A method for manufacturing a silicon carbide boat support

Abstract

The invention discloses a method for manufacturing a silicon carbide boat support, comprising the following steps: S1, raw material mixing: silicon carbide powder and a high-temperature resistant binder are evenly mixed according to a certain ratio, an appropriate amount of sintering aid is added to the mixture, and the mixed grinding is performed to prepare mud; S2, blank molding: a grouting molding process is adopted to obtain a blank of a boat support split component, the blank is naturally dried and hot-air dried to remove moisture, and then the blank is trimmed and carved into a semi-finished boat support split component that meets size requirements, the semi-finished product enters an induction furnace and is subjected to high-temperature purification and sintering at a temperature of 2000-2300°C under the protection of an inert gas, so as to obtain a silicon carbide boat support split component blank; S3, splicing and sintering: the silicon carbide boat support split component blanks are spliced, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650-1700°C, and after being discharged from the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

Description

Technical Field

[0001] The present invention relates to the technical field of boat support production and processing, and in particular to a method for manufacturing a silicon carbide boat support. Background Art

[0002] The boat support is a key bearing component of the diffusion process equipment in the photovoltaic industry. Its application in the photovoltaic industry is mainly in the production process of photovoltaic cells, as a carrier for photovoltaic cells. In the photovoltaic industry, the traditional boat support material is mainly quartz, but because the quartz boat support is easy to deform in a high temperature environment and has a short service life of about 3-6 months, silicon carbide boat support, as a new type of boat support material, has gradually become the preferred boat support material in the photovoltaic industry due to its good thermal stability and long service life.

[0003] Silicon carbide has excellent high temperature resistance and corrosion resistance, and its strength is high. Due to the chemical properties of silicon carbide ceramics, it is difficult to form, so it is usually prepared by reaction sintering. The reaction sintering method includes the steps of powder preparation, block pressing, drying and sintering. These steps involve many parameters. For example, the powder preparation stage requires a reasonable ratio of raw materials and the preparation of powder with a compliant particle size. The block pressing stage requires reasonable pressure conditions and block size design, and the temperature setting and processing time setting of the drying and sintering stages. If these steps are not designed reasonably, it will affect the hardness and other indicators of the finished product.

[0004] Silicon carbide boat supports can replace quartz boat supports and have a longer service life of more than 5 years. The use of silicon carbide boat supports can significantly reduce the cost of use, reduce downtime caused by maintenance and repairs, and reduce production capacity losses. Boat supports play an important role in the process equipment of the photovoltaic industry.

[0005] Therefore, in view of this, the inventor has conducted research and improvement on the existing technology and its deficiencies, and provided a method for manufacturing a silicon carbide boat support, in order to achieve a more practical purpose. Summary of the invention

[0006] In order to solve the problems mentioned in the above background technology, the present invention provides a method for manufacturing a silicon carbide boat support.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for manufacturing a silicon carbide boat support comprises the following steps:

[0009] S1. Raw material mixing

[0010] Silicon carbide powder and high temperature resistant binder are uniformly mixed in a ratio of 5-8:1.5-1.8, and a proper amount of sintering aid is added to the mixture. The mixture is mixed and ground to prepare a slurry; wherein the amount of the sintering aid added is 10-25% of the total amount of the silicon carbide powder and the high temperature resistant binder.

[0011] S2, blank forming

[0012] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying to remove moisture. The semi-finished product enters the induction furnace and is purified and sintered at a high temperature of 2000-2300°C under the protection of inert gas to obtain a silicon carbide boat support split component blank.

[0013] S3, splicing and sintering

[0014] The split components of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650-1700°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support.

[0015] The working environment of semi-finished product production processes such as raw material weighing, mud preparation, grouting molding, and natural drying must be controlled at room temperature of 25℃~35℃, relative humidity of 40~50%, and closed and dust-free.

[0016] The present invention adopts a grouting molding method. Strictly controlling the increase of impurity content, especially iron content, during the production process is the key to the present invention. Therefore, the equipment and tools such as mixers, ball mills, pressure grouting machines used in the semi-finished product production processes such as batching, mud preparation, grouting molding, and natural drying, and the parts in contact with the mud adopt non-metallic linings, which can be stainless steel and polyurethane linings, preferably polyurethane linings. The batching barrel, grouting tank, stirring paddle, and plastic cup must be cleaned every time without water droplets or debris.

[0017] The steps for mud preparation are as follows:

[0018] Weigh 100 kg of silicon carbide powder with three particle sizes of 90 to 100 μm, 8 to 10 μm and 1.5 to 2.5 μm respectively according to a weight ratio of 30 to 35:15 to 20:47 to 50, and add the fine powder and the coarse powder into the ball mill in sequence;

[0019] Determine the properties of the slurry after ball milling: fluidity and specific gravity. The fluidity of the slurry after ball milling is ≤35 seconds, and the specific gravity is ≥2.4g / cm 3 And if there is no lumps of undispersed material in the slurry, the discharge requirements are met;

[0020] Put the ball-milled slurry into a barrel and stir it with a stirring paddle. The slurry needs to be stirred for more than 40 hours and can only be used after the slurry performance reaches the use standard.

[0021] The present invention adopts grouting molding. All utensils for holding mud must be cleaned to avoid contamination with mud of other materials. When the gypsum mold is closed, the gypsum mold must be cleaned with a brush. After the mold is closed and clamped, the model is laid flat and blown clean again with compressed air to ensure that no impurities are mixed into the grouting process. Vacuum degassing must be performed before grouting, and the vacuum degree is controlled at -0.5 to -1 bar. During grouting, the surface of the gypsum mold is gently tapped with a rubber hammer to facilitate the removal of bubbles. After the product is solidified, it is demoulded and naturally dried for 24 hours after demoulding. The temperature is controlled at ≥25°C and the humidity is controlled at ≥40%. The side panels, short panels, connecting panels and small parts required for the splicing of silicon carbide boat brackets are obtained by grouting molding.

[0022] The present invention adopts a two-step drying method of natural drying and hot air drying. The naturally dried wool body is sent to a drying furnace for drying. The drying temperature is up to 80°C and the drying time is 46 hours. In this way, the natural drying and hot air drying processes prevent the rapid dissipation of surface moisture of the product in the early stage of drying, and the cracking problem of the product is well solved. The heat source of the drying furnace used is an electric heating pipe, and a heat circulation fan and pipeline are installed. A purification adsorber is installed at the inlet of the pipeline to purify dust, oil gas, water and other impurities in the circulating hot air.

[0023] Carving

[0024] The blanks of side panels, short panels, connecting panels and small parts required for the splicing of silicon carbide boat supports are processed by engraving machines into semi-finished blanks such as side panels, short panels, connecting panels, etc. that meet the requirements of the drawings.

[0025] Purification calcination

[0026] The semi-finished product is purified and sintered in a medium-frequency graphite induction furnace. Before heating, it is first evacuated to a vacuum degree below 5Pa, and heating is started. The temperature is from room temperature to 200℃ for 3 to 4 hours, and vacuum is evacuated; the temperature is from 201 to 900℃ for 4 to 6 hours, and the vacuum is stopped. High-purity nitrogen with a purity of 99.996% is filled to restore normal pressure. At the same time, the wax exhaust fan is started to remove organic matter, and high-purity nitrogen is continuously filled at a rate of 30 to 50 ml / min; heating at 900 to 1100℃ for 1 to 2 hours, and vacuum is evacuated; high-purity argon with a purity of 99.996% is filled at 1100 to 2000℃, and sintering is carried out at normal pressure for 8 to 9 hours; heating at 2000 to 2300℃ for 8 to 9 hours; and keeping warm at 2300℃ for 5 hours.

[0027] Splicing

[0028] The silicon carbide boat support split parts are spliced ​​into blanks, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering at 1650-1700℃

[0029] Siliconizing sintering

[0030] A vacuum graphite electrode furnace is used. Before heating, vacuum is first evacuated to a vacuum degree of less than 5Pa, and heating is started. The temperature is from room temperature to 200℃ for 1 to 2 hours, and vacuum is evacuated; from 201 to 900℃ for 5 to 6 hours, vacuum is stopped, and high-purity nitrogen is filled to restore normal pressure. At the same time, the wax exhaust fan is started to remove organic matter, and high-purity nitrogen is continuously filled at a rate of 80 to 100 ml / min; heating at 900 to 1100℃ for 1 to 2 hours, vacuum is evacuated; heating at 1100 to 1300℃ for 2 to 3 hours; heating at 1300 to 1500℃ for 3 to 4 hours; heating at 1500 to 1650℃ for 3 to 4 hours; and keeping at 1650℃ for 2 hours. High-purity nitrogen is filled when cooling down, and the temperature is naturally cooled down.

[0031] The silicon used for siliconizing sintering is semiconductor silicon with a purity of 99.99%. The particle size is 3-5mm. After surface coating treatment, the semiconductor silicon is roasted together with the boat support that needs siliconizing treatment, with a weight ratio of 15-30:100. The surface coating treatment is to add a slurry of ultra-pure carbon black, hexagonal boron nitride, PVP K90 and water during the heating and stirring of the semiconductor silicon, so that a layer of coating is applied to the surface of the silicon particles, a certain amount of water is quickly removed, and then slowly dried. Before being put into the kiln, it is forced to be dried at 80°C again to ensure that there is no water and the surface coating is intact.

[0032] Finished product processing and impurity removal

[0033] After leaving the kiln, it is processed by grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, drying and other processes. The finished product impurity removal process uses dilute hydrochloric acid, with a concentration controlled at 8-15%, a temperature controlled at 20-40℃, and a soaking time controlled at 20-60min; the product soaked in hydrochloric acid is repeatedly ultrasonically cleaned and dried, the purpose of which is to remove impurity oxides such as Fe, Al, Ca, Mg, and Ti on the surface of the product.

[0034] result

[0035] The product obtained after the above process is experimentally determined to have SiC% ≥ 95%, free silicon ≤ 5%, flexural strength ≥ 250Mpa, apparent porosity ≤ 0.01%, bulk density ≥ 3.02g / cm3, Fe content ≤ 5ppm, Ti content ≤ 5ppm, Mg content ≤ 3ppm, Zn content ≤ 2ppm, Al content ≤ 1ppm, Ca content ≤ 1ppm, and low impurity content, which can meet the requirements of silicon wafer diffusion process in photovoltaic and semiconductor industries for service life and pollution-free.

[0036] Preferably, the silicon carbide powder uses 3N green silicon carbide powder with three particle size distributions of average particle size 90-100 μm, 8-10 μm and 1.5-2.5 μm as raw material, and the ratio of the three is controlled at a weight ratio of 30-35:15-20:47-50.

[0037] Preferably, the high temperature resistant binder is a compound of silicate and graphite in a ratio of 1.3-1.5:0.9-1.1.

[0038] Graphite is a layered material composed of carbon atoms. The layers are bonded by weak van der Waals forces. This structure gives it some unique properties, such as good lubricity and conductivity. When graphite is mixed with silicate solution and used as a binder, a tight bonding layer can be formed between the surfaces of silicon carbide. The layered structure of graphite and the interaction between layers can achieve the purpose of making the two surfaces tightly bonded. Graphite and silicate solution are sintered at high temperatures to generate silicon carbide, thereby achieving solidification and forming.

[0039] Preferably, the silicate solution is selected from one of sodium silicate solution, lithium silicate solution, potassium silicate solution and ammonium silicate solution.

[0040] Preferably, the graphite is 2000 mesh ultrafine graphite powder.

[0041] Preferably, the sintering aid is activated carbon, porous silicon and alumina compounded in a ratio of 1.1:1.5-1.8:0.5-0.8.

[0042] Silicon carbide is a strong covalent bond compound with a relatively low grain boundary diffusion coefficient, which means that the migration rate of atoms or ions at the grain boundary is slow. In addition, its sintering driving force is limited, which means that the ability to push atoms or ions to rearrange during the sintering process is insufficient, and pure silicon carbide is difficult to sinter densely. Therefore, in order to assist the sintering process of silicon carbide ceramics, appropriate sintering aids must be added. The sintering aid will react with the SiO 2 The reaction at the low melting point forms a low-temperature eutectic liquid phase, thereby completing the liquid phase sintering process.

[0043] The activated carbon added in the present invention has the property of porous adsorption, and can be more fully and evenly mixed with silicon carbide. In addition, the carbon has a strong reducing ability and can eliminate oxygen impurities.

[0044] Porous silicon and activated carbon form silicon carbide at high temperature. Silicon carbide is an excellent deoxidizer that can reduce the oxygen content during the silicon carbide formation process. At the same time, the presence of silicon will inhibit the decomposition of silicon carbide crystals and enhance the strength of silicon carbide ceramic materials.

[0045] As an additive, alumina can promote the grain growth and grain boundary movement of the material, thereby improving the density and mechanical strength of alumina ceramics. This can not only enhance the thermal stability of the material, but also help improve its cavitation resistance; in the later stage of sintering, the growth of grains plays an important role in sintering densification. As a sintering aid, alumina can inhibit the abnormal growth of grains, thereby facilitating the densification process.

[0046] Preferably, the mixed grinding method is: the silicon carbide, high temperature resistant binder and sintering aid are placed in a ball mill lined with tetrafluoroethylene for wet mixing, and the ball mill is used for 12-15 hours at a speed of 280-300r / min, and the ball mill is reversed every 25 minutes, and the ball milling medium is silicon oxide ball milling beads. The ball milling time is long, and the sintering aid and silicon carbide powder can be effectively mixed. The use of silicon oxide ball milling beads can reduce the introduction of impurities that affect the thermal conductivity of the silicon carbide ceramic material.

[0047] Preferably, the mold filling method is: evenly coating the boron nitride ethanol solution on the inner wall of the graphite mold and both ends of the gasket, and after the ethanol evaporates, loading the completely dried powder and compacting it.

[0048] Adding boron nitride ethanol isolates the powder from the inner wall of the mold, prevents reaction and adhesion during sintering, and reduces the penetration of impurities in the mold into the silicon melt. After solidification, it can be demoulded smoothly to prevent the ceramic material and the mold from cracking due to stress of reaction adhesion during the condensation process. Usually, the mold can be reused after using the release agent, which reduces the production cost.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] 1. In the present invention, when graphite and silicate solution are mixed and used as a binder, a tight bonding layer can be formed between the surfaces of silicon carbide, and the layered structure of graphite and the interaction between layers are utilized to achieve the purpose of making the two surfaces tightly bonded. Graphite and silicate solution generate silicon carbide under high temperature sintering, thereby achieving solidification and forming.

[0051] 2. The activated carbon in the present invention has the property of porous adsorption, and can be mixed more fully and evenly with silicon carbide, and carbon has a strong reducing ability, which can eliminate oxygen impurities. Silicon and carbon form silicon carbide at high temperature. Silicon carbide is an excellent deoxidizer, which can reduce the oxygen content in the process of silicon carbide formation. At the same time, due to the presence of silicon, the decomposition of silicon carbide crystals will be inhibited and the strength of silicon carbide ceramic materials will be enhanced.

[0052] 3. The silicon carbide boat support manufactured according to the present invention can replace the quartz boat support in the photovoltaic and semiconductor industries. Because of its high compressive strength, excellent thermal conductivity and resistance to rapid cooling and heating, the service life of the boat support is greatly extended; at the same time, it overcomes the fatal weaknesses of traditional reaction-sintered silicon carbide, such as high iron content and serious pollution, and has high social use value and application prospects. DETAILED DESCRIPTION

[0053] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Unless otherwise specified, the raw materials used in the present invention are all from conventional products purchased on the market. Silicon carbide powder is purchased from Shandong Jialin Energy Technology Co., Ltd., with a silicon content of more than 98.80%;

[0055] Porous silicon was purchased from Lianyungang Wohua New Material Technology Co., Ltd., with a particle size of 400 mesh;

[0056] Silicates, graphite, activated carbon and alumina are all sourced from Aladdin.

[0057] The mixed grinding method is as follows: the silicon carbide, the high temperature resistant binder and the sintering aid are wet mixed in a ball mill jar lined with tetrafluoroethylene, and the ball mill is used for 13 hours at a rotation speed of 300 r / min, and the ball mill is reversed once every 25 minutes, and the ball milling medium is silicon oxide ball milling beads. The ball milling time is long, and the sintering aid and the silicon carbide powder can be effectively mixed. The use of silicon oxide ball milling beads can reduce the introduction of impurities and thus affect the thermal conductivity of the silicon carbide ceramic material.

[0058] The mold filling method comprises the following steps: applying the boron nitride ethanol solution evenly to the inner wall of the graphite mold and both ends of the gasket, and after the ethanol evaporates, filling in completely dried powder and compacting.

[0059] Example 1

[0060] S1. Raw material mixing

[0061] 50 g of silicon carbide powder and 15 g of high temperature resistant binder were mixed evenly, 10 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0062] The high temperature resistant binder is a mixture of sodium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.3:1.1;

[0063] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0064] S2, blank forming

[0065] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0066] S3, splicing and sintering

[0067] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0068] Example 2

[0069] S1. Raw material mixing

[0070] 100 g of silicon carbide powder and 30 g of high temperature resistant binder were mixed evenly, 20 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare slurry;

[0071] The high temperature resistant binder is a mixture of sodium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.3:1.1;

[0072] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0073] S2, blank forming

[0074] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0075] S3, splicing and sintering

[0076] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0077] Example 3

[0078] S1. Raw material mixing

[0079] 500 g of silicon carbide powder and 150 g of high temperature resistant binder were mixed evenly, 100 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0080] The high temperature resistant binder is a mixture of sodium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.3:1.1;

[0081] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0082] S2, blank forming

[0083] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2100°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0084] S3, splicing and sintering

[0085] The split components of the silicon carbide boat support are spliced ​​together into a complete boat support, which is then sent into a vacuum furnace for high-temperature siliconization and sintering at 1680°C. After leaving the kiln, it is subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support.

[0086] Example 4

[0087] S1. Raw material mixing

[0088] 50 g of silicon carbide powder and 15 g of high temperature resistant binder were mixed evenly, 10 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0089] The high temperature resistant binder is a mixture of lithium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.5:0.9;

[0090] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.7;

[0091] S2, blank forming

[0092] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2200°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0093] S3, splicing and sintering

[0094] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0095] Example 5

[0096] S1. Raw material mixing

[0097] 100 g of silicon carbide powder and 30 g of high temperature resistant binder were mixed evenly, 20 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0098] The high temperature resistant binder is a mixture of potassium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.5:1.1;

[0099] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0100] S2, blank forming

[0101] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2200°C under argon protection to obtain a silicon carbide boat support split component blank.

[0102] S3, splicing and sintering

[0103] The split components of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1700℃. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support.

[0104] Example 6

[0105] S1. Raw material mixing

[0106] 500 g of silicon carbide powder and 150 g of high temperature resistant binder were mixed evenly, 100 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0107] The high temperature resistant binder is a mixture of ammonium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.5:1.1;

[0108] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0109] S2, blank forming

[0110] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2300°C under argon protection to obtain a silicon carbide boat support split component blank.

[0111] S3, splicing and sintering

[0112] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0113] Example 7

[0114] S1. Raw material mixing

[0115] 80 g of silicon carbide powder and 18 g of high temperature resistant binder were mixed evenly, 20 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0116] The high temperature resistant binder is a mixture of ammonium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.3:1.1;

[0117] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0118] S2, blank forming

[0119] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2100°C under argon protection to obtain a silicon carbide boat support split component blank.

[0120] S3, splicing and sintering

[0121] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1690°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0122] Example 8

[0123] S1. Raw material mixing

[0124] 800 g of silicon carbide powder and 180 g of high temperature resistant binder were mixed evenly, 200 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0125] The high temperature resistant binder is a mixture of ammonium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.3:1.1;

[0126] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.5:0.5;

[0127] S2, blank forming

[0128] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under argon protection to obtain a silicon carbide boat support split component blank.

[0129] S3, splicing and sintering

[0130] The split components of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1700℃. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support.

[0131] Example 9

[0132] S1. Raw material mixing

[0133] 160 g of silicon carbide powder and 36 g of high temperature resistant binder were mixed evenly, 40 g of sintering aid was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0134] The high temperature resistant binder is a mixture of lithium silicate solution and 2000 mesh ultrafine graphite powder in a ratio of 1.5:1;

[0135] The sintering aid is a compound of activated carbon, porous silicon and alumina in the ratio of 1.1:1.8:0.7;

[0136] S2, blank forming

[0137] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under argon protection to obtain a silicon carbide boat support split component blank.

[0138] S3, splicing and sintering

[0139] The split components of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1700℃. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support.

[0140] Comparative Example 1

[0141] S1. Raw material mixing

[0142] 50 g of silicon carbide powder and 15 g of sodium silicate solution were mixed evenly, 10 g of activated carbon was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0143] S2, blank forming

[0144] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0145] S3, splicing and sintering

[0146] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0147] Comparative Example 2

[0148] S1. Raw material mixing

[0149] 50 g of silicon carbide powder and 15 g of 2000 mesh ultrafine graphite powder were mixed evenly, 10 g of porous silicon was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0150] S2, blank forming

[0151] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0152] S3, splicing and sintering

[0153] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0154] Comparative Example 3

[0155] S1. Raw material mixing

[0156] 50 g of silicon carbide powder and 15 g of high temperature resistant binder were mixed evenly, 10 g of aluminum oxide was added to the mixture, and the mixture was mixed and ground to prepare a slurry;

[0157] S2, blank forming

[0158] The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying. The semi-finished product enters the induction furnace and is purified and sintered at a temperature of 2000°C under nitrogen protection to obtain a silicon carbide boat support split component blank.

[0159] S3, splicing and sintering

[0160] The split blanks of the silicon carbide boat support are spliced ​​together, and after being spliced ​​into a complete boat support, they are sent into a vacuum furnace for high-temperature siliconization and sintering treatment at 1650°C. After leaving the kiln, they are subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain the silicon carbide boat support.

[0161] The bending strength adopts the GB / T 1965-1996 porous ceramic bending strength test method;

[0162] Thermal conductivity adopts GB / T22588-2008 flash method to measure thermal diffusivity or thermal conductivity;

[0163] The porosity adopts the GB / T 1966-1996 porous ceramic apparent porosity and capacity test method; the specific experimental data are shown in Table 1:

[0164] Table 1

[0165]

[0166]

[0167] In summary, the silicon carbide boat support prepared in the embodiment of the present invention has greatly improved bending strength and thermal conductivity compared to the control example, and the silicon carbide boat support prepared in the present application has a lower porosity, so it has a higher thermal conductivity, which plays an important role in the process equipment of the photovoltaic industry.

[0168] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for manufacturing a silicon carbide boat support, characterized in that: The following steps are involved: S1. Raw material mixing The silicon carbide powder and the high temperature resistant binder are mixed evenly in a certain proportion, an appropriate amount of sintering aid is added to the mixture, and the mixture is mixed and ground to prepare a slurry; S2, blank forming The blank of the boat support split component is obtained by the grouting molding process. The blank is trimmed and carved into a semi-finished boat support split component that meets the size requirements after natural drying and hot air drying to remove moisture. The semi-finished product enters the induction furnace and is purified and sintered at a high temperature of 2000-2300°C under the protection of inert gas to obtain a silicon carbide boat support split component blank. S3, splicing and sintering The silicon carbide boat support is spliced ​​into a complete boat support and then sent into a vacuum furnace for high-temperature siliconization and sintering at 1650-1700°C. After leaving the kiln, it is subjected to grinding, sandblasting, fine washing, impurity removal, ultrasonic cleaning, and drying processes to obtain a silicon carbide boat support; The high temperature resistant binder is a mixture of silicate solution and graphite in a ratio of 1.3-1.5:0.9-1.1; The sintering aid is activated carbon, porous silicon and alumina, which are compounded according to 1.1:1.5-1.8:0.5-0.

8.

2. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: The silicate solution is selected from one of sodium silicate solution, lithium silicate solution, potassium silicate solution and ammonium silicate solution.

3. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: The graphite is 2000 mesh ultrafine graphite powder.

4. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: The mixed grinding method is: placing the silicon carbide, high temperature resistant binder and sintering aid in a ball mill liner with tetrafluoroethylene for wet mixing, using a ball mill for ball milling for 12-15 hours, with a rotation speed of 280-300r / min, reversing once every 25 minutes, and the ball milling medium is silicon oxide ball milling beads.

5. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: When the slip casting process is adopted in step S2, the boron nitride ethanol solution is evenly coated on the inner wall of the graphite mold and both ends of the gasket, and after the ethanol evaporates, the completely dried powder is loaded and compacted.

6. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: The added amount of the sintering aid is 10-25% of the total amount of silicon carbide powder and high temperature resistant binder.

7. The method for manufacturing a silicon carbide boat support according to claim 1, characterized in that: The silicon carbide powder uses 3N green silicon carbide powder with three particle size distributions of average particle diameters of 90-100 μm, 8-10 μm and 1.5-2.5 μm as raw material, and the proportion of the three is controlled at a weight ratio of 30-35:15-20:47-50.

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