High-purity silicon carbide heat insulation plate base and preparation method thereof

Abstract

According to the high-purity silicon carbide heat insulation plate base and the preparation method thereof, the preparation method comprises the steps that a bottom plate blank body and a supporting rod blank body are subjected to split forming, bonding and drying are conducted in a graphite jig, and then the primarily-formed silicon carbide heat insulation plate base is obtained through sintering treatment; and carrying out machining treatment and purification treatment on the preliminarily formed silicon carbide heat insulation plate base to obtain the high-purity silicon carbide heat insulation plate base. The high-purity silicon carbide heat insulation plate base is obtained by placing the bottom plate blank body and the supporting rod blank body which are separated into each other in the graphite jig to be bonded and shaped, combining one-time sintering forming and then carrying out machining treatment and purification treatment, so that the machining difficulty of the silicon carbide heat insulation plate base is reduced, and the purity of the silicon carbide heat insulation plate base is improved. Therefore, the technical problem that in the prior art, a silicon carbide heat insulation plate base is large in machining difficulty is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of silicon carbide heat-insulating plate bases, and particularly relates to a high-purity silicon carbide heat-insulating plate base and a preparation method thereof. Background Art

[0002] Silicon carbide materials have advantages such as a large bandgap, a high breakdown field strength, and a small dielectric constant, and are extremely ideal semiconductor materials for high-temperature, high-frequency, radiation-resistant, and high-power applications. Silicon carbide devices can operate at higher temperatures, voltages, and frequencies, and the performance of devices based on silicon carbide ceramics is far superior to that of devices made of quartz materials. A diffusion furnace is one of the important process equipment in the front process of a semiconductor production line. The diffusion furnace cooperates with the furnace tubes inside it and is commonly used for the high-temperature diffusion of semiconductor wafers to produce chips. The quality of the furnace tube components directly affects the yield and reliability of semiconductor wafers.

[0003] In the prior art, as one of the furnace tube components inside the diffusion furnace, the heat-insulating plate base needs to be assembled and used in cooperation with a boat. When in use, multiple heat-insulating plates also need to be placed on the heat-insulating plate base to slow down the heat conduction and keep the internal temperature of the furnace tube constant so that the wafers can react in the constant-temperature zone. Silicon carbide has excellent high-temperature resistance and long-term resistance to strong corrosion environments, etc., and is very suitable for the preparation of furnace tube components for diffusion. However, due to the high hardness and high brittleness of silicon carbide, the processing difficulty of the silicon carbide heat-insulating plate base is very large. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-purity silicon carbide heat-insulating plate base and a preparation method thereof, which solve the technical problem of the large processing difficulty of the silicon carbide heat-insulating plate base in the prior art.

[0005] To achieve this purpose, the present invention adopts the following technical solutions: According to the first aspect, the present invention provides a preparation method of a high-purity silicon carbide heat-insulating plate base, including: Step S1, respectively forming a bottom plate blank and a support rod blank, and processing bonding holes on the bottom plate blank; the bottom plate blank and the support rod blank are made of silicon carbide slurry; Step S2, placing the bottom plate blank and the support rod blank in a graphite fixture for bonding to obtain an intermediate structure, and drying the intermediate structure; the intermediate structure includes a graphite fixture and a heat-insulating plate base blank; Step S3, sintering the dried intermediate structure to obtain a preliminarily formed silicon carbide heat-insulating plate base; Step S4, performing machining on the preliminarily formed silicon carbide heat-insulating plate base; Step S5, purify the machined heat insulation board base to obtain a high-purity silicon carbide heat insulation board base; wherein, the high-purity silicon carbide heat insulation board base includes a bottom plate and at least three support rods.

[0006] Optionally, step S1 includes: Step S11, prepare a silicon carbide slurry with a preset ratio; Step S12, inject the prepared silicon carbide slurry into corresponding gypsum molds respectively; Step S13, let it stand for 2 to 4 hours, and remove the gypsum molds after the silicon carbide slurry is formed to obtain a formed bottom plate blank and a formed support rod blank respectively.

[0007] Optionally, in step S11, the silicon carbide slurry includes a silicon carbide mixture, deionized water and an amino alcohol dispersant; the silicon carbide slurry is prepared by adding the deionized water and the amino alcohol dispersant to the uniformly mixed silicon carbide mixture and performing mechanical stirring.

[0008] Optionally, the silicon carbide mixture includes silicon carbide powder with a D50 particle size of 5 μm and silicon carbide powder with a D50 particle size of 150 μm.

[0009] Optionally, the graphite fixture includes a first graphite plate, a second graphite plate and at least three graphite support rods. The first graphite plate and the second graphite plate are arranged oppositely. One end of the graphite support rod is connected to the first graphite plate, and the other end of the graphite support rod is connected to the second graphite plate. The perpendicularity of the graphite fixture is less than 0.5; Step S2 includes: Step S21, fix the second graphite plate to one end of at least three graphite support rods respectively, and place the bottom plate blank on the second graphite plate; Step S22, sequentially insert at least three support rod blanks into the bonding holes of the bottom plate blank and fix them on the graphite support rods; the bonding holes and the joints of the support rod blanks are all coated with silicon carbide slurry; Step S23, fix the first graphite plate to the other end of the graphite support rods; Step S24, let it stand for 2 hours, and bond the bottom plate blank and at least three support rod blanks to obtain a heat insulation board base blank; Step S25, perform a drying treatment on the graphite fixture and the heat insulation board base blank.

[0010] Optionally, in step S25, perform a drying treatment on the graphite fixture and the heat insulation board base blank through a blast drying oven, the drying temperature is 80 to 105 °C, and the drying time is 8 hours.

[0011] Optionally, in step S3, the dried intermediate structure is sintered by a vacuum reaction sintering furnace, and the sintering temperature is 2200-2450 °C.

[0012] Optionally, step S4 includes: Step S41, machining the boss of the preliminarily formed silicon carbide heat insulation plate base so that the flatness of the boss is less than 0.1; Step S42, machining the end face of the rod away from the bottom plate so that the parallelism between the end face of the rod away from the bottom plate and the boss is less than 0.1.

[0013] Optionally, in step S5, the machined heat insulation plate base is purified by a purification furnace, and the gases introduced are argon and carbon tetrafluoride, and the purification temperature is 800-1400 °C.

[0014] According to a second aspect, the present invention provides a high-purity silicon carbide heat insulation plate base, which is obtained by the preparation method of the high-purity silicon carbide heat insulation plate base as described in the first aspect. The high-purity silicon carbide heat insulation plate base includes a bottom plate and a rod, and the bottom plate and the rod are sintered and formed.

[0015] Compared with the prior art, the present invention has the following beneficial effects: A high-purity silicon carbide heat insulation plate base and a preparation method thereof provided by the present invention are formed by separately forming a bottom plate blank and a rod blank, bonding and drying in a graphite fixture, and then obtaining a preliminarily formed silicon carbide heat insulation plate base through sintering treatment, and then machining and purifying the preliminarily formed silicon carbide heat insulation plate base to obtain a high-purity silicon carbide heat insulation plate base. By adopting the above preparation method, the processing difficulty of the silicon carbide heat insulation plate base is reduced, and the purity of the silicon carbide heat insulation plate base is improved. Therefore, the present invention solves the technical problem of the large processing difficulty of the silicon carbide heat insulation plate base in the prior art. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0017] The structures, proportions, sizes, etc. shown in the accompanying drawings of this specification are only used to cooperate with the content disclosed in the specification for those familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Therefore, they do not have substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed in the present invention.

[0018] Figure 1 It is a flowchart of a preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention; Figure 2 It is a schematic structural diagram of a bottom plate blank without bonding holes in the preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention; Figure 3 It is a schematic structural diagram of a bottom plate blank with bonding holes in the preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention; Figure 4 It is a schematic structural diagram of a support rod blank in the preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention; Figure 5 It is a schematic structural diagram of a heat-insulating plate base blank in the preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention; Figure 6 It is a schematic structural diagram of a graphite fixture in the preparation method for a high-purity silicon carbide heat-insulating plate base provided in the first embodiment of the present invention.

[0019] Illustration: 100. Bottom plate blank; 101. Bonding hole; 102. Boss; 200. Support rod blank; 300. Heat-insulating plate base blank; 400. Graphite fixture; 401. First graphite plate; 402. Second graphite plate; 403. Graphite support rod; 404. First opening; 405. Second opening. Detailed implementation manners

[0020] To make the invention purposes, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be intermediate components present simultaneously.

[0022] The technical solution of the present invention will be further described below in conjunction with the drawings and through specific embodiments.

[0023] Embodiment 1: As Figures 1 to 6 shown, the embodiment of the present invention provides a preparation method for a base of a high-purity silicon carbide heat-insulating plate, including: Step S1, respectively form a bottom plate blank 100 and a support rod blank 200, and process bonding holes 101 on the bottom plate blank 100; the bottom plate blank 100 and the support rod blank 200 are made of silicon carbide slurry. Specifically, the bottom plate blank 100 and the support rod blank 200 are made by injection molding. The number of the bonding holes 101 is at least three, and the number of the bonding holes 101 is not limited. The number of the bonding holes 101 is adjusted correspondingly according to the number of the support rods. The bonding holes 101 are processed on the bottom plate blank 100 by a commonly used precision engraving machine in the art, and will not be elaborated here.

[0024] In one embodiment, step S1 includes: Step S11, prepare a silicon carbide slurry with a preset ratio; Step S12, inject the prepared silicon carbide slurry into corresponding gypsum molds respectively; in this embodiment, the silicon carbide slurry is injected into the corresponding gypsum molds respectively by an injection molding machine well-known in the art, and will not be elaborated here; Step S13, let it stand for 2 to 4 hours. After the silicon carbide slurry is formed, remove the gypsum molds to obtain the formed bottom plate blank 100 and support rod blank 200 respectively. Specifically, the gypsum molds can be disassembled manually or mechanically, and will not be elaborated here.

[0025] In step S11, the silicon carbide slurry includes a silicon carbide mixture, deionized water and an amino alcohol dispersant; the silicon carbide slurry is prepared by mechanically stirring deionized water and an amino alcohol dispersant into the uniformly mixed silicon carbide mixture. The silicon carbide mixture includes silicon carbide powder with a D50 particle size of 5 μm and silicon carbide powder with a D50 particle size of 150 μm.

[0026] Specifically, in this forming method, by weight percentage of the silicon carbide mixture, 13-20% deionized water and 0.1-0.5% amino alcohol dispersant are added to the silicon carbide mixture to obtain a silicon carbide slurry with a preset ratio. Among them, the ratio of the two silicon carbide powders in the silicon carbide mixture is not limited.

[0027] It should be noted that D50 represents the median particle size of the particle distribution, that is, in the particle size distribution curve, 50% of the particle diameters are less than or equal to this value, and the remaining 50% of the particle diameters are greater than this value.

[0028] Step S2, place the bottom plate blank 100 and the support rod blank 200 in the graphite fixture 400 for bonding to obtain an intermediate structure, and perform a drying treatment on the intermediate structure; the intermediate structure includes the graphite fixture 400 and the heat insulation plate base blank 300.

[0029] Specifically, as Figure 6 shown, the heat insulation plate base blank 300 includes the bottom plate blank 100 and the support rod blank 200.

[0030] It should be noted that since the graphite fixture 400 plays a positioning role, it can position and bond the bottom plate blank 100 and the support rod blank 200, ensuring the perpendicularity of the support rod and the subsequent boss 102, and laying a foundation for the sintering in the subsequent step S3, and can effectively prepare a high-purity silicon carbide heat insulation plate base that meets the preparation requirements.

[0031] In one embodiment, as Figures 1 to 6 shown, step S2 includes: Step S21, fix one end of at least three graphite support rods 403 to the second graphite plate 402 respectively, and place the bottom plate blank 100 on the second graphite plate 402; Step S22, sequentially insert at least three support rod blanks 200 into the bonding holes 101 of the bottom plate blank 100 and fix them on the graphite support rods 403; the joints between the bonding holes 101 and the support rod blanks 200 are coated with silicon carbide slurry; Step S23, fix the first graphite plate 401 to the other end of the graphite support rod 403; Step S24, let it stand for 2 hours, and the bottom plate blank 100 is bonded to at least three support rod blanks 200 to obtain the heat insulation plate base blank 300; Step S25, perform a drying treatment on the graphite fixture 400 and the heat insulation plate base blank 300. In step S25, the graphite fixture 400 and the heat insulation plate base blank 300 are dried by a blast drying oven, the drying temperature is 80-105 °C, and the drying time is 8 hours.

[0032] It should be noted that after the bottom plate blank 100 and the support rod blank 200 are assembled in the graphite jig 400, the perpendicularity of the three graphite support rods 403 with respect to the second graphite plate 402 is less than 0.5; this enhances the accuracy of the entire jig, enabling precise docking of each component during the bonding process and avoiding problems such as cracks and pores caused by uneven stress during the high-temperature sintering process. In step S22, by applying silicon carbide slurry at the bonding hole 101 of the bottom plate blank 100 and inserting the support rod blank 200 into it, a tight bond between the support rod and the bottom plate is ensured; this enhances the bonding effect, causing a more stable bond to form at the connection between the support rod and the bottom plate, effectively improving the overall structural stability of the heat insulation plate base. In step S23, the first graphite plate 401 and the second graphite plate 402 are respectively fixed to the two ends of the graphite support rod 403 to form an integral structure, ensuring the parallelism and stability of the bottom plate and the support rod, enabling the heat insulation plate base to withstand stress changes in a high-temperature environment and improving its durability and long-term high-temperature stability. In step S24, the treatment time of standing for 2 hours provides sufficient time for the bonding of the bottom plate blank 100 and the support rod blank 200, enabling the slurry to solidify and ensuring the shape stability of the connection part; this helps reduce deformation caused by premature operation and simultaneously avoids stress concentration problems caused by uneven bonding. In the drying treatment in step S25, by controlling the temperature (80 - 105 °C) and drying time (8 hours) with a blast drying oven, the drying process can uniformly remove moisture, avoiding uneven thermal expansion or contraction during the drying process and ensuring that the heat insulation plate base does not deform during subsequent sintering.

[0033] Step S3: Sinter the dried intermediate structure to obtain a preliminarily formed silicon carbide heat insulation plate base. In step S3, the dried intermediate structure is sintered by a vacuum reactive sintering furnace, and the sintering temperature is 2200 - 2450 °C. The vacuum reactive sintering furnace is a well-known technology in the art and will not be elaborated here.

[0034] It should be noted that high-temperature sintering in a vacuum reactive sintering furnace can effectively improve the densification of silicon carbide materials, reduce internal pores, and thus enhance the strength and thermal stability of the product. This enables the final silicon carbide heat insulation plate base to have better structural integrity and be able to be used for a long time in a high-temperature environment. Using a vacuum environment for sintering helps avoid the influence of oxygen or other pollutants in the air on the material, maintaining the high purity of silicon carbide, especially at high temperatures, and avoiding the impact on material properties due to oxidation reactions. During the high-temperature sintering process, the crystal structure of silicon carbide is further optimized, ensuring that the heat insulation plate base has better heat resistance and corrosion resistance under harsh conditions such as high temperature and high frequency. By precisely controlling the sintering temperature (2200 - 2450 °C), the sintering degree of the material can be ensured to reach the optimal state, thereby avoiding material defects caused by insufficient or excessive sintering.

[0035] Specifically, the graphite fixture 400 has a first opening 404 and a second opening 405. The number of graphite support rods 403 is three. The first opening 404 is formed by enclosing a first graphite plate 401, a second graphite plate 402, and two adjacent graphite support rods 403. The second opening 405 is provided at one end of the graphite support rod 403 close to the second graphite plate 402. Both the first opening 404 and the second opening 405 are used for gas circulation.

[0036] The graphite fixture 400 adopts the following design method: Determine the height of the support rod according to the design requirements of the heat insulation plate base; According to the arc radius and arc angle of the graphite support rod 403, calculate the width of the first opening 404; Specifically, the width of the first opening 404 is calculated by the following formula: ; Where: W1 is the width of the first opening 404, R is the arc radius of the graphite support rod 403, and θ is the arc angle of the graphite support rod 403.

[0037] According to the width of the first opening 404 and the height of the graphite support rod 403, calculate the area of the first opening 404; Specifically, the area of the first opening 404 is calculated by the following formula: ; Where: A1 is the area of the first opening 404, and h1 is the height of the graphite support rod 403.

[0038] According to the width and height of the second opening 405, calculate the area of the second opening 405; Specifically, the area of the second opening 405 is calculated by the following formula: , ; Where: W2 is the width of the first opening 404, D s is the arc diameter of the support rod; A2 is the area of the second opening 405, and h2 is the height of the second opening 405.

[0039] According to the thermal expansion coefficients of the first graphite plate 401, the second graphite plate 402, and the sintering temperature, correct the areas of the first opening 404 and the second opening 405, and calculate the corrected areas of the first opening 404 and the second opening 405.

[0040] Specifically, the correction formula for the area of the first opening 404 at the sintering temperature is: ; The corrected area of the first opening 404 is calculated by the following formula: ; In the formula, T is the sintering temperature, α1 is the thermal expansion coefficient of the first graphite plate 401, and T0 is the reference temperature (usually room temperature); The correction formula for the area of the second opening 405 at the sintering temperature is: ; The corrected area of the second opening 405 is calculated by using the following formula: ; In the formula, T is the sintering temperature, α2 is the thermal expansion coefficient of the second graphite plate 402, and T0 is the reference temperature (usually room temperature).

[0041] It should be noted that the areas of the first opening 404 and the second opening 405 are determined by calculating the height and arc radius of the graphite support rod 403. To ensure gas flow and improve the structural stability, the first opening 404 and the second opening 405 need to be precisely designed and the areas calculated. During the working process of the graphite fixture 400, the areas of the first opening 404 and the second opening 405 will change due to thermal expansion during the sintering process. Therefore, the influence of the thermal expansion coefficient of the graphite material and the sintering temperature is considered in the design, and the opening areas are corrected to ensure structural stability during the sintering process. During the working process of the graphite fixture 400, the areas of the first opening 404 and the second opening 405 will change due to thermal expansion during the sintering process. Therefore, the influence of the thermal expansion coefficient of the graphite material and the sintering temperature is considered in the design, and the opening areas are corrected to ensure structural stability during the sintering process. The precise design of the first opening 404 and the second opening 405 and the reasonable selection of the sintering temperature are of great significance for ensuring the quality and function of the final product. Especially in applications under high-temperature environments, it can significantly improve the strength, stability, and durability of the product.

[0042] Step S4, perform machining on the preliminarily formed silicon carbide heat insulation plate base. In this embodiment, the machining is performed using a numerically controlled machine tool (such as a CNC machine tool) or a grinding machine well-known in the art, which will not be elaborated here.

[0043] In one embodiment, as Figures 1 to 6 shown, step S4 includes: Step S41, perform machining on the boss 102 of the preliminarily formed silicon carbide heat insulation plate base to make the flatness of the boss 102 less than 0.1; Step S42, perform machining on the end face of the support rod away from the bottom plate to make the parallelism between the end face of the support rod away from the bottom plate and the boss 102 less than 0.1.

[0044] It should be noted that in step S41, the uneven parts on the surface are precisely removed by a numerical control machine tool (such as a CNC machine tool) or a grinding machine to ensure that the surface of the boss 102 is flat and meets the accuracy requirements. In step S42, through the surface machining of equipment such as a numerical control machine tool or a grinding machine, the accuracy of the parallelism between the end face of the support rod and the surface of the boss 102 is ensured. Through fine machining, the flatness of the boss 102 and the parallelism between the end face of the support rod and the boss 102 both reach high-precision requirements (less than 0.1), ensuring that during the actual use of the silicon carbide heat insulation plate base, the connection between the support rod and the bottom plate is stable, and avoiding structural instability caused by uneven contact or deformation. By ensuring the precise fit between the base and the support rod, the stress concentration phenomenon caused by errors is reduced, and the risk of cracking or splitting is lowered, thereby improving the load-bearing capacity and durability of the product in high-temperature and high-pressure environments. This machining treatment step is an important link to ensure a high-precision structure, and finally realizes a high-quality finished product of the silicon carbide heat insulation plate base, which is particularly suitable for semiconductor and high-temperature application scenarios and can effectively meet the use requirements under high-temperature conditions.

[0045] Step S5: Purify the machined heat insulation plate base to obtain a high-purity silicon carbide heat insulation plate base; wherein, the high-purity silicon carbide heat insulation plate base includes a bottom plate and at least three support rods. In step S5, the machined heat insulation plate base is purified by a purification furnace, and the gases introduced are argon and carbon tetrafluoride, and the purification temperature is 800 - 1400 °C. In this embodiment, the purification furnace is a well-known device in the art and will not be elaborated here.

[0046] Specifically, the silicon carbide heat insulation plate base is purified by a purification furnace. The purification furnace is a high-temperature furnace with the function of precisely controlling temperature and atmosphere. The gas channels in the purification furnace are provided with argon and carbon tetrafluoride gas systems. Argon, as an inert gas, can prevent oxidation reactions, while carbon tetrafluoride helps to remove impurities in silicon carbide, such as metals and oxides. The gas flow rate and velocity in the purification furnace are precisely regulated according to the size and mass of the material. The purification temperature is controlled within the range of 800 - 1400 °C to effectively remove impurities in the silicon carbide material while avoiding damage or structural instability of silicon carbide caused by excessive temperature.

[0047] It should be noted that through the synergistic effect of argon and carbon tetrafluoride, impurities in silicon carbide, such as metals and oxides, are effectively removed, significantly improving the purity of the material. This purification process can ensure that the final product meets the required high purity, and is particularly suitable for fields with high-precision and high-performance requirements, such as semiconductors and high-temperature application environments. After removing impurities, the crystal structure of high-purity silicon carbide becomes more uniform and dense, significantly enhancing its stability and durability at high temperatures. The silicon carbide heat-insulating plate base after purification treatment can better withstand extreme high-temperature and high-pressure conditions and maintain its mechanical strength and thermal stability for a long time. By precisely controlling the atmosphere and temperature during the purification process, it is ensured that each batch of products has consistent high purity and high performance. For large-scale production, it can guarantee the consistent quality of each heat-insulating plate base and avoid quality fluctuations caused by material impurities.

[0048] After step S5, it further includes: Step S6, measuring the size of the high-purity silicon carbide heat-insulating plate base and performing GDMS (glow discharge mass spectrometry) detection.

[0049] Specifically, usually high-precision measuring tools, such as coordinate measuring machines, laser scanners or precision calipers, etc., are used to precisely measure the size of the high-purity silicon carbide heat-insulating plate base (such as perpendicularity, flatness, and parallelism, etc.) to ensure that its size meets the design requirements; the perpendicularity of the support rod is less than 0.5, the flatness of the boss 102 is less than 0.1, and the parallelism between the top of the support rod and the boss 102 is less than 0.1. In this step, GDMS is used to detect impurity elements (such as metal elements Fe, Al and non-metal element P, etc.) in the high-purity silicon carbide heat-insulating plate base. By putting the sample into a glow discharge mass spectrometer well-known in the art and using gas ionization caused by glow discharge and mass spectrometry analysis, trace elements in the material can be detected, thereby evaluating the purity and impurity content of the material.

[0050] It should be noted that after the high-purity silicon carbide heat-insulating plate base is detected by GDMS, its impurity content is less than 100 ppm, that is, the purity can reach 99.99%.

[0051] Working principle: A preparation method of a high-purity silicon carbide heat-insulating plate base provided by the present invention is to separately form the bottom plate blank 100 and the support rod blank 200, perform bonding and drying in the graphite fixture 400, then obtain a preliminarily formed silicon carbide heat-insulating plate base through sintering treatment, and then perform machining treatment and purification treatment on the preliminarily formed silicon carbide heat-insulating plate base to obtain a high-purity silicon carbide heat-insulating plate base. By adopting the above preparation method, the processing difficulty of the silicon carbide heat-insulating plate base is reduced, and the purity of the silicon carbide heat-insulating plate base is improved. Therefore, the present invention solves the technical problem of the large processing difficulty of the silicon carbide heat-insulating plate base in the prior art.

[0052] Example Two: An embodiment of the present invention provides a high-purity silicon carbide heat-insulating plate base, which is obtained by the preparation method of the high-purity silicon carbide heat-insulating plate base as in Example One. The high-purity silicon carbide heat-insulating plate base includes a bottom plate and support rods, and the bottom plate and the support rods are sintered and formed.

[0053] It should be noted that the high-purity silicon carbide heat-insulating plate base is obtained by the preparation method provided in Example One. By placing the split bottom plate blank 100 and the support rod blank 200 in the graphite fixture 400 for bonding and shaping, and combining with one-time sintering and forming, then performing machining treatment and purification treatment, the high-purity silicon carbide heat-insulating plate base is obtained, reducing the processing difficulty of the silicon carbide heat-insulating plate base and improving the purity of the silicon carbide heat-insulating plate base.

[0054] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a high-purity silicon carbide heat-insulating plate base, characterized in that, Including: Step S1, respectively forming a bottom plate blank and a support rod blank, the bottom plate blank and the support rod blank being made of silicon carbide slurry; Step S2, placing the bottom plate blank and the support rod blank in a graphite fixture for bonding to obtain an intermediate structure, and drying the intermediate structure; the intermediate structure includes a graphite fixture and a heat insulation plate base blank; Step S3, sintering the dried intermediate structure to obtain a preliminarily formed silicon carbide heat insulation plate base; Step S4, performing machining on the preliminarily formed silicon carbide heat insulation plate base; Step S5, purifying the machined heat insulation plate base to obtain a high-purity silicon carbide heat insulation plate base; wherein, the high-purity silicon carbide heat insulation plate base includes a bottom plate and at least three support rods.

2. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 1, characterized in that, The step S1 includes: Step S11, preparing a silicon carbide slurry in a preset ratio; Step S12, injecting the prepared silicon carbide slurry into corresponding gypsum molds respectively; Step S13, standing for 2 to 4 hours, and removing the gypsum molds after the silicon carbide slurry is formed to obtain the formed bottom plate blank and support rod blank respectively.

3. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 2, characterized in that, In the step S11, the silicon carbide slurry includes a silicon carbide mixture, deionized water and an amino alcohol dispersant; the silicon carbide slurry is prepared by mechanically stirring the deionized water and the amino alcohol dispersant into the uniformly mixed silicon carbide mixture.

4. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 3, characterized in that, The silicon carbide mixture includes silicon carbide powder with a D50 particle size of 5μm and silicon carbide powder with a D50 particle size of 150μm.

5. The preparation method of the high-purity silicon carbide heat-insulating plate base according to any one of claims 1 to 4, characterized in that, The graphite fixture includes a first graphite plate, a second graphite plate and at least three graphite support rods, the first graphite plate and the second graphite plate are arranged oppositely, one end of the graphite support rod is connected to the first graphite plate, the other end of the graphite support rod is connected to the second graphite plate, and the perpendicularity of the graphite fixture is less than 0.5; Processing bonding holes on the bottom plate blank; The step S2 includes: Step S21, fixing one end of each of at least three graphite support rods to the second graphite plate respectively, and placing the bottom plate blank on the second graphite plate; Step S22, sequentially inserting at least three support rod blanks into the bonding holes of the bottom plate blank and fixing them on the graphite support rods; the joints of the bonding holes and the support rod blanks are coated with silicon carbide slurry; Step S23, fixing the first graphite plate to the other ends of the graphite support rods; Step S24, standing for 2 hours, bonding the bottom plate blank and at least three support rod blanks to obtain a heat insulation plate base blank; Step S25, drying the graphite fixture and the heat insulation plate base blank.

6. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 5, characterized in that, In step S25, the graphite fixture and the heat insulation plate base blank are dried by a blast drying oven, the drying temperature is 80 to 105°C, and the drying time is 8 hours.

7. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 1, characterized in that, In step S3, the dried intermediate structure is sintered by a vacuum reactive sintering furnace, and the sintering temperature is 2200 to 2450°C.

8. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 1, characterized in that, The step S4 includes: Step S41, perform machining on the boss of the preliminarily formed silicon carbide heat insulation plate base, so that the flatness of the boss is less than 0.1; Step S42, perform machining on the end face of the rod away from the bottom plate, so that the parallelism between the end face of the rod away from the bottom plate and the boss is less than 0.

1.

9. The preparation method of the high-purity silicon carbide heat-insulating plate base according to claim 1, characterized in that, In step S5, the machined heat insulation plate base is purified by a purification furnace, and the gases introduced are argon and carbon tetrafluoride, and the purification temperature is 800 - 1400 °C.

10. A high-purity silicon carbide heat-insulating plate base, characterized in that, Obtained by the preparation method of the high-purity silicon carbide heat insulation plate base according to any one of claims 1 to 9, the high-purity silicon carbide heat insulation plate base includes a bottom plate and a rod, and the bottom plate and the rod are sintered and formed.

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