during sintering. Simultaneously, uniform mixing also allows for sufficient contact between the reactants, thereby increasing the reaction rate.

[0016] According to embodiments of this application, the method further includes sintering, which comprises: performing a first sintering on the raw material mixture, causing the carbon source to undergo a reduction reaction with the tantalum pentoxide to generate elemental tantalum and carbon monoxide, obtaining a first-sintering product; annealing the first-sintering product to obtain an annealed product; and performing a second sintering on the annealed product, causing the elemental tantalum and the carbon source to react, obtaining the porous tantalum carbide material. Therefore, this method uses a stepwise sintering reaction to obtain porous tantalum carbide material, which can avoid the generation of other carbide (such as Ta₂C) impurities during one-step sintering, improve the purity of the porous tantalum carbide material, and reduce the probability of hot-field components.

[0017] According to embodiments of this application, at least one of the following conditions is satisfied:

[0018] The first sintering temperature is 1900℃-2050℃;

[0019] The first sintering time is 2-3 hours;

[0020] The pressure of the first sintering is 1×10 -4 Pa to 2×10 -3 Pa;

[0021] The second sintering temperature is 2150℃-2250℃;

[0022] The second sintering time is 50-80 hours;

[0023] The pressure of the second sintering is 10Pa-20Pa.

[0024] Therefore, appropriate temperature, pressure, and time for the first sintering facilitate the melting of tantalum pentoxide, thereby increasing the contact area between the raw materials and allowing the reduction reaction to proceed fully. Simultaneously, it ensures a moderate rate of CO gas generation, allowing the gas to escape orderly through the gaps, forming uniformly interconnected pores. Appropriate temperature, pressure, and time for the second sintering promote the diffusion of elemental tantalum and carbon atoms, ensuring their complete reaction and conversion into tantalum carbide.

[0025] According to an embodiment of this application, the annealing temperature is 1000℃-1200℃; the annealing time is 5h-10h; and the annealing pressure is 7×10⁻⁶. 3 Pa-8×10 3 Pa. Therefore, appropriate annealing temperature, pressure and time are beneficial to eliminating the thermal stress and phase transformation stress generated during the first sintering process, and to avoiding the collapse or deformation of the pore structure.

[0026] According to embodiments of this application, at least one of the following conditions is met: the particle size of the tantalum pentoxide is 1 μm-10 μm; and the particle size of the carbon particles is 100 μm-1 mm. Thus, within the aforementioned particle size range of tantalum pentoxide, the specific surface area of ​​tantalum pentoxide is moderate, allowing for sufficient contact with the carbon source and accelerating the reaction rate. Within the aforementioned particle size range of the carbon particles, the carbon particles can be better dispersed during stirring, reducing agglomeration; simultaneously, the larger void structure formed by the particle structure is more conducive to gas expulsion.

[0027] According to an embodiment of this application, the tantalum source comprises tantalum particles, and the carbon source comprises carbon powder. The tantalum particles have a particle size of 100 μm-1 mm, and the carbon powder has a particle size of 5 μm-10 μm. The method further includes: alternately layering the tantalum particles and the carbon powder to obtain the raw material mixture. Thus, within the aforementioned particle size range of tantalum particles and carbon powder, due to the significant difference in particle size between the tantalum particles and carbon powder, when the tantalum particles and carbon powder are alternately layered, the finer carbon powder fills the gaps between the coarser tantalum particles, thereby facilitating the formation of a porous structure at the interlayer interface during subsequent synthesis reactions.

[0028] According to embodiments of this application, the method further includes: maintaining a pressure of 10 Pa to 20 Pa and sintering at a temperature of 2150°C to 2250°C for 50 h to 80 h. Thus, suitable sintering temperature, pressure, and time can promote the diffusion of carbon atoms into the interior of the tantalum particles, resulting in uniform growth of the tantalum carbide shell layer; simultaneously, it facilitates the formation of appropriate grain sizes, resulting in a uniform distribution of pores.

[0029] A third aspect of this application proposes a thermal field for SiC crystal growth, which includes the thermal field components for SiC crystal growth described above. All features and advantages of this thermal field are consistent with those of the thermal field components described above, and will not be repeated here. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a mold according to an embodiment of this application.

[0031] Figure 2 This is a schematic diagram of the structure of a mold according to another embodiment of this application.

[0032] Figure 3 This is a schematic diagram of the thermal field structure of the sintering apparatus of this application.

[0033] Figure 4 This is a schematic diagram of a thermal field component according to an embodiment of this application.

[0034] Figure 5 This is a schematic diagram of a thermal field component according to another embodiment of this application.

[0035] Figure 6 This is a SEM image of the porous tantalum carbide material of Example 1 of this application.

[0036] Figure 7 This is the EDS energy spectrum of the porous tantalum carbide material in Example 1 of this application.

[0037] Reference numerals: 1: Upper insulation component; 2: Temperature measuring hole; 3: Bolt; 4: Upper part of mold; 5: Lower part of mold; 6: Loading chamber of mold; 7: Heating cylinder; 8: Lower insulation component; 9: Heating system. Detailed Implementation

[0038] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0039] The first aspect of this application provides a thermal field component for SiC crystal growth, the thermal field component comprising a thermal field component body made of porous tantalum carbide material.

[0040] This application replaces the graphite components in the hot zone entirely with porous tantalum carbide material. On the one hand, porous tantalum carbide has uniform pore size and porosity, which can efficiently and stably filter free carbon particles of different sizes, significantly improving the filtration efficiency of carbon particles, thereby improving the quality and yield of SiC crystals. On the other hand, porous tantalum carbide material has excellent corrosion resistance and high hardness, and its service life can be extended to 20 times, which greatly reduces the replacement frequency of hot zone components, thereby reducing production costs.

[0041] In this article, "body" refers to the main component that plays a core role in the thermal field component, excluding parts such as modified coatings. For example, the seed crystal rod includes the seed crystal holder and the lifting rod. The body of the seed crystal rod refers to the seed crystal holder, which is used to fix the seed crystal.

[0042] According to embodiments of this application, the pore size of the porous tantalum carbide material is 10μm-20μm, specifically within the ranges of 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 6μm, 17μm, 18μm, 19μm, 20μm, or any two of these ranges. Therefore, within this pore size range, it is beneficial to effectively filter carbon particles while ensuring the smooth transport of gaseous components (Si, C2, Si2C, SiC2, etc.), which helps improve the raw material supply efficiency required for SiC crystal growth. If the pore size is too large, larger carbon particles may enter the growth region through the pores, reducing filtration efficiency and affecting the growth quality of the SiC crystal; if the pore size is too small, it may increase the transport resistance of gaseous components, reducing transport efficiency and thus affecting the growth efficiency of the SiC crystal.

[0043] According to embodiments of this application, the porosity of the porous tantalum carbide material is 40%-60%, specifically 40%, 45%, 50%, 55%, 60%, or any two of these ranges. Therefore, within this porosity range, sufficient transport channels for gaseous components can be provided to meet the raw material supply requirements for SiC crystal growth, while also possessing sufficient mechanical strength to support the thermal components. If the porosity is too high, the mechanical strength may be low, making it prone to deformation or fracture under high temperature and mechanical stress. If the porosity is too low, the material may have fewer pore structures, resulting in insufficient transport channels for gaseous components, thereby increasing transport resistance and reducing transport efficiency.

[0044] According to embodiments of this application, the thermal field component includes at least one of the following in a SiC crystal growth apparatus: a crucible, a crucible cover, a seed crystal rod, an insulation layer, and a tooling mold assembly. Therefore, porous tantalum carbide material has wide applicability and can meet the needs of different thermal field components in SiC crystal growth apparatuses.

[0045] A second aspect of this application proposes a method for preparing a thermal field component for SiC crystal growth, comprising: sintering a raw material mixture in a mold to obtain a porous tantalum carbide material. This method is simple to operate and easy to implement, reducing complex process steps and thus improving production efficiency.

[0046] It is understood that the specific shape of the mold used in this application is not limited and can be selected according to the specific shape of the required hot zone component. In some embodiments, the mold shape can be cylindrical, and the structure is as follows: Figure 1 As shown, the shape of the thermal field component obtained using this mold is as follows: Figure 4 As shown; in other embodiments, the mold may be elongated in shape, with a structure as shown. Figure 2 As shown.

[0047] The mold is divided into an upper part 4 and a lower part 5. During use, the raw material mixture is added to the loading chamber 6 of the mold, and then secured with bolts 3. After completing the above operations, it is placed into a sintering apparatus. The thermal field structure of this sintering apparatus is as follows... Figure 3 As shown, it includes a heating system 9 for heating the hot zone to increase energy for sintering; a heating cylinder 7 for heating the mold; an upper insulation component 1 and a lower insulation component 8 for insulating the hot zone; and a temperature measuring hole 2 for measuring the temperature of the hot zone during the sintering process.

[0048] According to embodiments of this application, the mold material includes either graphite or tantalum metal. As an example, the mold material of this application is tantalum metal. Therefore, the above material can withstand high temperatures, providing a stable environment for the sintering reaction.

[0049] According to embodiments of this application, the raw material mixture consists of a carbon source and a tantalum source. Therefore, the raw materials are singular, simplifying the preparation process and preventing the introduction of other impurities into the reaction.

[0050] According to embodiments of this application, the tantalum source includes at least one of tantalum pentoxide and tantalum particles. Therefore, the aforementioned tantalum source has different physical morphologies, improving process flexibility and enabling better adaptation to different process conditions.

[0051] According to embodiments of this application, the carbon source includes at least one of carbon particles and carbon powder. Therefore, the aforementioned carbon sources have different physical forms, improving process flexibility and enabling better adaptation to different process conditions.

[0052] In this article, the criteria for defining powder and granules are as follows: particles with a diameter range of 1μm-50μm are called powder, and particles with a diameter range of 50μm-1000μm are called granules. The specific choice between powder and granules can be made flexibly based on different process conditions and actual needs.

[0053] In some embodiments, when the tantalum source comprises tantalum pentoxide, the method for fabricating the thermal field component may include:

[0054] S10: The tantalum pentoxide powder and the carbon source are stirred and mixed to obtain the raw material mixture.

[0055] This facilitates the uniform distribution of the two raw materials in the mixture, ensuring simultaneous and complete reaction in all regions during sintering. Simultaneously, uniform mixing allows for sufficient contact between reactants, thereby increasing the reaction rate.

[0056] According to embodiments of this application, the mixing method includes, but is not limited to, mixing with a stirrer. Therefore, the operation is simple and easy to implement.

[0057] According to embodiments of this application, the stirring speed is 100 r / min-200 r / min, specifically 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, 200 r / min, or any range between two of these. Within this speed range, the raw materials are effectively broken down, ensuring uniform mixing and reducing agglomeration, which facilitates better subsequent reactions. Excessive speed may lead to accelerated equipment wear and shorten its lifespan; insufficient speed may cause heavier particles to settle to the bottom, failing to disperse evenly in the mixture, resulting in localized unevenness during subsequent sintering.

[0058] According to embodiments of this application, the stirring time is 1-1.5 hours, specifically 1 hour, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, or any range between two of these. Therefore, a suitable stirring time helps all raw materials to be thoroughly crushed, allowing for uniform distribution. If the stirring time is too long, it will lead to over-mixing, consuming excessive energy and increasing production costs; if the stirring time is too short, the raw materials may not be sufficiently crushed or mixed.

[0059] It is understood that there are no restrictions on the specific type of carbon source; both carbon particles and carbon powder can be used, and the choice can be made according to the specific process and actual needs. In some embodiments, carbon particles are used as the carbon source.

[0060] According to the embodiments of this application, the mass ratio of tantalum pentoxide to carbon source is 7-7.5:1, specifically 7:1, 7.1:1, 7.2:1, 7.3:1, 7.4:1, and 7.5:1. Within this mass ratio range, it is beneficial for the complete consumption of carbon source, ensuring a sufficient reaction and leaving no impurities. If the mass ratio is too high, the tantalum pentoxide may not react completely, resulting in waste of raw materials; if the mass ratio is too low, it may result in an excess of carbon source, also leading to waste of raw materials.

[0061] According to embodiments of this application, the particle size of tantalum pentoxide is 1μm-10μm, specifically within the range of 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any two of these ranges. Therefore, within the aforementioned particle size range of tantalum pentoxide, the specific surface area is moderate, allowing for sufficient contact with the carbon source and accelerating the reaction rate. If the particle size of tantalum pentoxide is too large, the small specific surface area may reduce the contact area with the carbon source, leading to incomplete reaction; if the particle size of tantalum pentoxide is too small, it may easily agglomerate, making it difficult for the agglomerates to contact the carbon source, resulting in incomplete reaction.

[0062] According to embodiments of this application, the carbon particles have a particle size of 100 μm-1 mm, specifically within the range of 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, or any two of these ranges. Therefore, within this particle size range, the carbon particles can be better dispersed during stirring, reducing agglomeration; simultaneously, the larger void structure formed by the particle structure facilitates gas expulsion. If the carbon particle size is too small, the resulting voids may be too small, potentially hindering gas expulsion and leading to pore formation; if the carbon particle size is too large, the stirring and crushing time may be longer, increasing production costs.

[0063] According to embodiments of this application, after stirring and mixing, the process further includes sintering the raw material mixture, wherein sintering includes:

[0064] S20: The raw material mixture is subjected to a first sintering, in which the carbon source and the tantalum pentoxide undergo a reduction reaction to generate elemental tantalum and carbon monoxide, thus obtaining the first sintering product.

[0065] In this step, the raw material mixture is loaded into the loading chamber 6 of the mold, and the upper part 4 and the lower part 5 of the mold are fastened with bolts 3 for sintering. Tantalum pentoxide and carbon undergo a reduction reaction in the loading chamber 6, with the following reaction equation: Ta₂O₅ + 5C = 2Ta + 5CO, producing elemental tantalum and CO gas simultaneously. This process occurs at the interface region where tantalum pentoxide and carbon are in close contact. The newly generated CO gas molecules rapidly accumulate near the reaction interface in the closed reaction space, generating extremely high pressure. As a large amount of CO gas diffuses outward from the interior of the mixture, it leaves interconnected channels in the mixture. The elemental tantalum and unreacted carbon together form the initial framework of the porous structure after the gas escapes.

[0066] According to an embodiment of this application, before sintering, the process further includes: passing an inert gas through the equipment under vacuum to maintain a pressure of 1×10⁻⁶. -4 Pa-1×10 -3 Pa, inert gases including but not limited to Ar. Therefore, evacuating the vacuum before the first sintering can completely remove impurities such as oxygen and water vapor in the thermal field, avoiding side reactions of the raw materials that would affect the purity of the product; then, introducing inert gas to increase the pressure helps to suppress the volatilization loss of the raw materials in the early stage of the reaction using high-pressure inert gas.

[0067] According to an embodiment of this application, the first sintering temperature is 1900℃-2050℃, specifically within the range of 1900℃, 1950℃, 2000℃, 2050℃, or any two thereof. Within this sintering range, tantalum pentoxide is readily melted, thereby increasing the contact area between the raw materials and allowing the reduction reaction to proceed fully. If the first sintering temperature is too low, the tantalum pentoxide powder may not completely melt, reducing the contact area between the raw materials and resulting in an insufficient reduction reaction; if the first sintering temperature is too high, the grains may overgrow, and the connecting channels may break or close due to excessive grain growth, resulting in uneven pore distribution.

[0068] According to the embodiments of this application, the time required to reach the first sintering temperature is 1-2 hours, specifically 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, or any range between two of these. Therefore, a suitable heating time ensures a moderate rate of CO gas generation, allowing the gas to escape in an orderly manner and form uniformly interconnected pores. If the heating time is too short, the CO gas generation rate will be too fast, and the gas cannot escape in time, resulting in accumulation and the formation of large cavities. If the heating time is too long, side reactions may occur, generating incompletely reduced products and introducing impurities.

[0069] According to the embodiments of this application, the first sintering time is 2-3 hours, specifically 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, or any combination thereof. Therefore, a suitable sintering time ensures that tantalum pentoxide reacts fully with carbon, reducing the residue of unreacted raw materials; simultaneously, it allows CO gas to escape in an orderly manner to form uniform pores. If the sintering time is too short, the reaction may be incomplete, and incomplete escape of CO gas may lead to uneven pore structure; if the time is too long, excessive grain growth may occur, and the connecting channels may break or close due to excessive grain growth, resulting in uneven pore distribution.

[0070] According to an embodiment of this application, the pressure of the first sintering is 1×10⁻⁶. -4 Pa-2×10 -3 Pa, specifically 1×10 -4 Pa, 2×10 -4 Pa, 4×10 -4 Pa, 6×10 -4 Pa, 8×10 -4 Pa, 1×10 -3 Pa, 2×10 -3 The pressure is within the range of Pa or any two of these. Therefore, a suitable first sintering pressure is beneficial for the continuous escape of CO gas and avoids bubbling. If the first sintering pressure is too high, the formed pore structure may be compressed and closed, resulting in a decrease in porosity; if the first sintering pressure is too low, the CO gas may escape too quickly, and a large amount of gas may impact the gaps between the raw materials in a short period of time, easily destroying the initially formed pore structure.

[0071] S30: Anneal the calcined product to obtain an annealed product.

[0072] In this step, annealing helps to eliminate the thermal stress and phase transformation stress generated during the first sintering process, and avoids the collapse of the pore structure or the formation of microcracks in the pore walls.

[0073] According to embodiments of this application, the annealing temperature is 1000℃-1200℃, specifically 1000℃, 1100℃, 1200℃, or any range between two of these. Therefore, a suitable annealing temperature helps eliminate the thermal stress and phase transformation stress generated during the first sintering process, preventing the pore structure from collapsing or deforming. If the annealing temperature is too high, it may cause abnormal grain growth, thereby compressing and closing the pores; if the annealing temperature is too low, it may not be able to fully release the residual thermal stress and phase transformation stress.

[0074] According to the embodiments of this application, the time required to reach the annealing temperature is 4-5 hours, specifically 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, or any range between two of these. Therefore, a suitable heating time ensures that all reaction zones are heated simultaneously, avoiding new thermal stress caused by a sudden temperature rise. If the heating time is too fast, it may cause excessive local temperature differences, generating new thermal stress; if the heating time is too short, it may require extending the process cycle and increasing production costs.

[0075] According to embodiments of this application, the annealing time is 5-10 hours, specifically 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or any range between two of these. Therefore, a suitable annealing time helps to fully eliminate the thermal stress and phase transformation stress generated during the first sintering process, preventing the collapse of the pore structure or the formation of microcracks in the pore walls. If the annealing time is too long, the effect of eliminating thermal stress and phase transformation stress is not significantly improved, resulting in a waste of time; if the annealing time is too short, the residual thermal stress and phase transformation stress may not be fully released.

[0076] According to an embodiment of this application, the annealing treatment pressure is 7 × 10⁻⁶. 3 Pa-8×10 3 Pa, specifically 7 × 10 3 Pa, 7.2 × 10 3 Pa, 7.4 × 10 3 Pa, 7.6 × 10 3 Pa, 7.8 × 10 3 Pa, 8×10 3 The range of Pa or any two thereof. Therefore, an appropriate annealing pressure helps to fully release residual thermal stress and phase transformation stress, preventing the collapse of the pore structure or the formation of microcracks in the pore walls. If the annealing pressure is too high, it may cause the pore structure to collapse, resulting in a decrease in porosity; if the annealing pressure is too low, the residual thermal stress will not be fully released, which may lead to the formation of microcracks in the pore walls.

[0077] S40: The annealed product is subjected to a second sintering to react elemental tantalum with the carbon source to obtain the porous tantalum carbide material.

[0078] In this step, elemental tantalum and unreacted carbon undergo a synthesis reaction via atomic diffusion to generate porous tantalum carbide, with the reaction equation being Ta + C = TaC. Simultaneously, the porous structure formed during the first sintering process interconnects through atomic diffusion, gradually smoothing the pore walls and making the porous network more stable.

[0079] According to embodiments of this application, the second sintering temperature is 2150℃-2250℃, specifically 2150℃, 2200℃, 2250℃, or any range between two of these. Therefore, a suitable second sintering temperature facilitates the diffusion of elemental tantalum and carbon atoms, allowing them to fully react and completely transform into tantalum carbide. If the second sintering temperature is too low, it may result in insufficient atomic diffusion, incomplete reaction between elemental tantalum and carbon, and reduced purity and hardness of the porous tantalum carbide material. If the second sintering temperature is too high, TaC grains may overgrow, thereby compressing surrounding pores and causing pore closure or uneven distribution.

[0080] According to embodiments of this application, the time to reach the second sintering temperature is 1-2 hours, specifically 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, or any range between two of these. Therefore, a suitable heating time facilitates simultaneous heating of all regions within the porous tantalum carbide material, preventing internal stress caused by localized thermal expansion differences, thereby avoiding structural cracking or pore collapse. If the heating time is too long, it may prolong the second sintering time, increasing production costs; if the heating time is too short, a large temperature difference may occur between the surface and interior of the porous tantalum carbide material, leading to thermal stress concentration and causing cracking.

[0081] According to embodiments of this application, the second sintering time is 50-80 hours, specifically 50 hours, 60 hours, 70 hours, 80 hours, or any range between two of these. Therefore, a suitable second sintering time facilitates atomic diffusion and ensures sufficient synthesis reaction. If the second sintering time is too short, it may result in insufficient atomic diffusion rate, incomplete reaction between tantalum and carbon, and reduced purity and hardness of the porous tantalum carbide material. If the second sintering time is too long, TaC grains may overgrow, thereby compressing surrounding pores and causing pore closure or uneven distribution.

[0082] According to embodiments of this application, the pressure of the second sintering is 10 Pa to 20 Pa, specifically 10 Pa, 11 Pa, 12 Pa, 13 Pa, 14 Pa, 15 Pa, 16 Pa, 17 Pa, 18 Pa, 19 Pa, 20 Pa, or any range between two of these. Therefore, a suitable sintering pressure can moderately compress the tantalum particles and carbon source, increasing the contact area between particles, thereby accelerating the reaction and the growth of tantalum carbide grains. If the pressure of the second sintering is too high, it may excessively compress the pores, causing most of the interconnected pores to close or their diameter to shrink; if the pressure of the second sintering is too low, it may result in loose particles and weak bonding, leading to a decrease in the overall strength and stability of the porous tantalum carbide material.

[0083] According to embodiments of this application, after sintering, the process further includes cooling to room temperature for 20-30 hours, specifically 20 hours, 25 hours, 30 hours, or any combination thereof. Therefore, a suitable cooling rate can help to achieve uniform temperature change within the porous tantalum carbide material, reduce stress accumulation caused by differences in thermal expansion coefficients, and obtain a structurally complete porous tantalum carbide material.

[0084] In other embodiments, when the tantalum source comprises tantalum particles and the carbon source comprises carbon powder, the method for preparing the thermal field component includes:

[0085] S10: The tantalum particles and the carbon powder are alternately layered to obtain the raw material mixture.

[0086] In this step, tantalum particles and carbon powder are alternately layered and loaded into the loading chamber 6 of the mold. The upper part 4 and the lower part 5 of the mold are fastened with bolts 3 for sintering. Because the particle size of tantalum particles and carbon powder differs greatly, when tantalum particles and carbon powder are alternately layered, the fine carbon powder fills the gaps between the coarse tantalum particles, forming a dense initial packing structure.

[0087] According to embodiments of this application, the tantalum particles have a particle size of 100 μm-1 mm, specifically within the range of 100 μm, 200 μm, 400 μm, 600 μm, 800 μm, 1 mm, or any two of these ranges. Therefore, within the aforementioned particle size range of the tantalum particles, sufficient specific surface area can be provided for reaction with the carbon powder, ensuring a complete reaction. If the particle size of the tantalum particles is too large, the specific surface area will be too small, potentially reducing the contact area with the carbon powder and leading to incomplete reaction; if the particle size of the tantalum particles is too small, the particles may easily agglomerate, resulting in smaller gaps between particles, making it difficult for the carbon powder to fill uniformly, thus reducing the number of pores formed.

[0088] According to embodiments of this application, the particle size of the carbon powder is 5μm-10μm, specifically 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any combination thereof. Within this particle size range, the carbon powder helps to fully fill the gaps between tantalum particles, increasing the contact area between carbon and tantalum, thereby promoting a complete reaction. If the carbon powder particle size is too large, the large-diameter carbon powder will have difficulty entering the gaps between tantalum particles, potentially preventing some tantalum particle surfaces from contacting the carbon powder, resulting in uneven reaction and affecting the uniformity of the porous tantalum carbide material. If the carbon powder particle size is too small, the carbon powder may easily agglomerate, forming large carbon blocks that cannot fill the gaps between tantalum particles, or even block the gaps.

[0089] According to embodiments of this application, the mass ratio of tantalum particles to carbon powder is 1:1.1-1.3. This helps the tantalum particles to be completely consumed, ensuring a sufficient reaction. If the mass ratio is too low, there will be too much carbon powder, which may lead to agglomeration of carbon powder or the formation of other carbides or other impurities, thereby reducing the purity of the porous tantalum carbide material. If the mass ratio is too high, there will be insufficient carbon powder, and some tantalum particles may not be able to react completely, thus reducing the purity of the porous tantalum carbide material.

[0090] S20: Sinter the raw material mixture to obtain porous tantalum carbide material.

[0091] In this step, tantalum and carbon react to form tantalum carbide, with the reaction equation being Ta + C = TaC. Initially, a tantalum carbide shell forms on the surface of the tantalum particles. This process is accompanied by volume expansion, which exerts a squeezing effect on adjacent particles, compressing the carbon powder layer. As the reaction continues, carbon powder is continuously consumed in the reaction, and its volume gradually decreases. Unable to fill the space left by the expansion of the tantalum carbide shell and its own consumption, a porous structure is eventually formed at the interlayer interface.

[0092] According to embodiments of this application, the sintering temperature is 2150℃-2250℃, specifically 2150℃, 2200℃, 2250℃, or any range between two of these. Therefore, a suitable temperature promotes the diffusion of carbon atoms into the tantalum particles, resulting in uniform growth of the tantalum carbide shell layer; it also facilitates the formation of appropriate grain sizes, leading to a uniform distribution of pores. If the sintering temperature is too high, it may cause excessive growth of the tantalum carbide grains, with large grains compressing the interlayer pores and causing pore closure; if the sintering temperature is too low, the tantalum carbide shell layer may form slowly and the reaction may be incomplete, with residual tantalum or carbon disrupting the continuity of the porous structure.

[0093] According to the embodiments of this application, the time required to reach the sintering temperature is 1-2 hours, specifically 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, or any range between two of these. Therefore, a suitable heating time facilitates simultaneous heating of the tantalum particles and the carbon powder layer, avoiding cracking of the porous tantalum carbide material due to thermal stress caused by localized temperature differences. If the heating time is too long, the reaction becomes prolonged, potentially leading to carbon powder agglomeration, reducing its efficiency in filling the gaps between tantalum particles, and affecting the uniformity of the reaction. If the heating time is too short, it may cause differences in thermal expansion between the tantalum particles and the carbon powder layer, resulting in interlayer delamination or internal cracks within the tantalum particles.

[0094] According to embodiments of this application, the sintering time is 50-80 hours, specifically 50 hours, 60 hours, 70 hours, 80 hours, or any range between two of these. Therefore, a suitable sintering time facilitates atomic diffusion, allowing for a more complete reaction. If the sintering time is too long, it may lead to excessive growth of tantalum carbide grains, with large grains compressing interlayer pores and causing pore closure; if the sintering time is too short, it may lead to incomplete reaction of tantalum particles, with residual tantalum and carbon powder clogging the pores, resulting in a porous structure with insufficient strength.

[0095] According to an embodiment of this application, the sintering pressure is 7 × 10⁻⁶. 3 Pa-8×10 3 Pa, specifically 7 × 10 3 Pa, 7.2 × 10 3 Pa, 7.4 × 10 3 Pa, 7.6 × 10 3 Pa, 7.8 × 10 3 Pa, 8×10 3 The pressure is within the range of Pa or any two of these. Therefore, a suitable sintering pressure can moderately compress the tantalum particles and carbon powder, increasing their contact area and thus promoting the reaction. If the sintering pressure is too high, excessive pressure may over-compress the pores, causing most of the interconnected pores to close or their diameter to shrink; if the sintering pressure is too low, it may result in insufficient contact between the tantalum particles and carbon powder, leading to a decrease in the reaction rate.

[0096] A third aspect of this application proposes a thermal field for SiC crystal growth, which includes the thermal field components for SiC crystal growth described above. All features and advantages of this thermal field are consistent with those of the thermal field components described above, and will not be repeated here.

[0097] The embodiments of this application are described in detail below.

[0098] Example 1

[0099] 750g of tantalum pentoxide (average particle size 4μm) and 100g of carbon particles (average particle size 200μm) were placed in a stirrer and stirred at 100r / min for 1 hour to obtain a raw material mixture. The raw material mixture was then placed in a sintering mold (made of tantalum metal), pressed using a press, and secured with bolts. The sintering mold was placed in the hot zone of the sintering apparatus, the structure of which is as follows: Figure 3 As shown, sintering is carried out according to the following process steps:

[0100] 1. Evacuate the sintering apparatus;

[0101] 2. Purge with inert gas Ar, setting the pressure to 1×10⁻⁶. -4 Pa;

[0102] 3. Increase power and raise the temperature to 1950℃ for the first sintering. The time required to reach this temperature is 1 hour, while maintaining the pressure at 1×10⁻⁶. -4 Pa, and maintained at this temperature for 2.5 hours;

[0103] 4. Annealing is carried out at a temperature of 1000℃, which takes 5 hours to reach. Simultaneously, the pressure is increased to 8 × 10⁻⁶. 3 Pa, annealed at this temperature for 10 hours;

[0104] 5. The second sintering is carried out at a temperature of 2250℃, and the time required to reach this temperature is 2 hours; the pressure is 20 Pa, and the temperature is maintained for 80 hours.

[0105] 6. The temperature is lowered to room temperature (25℃), and the time required to reach that temperature is 24 hours.

[0106] 7. Open the furnace, remove the sintering mold, and demold to obtain the prepared part.

[0107] Example 2

[0108] Take 100g of tantalum particles (average particle size 400μm) and 120g of carbon powder (average particle size 5μm). Spread 12g of carbon powder as the first layer in a mold (made of tantalum metal). Then, spread a layer of 10g of tantalum particles on top of the carbon powder. Repeat this alternating layering process until the mold is full. Pressurize the mold cover and tighten it with bolts. Place the mold in the hot zone of the sintering apparatus and sinter according to the following process:

[0109] 1. Evacuate the sintering apparatus;

[0110] 2. Purge with inert gas Ar, setting the pressure to 1×10⁻⁶. -3 Pa;

[0111] 3. Increase power and raise the temperature to 2250℃ for sintering. The time required to reach this temperature is 2 hours, and the pressure is increased to 10 Pa. Maintain this temperature for 80 hours.

[0112] 4. The temperature is lowered to room temperature (25℃), and the time required to reach that temperature is 24 hours.

[0113] 5. Open the furnace, remove the sintering mold, and demold to obtain the prepared part.

[0114] Depend on Figure 6 It can be seen that the prepared porous tantalum carbide material has a layered morphology. From Figure 7 It can be seen that Ta and C elements are present at the same time, and Ta and C elements are uniformly distributed in the porous tantalum carbide material.

[0115] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0116] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0117] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A thermal field component for SiC crystal growth, characterized in that, The thermal field component includes a thermal field component body, which is made of porous tantalum carbide material.

2. The thermal field component according to claim 1, characterized in that, At least one of the following conditions must be met: The pore size of the porous tantalum carbide material is 10μm-20μm, preferably 10μm; The porosity of the porous tantalum carbide material is 40%-60%.

3. The thermal field component according to claim 1, characterized in that, The thermal field components include at least one of the following in the SiC crystal growth apparatus: crucible, crucible cover, seed crystal rod, insulation layer, and tooling mold assembly.

4. A method for preparing a thermal field component for SiC crystal growth, characterized in that, include: The raw material mixture is sintered in a mold to obtain porous tantalum carbide material; The raw material mixture is composed of a carbon source and a tantalum source; The tantalum source includes at least one of tantalum pentoxide and tantalum particles; The carbon source includes at least one of carbon particles and carbon powder.

5. The method according to claim 4, characterized in that, The tantalum source includes tantalum pentoxide, and the method further includes: The tantalum pentoxide and the carbon source are stirred and mixed to obtain the raw material mixture.

6. The method according to claim 5, characterized in that, The sintering includes: The raw material mixture is subjected to a first sintering, in which the carbon source and the tantalum pentoxide undergo a reduction reaction to generate elemental tantalum and carbon monoxide, thus obtaining the first sintering product; The calcined product is annealed to obtain an annealed product. The annealed product is subjected to a second sintering process to react elemental tantalum with the carbon source, thereby obtaining the porous tantalum carbide material.

7. The method according to claim 6, characterized in that, At least one of the following conditions must be met: The first sintering temperature is 1900℃-2050℃; The first sintering time is 2-3 hours; The pressure of the first sintering is 1×10 -4 Pa to 2×10 -3 Pa; The annealing temperature is 1000℃-1200℃; The annealing process takes 5-10 hours. The annealing process is performed at a pressure of 7 × 10⁻⁶. 3 Pa-8×10 3 Pa; The second sintering temperature is 2150℃-2250℃; The second sintering time is 50-80 hours; The pressure of the second sintering is 10Pa-20Pa.

8. The method according to claim 4, characterized in that, At least one of the following conditions must be met: The particle size of the tantalum pentoxide is 1μm-10μm; The carbon particles have a particle size of 100 μm-1 mm.

9. The method according to claim 4, characterized in that, The tantalum source comprises tantalum particles, the carbon source comprises carbon powder, the tantalum particles have a particle size of 100 μm-1 mm, and the carbon powder has a particle size of 5 μm-10 μm. The method further includes: The tantalum particles and the carbon powder are alternately layered to obtain the raw material mixture.

10. The method according to claim 9, characterized in that, The sintering process includes maintaining a pressure of 10 Pa to 20 Pa and sintering at a temperature of 2150°C to 2250°C for 50 to 80 hours.

11. A thermal field for SiC crystal growth, characterized in that, It includes the thermal field component for SiC crystal growth as described in any one of claims 1 to 3.

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