Silicon carbide ceramic component and method of making the same

Abstract

The application provides a silicon carbide ceramic part and a preparation method thereof, and the preparation method comprises the following steps: (1) cold isostatic pressing silicon carbide powder to obtain a silicon carbide blank; the average particle size of the silicon carbide powder is 0.5-2 microns; (2) the silicon carbide blank obtained in step (1) is subjected to canning, degassing and hot isostatic pressing in sequence, and then the canning is removed to obtain the silicon carbide ceramic part. The silicon carbide powder with high fineness is used as raw material, and the silicon carbide ceramic part with different sizes and shapes can be prepared through the process combining cold isostatic pressing and hot isostatic pressing, and the purity and the density of the prepared silicon carbide ceramic part are both high, and the high performance requirement of the semiconductor can be met.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor device technology, and particularly relates to a silicon carbide ceramic component and its preparation method. Background Technology

[0002] Silicon carbide (SiC), as an important high-end precision semiconductor material, possesses excellent properties such as high temperature resistance, corrosion resistance, wear resistance, high-temperature mechanical properties, and oxidation resistance, making it promising for applications in high-tech fields such as semiconductors, nuclear energy, defense, and space technology. Silicon carbide components, namely equipment parts made primarily of silicon carbide and its composite materials, are widely used in equipment used in key semiconductor manufacturing processes such as epitaxial growth, plasma etching, rapid thermal processing, thin film deposition, oxidation / diffusion, and ion implantation.

[0003] Currently, the density of traditionally hot-pressed silicon carbide ceramics generally does not reach 3.20-3.21 g / cm³. 3 However, a small number of pores may exist internally, and the hot-pressing process requires ultra-high temperature and ultra-high pressure, placing higher demands on the service life of CFC molds or graphite molds; while pressureless sintered silicon carbide ceramics have a density of 3.12-3.15 g / cm³. 3 However, sintering aids are usually added to facilitate faster densification of silicon carbide ceramics and reduce porosity during the sintering process. But the addition of sintering aids will definitely affect the purity of silicon carbide ceramic parts for semiconductors.

[0004] Currently, the density of silicon carbide ceramic parts produced often fails to meet requirements, and due to the poor frictional properties of silicon carbide materials, they usually need to be combined with other materials to prepare composite targets. The preparation process of single high-purity silicon carbide ceramics is rarely involved.

[0005] CN105541336A discloses a method for preparing a boron carbide / silicon carbide ceramic plate. The method includes the following steps: mixing boron carbide powder, silicon carbide powder, carbon powder, binder, dispersant, and water, and then ball-milling to obtain a slurry; drying and granulating the slurry using a spray granulation and drying process to obtain granulated material; pressing the granulated material into a green body using a cold isostatic pressing process to obtain a green body; and subjecting the green body to pressureless sintering and cooling to obtain the ceramic plate. This method uses boron carbide and silicon carbide as the main raw materials to prepare the ceramic plate, and the product is mainly used as a bulletproof plate. However, the process is not suitable for preparing silicon carbide ceramics alone, and its applicable fields are also different.

[0006] In summary, for the fabrication process of silicon carbide ceramic parts, especially high-purity silicon carbide ceramic components, it is necessary to select appropriate process conditions based on the performance requirements of the components to ensure that their purity, density, and microstructure all meet the requirements. Summary of the Invention

[0007] The purpose of this invention is to provide a silicon carbide ceramic component and its preparation method. Using high-fineness silicon carbide powder as raw material, silicon carbide ceramic components of different sizes and shapes can be prepared by a combination of cold isostatic pressing and hot isostatic pressing. The silicon carbide ceramic components prepared have high purity and density, which can meet the high performance requirements of semiconductors.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing silicon carbide ceramic parts, the method comprising the following steps:

[0010] (1) Silicon carbide powder is subjected to cold isostatic pressing to obtain silicon carbide billet;

[0011] The average particle size of the silicon carbide powder is 0.5-2 μm;

[0012] (2) The silicon carbide blank obtained in step (1) is sequentially subjected to encapsulation welding, degassing and hot isostatic pressing, and then the encapsulation is removed to obtain the silicon carbide ceramic parts.

[0013] In this invention, the average particle size of the silicon carbide powder is 0.5-2μm, for example, it can be 0.7μm, 0.9μm, 1μm, 1.2μm, 1.5μm, 1.7μm or 1.9μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] The preparation method described in this invention uses fine silicon carbide powder as raw material and combines cold isostatic pressing and hot isostatic pressing processes to produce silicon carbide ceramic parts of different sizes and shapes, such as ultra-long cuboids and ultra-thick ceramics. Moreover, the silicon carbide ceramic parts produced have high purity and density, which can meet the high performance requirements of semiconductors.

[0015] As a preferred technical solution of the present invention, the purity of the silicon carbide powder in step (1) is 3N-4N, for example, it can be 3N1, 3N3, 3N5, 3N7 or 3N9, etc., but is not limited to the listed values. Other unlisted values ​​within the value range are also applicable.

[0016] As a preferred technical solution of the present invention, the cold isostatic pressing in step (1) is carried out in a rubber sleeve.

[0017] Preferably, the pressure of the cold isostatic pressing in step (1) is 150-250 MPa, for example, it can be 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, 210 MPa, 220 MPa, 230 MPa or 240 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] It is worth noting that by performing cold isostatic pressing under greater pressure, the strength of the silicon carbide preform is enhanced, and the introduction of external impurities is effectively reduced.

[0019] Preferably, the holding time of cold isostatic pressing in step (1) is 5-15 min, for example, it can be 6 min, 7 min, 8 min, 9 min, 10 min, 11 min, 12 min, 13 min, 14 min or 15 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, after cold isostatic pressing in step (1), milling is also performed.

[0021] In this invention, milling can completely smooth the raw blank obtained by cold isostatic pressing, thereby improving the effect of subsequent degassing and hot isostatic pressing, and thus improving the density of silicon carbide ceramic parts.

[0022] As a preferred technical solution of the present invention, the cladding welding in step (2) adopts a niobium alloy cladding.

[0023] In this invention, the niobium alloy sheath is provided with a perforated degassing pipe, which connects the interior and exterior of the niobium alloy sheath.

[0024] Preferably, the sheath welding method in step (2) is argon arc welding.

[0025] As a preferred technical solution of the present invention, the degassing temperature in step (2) is 450-700℃, for example, it can be 470℃, 500℃, 520℃, 550℃, 570℃, 600℃, 620℃, 650℃, 670℃ or 690℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] In this invention, the degassing is carried out in a resistance furnace and is connected to a molecular pump via a degassing pipe.

[0027] Preferably, the vacuum degree inside the niobium alloy sheath during step (2) is <3×10⁻⁶. -3 Pa, for example, could be 2.9 × 10⁻⁶. -3 Pa, 2.7 × 10 -3 Pa, 2.5 × 10 -3Pa, 2×10 -3 Pa or 1×10 -3 Pa, etc., but not limited to the listed values, and other unlisted values ​​within the range also apply.

[0028] Preferably, after degassing in step (2), the degassing tube is sealed by argon arc welding.

[0029] In this invention, after degassing, the heat preservation is stopped, and then the degassing tube is sealed by argon arc welding, so that the inside of the niobium alloy sheath is in a vacuum state.

[0030] As a preferred technical solution of the present invention, the hot isostatic pressing in step (2) includes a first heating and pressurizing process, a second heat preservation and pressurizing process, a third heating and pressurizing process, a fourth heating and pressurizing process, a fifth heat preservation and pressurizing process, and a cooling and depressurization process performed sequentially.

[0031] In this invention, the cladding of the hot isostatically pressed silicon carbide billet is removed by milling.

[0032] It is worth noting that by controlling the hot isostatic pressing process, especially the parameter control of the multiple heating and pressurization stages, the silicon carbide ceramic parts after hot isostatic pressing have high density and purity, and fewer impurities, which can meet the dual requirements of purity and density for semiconductor applications of silicon carbide ceramic parts.

[0033] As a preferred technical solution of the present invention, the heating rate of the first heating and pressurizing treatment is 4-8℃ / min, such as 4.5℃ / min, 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min or 7.5℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the temperature of the first heating and pressurizing treatment is 820-870℃, such as 825℃, 830℃, 835℃, 840℃, 845℃, 850℃, 855℃, 860℃ or 865℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the pressure of the first heating and pressurizing treatment is 8-12 MPa, for example, it can be 8.5 MPa, 9 MPa, 9.5 MPa, 10 MPa, 10.5 MPa, 11 MPa, 11.5 MPa or 11.9 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the pressure of the second heat preservation and pressurization treatment is 18-22 MPa, for example, it can be 18.5 MPa, 19 MPa, 19.5 MPa, 20 MPa, 20.5 MPa, 21 MPa, 21.5 MPa or 21.9 MPa, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] Preferably, the second heat preservation and pressurization treatment time is 50-70 minutes, for example, it can be 52 minutes, 55 minutes, 57 minutes, 60 minutes, 62 minutes, 65 minutes, 67 minutes or 69 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] Preferably, the heating rate of the third heating and pressurizing treatment is 2.5-3.5℃ / min, such as 2.6℃ / min, 2.7℃ / min, 2.8℃ / min, 2.9℃ / min, 3℃ / min, 3.1℃ / min, 3.3℃ / min or 3.4℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the temperature of the third heating and pressurizing treatment is 1450-1550℃, such as 1460℃, 1470℃, 1480℃, 1490℃, 1500℃, 1510℃, 1520℃, 1530℃ or 1540℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the pressure of the third heating and pressurizing treatment is 95-105 MPa, for example, it can be 96 MPa, 97 MPa, 98 MPa, 99 MPa, 100 MPa, 101 MPa, 102 MPa, 103 MPa or 104 MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] As a preferred technical solution of the present invention, the heating rate of the fourth heating and pressurizing treatment is 1-2℃ / min, such as 1.1℃ / min, 1.2℃ / min, 1.3℃ / min, 1.4℃ / min, 1.5℃ / min, 1.6℃ / min, 1.7℃ / min or 1.9℃ / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the temperature of the fourth heating and pressurizing treatment is 1900-2000℃, such as 1910℃, 1920℃, 1930℃, 1940℃, 1950℃, 1960℃, 1970℃, 1980℃ or 1990℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the pressure of the fourth heating and pressurizing treatment is 140-200 MPa, for example, it can be 145 MPa, 150 MPa, 155 MPa, 160 MPa, 165 MPa, 170 MPa, 175 MPa, 180 MPa, 190 MPa or 195 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] Preferably, the fifth heat preservation and pressure holding process takes 4-6 hours, such as 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, 5 hours, 5.2 hours, 5.4 hours, 5.6 hours, 5.8 hours, or 5.9 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0046] (1) Silicon carbide powder with a purity of 3N-4N and an average particle size of 0.5-2μm is subjected to cold isostatic pressing at 150-250MPa for 5-15min, and then milled to obtain silicon carbide billet;

[0047] (2) The silicon carbide billet obtained in step (1) is subjected to argon arc welding with a niobium alloy sheath, and degassed at 450-700℃ until the vacuum degree inside the niobium alloy sheath is <3×10⁻⁶. -3 Pa, then the degassing tube is sealed by argon arc welding, followed by hot isostatic pressing, and the silicon carbide ceramic parts are obtained after removing the cladding;

[0048] The hot isostatic pressing includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially.

[0049] The first heating and pressurization process involves heating to 820-870°C and pressurizing to 8-12 MPa at a heating rate of 4-8°C / min.

[0050] The second heat preservation and pressurization treatment is carried out at 820-870℃ and 18-22MPa for 50-70 minutes;

[0051] The third heating and pressurization process involves heating to 1450-1550℃ and pressurizing to 95-105MPa at a heating rate of 2.5-3.5℃ / min.

[0052] The fourth heating and pressurization process involves heating to 1900-2000℃ and pressurizing to 140-200MPa at a heating rate of 1-2℃ / min.

[0053] The fifth heat preservation and pressure holding process takes 4-6 hours.

[0054] In a second aspect, the present invention provides a silicon carbide ceramic component, which is prepared by the preparation method described in the first aspect.

[0055] Preferably, the purity of the silicon carbide ceramic component is 3N-4N, such as 3N1, 3N3, 3N5, 3N7 or 3N9, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] Preferably, the density of the silicon carbide ceramic component is >99%, for example, it can be 99.1%, 99.2%, 99.5%, 99.7%, 99.8%, 99.9%, 99.91%, 99.95%, or 99.99%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] In this invention, the silicon carbide ceramic component is used in the field of semiconductor equipment.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The preparation method provided by this invention uses fine silicon carbide powder as raw material. By controlling the pressure parameters of cold isostatic pressing, the density of the raw blank is increased and the introduction of external impurities is effectively reduced. Then, milling is used to smooth the raw blank. After that, cladding welding, degassing and hot isostatic pressing are performed in sequence. By controlling the heating and pressurization process of hot isostatic pressing, especially the parameter control of multiple heating and pressurization stages, the silicon carbide ceramic parts after hot isostatic pressing have high density and purity and fewer impurities, which can meet the dual requirements of purity and density of silicon carbide ceramic parts for semiconductor applications. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0061] Example 1

[0062] This embodiment provides a method for preparing silicon carbide ceramic parts, the method comprising the following steps:

[0063] (1) Silicon carbide powder with a purity of 3N5 and an average particle size of 1μm was subjected to cold isostatic pressing at 200MPa for 10min, and then milled to obtain silicon carbide billet.

[0064] (2) The silicon carbide billet obtained in step (1) is subjected to argon arc welding with a niobium alloy sheath, and degassed at 600°C until the vacuum degree inside the niobium alloy sheath is 2.5 × 10⁻⁶. -3 Pa, then stop the heat preservation, seal the degassing tube by argon arc welding, so that the inside of the niobium alloy cladding is in a vacuum state, then perform hot isostatic pressing, and after removing the cladding, the silicon carbide ceramic parts are obtained.

[0065] The hot isostatic pressing includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially.

[0066] The first heating and pressurization process involves heating to 850°C and pressurizing to 10MPa at a heating rate of 5°C / min.

[0067] The second heat preservation and pressurization treatment is performed at 850℃ and 20MPa for 60 minutes;

[0068] The third heating and pressurization process involves heating to 1500°C and pressurizing to 100MPa at a heating rate of 3°C / min.

[0069] The fourth heating and pressurization process involves heating to 1950°C and pressurizing to 180MPa at a heating rate of 1.5°C / min.

[0070] The fifth heat preservation and pressure holding process takes 5 hours.

[0071] Example 2

[0072] This embodiment provides a method for preparing silicon carbide ceramic parts, the method comprising the following steps:

[0073] (1) Silicon carbide powder with a purity of 4N and an average particle size of 0.5μm was subjected to cold isostatic pressing at 160MPa for 15min, and then milled to obtain silicon carbide billet;

[0074] (2) The silicon carbide billet obtained in step (1) is subjected to argon arc welding with a niobium alloy sheath, and degassed at 700°C until the vacuum degree inside the niobium alloy sheath is 1×10⁻⁶. -3Pa, then stop the heat preservation, seal the degassing tube by argon arc welding, so that the inside of the niobium alloy cladding is in a vacuum state, then perform hot isostatic pressing, and after removing the cladding, the silicon carbide ceramic parts are obtained.

[0075] The hot isostatic pressing includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially.

[0076] The first heating and pressurization process involves heating to 820°C and pressurizing to 12MPa at a heating rate of 4°C / min.

[0077] The second heat preservation and pressurization treatment is performed at 820℃ and 22MPa for 50 minutes;

[0078] The third heating and pressurization process involves heating to 1450°C and pressurizing to 105 MPa at a heating rate of 2.5°C / min.

[0079] The fourth heating and pressurization process involves heating to 1900°C and pressurizing to 140MPa at a heating rate of 1°C / min.

[0080] The fifth heat preservation and pressure holding process takes 6 hours.

[0081] Example 3

[0082] This embodiment provides a method for preparing silicon carbide ceramic parts, the method comprising the following steps:

[0083] (1) Silicon carbide powder with a purity of 3N and an average particle size of 2μm was subjected to cold isostatic pressing at 250MPa for 6min, and then milled to obtain silicon carbide billet;

[0084] (2) The silicon carbide billet obtained in step (1) is subjected to argon arc welding with a niobium alloy sheath, and degassed at 450°C until the vacuum degree inside the niobium alloy sheath is 1×10⁻⁶. -3 Pa, then stop the heat preservation, seal the degassing tube by argon arc welding, so that the inside of the niobium alloy cladding is in a vacuum state, then perform hot isostatic pressing, and after removing the cladding, the silicon carbide ceramic parts are obtained.

[0085] The hot isostatic pressing includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially.

[0086] The first heating and pressurization process involves heating to 870°C and pressurizing to 8MPa at a heating rate of 8°C / min.

[0087] The second heat preservation and pressurization treatment is performed at 870℃ and 18MPa for 70 minutes;

[0088] The third heating and pressurization process involves heating to 1550°C and pressurizing to 95MPa at a heating rate of 3.5°C / min.

[0089] The fourth heating and pressurization process involves heating to 2000℃ and pressurizing to 200MPa at a heating rate of 2℃ / min.

[0090] The fifth heat preservation and pressure holding process takes 4 hours.

[0091] Example 4

[0092] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the pressure of cold isostatic pressing in step (1) being 120 MPa, all other conditions are the same as in embodiment 1.

[0093] Example 5

[0094] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the pressure of cold isostatic pressing in step (1) being 280 MPa, all other conditions are the same as in embodiment 1.

[0095] Example 6

[0096] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for step (2), which involves hot isostatic pressing without the second and third heat preservation and pressurization treatments, i.e. directly heating and pressurizing from 850℃ and 10MPa to 1950℃ and 180MPa at a heating rate of 1.5℃ / min, all other conditions are the same as in embodiment 1.

[0097] Example 7

[0098] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the hot isostatic pressing in step (2) which does not involve the fourth heat preservation and pressurization process, i.e., directly heating and pressurizing from 850℃ and 20MPa to 1950℃ and 180MPa at a heating rate of 3℃ / min, all other conditions are the same as in embodiment 1.

[0099] Example 8

[0100] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for step (2), where the hot isostatic pressing is adjusted to directly heat to 1950°C at a heating rate of 5°C / min, pressurize to 180MPa, and hold at the temperature and pressure for 5 hours, all other conditions are the same as in embodiment 1.

[0101] Example 9

[0102] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the temperature of the fourth heating and pressurizing treatment in step (2) being 1700°C, all other conditions are the same as in embodiment 1.

[0103] Example 10

[0104] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the temperature of the fourth heating and pressurizing treatment in step (2) being 2200℃, all other conditions are the same as in embodiment 1.

[0105] Example 11

[0106] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the pressure of the fourth heating and pressurizing treatment in step (2), which is 120 MPa, all other conditions are the same as in embodiment 1.

[0107] Example 12

[0108] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the pressure of the fourth heating and pressurizing treatment in step (2) being 220 MPa, all other conditions are the same as in embodiment 1.

[0109] Example 13

[0110] This embodiment provides a method for preparing silicon carbide ceramic parts. Except for the fifth heat preservation and pressure treatment time of 2h in step (2), all other conditions are the same as in embodiment 1.

[0111] Comparative Example 1

[0112] This comparative example provides a method for preparing silicon carbide ceramic parts. Except for the average particle size of the silicon carbide powder in step (1) being 3 μm, all other conditions are the same as in Example 1.

[0113] The density and purity of the silicon carbide ceramic parts prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.

[0114] Table 1

[0115]

[0116]

[0117] As shown in Table 1:

[0118] (1) The preparation method provided by the present invention can produce silicon carbide ceramic parts with a density of over 99.1% and a purity of 3N-4N, which can meet the dual requirements of purity and density for semiconductor applications of silicon carbide ceramic parts.

[0119] (2) Comparing Examples 1 and 4-5, it can be seen that when the pressure of cold isostatic pressing is too low, the silicon carbide powder particles are not dense and the distance is too large, resulting in a decrease in the density of the silicon carbide ceramic parts but no decrease in purity; when the pressure of cold isostatic pressing is too high, the silicon carbide powder particles are tightly connected, and the density of the silicon carbide ceramic parts is slightly higher than that of Example 1, but it has higher requirements for equipment, greater equipment wear and tear, and increased production costs.

[0120] (3) Comparing Examples 1 and 6-8, it can be seen that when hot isostatic pressing does not undergo the second and third heat preservation and pressurization processes, the density of the silicon carbide ceramic parts may be slightly lower due to uneven or insufficient heating. When hot isostatic pressing does not undergo the fourth heat preservation and pressurization process or uses a single-stage heating and pressurization process, the heating and pressurization rate is maintained at a high temperature and pressure, which will cause uneven temperature during heating and pressurization, resulting in uneven internal structure of silicon carbide and thus a decrease in density.

[0121] (4) Comparing Examples 1 and 9-10, it can be seen that when the final temperature of hot isostatic pressing is low, the activity of silicon carbide particles is relatively weak, and the density of the silicon carbide ceramic parts is low. When the final temperature of hot isostatic pressing is high, the kinetic energy of silicon carbide powder particles is large and the activation is high, and the density of the silicon carbide ceramic parts is slightly higher than that of Example 1. However, it requires higher equipment and causes greater equipment wear, thus increasing production costs. Comparing Examples 1 and 11-12, it can be seen that when the final pressure of hot isostatic pressing is low, the distance between silicon carbide powder particles is large due to the low external pressure difference, and the grain growth is insufficient, resulting in a low density of the silicon carbide ceramic parts. When the final pressure of hot isostatic pressing is high, the silicon carbide powder particles are denser and the particle spacing is smaller, and the silicon carbide grains grow sufficiently, resulting in a slightly higher density of the silicon carbide ceramic parts than that of Example 1. However, it requires higher equipment and causes greater equipment wear, thus increasing production costs.

[0122] (5) Comparing Example 1 and Comparative Example 1, it can be seen that when the average particle size of silicon carbide powder is too large, the gap between the powders is relatively large, resulting in relatively small silicon carbide ceramic parts.

[0123] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing silicon carbide ceramic parts, characterized in that, The preparation method includes the following steps: (1) Silicon carbide powder is cold isostatically pressed to obtain silicon carbide billet; The average particle size of the silicon carbide powder is 0.5-2 μm; (2) The silicon carbide blank obtained in step (1) is sequentially subjected to encapsulation welding, degassing and hot isostatic pressing, and then the encapsulation is removed to obtain the silicon carbide ceramic parts; The hot isostatic pressing in step (2) includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially. The heating rate of the first heating and pressurization treatment is 4-8℃ / min; The temperature of the first heating and pressurizing treatment is 820-870℃; The pressure of the first heating and pressurization treatment is 8-12 MPa; The pressure of the second heat preservation and pressurization treatment is 18-22 MPa; The second heat preservation and pressurization treatment time is 50-70 minutes; The heating rate of the third heating and pressurization treatment is 2.5-3.5℃ / min; The temperature of the third heating and pressurizing treatment is 1450-1550℃; The pressure of the third heating and pressurization process is 95-105 MPa; The heating rate of the fourth heating and pressurizing treatment is 1-2℃ / min; The temperature for the fourth heating and pressurizing treatment is 1900-2000℃; The pressure of the fourth heating and pressurization process is 140-200 MPa; The fifth heat preservation and pressure holding process takes 4-6 hours.

2. The preparation method according to claim 1, characterized in that, The purity of the silicon carbide powder in step (1) is 3N-4N.

3. The preparation method according to claim 1, characterized in that, The cold isostatic pressing in step (1) is carried out in a rubber sleeve.

4. The preparation method according to claim 1, characterized in that, The pressure of the cold isostatic pressing in step (1) is 150-250 MPa.

5. The preparation method according to claim 1, characterized in that, The holding time for cold isostatic pressing in step (1) is 5-15 minutes.

6. The preparation method according to claim 1, characterized in that, Step (1) after cold isostatic pressing also includes milling.

7. The preparation method according to claim 1, characterized in that, The cladding welding in step (2) uses a niobium alloy cladding.

8. The preparation method according to claim 1, characterized in that, The welding method for the sheath in step (2) is argon arc welding.

9. The preparation method according to claim 1, characterized in that, The degassing temperature in step (2) is 450-700℃.

10. The preparation method according to claim 1, characterized in that, The vacuum level inside the niobium alloy cladding during degassing in step (2) is <3×10⁻⁶. -3 Pa.

11. The preparation method according to claim 1, characterized in that, After degassing in step (2), the degassing tube is sealed by argon arc welding.

12. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Silicon carbide powder with a purity of 3N-4N and an average particle size of 0.5-2μm is subjected to cold isostatic pressing at 150-250MPa for 5-15min, and then milled to obtain silicon carbide billet; (2) The silicon carbide billet obtained in step (1) is subjected to argon arc welding with a niobium alloy sheath, and degassed at 450-700℃ until the vacuum degree inside the niobium alloy sheath is <3×10 -3 Pa, then the degassing tube is sealed by argon arc welding, followed by hot isostatic pressing, and the silicon carbide ceramic parts are obtained after removing the cladding; The hot isostatic pressing includes a first heating and pressurization process, a second heat preservation and pressurization process, a third heating and pressurization process, a fourth heating and pressurization process, a fifth heat preservation and pressurization process, and a cooling and depressurization process performed sequentially. The first heating and pressurization process involves heating to 820-870°C and pressurizing to 8-12 MPa at a heating rate of 4-8°C / min. The second heat preservation and pressurization treatment is carried out at 820-870℃ and 18-22MPa for 50-70 minutes; The third heating and pressurization process involves heating to 1450-1550℃ and pressurizing to 95-105MPa at a heating rate of 2.5-3.5℃ / min. The fourth heating and pressurization process involves heating to 1900-2000℃ and pressurizing to 140-200MPa at a heating rate of 1-2℃ / min. The fifth heat preservation and pressure holding process takes 4-6 hours.

13. A silicon carbide ceramic component, characterized in that, The silicon carbide ceramic component is prepared by the preparation method according to any one of claims 1-12; The purity of the silicon carbide ceramic components is 3N-4N; The density of the silicon carbide ceramic component is >99%.

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