Silicon carbide setter plate and preparation method thereof

Abstract

The present invention discloses a silicon carbide support plate and a preparation method thereof, and belongs to the field of refractory materials. The preparation of the silicon carbide support plate includes: S1, preparing granulated powder: mixing silicon carbide nano powder, a binder, a dispersant and a grinding medium, grinding and dispersing, then adding an auxiliary agent for secondary grinding, filtering out the grinding medium, adding pure water for tertiary grinding, and then spray granulating to obtain granulated powder; the auxiliary agent includes boron carbide, hafnium carbide and tantalum carbide; S2, pressing and molding to obtain a green body; S3, wet isostatic pressing treatment; S4, pressureless sintering to obtain a silicon carbide support plate. The present invention adopts a pressureless sintering method to prepare a silicon carbide support plate, which can not only reduce the sintering densification temperature, but also reduce the process cost caused by brushing slurry. The support plate product has the advantages of long service life, high strength and fast thermal conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials, and in particular relates to a silicon carbide setter plate and a preparation method thereof. Background Art

[0002] The setter plate is a substrate used to support and sinter the target material in a high-temperature industrial furnace, and is usually used in industries such as ceramics, glass, and metallurgy. In order to ensure its stability and service life in a high-temperature environment, the setter plate has strict requirements on the bearing strength and performance stability at high temperatures, and cannot react or adhere to the target material at high temperatures.

[0003] At present, the daily-use porcelain support plates are mainly made of mullite and reaction-sintered silicon carbide. Mullite is an aluminum silicate mineral with excellent thermal stability and thermal shock resistance. It is often used in the lining and high-temperature support plates of high-temperature kilns. However, the low strength and insufficient thermal conductivity of mullite support plates are the pain points of the industry. The industry has great expectations for new materials to replace the performance problems of mullite support plate materials. The theoretical number of uses of mullite support plates currently used in enterprises is about 150 times, and its service life is less than one month (about 100 times) under full-load production conditions; at the same time, in order to meet the load-bearing requirements, the thickness of mullite support plates is between 1cm-1.2cm, which occupies a large space in the kiln and absorbs a lot of heat energy. The increase in natural gas prices continues to increase the energy consumption cost of enterprises; and due to the low strength of mullite, it is easy for the support plates to break and cause kiln blockage. If the kiln needs to be stopped for cleaning, the indirect loss will cost more than 100,000 yuan per time. Moreover, after a long period of friction between the bottom plate of the mullite support plate and the alumina roller, the mullite sticks to the alumina roller at high temperature, which causes the surface of the roller to form a blister after a long period of time (mainly occurring in the high temperature area of ​​about 1200°C).

[0004] Silicon carbide has extremely high hardness and high temperature resistance, as well as excellent thermal conductivity and thermal shock resistance. It is suitable for applications with high temperature, high strength and rapid thermal cycles. Among them, reaction-sintered silicon carbide has relatively low cost and relatively simple process, and is one of the two commonly used materials in the industry. However, when the reaction-sintered silicon carbide support plate is used, the surface of the support plate is prone to adhesion to the bottom of the porcelain, and alumina slurry should be applied to avoid adhesion. Brushing the coating on the contact surface increases the operating procedures and causes product erosion. In addition, the alumina coating is dried and dust is easily generated during the use of the support plate. After each sintering of 1-2 furnaces, the surface of the support plate should be scraped flat and re-coated with alumina slurry.

[0005] Therefore, there is an urgent need to develop a new silicon carbide support plate and a preparation method thereof to meet production and use requirements. Summary of the invention

[0006] The problem to be solved by the present invention is to provide a silicon carbide support plate and a preparation method thereof, which adopts a pressureless sintering method and obtains a support plate product through granulation, compacting, isostatic pressing and pressureless sintering, thereby avoiding the problems of insufficient strength of the support plate in the prior art, adhesion and erosion with the target product, complex production process, environmental pollution, and complex use process.

[0007] The present invention includes a method for preparing a silicon carbide setter plate, comprising the following steps:

[0008] S1. Preparation of granulated powder: mixing silicon carbide nanopowder, a binder, a dispersant and a ball mill medium, grinding and dispersing them, adding an auxiliary agent for secondary grinding, filtering out the ball mill medium, adding pure water for tertiary grinding, and then spray granulating to obtain granulated powder; the auxiliary agent includes boron carbide, hafnium carbide and tantalum carbide;

[0009] Furthermore, the boron carbide in the additive is 0.5wt.%-2.0wt.% of the silicon carbide nanopowder, the hafnium carbide is 0.2wt.%-0.8wt.% of the silicon carbide nanopowder, the tantalum carbide is 0.1wt.%-0.5wt.% of the silicon carbide nanopowder, and the total amount of the additive is 1wt.%-3wt.% of the silicon carbide nanopowder;

[0010] Furthermore, the binder is a water-soluble phenolic resin, and the amount used is 5wt.%-10wt.% of the silicon carbide nanopowder; the dispersant is 90%-95% ethanol, and the amount used is 30wt.%-50wt.% of the silicon carbide nanopowder;

[0011] Furthermore, the grinding medium is silicon carbide grinding balls, and the mass ratio of silicon carbide grinding balls to silicon carbide nanopowder is (5-10):1; the linear speed of grinding and dispersion is 18m / s-20m / s, and the time is 2h-3h; the linear speed of secondary grinding is 16m / s-18m / s, and the time is 1h-2h; the linear speed of tertiary grinding is 16m / s-18m / s, and the time is 2h-3h;

[0012] S2, compression molding: placing the granulated powder obtained in S1 into a steel mold for pressure maintenance to obtain a green body;

[0013] Furthermore, one side of the inner surface of the steel mold is provided with concave and convex patterns;

[0014] Furthermore, the pressure of the pressing molding is 10MPa-12MPa, and the holding time is 1min-3min;

[0015] S3, wet isostatic pressing treatment: the green body obtained in S2 is subjected to isostatic pressing treatment;

[0016] Furthermore, the pressure of the isostatic pressing treatment is 150MPa-200MPa, and the treatment time is 2min-6min;

[0017] Furthermore, before S4, it also includes opening a matching hole on the green body processed in S3;

[0018] S4, pressureless sintering: the green body treated in S3 is subjected to pressureless sintering to obtain a silicon carbide setter plate;

[0019] Furthermore, the sintering procedure of pressureless sintering includes:

[0020] In the first stage, negative pressure degumming, argon is filled to the furnace pressure of 15-25mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at 850℃-950℃ for 2h-6h;

[0021] The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min;

[0022] The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-2h;

[0023] The fourth stage is cooling. The cooling rate is ≤2℃ / min above 1800℃ and natural cooling is allowed below 1800℃.

[0024] As a general inventive concept, the present invention also includes a silicon carbide setter plate prepared by any of the above-mentioned methods for preparing a silicon carbide setter plate.

[0025] Beneficial effects of the present invention:

[0026] The present invention designs a pressureless sintered silicon carbide support plate and a preparation method thereof through research and development, obtains a silicon carbide support plate product through granulation, compacting, isostatic pressing, and pressureless sintering, and realizes densification through pressureless sintering, which can not only reduce the sintering densification temperature, but also reduce the process treatment of brushing alumina slurry on the reaction sintered silicon carbide support plate before each use. Pressureless sintering does not require the application of external pressure, and densification is mainly achieved by controlling the sintering temperature. The equipment is simple and easy to industrialize. It does not require pressurization or electricity for the sintered material, and is cost-effective. The optimal parameters such as heating rate, holding time, and maximum temperature are obtained through research, and the densification of the blank can be achieved under the premise of minimum grain growth; it is suitable for the firing of objects of different shapes and sizes.

[0027] After testing, the density of the silicon carbide support plate obtained by the present invention is 3.0g / cm 3 -3.1g / cm3 , flexural strength is 320MPa-420MPa, Vickers hardness (HV0.5) is 24GPa-27GPa, fracture toughness is Mpa / m 1 / 2 It is 3.2-4.8.

[0028] The support plate product obtained by the present invention has the advantages of long service life, high strength and fast heat conduction: the support plate of the present invention has high bending strength, good load-bearing capacity and long service life. After testing, the support plate was used for 2 months in a high-temperature sintering environment of 1800°C without deformation, and the service life is more than one year, showing excellent stability and durability; the support plate of the present invention has good thermal conductivity and reduces the energy consumption caused by absorbing heat energy; the support plate of the present invention will not adhere to the target material to be sintered, and there is no need to add additional processes to solve the adhesion problem or even cause environmental pollution, and the production process is more environmentally friendly and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attached Figure 1 1 is a process flow chart of a method for preparing a silicon carbide setter plate according to an embodiment of the present invention;

[0030] Attached Figure 2 This is a structural schematic diagram of a fish-shaped wave-dot pattern setter plate product in one embodiment of the present invention;

[0031] Attached Figure 3 for Figure 2 A cross-sectional view of

[0032] Attached Figure 4 This is a schematic structural diagram of a grid pattern setter plate product in one embodiment of the present invention;

[0033] Attached Figure 5 It is a structural schematic diagram of a fish-shaped grid pattern setter plate product in one embodiment of the present invention;

[0034] Attached Figure 6 This is a schematic structural diagram of a fish-shaped triangular grid-patterned support plate product in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that the specific implementation methods described here are only used to explain the present invention and are not intended to limit the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] like Figure 1 As shown, an embodiment of the present invention provides a method for preparing a silicon carbide setter plate, comprising the following steps:

[0038] S1, preparing granulated powder; mixing silicon carbide nanopowder with an average particle size of 10 μm-50 μm, a binder, a dispersant and a ball mill medium, grinding and dispersing, adding an auxiliary agent for secondary grinding, filtering out the ball mill medium, adding pure water for tertiary grinding, and then spray granulating to obtain granulated powder; the auxiliary agent includes boron carbide, hafnium carbide and tantalum carbide;

[0039] S2, compression molding: placing the granulated powder obtained in S1 in a steel mold and maintaining pressure for a period of time to obtain a green body;

[0040] S3, wet isostatic pressing treatment: the green body obtained in S2 is subjected to isostatic pressing treatment;

[0041] S4, pressureless sintering: The green body treated in S3 is subjected to pressureless sintering to obtain a silicon carbide support plate.

[0042] The embodiment of the present invention develops and designs a pressureless sintered silicon carbide support plate and a preparation method thereof, adopts a pressureless sintering method, and obtains a silicon carbide support plate product through granulation, compacting, isostatic pressing, and pressureless sintering. Densification is achieved through pressureless sintering, which can reduce the sintering densification temperature and reduce oxygen pollution caused by mixed powder.

[0043] The in-situ self-generated high entropy diboride and silicon carbide in the product of the present invention have fine grains (grain size is about 1 μm) and good compatibility, thereby improving the mechanical properties and high temperature resistance of the product. According to tests, the density of the silicon carbide setter obtained by the present invention is 3.0g / cm 3 -3.1g / cm 3 , flexural strength is 320MPa-420MPa, Vickers hardness (HV0.5) is 24GPa-27GPa, fracture toughness is Mpa / m 1 / 2 It is 3.2-4.8.

[0044] The silicon carbide support plate product obtained by the present invention has the advantages of long service life, high strength and fast heat conduction; high bending strength, good load-bearing capacity and long service life. According to tests, the support plate has no deformation after being used for 2 months and has a service life of more than one year, showing excellent stability and durability; the support plate of the present invention has good thermal conductivity, reduces energy consumption caused by absorbing heat energy, and can reduce the actual sintering temperature (1200°C-1380°C); the support plate of the present invention will not stick to porcelain, and there is no need to add additional processes to solve the adhesion problem or even cause environmental pollution, and the production process is more environmentally friendly and convenient.

[0045] Among them, in S1, the boron carbide in the additive is 0.5wt.%-2.0wt.% of the silicon carbide nanopowder, the hafnium carbide is 0.2wt.%-0.8wt.% of the silicon carbide nanopowder, the tantalum carbide is 0.1wt.%-0.5wt.% of the silicon carbide nanopowder, and the total amount of the additive is 1wt.%-3wt.% of the silicon carbide nanopowder. Boron carbide has a lower co-sintering temperature and can form a liquid phase during the sintering process, promoting the rearrangement and bonding of silicon carbide particles, thereby reducing the sintering temperature. At the same time, boron carbide can form a eutectic phase with silicon carbide, promote the densification of silicon carbide particles, and improve the density and strength of the material. Hafnium carbide has an extremely high melting point and chemical stability, and can maintain its structure and performance at high temperatures, thereby improving the high-temperature performance of silicon carbide materials. In addition, hafnium carbide can be used as a grain refiner to control the grain growth of silicon carbide and improve the densification level and mechanical properties of the material. In addition, the thermal expansion coefficient of hafnium carbide is close to that of silicon carbide, which improves the thermal shock resistance. Tantalum carbide has an extremely high hardness and melting point, which can improve the wear resistance and high-temperature performance of silicon carbide. Tantalum carbide can form a liquid phase during the sintering process, promote the rearrangement and densification of silicon carbide particles, and reduce the sintering temperature. Using boron carbide, tantalum carbide and hafnium carbide as additives can reduce the sintering temperature (to below 2150°C), improve the bonding force between the interfaces of silicon carbide micropowder particles, increase the material density, enhance the mechanical properties, increase the bending strength, increase the toughness, and improve the strength and chemical stability of the material at high temperatures, improve the thermal shock resistance and oxidation resistance, make the silicon carbide setter more suitable for applications in high temperature and high strength environments, and increase its service life.

[0046] In a preferred embodiment, in S1, the additives are composed of boron carbide, tantalum carbide and hafnium carbide, wherein boron carbide is 0.5wt.%-2.0wt.% of the silicon carbide nanopowder, hafnium carbide is 0.2wt.%-0.8wt.% of the silicon carbide nanopowder, tantalum carbide is 0.1wt.%-0.5wt.% of the silicon carbide nanopowder, and the total amount of the additives is 1wt.%-3wt.% of the silicon carbide nanopowder.

[0047] Among them, in S1, the binder is a water-soluble phenolic resin, and the amount used is 5wt.%-10wt.% of the silicon carbide nanopowder; the dispersant is 90%-95% ethanol, and the amount used is 30wt.%-50wt.% of the silicon carbide nanopowder.

[0048] Among them, in S1, the grinding medium is silicon carbide grinding balls, and the mass ratio of silicon carbide grinding balls to silicon carbide nanopowder is (5-10):1; the linear speed of grinding and dispersion is 18m / s-20m / s, and the time is 2h-3h; the linear speed of secondary grinding is 16m / s-18m / s, and the time is 1h-2h; the linear speed of tertiary grinding is 16m / s-18m / s, and the time is 2h-3h.

[0049] Among them, in S2, a steel mold with a concave-convex pattern on the inner surface of one side is used, and a corresponding concave-convex structure is generated on the surface of one side of the green body obtained after pressing, and a support plate with a concave-convex structure is obtained after sintering, which has anti-slip and anti-stick effects. By selecting a suitable type of concave-convex pattern, the heat conduction, friction, air flow channel, anti-adhesion and structural strength of the support plate can be optimized according to specific application requirements. Specifically, the concave-convex structure can be a wave dot pattern, a grid pattern, a strip pattern, a honeycomb pattern, a wave pattern or a spiral pattern, etc.; specifically, according to the use requirements, the support plate of the present invention can be rectangular, fish-shaped or other shapes. The spiral concave-convex pattern is arranged along the spiral direction, providing a special stress distribution and air flow channel effect, which is suitable for target materials of specific shapes and sizes; the honeycomb concave-convex pattern provides a hexagonal support unit with high strength and stability, which is suitable for applications requiring high bearing capacity and deformation resistance.

[0050] like Figure 2 and Figure 3 The schematic diagram of the product structure of the fish-shaped wavy dot pattern supporting plate shown in the figure has a concave and convex wavy dot pattern structure on the surface, forming multiple independent supporting points on the surface, which can reduce the contact area with the daily-use porcelain and prevent adhesion to the bottom of the daily-use porcelain. It is suitable for the sintering process of easily adhered materials.

[0051] like Figure 4 As shown, it is a schematic diagram of the structure of the rectangular grid-patterned silicon carbide support plate in an embodiment of the present invention. The concave and convex patterns are interwoven in two directions to form a grid structure, which provides more uniform support and airflow distribution and is suitable for sintered objects of complex shapes.

[0052] like Figure 5 As shown, it is a schematic diagram of the structure of the fish-shaped grid-patterned silicon carbide support plate in an embodiment of the present invention. The flat concave and convex patterns are interwoven in two directions to form a grid structure, which enhances the effects of heat conduction and airflow channels, and is often used in application scenarios requiring efficient heat conduction.

[0053] Among them, in S2, the pressing pressure is 10MPa-12MPa, and the holding time is 1min-3min. By setting the appropriate pressing pressure and holding time, a sintered plate product with good uniformity, good integrity, and stable performance after sintering can be obtained. If the pressing pressure is too high, the green body will be too dense, and the shrinkage coefficient will be uneven at various places during sintering, affecting the overall consistency of the finished product; if the pressing pressure is too low, the green body will be loose and fragile, and cracks will easily appear during the transfer to the vacuum sintering furnace and the sintering process.

[0054] Among them, in S3, the isostatic pressing pressure is 150MPa-200MPa, and the processing time is 2min-6min. By setting the appropriate isostatic pressing pressure and processing time, the isostatic pressing technology can apply the same pressure in all directions of the material, which helps to achieve uniform distribution of internal stress of the material, thereby avoiding local stress concentration and reducing the generation of cracks; significantly improve the density of powder or granular materials, reduce pores, thereby improving the mechanical strength and hardness of the material; help to achieve uniformity of the microstructure of the material, reduce pores and defects, thereby improving the overall performance of the material; can enhance the bonding force between particles, improve the fracture toughness and durability of the material; reduce defects in the material processing process, such as cracks, delamination and uneven deformation, thereby improving the reliability of the material.

[0055] Among them, according to the use requirements, matching holes are opened on some of the setters for assembly into a multi-layer structure. Each layer of the setter is used as a placement plane, and the daily-use porcelain is placed on the surface of the setter for firing. Specifically, the setter green body after the S3 wet isostatic pressing treatment is CNC processed to punch matching holes. Figure 6 As shown, it is a structural schematic diagram of the fish-shaped triangular grid pattern supporting plate product in an embodiment of the present invention. Three matching holes are set at the three ends of the supporting plate. When in use, three support columns are connected with the three matching holes to form a layer of supporting structure. Multiple supporting plates are arranged at intervals to form a multi-layer supporting structure to increase the supporting space.

[0056] Among them, in S4, the sintering procedure of pressureless sintering includes:

[0057] In the first stage, negative pressure degumming is carried out, argon is filled to the furnace pressure of 15-25mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at about 850℃-950℃ for 2h-6h; the degumming process is used to carbonize all the binders in the material to avoid residue; negative pressure degumming is used to avoid blackening of the product surface or the generation of small pores or bulging, which effectively improves the density and physical properties of the product;

[0058] The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min;

[0059] The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-2h;

[0060] The fourth stage is cooling. The cooling rate is ≤2℃ / min above 1800℃ and natural cooling is allowed below 1800℃.

[0061] In a preferred embodiment, the process further includes S5, ultrasonically cleaning and packaging the support plate after the pressureless sintering in S4.

[0062] The present invention also provides a silicon carbide setter plate, which is prepared by any of the above-mentioned methods for preparing a silicon carbide setter plate. The density of the silicon carbide setter plate obtained by the present invention is 3.0 g / cm 3 -3.1g / cm 3 , bending strength is 320MPa-420MPa, Vickers hardness (HV0.5) is 24GPa-27GPa, fracture toughness (Mpa / m 1 / 2 ) is 3.2-4.8, and has the advantages of long service life, high strength and fast thermal conductivity.

[0063] Example 1

[0064] This embodiment provides a method for preparing a silicon carbide setter plate, comprising the following steps:

[0065] S1. Preparation of granulated powder: Add 5wt.% water-soluble phenolic resin as a binder to silicon carbide nanopowder with an average particle size of 10μm-50μm, add silicon carbide grinding balls as grinding media, the mass ratio of silicon carbide grinding balls to the total amount of silicon carbide nanopowder is (5-10):1, add 90%-95% ethanol as a dispersant, the amount of the dispersant is 30wt.%-50wt.% of the silicon carbide nanopowder, grind and disperse, the grinding line speed is 18m / s-20m / s, and the time is 2h-3h;

[0066] Then add 2wt.% of silicon carbide nanopowder additives, including boron carbide, hafnium carbide and tantalum carbide, and perform secondary grinding at a speed of 16m / s-18m / s and a time of 1h-2h;

[0067] The silicon carbide grinding balls as grinding media were filtered out, and 100%-120% pure water of silicon carbide nanopowder was added. The grinding was performed three times at a linear speed of 16m / s-18m / s and a time of 2h-3h, and then spray granulation was performed to obtain granulated powder.

[0068] S2. Compression molding: The granulated powder obtained in S1 is placed in a steel mold, the inner surface of one side of the steel mold is provided with a concave-convex wave dot pattern structure, the pressure is 10MPa-11Mpa, the pressure is maintained for 1min-3min, and the steel mold is removed to obtain a green body.

[0069] S3, wet isostatic pressing treatment: the green body obtained in S2 is placed in a waterproof rubber sleeve, and then placed together with the waterproof rubber sleeve in an isostatic pressing device, with a pressure of 150Mpa-160Mpa, and isostatic pressing treatment is carried out at room temperature for 5min-6min to obtain a green body after isostatic pressing treatment.

[0070] S4, pressureless sintering: placing a plurality of green bodies processed in S3 in a boat for pressureless sintering to obtain a setter plate;

[0071] The pressureless sintering procedure is:

[0072] In the first stage, negative pressure degumming, argon is filled to the furnace pressure of 15mbar-20mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at about 900℃ for 2h-6h;

[0073] The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min;

[0074] The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-1.5h;

[0075] The fourth stage is cooling, the cooling rate is ≤2℃ / min above 1800℃, and it is cooled naturally after the temperature drops below 1800℃;

[0076] S5. Cleaning and packaging: The setter plates obtained in S4 are ultrasonically cleaned and then packaged.

[0077] This embodiment also provides a silicon carbide support plate prepared by the above method.

[0078] Example 2

[0079] This embodiment provides a method for preparing a silicon carbide setter plate, comprising the following steps:

[0080] S1. Preparation of granulated powder: Add 8wt.% water-soluble phenolic resin as a binder to silicon carbide nanopowder with an average particle size of 10μm-50μm, add silicon carbide grinding balls as grinding media, the mass ratio of silicon carbide grinding balls to the total amount of silicon carbide nanopowder is (5-10):1, add 90%-95% ethanol as a dispersant, the amount of the dispersant is 30wt.%-50wt.% of the silicon carbide nanopowder, grind and disperse, the grinding line speed is 18m / s-20m / s, and the time is 2h-3h;

[0081] Then add 3wt.% of silicon carbide nanopowder additives, including boron carbide, hafnium carbide and tantalum carbide, and perform secondary grinding at a speed of 16m / s-18m / s and a time of 1h-2h;

[0082] The silicon carbide grinding balls as grinding media were filtered out, and 100%-120% pure water of silicon carbide nanopowder was added. The grinding was performed three times at a linear speed of 16m / s-18m / s and a time of 2h-3h, and then spray granulation was performed to obtain granulated powder.

[0083] S2. Compression molding: The granulated powder obtained in S1 is placed in a steel mold, the inner surface of one side of the steel mold is provided with a concave-convex grid structure, the pressure is 12 MPa, the pressure is maintained for 2 minutes, and the steel mold is removed to obtain a green body.

[0084] S3, wet isostatic pressing treatment: the green body obtained in S2 is placed in a waterproof rubber sleeve, and then placed together with the waterproof rubber sleeve in an isostatic pressing device, with a pressure of 150Mpa-160Mpa, and isostatic pressing treatment is carried out at room temperature for 2 minutes to obtain a green body after isostatic pressing treatment.

[0085] S4, pressureless sintering: placing a plurality of green bodies processed in S3 in a boat for pressureless sintering to obtain a setter plate;

[0086] The pressureless sintering procedure is:

[0087] In the first stage, negative pressure degumming, argon is filled to the furnace pressure of 20-25mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at about 900℃ for 2h-6h;

[0088] The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min;

[0089] The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-1.5h;

[0090] The fourth stage is cooling, the cooling rate is ≤2℃ / min above 1800℃, and it is cooled naturally after the temperature drops below 1800℃;

[0091] S5. Cleaning and packaging: The setter plates obtained in S4 are ultrasonically cleaned and then packaged.

[0092] This embodiment also provides a silicon carbide support plate prepared by the above method.

[0093] Example 3

[0094] This embodiment provides a method for preparing a silicon carbide setter plate, comprising the following steps:

[0095] S1. Preparation of granulated powder: Add 10wt.% water-soluble phenolic resin as a binder to silicon carbide nanopowder with an average particle size of 10μm-50μm, add silicon carbide grinding balls as grinding media, the mass ratio of silicon carbide grinding balls to the total amount of silicon carbide nanopowder is (5-10):1, add 90%-95% ethanol as a dispersant, the amount of the dispersant is 30wt.%-50wt.% of the silicon carbide nanopowder, grind and disperse, the grinding line speed is 18m / s-20m / s, and the time is 2h-3h;

[0096] Then add 1wt.% of silicon carbide nanopowder additives, including boron carbide, hafnium carbide and tantalum carbide, and perform secondary grinding at a speed of 16m / s-18m / s and a time of 1h-2h;

[0097] The silicon carbide grinding balls as grinding media were filtered out, and 100%-120% pure water of silicon carbide nanopowder was added. The grinding was performed three times at a linear speed of 16m / s-18m / s and a time of 2h-3h, and then spray granulation was performed to obtain granulated powder.

[0098] S2. Compression molding: The granulated powder obtained in S1 is placed in a steel mold, the inner surface of one side of the steel mold is provided with a concave-convex triangular grid structure, the pressure is 10Mpa-11Mpa, the pressure is maintained for 2 minutes, and the steel mold is removed to obtain a green body.

[0099] S3, wet isostatic pressing treatment: the green body obtained in S2 is placed in a waterproof rubber sleeve, and then placed together with the waterproof rubber sleeve in an isostatic pressing device, with a pressure of 180Mpa-200Mpa, and isostatic pressing treatment at room temperature for 2min-3min to obtain a green body after isostatic pressing treatment.

[0100] S4, pressureless sintering: placing a plurality of green bodies processed in S3 in a boat for pressureless sintering to obtain a setter plate;

[0101] The pressureless sintering procedure is:

[0102] In the first stage, negative pressure degumming, argon is filled to the furnace pressure of 15mbar-25mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at about 900℃ for 2h-6h;

[0103] The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min;

[0104] The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-1.5h;

[0105] The fourth stage is cooling, the cooling rate is ≤2℃ / min above 1800℃, and it is cooled naturally after the temperature drops below 1800℃;

[0106] S5. Cleaning and packaging: The setter plates obtained in S4 are ultrasonically cleaned and then packaged.

[0107] This embodiment also provides a silicon carbide support plate prepared by the above method.

[0108] Comparative Example 1

[0109] The difference between this comparative example and Example 1 is that the auxiliary agent in S1 is boron carbide, and S3 wet isostatic pressing treatment is not performed, and other settings are the same as Example 1.

[0110] Comparative Example 2

[0111] The difference between this comparative example and Example 1 is that the additives in S1 are carbon black + boron carbide, and the other settings are the same as those in Example 1.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is that the additives in S1 are boron carbide and tantalum carbide, and the other settings are the same as those in Example 1.

[0114] Comparative Example 4

[0115] The difference between this comparative example and Example 1 is that no additives are added to S1, S3 wet isostatic pressing treatment is not performed, and the third stage of the S4 pressureless sintering procedure is "sintering, heating rate 0.2°C / min-1°C / min, heating to 2100°C-2200°C and keeping warm for 1h". The rest of the settings are the same as Example 1.

[0116] Comparative Example 5

[0117] The difference between this comparative example and Example 1 is that the additive in S1 is boron carbide: Al2O 3=1:1 (weight ratio), the steel mold in S2 is not provided with inner surface concave-convex patterns, and the rest of the settings are the same as those in Example 1.

[0118] Comparative Example 6

[0119] The difference between this comparative example and Example 1 is that the additives in S1 are K2O:Na2O:boron carbide=1:1:1 (weight ratio), the steel mold in S2 is not provided with inner surface concave-convex patterns, and the other settings are the same as those in Example 1.

[0120] Comparative Example 7

[0121] The difference between this comparative example and Example 1 is that the auxiliary agent in S1 is MgO: boron carbide: carbon = 1:1:1 (weight ratio), and the other settings are the same as Example 1.

[0122] The performance of the silicon carbide support plates obtained in Examples 1-3 and Comparative Examples 1-7 was tested, and the support plates were used to carry daily-use porcelain in a daily-use porcelain sintering kiln (1200-1400°C) for sintering trials (without applying slurry). The test results are shown in Table 1 below.

[0123] Table 1 Performance test results of silicon carbide setter plates obtained in Examples 1-3 and Comparative Examples 1-4

[0124]

[0125] By comparing the results in Table 1 above, it can be seen that: compared with Example 1, Comparative Example 4 did not add auxiliary agents and did not undergo wet isostatic pressing treatment, and the mechanical properties of the silicon carbide support plate obtained were the worst. Local fractures occurred during trial use, and the bearing capacity at high temperatures was poor. Compared with Example 1, Comparative Examples 2 and 3 were the same in all processes except for the different auxiliary agents. The various mechanical property tests of Comparative Examples 2 and 3 were significantly lower than those of Example 1, and the density was also significantly reduced. Compared with Example 1, Comparative Example 4 did not undergo wet isostatic pressing treatment, and its density was significantly lower than that of Example 1 and other embodiments and comparative examples. Comparative Examples 5 and 6 added different oxides together with boron carbide as auxiliary agents, and no concave-convex structure was set on the surface of the product. The mechanical properties of the support plates obtained were not significantly different from those of Example 1. During trial use, there were phenomena such as adhesion of daily-use porcelain, adhesion after particles appeared on the plate surface, or discoloration of daily-use porcelain. In Comparative Example 7, a concave-convex structure is set on the product surface, and different additives are added. After 3 furnaces of trial use, surface particles appear on the firing plate, the particles are slightly adhered to the daily-use porcelain, and the light-colored daily-use porcelain changes color. This shows that setting a concave-convex structure on the product surface can effectively avoid the adhesion between the firing plate and the daily-use porcelain, and the type of additives will affect the firing effect of the light-colored daily-use porcelain.

[0126] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

[0128] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for preparing a silicon carbide setter plate, characterized in that: The following steps are involved: S1. Preparing granulated powder: mixing silicon carbide nanopowder, a binder, a dispersant and a grinding medium, grinding and dispersing them, adding an auxiliary agent for secondary grinding, filtering out the grinding medium, adding pure water for tertiary grinding, and then spray granulating to obtain granulated powder; the auxiliary agent includes boron carbide, hafnium carbide and tantalum carbide; In S1, the boron carbide is 0.5wt.%-2.0wt.% of the silicon carbide nanopowder, the hafnium carbide is 0.2wt.%-0.8wt.% of the silicon carbide nanopowder, the tantalum carbide is 0.1wt.%-0.5wt.% of the silicon carbide nanopowder, and the total amount of the additives is 1wt.%-3wt.% of the silicon carbide nanopowder; S2, compression molding: placing the granulated powder obtained in S1 into a steel mold for pressure maintenance to obtain a green body; S3, wet isostatic pressing: performing isostatic pressing on the green body obtained in S2; S4, pressureless sintering: performing pressureless sintering on the green body processed in S3 to obtain the silicon carbide setter plate; In S4, the pressureless sintering includes: In the first stage, negative pressure degumming, argon is filled to the furnace pressure of 15mbar-25mbar in the insulation stage, the heating rate is ≤2℃ / min, and the temperature is kept at 300℃-400℃ for 3h-4h, then the heating rate is ≤4℃ / min, and the temperature is kept at 850℃-950℃ for 2h-6h; The second stage is pre-burning, with a heating rate of ≤2℃ / min, and keeping at 1600℃-1800℃ for 55min-65min; The third stage is sintering, with a heating rate of 0.2℃ / min-1℃ / min, heating to 1980℃-2150℃ and keeping it for 1h-2h; The fourth stage is cooling. The cooling rate is ≤2℃ / min above 1800℃ and natural cooling is allowed below 1800℃.

2. The method for preparing a silicon carbide setter plate according to claim 1, characterized in that: In S1, the binder is a water-soluble phenolic resin, and the amount used is 5wt.%-10wt.% of the silicon carbide nanopowder; the dispersant is 90%-95% ethanol, and the amount used is 30wt.%-50wt.% of the silicon carbide nanopowder.

3. The method for preparing a silicon carbide setter plate according to claim 1, characterized in that: In S1, the grinding medium is silicon carbide grinding balls, and the mass ratio of the silicon carbide grinding balls to the silicon carbide nanopowder is (5-10):1; The linear speed of the grinding and dispersion is 18m / s-20m / s, and the time is 2h-3h; the linear speed of the secondary grinding is 16m / s-18m / s, and the time is 1h-2h; the linear speed of the tertiary grinding is 16m / s-18m / s, and the time is 2h-3h.

4. The method for preparing a silicon carbide setter plate according to claim 1, characterized in that: In S2, the inner surface of one side of the steel mold is provided with concave-convex patterns.

5. The method for preparing a silicon carbide setter plate according to claim 1, characterized in that: In S2, the pressing pressure is 10MPa-12MPa, and the holding time is 1min-3min.

6. The method for preparing a silicon carbide setter according to claim 1, characterized in that: In S3, the pressure of the isostatic pressing treatment is 150 MPa-200 MPa, and the treatment time is 2 min-6 min.

7. The method for preparing a silicon carbide setter according to claim 1, characterized in that: Before the step S4, a matching hole is also formed on the green body processed in the step S3.

8. A silicon carbide setter plate, characterized in that: The silicon carbide setter is prepared by the method for preparing the silicon carbide setter according to any one of claims 1 to 7.

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