A silicon carbide particle trap and its preparation method

Abstract

This invention provides a silicon carbide particle trap and its preparation method. The preparation method includes the following steps: (1) mixing silicon carbide raw materials, pore-forming agents, metallic silicon powder and high-temperature sintering aids to obtain a mixture; (2) mixing the mixture, binder and dispersant, molding and then sintering at high temperature to obtain the silicon carbide particle trap; wherein, the high-temperature sintering aid includes any one or a combination of at least two of boron carbide, boron nitride or yttrium zirconium powder. This invention optimizes the formulation composition, and the selected high-temperature sintering aid can, on the one hand, improve the phenomenon of product layering caused by the flow during the liquefaction of low-temperature sintering boride, significantly improving the refractoriness and strength of the product; on the other hand, it can optimize the compressive strength, thermal conductivity and coefficient of thermal expansion of the product, enabling it to better withstand high thermal shock during vehicle start-up and shutdown, and improving the overall performance of the particle trap.

Description

Technical Field

[0001] This invention belongs to the field of particle trap preparation, specifically relating to a silicon carbide particle trap and its preparation method. Background Technology

[0002] To meet the emission standards for light-duty diesel engines, a particulate filter (DPF) with ultra-high porosity is needed, enabling it to withstand high thermal shock during vehicle start-up and shutdown while simultaneously meeting requirements for high temperature resistance and high thermal conductivity. Based on product performance requirements, silicon carbide (SiC) is considered the best material for such a particulate filter.

[0003] Existing methods for fabricating silicon carbide particulate filters (SDPFs) have certain limitations. These limitations primarily concern the performance parameters of the particulate filters, such as the coefficient of thermal expansion (CTE) and thermal conductivity. Firstly, the CTE of existing SDPF fabrication methods is relatively high, which may lead to excessive internal stress during high-temperature operation, potentially causing damage or failure. Therefore, reducing the CTE is crucial for improving the stability of the particulate filter. Secondly, the thermal conductivity of existing SDPF fabrication methods is insufficient, resulting in uneven temperature distribution. This can reduce filtration efficiency in some areas or cause excessive heat generation, affecting overall performance. Therefore, improving thermal conductivity helps achieve more efficient heat transfer, ensuring that the particulate filter maintains stable and efficient filtration throughout its operation.

[0004] In summary, there is an urgent need to design a new method for preparing silicon carbide particle traps, so that the prepared silicon carbide particle traps have a low coefficient of thermal expansion and high thermal conductivity. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a silicon carbide particulate filter and its preparation method. This invention optimizes the formulation composition, and the selected high-temperature calcining aid can, on the one hand, mitigate the flow and product stratification phenomenon caused by the liquefaction of low-temperature calcining boride, significantly improving the product's refractoriness and strength; on the other hand, it optimizes the product's compressive strength, thermal conductivity, and coefficient of thermal expansion, enabling it to better withstand high thermal shock during vehicle start-up and shutdown, thus enhancing the overall performance of the particulate filter. This method meets the performance requirements of particulate filters for light-duty diesel engines operating under complex conditions, is environmentally friendly, and is conducive to practical application and promotion.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0008] (1) Mix silicon carbide raw material, pore-forming agent, metallic silicon powder and high-temperature sintering aid to obtain a mixture;

[0009] (2) The mixture, binder and dispersant are mixed, and after molding, they are sintered at high temperature to obtain the silicon carbide particle trap.

[0010] The high-temperature sintering aid includes any one or a combination of at least two of boron carbide, boron nitride, or yttrium zirconium powder.

[0011] This invention optimizes the formulation composition. The selected high-temperature calcining aid can, on the one hand, improve the product's refraction and strength by mitigating the flow and stratification that occurs during the liquefaction of low-temperature calcining borides, thus significantly enhancing the product's refractoriness and strength. On the other hand, it optimizes the product's compressive strength, thermal conductivity, and coefficient of thermal expansion, enabling it to better withstand high thermal shock during vehicle start-up and shutdown, thereby improving the overall performance of the particulate filter. This method meets the performance requirements of particulate filters for light-duty diesel engines operating under complex conditions, is environmentally friendly, and is conducive to practical application and promotion.

[0012] In this invention, borides (such as boron carbide or boron nitride) can inhibit the growth of silicon carbide crystals during the sintering process, thereby reducing the porosity of the product and increasing the coefficient of thermal expansion; yttrium zirconium powder can improve the bonding strength between silicon carbide powder particles, thereby increasing the mechanical strength of porous silicon carbide products; at the same time, the yttrium element in the yttrium zirconium powder can improve the oxidation resistance of metallic silicon after high-temperature liquefaction.

[0013] As a preferred technical solution of the present invention, based on the total weight of silicon carbide raw material, silicon metal powder and high-temperature sintering aid mentioned in step (1), the content of the high-temperature sintering aid is 2-5%, for example, it can be 2%, 3%, 4%, 5%, etc.

[0014] In this invention, if the content of the high-temperature sintering aid is too low, the mechanical strength of the product will decrease, the coefficient of thermal expansion will increase, and the antioxidant capacity will decrease; if the content of the high-temperature sintering aid is too high, the sintering temperature of the product will increase, the raw material cost will increase, and the manufacturing cost of the product will increase.

[0015] Preferably, the yttrium zirconium powder is yttrium-doped zirconium oxide powder.

[0016] As a preferred embodiment of the present invention, the high-temperature sintering aid comprises boron carbide and yttrium zirconium powder, wherein the mass ratio of boron carbide to yttrium zirconium powder is (0.5-1.5):(1-3), wherein the range of boron carbide selection "0.5-1.5" can be, for example, 0.5, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5, etc., and the range of yttrium zirconium powder selection "1-3" can be, for example, 1, 1.5, 2, 2.5 or 3, etc.

[0017] In this invention, boron carbide and yttrium zirconium powder work synergistically to improve the product's mechanical strength, thermal shock resistance, and oxidation resistance. If the mass ratio of boron carbide to yttrium zirconium powder is too small, the product's mechanical strength decreases, its coefficient of thermal expansion increases, and its oxidation resistance decreases; if the mass ratio is too large, the product's sintering temperature increases, raw material costs increase, and the product's manufacturing cost increases.

[0018] Preferably, the yttrium oxide content in the yttrium-doped zirconium oxide powder is 3-5%, for example, it can be 3%, 3.5%, 4%, 4.5% or 5%, etc.

[0019] As a preferred technical solution of the present invention, based on the total weight of silicon carbide raw material, silicon metal powder and high-temperature sintering aid mentioned in step (1), the content of silicon carbide raw material is 60-90%, for example, it can be 60%, 70%, 80% or 90%, etc., and the content of silicon metal powder is 5-15%, for example, it can be 5%, 10% or 15%, etc.

[0020] As a preferred technical solution of the present invention, the silicon carbide raw material in step (1) includes silicon carbide coarse powder and silicon carbide fine powder, wherein the mass ratio of silicon carbide coarse powder and silicon carbide fine powder is (55-85):(5-25), wherein the selection range of silicon carbide coarse powder "55-85" can be, for example, 55, 60, 65, 70, 75, 80 or 85, and the selection range of silicon carbide fine powder "5-25" can be, for example, 5, 10, 15, 20 or 25, preferably (65-85):(8-15).

[0021] Preferably, the average particle size of the silicon carbide coarse powder is 20-50 μm, for example, it can be 20 μm, 30 μm, 40 μm or 50 μm, and more preferably 25-35 μm.

[0022] Preferably, the average particle size of the silicon carbide fine powder is ≤0.8μm, for example, it can be 0.8μm, 0.6μm, 0.4μm or 0.2μm, and more preferably ≤0.5μm.

[0023] As a preferred technical solution of the present invention, the pore-forming agent in step (1) includes any one or a combination of at least two of polystyrene microspheres, corn starch, dextrin, industrial paraffin, foamed microspheres or porous silica.

[0024] Preferably, the adhesive in step (2) comprises any one or a combination of at least two of polyvinyl alcohol, sodium polyacrylate, methylcellulose or hydroxyethylcellulose.

[0025] Preferably, the dispersant in step (2) includes any one or a combination of at least two of polyether polyol, polyacrylic acid, polymethacrylic acid, sodium polyphosphate or ammonium polyphosphate.

[0026] As a preferred technical solution of the present invention, the atmosphere of high-temperature sintering in step (2) is an inert atmosphere.

[0027] It should be noted that the present invention does not limit the gas in the inert atmosphere; for example, it may be argon.

[0028] Preferably, the high-temperature sintering temperature in step (2) is 1600-2000℃, for example, it can be 1600℃, 1700℃, 1800℃, 1900℃ or 2000℃.

[0029] In this invention, if the high-temperature sintering temperature is too low, the amount of liquid phase generated in the product will be insufficient, the median pore size of the product will be too small, the back pressure of the product will increase, the mechanical strength of the product will not meet the standard, and the thermal conductivity will decrease; if the high-temperature sintering temperature is too high, the porosity of the product will decrease, the median pore size will be too large, the product's trapping efficiency will decrease, the product's shrinkage will increase, and the product's size will be too small.

[0030] Preferably, the high-temperature sintering time in step (2) is 2-5 hours, for example, 2 hours, 3 hours, 4 hours or 5 hours.

[0031] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0032] (1) Mix coarse silicon carbide powder, fine silicon carbide powder, pore-forming agent, metallic silicon powder and high-temperature sintering aid to obtain a mixture;

[0033] Based on the total mass of the silicon carbide raw material, metallic silicon powder, and high-temperature sintering aid, the content of each component is as follows:

[0034] The mixture comprises 55-85% coarse silicon carbide powder, 5-25% fine silicon carbide powder, 5-15% metallic silicon powder, and 2-5% high-temperature sintering aid. The high-temperature sintering aid includes boron carbide and yttrium zirconium powder in a mass ratio of (0.5-1.5):(1-3). The content of the pore-forming agent is 15-35% of the total mass of the silicon carbide raw material, metallic silicon powder, and high-temperature sintering aid (e.g., 15%, 20%, 25%, 30%, or 35%).

[0035] (2) The mixture, binder, dispersant and water are mixed and then extruded to obtain the molded product;

[0036] (3) The molded product is dried and then sintered at high temperature under an inert atmosphere. The high temperature sintering temperature is 1600-2000℃ and the high temperature sintering time is 2-5h. After the sintering is completed, the silicon carbide particle trap is obtained.

[0037] In a second aspect, the present invention provides a silicon carbide particle trap, which is prepared by the preparation method described in the first aspect;

[0038] The porosity of the silicon carbide particle trap is 55-65%, for example, it can be 55%, 57%, 60%, 62% or 65%, etc.

[0039] As a preferred embodiment of the present invention, the A-axis compressive strength of the silicon carbide particle trap is 10-15 MPa, for example, it can be 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa or 15 MPa.

[0040] Preferably, the coefficient of thermal expansion of the silicon carbide particle collector is 3.8 × 10⁻⁶. -6 -4.5×10 -6 / ℃, for example, could be 3.8×10 -6 / ℃, 4×10 -6 / ℃, 4.2×10 -6 / ℃ or 4.5×10 -6 / ℃, etc.

[0041] Preferably, the thermal conductivity of the silicon carbide particle collector is 10-20 W / (M·K), for example, it can be 10 W / (M·K), 12 W / (M·K), 14 W / (M·K), 16 W / (M·K), 18 W / (M·K) or 20 W / (M·K).

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) This invention optimizes the formulation composition. The selected high-temperature calcining aid can, on the one hand, improve the phenomenon of product layering caused by the flow during the liquefaction of low-temperature calcining boride, significantly improving the product's refractoriness and strength. On the other hand, it can overcome the problems of silicon carbide powder oxidation and the inability to fill and connect particles, optimizing the product's compressive strength, thermal conductivity, and coefficient of thermal expansion, enabling it to better withstand high thermal shock during vehicle start-up and shutdown, thus improving the overall performance of the particulate filter. This method meets the performance requirements of light-duty diesel engines for particulate filters under complex operating environments and is environmentally friendly.

[0045] (2) The preparation method provided by the present invention can improve the fire resistance of the product to above 1800℃, and at the same time, the strength of the product can also be improved to 10-15 MPa.

[0046] (3) The preparation method of the present invention is simple, convenient to operate and easy to implement, which gives the product advantages in cost control and preparation efficiency, and is conducive to practical application and promotion. Attached Figure Description

[0047] Figure 1 This is a scanning electron microscope image of the silicon carbide particle trap prepared in Example 1 of this invention.

[0048] Figure 2 This is a scanning electron microscope image of the silicon carbide particle trap prepared in Example 11 of this invention.

[0049] Figure 3 This is a scanning electron microscope image of the silicon carbide particle trap prepared in Comparative Example 1 of this invention. Detailed Implementation

[0050] 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.

[0051] Example 1

[0052] This embodiment provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0053] (1) Mix coarse silicon carbide powder with an average particle size of 28 μm and fine silicon carbide powder with an average particle size of 0.4 μm, then add polystyrene microspheres, metallic silicon powder and high-temperature sintering aid and stir to obtain a mixture;

[0054] Based on the mass of the mixture, the content of each component is as follows:

[0055] The mixture contains 62% coarse silicon carbide powder, 10% fine silicon carbide powder, 15% polystyrene microspheres, 10% metallic silicon powder, and 3% high-temperature sintering aid. The high-temperature sintering aid comprises boron carbide and yttrium zirconium powder in a mass ratio of 1:2.

[0056] (2) Mix the mixture, polyvinyl alcohol, polyacrylic acid and water, stir and knead for 15 minutes to form a plastic clay, and then extrude it to obtain an unsintered ceramic body in the shape of a pre-formed cylindrical shape.

[0057] (3) Place the unsintered porcelain body in a natural environment and allow it to dry naturally within 24 hours. When the surface moisture content drops to a certain level, place the unsintered porcelain body in a drying oven and control the drying temperature at 80°C for 48 hours to remove excess moisture.

[0058] (4) The dried ceramic body is sintered at high temperature in an argon atmosphere. The high temperature sintering temperature is 1800℃, the high temperature sintering time is 3h, the argon flow rate is 2L / min, and the end is slow cooling to obtain the silicon carbide particle trap.

[0059] Figure 1 The image shows a microscopic scanning electron microscope (SEM) image of the silicon carbide particle trap prepared in this embodiment. As can be seen from the image, the particle trap has a stable crystal structure and a suitable porosity.

[0060] Example 2

[0061] This embodiment provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0062] (1) Mix coarse silicon carbide powder with an average particle size of 30 μm and fine silicon carbide powder with an average particle size of 0.5 μm, then add porous silica, metallic silicon powder and high-temperature sintering aid and stir to obtain a mixture;

[0063] Based on the mass of the mixture, the content of each component is as follows:

[0064] The composition includes 57% coarse silicon carbide powder, 15% fine silicon carbide powder, 20% porous silica, 5% metallic silicon powder, and 3% high-temperature sintering aid, wherein the high-temperature sintering aid is boron nitride.

[0065] (2) Mix the mixture, polyvinyl alcohol, polyacrylic acid and water, stir and knead for 15 minutes to form a plastic clay, and then extrude it to obtain an unsintered ceramic body in the shape of a pre-formed cylindrical shape.

[0066] (3) Place the unsintered porcelain body in a natural environment and allow it to dry naturally within 24 hours. When the surface moisture content drops to a certain level, place the unsintered porcelain body in a drying oven and control the drying temperature at 80°C for 48 hours to remove excess moisture.

[0067] (4) The dried ceramic body is sintered at high temperature in an argon atmosphere. The high temperature sintering temperature is 1700℃, the high temperature sintering time is 4h, the argon flow rate is 2L / min, and the end is slow cooling to obtain the silicon carbide particle trap.

[0068] Example 3

[0069] This embodiment provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0070] (1) Mix coarse silicon carbide powder with an average particle size of 30 μm and fine silicon carbide powder with an average particle size of 0.2 μm, then add corn starch, metallic silicon powder and high-temperature sintering aid and stir to obtain a mixture;

[0071] Based on the mass of the mixture, the content of each component is as follows:

[0072] The composition includes 70% coarse silicon carbide powder, 5% fine silicon carbide powder, 15% corn starch, 7% metallic silicon powder, and 3% high-temperature sintering aid, wherein the high-temperature sintering aid is yttrium zirconium powder.

[0073] (2) Mix the mixture, polyvinyl alcohol, polyacrylic acid and water, stir and knead for 15 minutes to form a plastic clay, and then extrude it to obtain an unsintered ceramic body in the shape of a pre-formed cylindrical shape.

[0074] (3) Place the unsintered porcelain body in a natural environment and allow it to dry naturally within 24 hours. When the surface moisture content drops to a certain level, place the unsintered porcelain body in a drying oven and control the drying temperature at 80°C for 48 hours to remove excess moisture.

[0075] (4) The dried ceramic body is sintered at high temperature in an argon atmosphere. The high temperature sintering temperature is 1900℃, the high temperature sintering time is 3h, the argon flow rate is 2L / min, and the end is slow cooling to obtain the silicon carbide particle trap.

[0076] Example 4

[0077] This embodiment provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0078] (1) Mix coarse silicon carbide powder with an average particle size of 25 μm and fine silicon carbide powder with an average particle size of 0.6 μm, then add dextrin, metallic silicon powder and high-temperature sintering aid and stir to obtain a mixture;

[0079] Based on the mass of the mixture, the content of each component is as follows:

[0080] The mixture contains 68% coarse silicon carbide powder, 5% fine silicon carbide powder, 20% dextrin, 5% metallic silicon powder, and 2% high-temperature sintering aid. The high-temperature sintering aid comprises boron carbide and yttrium zirconium powder in a mass ratio of 0.5:3.

[0081] (2) Mix the mixture, polyvinyl alcohol, polyacrylic acid and water, stir and knead for 15 minutes to form a plastic clay, and then extrude it to obtain an unsintered ceramic body in the shape of a pre-formed cylindrical shape.

[0082] (3) Place the unsintered porcelain body in a natural environment and allow it to dry naturally within 24 hours. When the surface moisture content drops to a certain level, place the unsintered porcelain body in a drying oven and control the drying temperature at 80°C for 48 hours to remove excess moisture.

[0083] (4) The dried ceramic body is sintered at high temperature in an argon atmosphere. The high temperature sintering temperature is 1600℃, the high temperature sintering time is 5h, the argon flow rate is 2L / min, and the end is slow cooling to obtain the silicon carbide particle trap.

[0084] Example 5

[0085] This embodiment provides a method for preparing a silicon carbide particle trap, the method comprising the following steps:

[0086] (1) Mix coarse silicon carbide powder with an average particle size of 35 μm and fine silicon carbide powder with an average particle size of 0.8 μm, then add industrial paraffin, metallic silicon powder and high-temperature sintering aid and stir to obtain a mixture;

[0087] Based on the mass of the mixture, the content of each component is as follows:

[0088] The mixture contains 70% coarse silicon carbide powder, 5% fine silicon carbide powder, 15% industrial paraffin wax, 5% metallic silicon powder, and 5% high-temperature sintering aid. The high-temperature sintering aid includes boron carbide and yttrium zirconium powder in a mass ratio of 1.5:1.

[0089] (2) Mix the mixture, polyvinyl alcohol, polyacrylic acid and water, stir and knead for 15 minutes to form a plastic clay, and then extrude it to obtain an unsintered ceramic body in the shape of a pre-formed cylindrical shape.

[0090] (3) Place the unsintered porcelain body in a natural environment and allow it to dry naturally within 24 hours. When the surface moisture content drops to a certain level, place the unsintered porcelain body in a drying oven and control the drying temperature at 80°C for 48 hours to remove excess moisture.

[0091] (4) The dried ceramic body is sintered at high temperature in an argon atmosphere. The high temperature sintering temperature is 2000℃, the high temperature sintering time is 2h, the argon flow rate is 2L / min, and the end is slow cooling to obtain the silicon carbide particle trap.

[0092] Example 6

[0093] The difference between this embodiment and embodiment 1 is that the content of the high-temperature sintering aid in step (1) is 1%, and the content of silicon carbide coarse powder is adjusted to 64% for adaptability.

[0094] The remaining preparation methods and parameters are consistent with those in Example 1.

[0095] Example 7

[0096] The difference between this embodiment and embodiment 1 is that the content of the high-temperature sintering aid in step (1) is 8%, and the content of silicon carbide coarse powder is adjusted to 57% for adaptability.

[0097] The remaining preparation methods and parameters are consistent with those in Example 1.

[0098] Example 8

[0099] The difference between this embodiment and embodiment 1 is that the mass ratio of boron carbide to yttrium zirconium powder in step (1) is 0.3:3.

[0100] The remaining preparation methods and parameters are consistent with those in Example 1.

[0101] Example 9

[0102] The difference between this embodiment and embodiment 1 is that the mass ratio of boron carbide powder to yttrium zirconium powder in step (1) is 2:1.

[0103] The remaining preparation methods and parameters are consistent with those in Example 1.

[0104] Example 10

[0105] The difference between this embodiment and embodiment 1 is that the high-temperature sintering temperature in step (4) is 1500℃.

[0106] The remaining preparation methods and parameters are consistent with those in Example 1.

[0107] Example 11

[0108] The difference between this embodiment and embodiment 1 is that the high-temperature sintering temperature in step (4) is 2200℃.

[0109] The remaining preparation methods and parameters are consistent with those in Example 1.

[0110] Figure 2 The image shows a microscopic scanning electron microscope image of the silicon carbide particle trap prepared in this embodiment. As can be seen from the image, the crystals of this particle trap are larger and the porosity is reduced compared to that of Example 1.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 1 is that the high-temperature sintering aid in step (1) is replaced with high borosilicate glass powder.

[0113] The remaining preparation methods and parameters are consistent with those in Example 1.

[0114] Figure 3 The image shows a microscopic scanning electron microscope (SEM) image of the silicon carbide particle trap prepared in this comparative example. As can be seen from the image, this silicon carbide particle trap with crystal structure has a low sintering temperature and a high liquid phase content.

[0115] Comparative Example 2

[0116] The difference between this comparative example and Example 1 is that the high-temperature sintering aid in step (1) is replaced with triboric acid.

[0117] The remaining preparation methods and parameters are consistent with those in Example 1.

[0118] Performance testing

[0119] The silicon carbide particle traps prepared in the above embodiments and comparative examples were tested for performance, including coefficient of thermal expansion, porosity, A-axis compressive strength, and thermal conductivity.

[0120] The test results are shown in Table 1.

[0121] Table 1

[0122]

[0123]

[0124] analyze:

[0125] As shown in the table above, the optimized formulation of this invention, using a high-temperature sintering aid, can, on the one hand, improve the phenomenon of product layering caused by the flow during the liquefaction of low-temperature sintering boride, significantly improving the product's refractoriness and strength. On the other hand, it can overcome the problems of silicon carbide powder oxidation and the inability to fill and connect particles, optimizing the product's compressive strength, thermal conductivity, and coefficient of thermal expansion, enabling it to better withstand high thermal shock during vehicle start-up and shutdown, thus improving the overall performance of the particulate filter. As shown in Examples 1-11, a product manufactured with 3% high-temperature sintering aid (including boron carbide and yttrium zirconium powder in a mass ratio of 1:2) + 97% mixture (various particle size distributions of mixed powder) can achieve an A-axis compressive strength of 15 MPa when the porosity is 64%.

[0126] As can be seen from Examples 1 and 6-7, if the content of high-temperature sintering aid is too low, the mechanical strength of the product will decrease, the coefficient of thermal expansion will increase, and the antioxidant capacity will decrease; if the content of high-temperature sintering aid is too high, the sintering temperature of the product will increase, the raw material cost will increase, and the manufacturing cost of the product will increase.

[0127] As can be seen from Examples 1 and 8-9, if the mass ratio of boron carbide to yttrium zirconium powder is too small, the mechanical strength of the product will decrease, the coefficient of thermal expansion will increase, and the oxidation resistance will decrease; if the mass ratio of boron carbide to yttrium zirconium powder is too large, the sintering temperature of the product will increase, the raw material cost will increase, and the manufacturing cost of the product will increase.

[0128] As can be seen from Examples 1 and 10-11, if the high-temperature sintering temperature is too low, the amount of liquid phase generated in the product will be insufficient, the median pore size of the product will be too small, the back pressure of the product will increase, the mechanical strength of the product will not meet the standard, and the thermal conductivity will decrease; if the high-temperature sintering temperature is too high, the porosity of the product will decrease, the median pore size will be too large, the product trapping efficiency will decrease, the product shrinkage will increase, and the product size will be too small.

[0129] As can be seen from Example 1 and Comparative Examples 1-2, if high borosilicate glass powder or triboric acid is used to replace the high-temperature sintering aid, the compressive strength, thermal conductivity and coefficient of thermal expansion of the product will not decrease sharply.

[0130] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition 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 of making a silicon carbide particulate trap, characterized by, The preparation method comprises the following steps: (1) mixing silicon carbide raw material, pore-forming agent, metal silicon powder and high-temperature sintering aid to obtain a mixture; The content of the high-temperature sintering aid is 2-5% based on the total weight of the silicon carbide raw material, metal silicon powder and high-temperature sintering aid in step (1); (2) mixing the mixture, a binder and a dispersing agent, and then performing high-temperature sintering after shaping treatment to obtain the silicon carbide particle trap; The high-temperature sintering aid comprises boron carbide and yttrium zirconium powder, and the mass ratio of the boron carbide to the yttrium zirconium powder is (0.5-1.5):(1-3); the yttrium zirconium powder is yttria-doped zirconia powder; The temperature of the high-temperature sintering in step (2) is 1600-2000 ℃; and the time of the high-temperature sintering in step (2) is 2-5 h.

2. The production method according to claim 1, characterized by, The content of the silicon carbide raw material is 60-90%, and the content of the metal silicon powder is 5-15% based on the total weight of the silicon carbide raw material, metal silicon powder and high-temperature sintering aid in step (1).

3. The preparation method according to claim 1, characterized in that, The silicon carbide raw material in step (1) comprises silicon carbide coarse powder and silicon carbide fine powder, and the mass ratio of the silicon carbide coarse powder to the silicon carbide fine powder is (55-85):(5-25).

4. The production method according to claim 3, characterized by, The mass ratio of the silicon carbide coarse powder to the silicon carbide fine powder is (65-85):(8-15).

5. The preparation method according to claim 3, characterized in that, The average particle size of the silicon carbide coarse powder is 20-50 μm.

6. The production method according to claim 5, wherein The average particle size of the silicon carbide coarse powder is 25-35 μm.

7. The preparation method according to claim 3, characterized in that, The average particle size of the silicon carbide fine powder is ≤0.8 μm.

8. The preparation method according to claim 7, characterized in that, The average particle size of the silicon carbide fine powder is ≤0.5 μm.

9. The method of claim 1, wherein, The pore-forming agent in step (1) comprises any one or a combination of at least two of polystyrene microbeads, corn starch, dextrin, industrial paraffin, foaming beads or porous silicon dioxide.

10. The method of claim 1, wherein, The binder in step (2) comprises any one or a combination of at least two of polyvinyl alcohol, sodium polyacrylate, methyl cellulose or hydroxyethyl cellulose.

11. The method of claim 1, wherein, The dispersing agent in step (2) comprises any one or a combination of at least two of polyether polyol, polyacrylic acid, polymethacrylic acid, sodium polyphosphate or ammonium polyphosphate.

12. The method of claim 1, wherein, The atmosphere of the high-temperature sintering in step (2) is inert atmosphere.

13. The method of claim 1, wherein, The preparation method comprises the following steps: (1) stirring and mixing silicon carbide coarse powder, silicon carbide fine powder, pore-forming agent, metal silicon powder and high-temperature sintering aid to obtain a mixture; The content of each component is as follows based on the total mass of the silicon carbide raw material, metal silicon powder and high-temperature sintering aid: The silicon carbide coarse powder is 55-85%, the silicon carbide fine powder is 5-25%, the metal silicon powder is 5-15%, and the high-temperature sintering aid is 2-5%; the high-temperature sintering aid comprises boron carbide and yttrium zirconium powder with a mass ratio of (0.5-1.5):(1-3); and the content of the pore-forming agent is 15-35% of the total mass of the silicon carbide raw material, metal silicon powder and high-temperature sintering aid; (2) mixing the mixture, a binder, a dispersing agent and water, and then performing extrusion molding to obtain a molded product; (3) drying the shaped product, and then high-temperature sintering under an inert atmosphere, the high-temperature sintering temperature being 1600-2000℃, the high-temperature sintering time being 2-5h, and the silicon carbide particle trap being obtained after the high-temperature sintering is completed.

14. A silicon carbide particulate trap characterized by, The silicon carbide particle trap is prepared by the preparation method according to any one of claims 1-13. The porosity of the silicon carbide particle trap is 55-65%.

15. The silicon carbide particulate trap of claim 14, wherein, The A-axis compressive strength of the silicon carbide particle trap is 10-15MPa.

16. The silicon carbide particulate trap of claim 14, wherein, The coefficient of thermal expansion of the silicon carbide particle trap is 3.8 x 10 -6 -4.5 x 10 -6 / °C.

17. The silicon carbide particulate trap of claim 14, wherein, The thermal conductivity of the silicon carbide particle trap is 10-20w / (M•K).

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