Wall-flow honeycomb ceramic filter and extrusion die for manufacturing it

Abstract

The application provides a wall flow honeycomb ceramic filter, which comprises a honeycomb ceramic structure body with a plurality of first channels and a plurality of second channels, the plurality of first channels extend in the axial direction of the honeycomb ceramic structure body, are open at an air inlet end face, and are sealed at an air outlet end face, the plurality of second channels extend in the axial direction of the honeycomb ceramic structure body, are open at the air outlet end face, and are sealed at the air inlet end face, and the first channels and the second channels are communicated, the cross section of the first channel is a square with a curvature radius R1 and a side length L1, the cross section of the second channel is a square with a curvature radius R2 and a side length L2, wherein L1>L2 and R1>R2. The wall flow honeycomb ceramic filter provided by the application can achieve the balance between high strength and low back pressure.

Description

Technical Field

[0001] This invention relates to the field of honeycomb ceramic technology, and more specifically to a wall-flow honeycomb ceramic filter and an extrusion die for manufacturing it. Background Technology

[0002] As a core component of diesel vehicle exhaust aftertreatment systems, the wall-flow honeycomb ceramic filter (DPF) is crucial in its structural design and performance. Currently, the industry mainstream adopts an alternating-block honeycomb structure, which captures particulate matter by forcing it through the filter-equipped grid walls. In this structure, the inlet end of each unit channel is a first-formed hole, and the outlet end is a second-formed hole. This alternating design of large second-formed holes constitutes the basic principle of particulate matter capture. However, this conventional large second-formed hole structure design has a long-standing inherent contradiction: the trade-off between mechanical strength and system back pressure. Specifically, during periodic high-temperature regeneration of the filter, the unit bars bear enormous thermal stress. The diagonal area of ​​the inlet first-formed hole, due to its structural characteristics, becomes the weakest point where stress is most concentrated, easily causing cracks in the honeycomb ceramic carrier along this direction, severely affecting the product's reliability and service life. To enhance mechanical strength, traditional techniques employ rounded corners at the intersections of the grid walls. While this does strengthen the intersections and mitigate cracking risks to some extent, it also significantly increases resistance to exhaust gas flow because it lengthens the actual path of some gas passing through the grid walls, directly leading to increased system back pressure. Increased back pressure not only raises engine fuel consumption but also negatively impacts engine power and fuel economy over long-term operation.

[0003] Therefore, how to ensure strength without increasing back pressure is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a wall-flow honeycomb ceramic filter and an extrusion die for manufacturing it, solving the technical problem of how to improve the strength of the wall-flow honeycomb ceramic filter without increasing the back pressure.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A wall-flow honeycomb ceramic filter, wherein the honeycomb ceramic structure has multiple first channels and multiple second channels. The plurality of first channels extend axially in the honeycomb ceramic structure, opening at the air inlet end face and being sealed at the air outlet end face; the plurality of second channels extend axially in the honeycomb ceramic structure, opening at the air outlet end face and being sealed at the air inlet end face; and the first channels and the second channels are in communication. The first channel has a cross-section that is a square with a radius of curvature R1 and a side length of L1, and the second channel has a cross-section that is a square with a radius of curvature R2 and a side length of L2, wherein L1>L2 and R1 / R2≥2.

[0007] To achieve the above objectives, the present invention also provides the following technical solution: An extrusion die for manufacturing the wall-flow honeycomb ceramic filter includes a forming plate, the forming plate including a first forming hole and a second forming hole, the first forming hole being used to form a first channel and the second forming hole being used to form a second channel; The first forming hole has a cross-section that is a square with a radius of curvature R1 and a side length of L1, and the second forming hole has a cross-section that is a square with a radius of curvature R2 and a side length of L2, wherein L1>L2 and R1>R2.

[0008] The descriptions and specific examples in the invention summary are intended to be illustrative only and are not intended to limit the scope of the invention.

[0009] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The wall-flow honeycomb ceramic filter provided by this invention has multiple first channels and multiple second channels. The cross-section of the first channel is a square with rounded corners having a radius of curvature R1 and a side length L1. The cross-section of the second channel is a square with rounded corners having a radius of curvature R2 and a side length L2, wherein L1>L2 and R1 / R2≥2. By designing different cross-sections of the different channels, the radius of curvature R1 of the first channel, which has a larger hydraulic diameter (larger side length L1), is greater than the radius of curvature R2 of the second channel, which has a relatively smaller hydraulic diameter (smaller side length L2). Since the greater the wall thickness of the wall-flow honeycomb ceramic filter, the greater the resistance, the rounded corner structure introduced by traditional technology to enhance mechanical strength leads to an increase in wall thickness, further increasing the resistance to gas entry. While the wall-flow honeycomb ceramic filter of this application also incorporates a rounded corner structure, its inlet end is a first channel with a larger rounded corner curvature radius R1, while the outlet end is a second channel with a smaller rounded corner curvature radius R2. This design results in relatively low resistance for gas entering the first channel, while simultaneously shortening the gas path through the second channel. This structural design maximizes the effective gas transmission area while enhancing the rounded corner structure, significantly reducing flow resistance and optimizing the flow field distribution, thus achieving a balance between high strength and low back pressure. The wall-flow honeycomb ceramic filter of this invention achieves a significant comprehensive improvement in thermal shock resistance, pressure drop, and durability. Specifically, in thermal shock resistance testing, the wall-flow honeycomb ceramic filter of this invention remained structurally intact after three cycles of heating and cooling at 500°C, demonstrating strong reliability. In terms of pressure drop, under the same airspeed test conditions, its pressure drop value is reduced by about 3%-10% compared with the traditional rounded corner honeycomb ceramic filter. Compared with the traditional square channel honeycomb ceramic filter, its pressure drop increase is less than 3%, and its pore distortion rate is significantly reduced, controlled below 1%.

[0010] Furthermore, the extrusion die based on this wall-flow honeycomb ceramic filter provided by this invention can effectively reduce die wear, while improving material flowability and die stress during extrusion molding. After continuously extruding 5000 meters of this wall-flow honeycomb ceramic filter, the groove width variation in key parts of the die was successfully controlled to ≤0.001 micrometers, extending die life, reducing production costs, and promoting product dimensional consistency and excellent yield. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other solutions can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of a wall-flow honeycomb ceramic filter provided in one embodiment of the present invention; Figure 2 A cross-sectional view along the axial direction of a wall-flow honeycomb ceramic filter provided in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the first channel of a wall-flow honeycomb ceramic filter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the second channel of a wall-flow honeycomb ceramic filter provided in one embodiment of the present invention. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention.

[0014] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0015] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0016] Any method steps, processes, and operations described in this invention should not be construed as necessarily requiring them to be performed in the specific order discussed or shown, unless explicitly specified. It should also be understood that, unless otherwise stated, additional or alternative steps may be used.

[0017] In this invention, except where explicitly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any embodiment described in this invention can be freely combined with one or more other embodiments described in this invention, and the resulting technical solutions or concepts are considered part of the original disclosure or original record of this invention, and should not be regarded as new content not disclosed or anticipated by this invention, unless those skilled in the art consider the combination to be clearly unreasonable.

[0018] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0019] Unless otherwise stated, when % is mentioned in this document, it refers to wt%.

[0020] First aspect The first aspect of this invention provides a wall-flow honeycomb ceramic filter, see [link to relevant documentation]. Figures 1-2 It includes a honeycomb ceramic structure 100. The honeycomb ceramic structure 100 has a plurality of first channels 11 and a plurality of second channels 12, separated by partitions and extending axially along the honeycomb ceramic structure. The first channels 11 are open at the air inlet end face 1A and sealed at the air outlet end face 1B. The second channels 12 are open at the air outlet end face 1B and sealed at the air inlet end face 1A, as shown below. Figure 2 Multiple first channels 11 and multiple second channels 12 are connected to form a fluid flow path extending from the air inlet end face 1A to the air outlet end face 1B.

[0021] Please see Figure 3 and Figure 4 The hydraulic diameter of the first channel 11 is greater than that of the second channel 12. The cross-section of the first channel is a square with a radius of curvature R1 and a side length of L1. The cross-section of the second channel is a square with a radius of curvature R2 and a side length of L2, wherein L1>L2 and R1>R.

[0022] The radius of curvature has a well-known meaning in the art. It can be tested by taking a picture with an image measuring instrument with image analysis function (such as Novator432) and then directly capturing the rounded corner with software measurement tools.

[0023] In some embodiments of the present invention, the honeycomb ceramic carrier is a cylinder or a polygonal prism.

[0024] In some embodiments of the present invention, R2 ≤ 0.15 mm. Understandably, R2 can take values ​​of 0.15 mm, 0.14 mm, 0.13 mm, 0.12 mm, 0.11 mm, 0.10 mm, and any value between them, or any combination thereof. Controlling the curvature diameter R2 of the rounded corners of the square cross-section of the second channel to be less than or equal to 0.15 mm further reduces the proportion of the thickened area (i.e., the thickening caused by the rounded corners) of the first and / or second channels while maintaining high mechanical strength of the honeycomb ceramic filter, further reducing airflow resistance, optimizing the flow field distribution, and lowering back pressure. In some embodiments of the present invention, 0.15 mm < R1 ≤ 0.4 mm. Understandably, R1 can take values ​​of 0.16 mm, 0.18 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, and any value between them, or any combination thereof.

[0025] In some embodiments of the present invention, R1 / R2 ≥ 2, and may be greater than 3, 4, 5 or more. R1 / R2 ≥ 2 can further reduce the resistance of airflow from the inlet to the outlet.

[0026] In some embodiments of the present invention, 3≥R1 / R2≥2, for example, R1 / R2 can also be 2.2, 2.4, 2.5, 2.6, or 2.8.

[0027] In some embodiments of the present invention, 0.7mm ≤ L1 ≤ 1.6mm. Understandably, L1 can take the values ​​of 1.6mm, 1.4mm, 1.2mm, 1.0mm, 0.9mm, 0.8mm, 0.7mm, and any values ​​between them and any range thereof.

[0028] In some embodiments of the present invention, 0.7mm ≤ L2 ≤ 1.25mm. Understandably, L2 can take the values ​​of 1.25mm, 1.20mm, 1.10mm, 1.0mm, 0.9mm, 0.8mm, 0.7mm, and any value between them and any range thereof.

[0029] In some embodiments of the present invention, 1 < L1 / L2 ≤ 1.6, for example, L1 / L2 can also be 1.1, 1.2, 1.3, 1.4, or 1.5. The airflow travels a shorter distance from the inlet end face to the outlet end face, further reducing pressure drop.

[0030] In some embodiments of the present invention, the honeycomb ceramic structure is a cylinder, the axial height of the cylinder is H, 120mm≤H≤300mm; the diameter of the cross-section of the cylinder is Z, 140mm≤Z≤350mm.

[0031] In some embodiments of the present invention, the plurality of first channels and the plurality of second channels are separated by a partition wall, the wall thickness of which is 5 mil to 14 mil.

[0032] In some embodiments of the present invention, the total number density of the plurality of first channels and the plurality of second channels is 100 to 500 per square inch on the interface perpendicular to the axis of the honeycomb ceramic structure.

[0033] In some embodiments of the present invention, the honeycomb ceramic structure is a honeycomb ceramic structure whose crystalline phase is mainly composed of cordierite or silicon carbide.

[0034] In some embodiments of the present invention, according to GB / T 25994-2010, the thermal shock resistance temperature of the wall-flow honeycomb ceramic filter is greater than or equal to 500°C.

[0035] In some embodiments of the present invention, the pressure drop of the wall-flow honeycomb ceramic filter is less than 10 kPa. The pressure drop is measured on a SuperFlow SF-1020 pressure drop test bench in intake mode, at a room temperature of 24℃~26℃, a flow rate of 600 CMH, with the airbag sealed and in a clean state.

[0036] In some embodiments of the present invention, the pore distortion rate of the wall-flow honeycomb ceramic filter is less than 1%. The method for testing the pore distortion rate is as follows: Take a wall-flow honeycomb ceramic filter, cut the end face flat, and place it under a digital microscope (such as Keyence VHX-7000) to acquire an image of the entire end face. Observe the shape of each pore cell, and count any pore cell that meets any of the following conditions as a distorted pore cell: (1) The shape of the pore cell deviates from the design shape, and the angle deviation is >1°; (2) The offset of the center position of the pore cell is >0.1 mm; (3) The pore wall shows obvious non-linear bending; (4) The pore cell is not connected or is blocked. Count the number of distorted pore cells and the total number of pore cells on the end face, and calculate the pore cell distortion rate according to the following formula: Pore cell distortion rate = (Number of distorted pore cells / Total number of pore cells on the end face) × 100%. It is required to measure no less than 3 samples and take the average value as the final result.

[0037] Second aspect The present invention also provides an extrusion die for manufacturing a wall-flow honeycomb ceramic filter as described in any embodiment of the first aspect, comprising a forming plate, the forming plate including a first forming hole and a second forming hole, the first forming hole being used to form a first channel and the second forming hole being used to form a second channel.

[0038] It should be noted that the molding plate has the meaning of the formula in this field and is a conventional component of the extrusion die for wall-flow honeycomb ceramic filters.

[0039] The first forming hole has a cross-section that is a square with a radius of curvature R1 and a side length L1, and the second forming hole has a cross-section that is a square with a radius of curvature R2 and a side length L2, wherein L1>L2 and R1>R2. When this extrusion die is in use, the groove width variation of the forming plate can be controlled to be within 0.001 micrometers or less. The groove width refers to the gap between the first forming hole and / or the second forming hole.

[0040] In some embodiments of the present invention, R2 ≤ 0.15 mm, which can further reduce the variation in groove width in the molding plate.

[0041] In some embodiments of the present invention, 3≥R1 / R2≥2, which can avoid the negative effects caused by excessively large R2.

[0042] Example To better understand the present invention, the following description is provided in conjunction with embodiments. However, the scope of protection of the present invention is not limited to the scope of the embodiments.

[0043] In the following examples, unless otherwise specified, all experimental instruments, raw materials, and quantities involved are commercially available products or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0044] Unless otherwise specified, the specific parameters used in each step of the preparation process of the materials in each embodiment and comparative example are the same.

[0045] Silicon carbide Example 1 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.15 mm, the radius of curvature R2 of the second forming hole cross-section is 0.065 mm, the side length L1 of the first forming hole cross-section is 1.37 mm, the side length L2 of the second forming hole cross-section is 1.07 mm, R1 / R2=2.31, L1 / L2=1.28.

[0046] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0047] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0048] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0049] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0050] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0051] 6) Microwave drying to obtain unit blanks.

[0052] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0053] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0054] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0055] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0056] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0057] Silicon carbide Example 2 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.2 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.4 mm, the side length L2 of the second forming hole cross-section is 1.1 mm, R1 / R2=2, L1 / L2=1.27.

[0058] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0059] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0060] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0061] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0062] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0063] 6) Microwave drying to obtain unit blanks.

[0064] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0065] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0066] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0067] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0068] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0069] Silicon carbide Example 3 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.3 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.4 mm, the side length L2 of the second forming hole cross-section is 0.875 mm, R1 / R2=3, L1 / L2=1.6.

[0070] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0071] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0072] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0073] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0074] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0075] 6) Microwave drying to obtain unit blanks.

[0076] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0077] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0078] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0079] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0080] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0081] Silicon carbide Example 4 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.2 mm, the radius of curvature r of the second forming hole cross-section is 20.1 mm, the side length L1 of the first forming hole cross-section is 1.5 mm, the side length L2 of the second forming hole cross-section is 1.25 mm, R1 / R2=2, L1 / L2=1.2.

[0082] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0083] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0084] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0085] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0086] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0087] 6) Microwave drying to obtain unit blanks.

[0088] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0089] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0090] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0091] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0092] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0093] Silicon carbide Example 5 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.3 mm, the radius of curvature R2 of the second forming hole cross-section is 0.10 mm, the side length L1 of the first forming hole cross-section is 1.45 mm, the side length L2 of the second forming hole cross-section is 1.21 mm, R1 / R2=3, L1 / L2=1.2.

[0094] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0095] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0096] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0097] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0098] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0099] 6) Microwave drying to obtain unit blanks.

[0100] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0101] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0102] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0103] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0104] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0105] Silicon carbide Example 6 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.2 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.6 mm, the side length L2 of the second forming hole cross-section is 1 mm, R1 / R2=2, L1 / L2=1.6.

[0106] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0107] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0108] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0109] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0110] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0111] 6) Microwave drying to obtain unit blanks.

[0112] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0113] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0114] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0115] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0116] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0117] Silicon carbide Example 7 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.2 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 0.8 mm, the side length L2 of the second forming hole cross-section is 0.7 mm, R1 / R2=2, L1 / L2=1.14.

[0118] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0119] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0120] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0121] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0122] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0123] 6) Microwave drying to obtain unit blanks.

[0124] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0125] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0126] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0127] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0128] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0129] Silicon carbide Example 8 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.45mm, the radius of curvature R2 of the second forming hole cross-section is 0.15mm, the side length L1 of the first forming hole cross-section is 1.0mm, the side length L2 of the second forming hole cross-section is 0.85mm, R1 / R2=3, L1 / L2=1.17.

[0130] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0131] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0132] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0133] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0134] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the die.

[0135] 6) Microwave drying to obtain unit blanks.

[0136] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0137] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0138] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0139] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0140] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0141] Cordierite Example 9 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.104 mm, the radius of curvature R2 of the second forming hole cross-section is 0.047 mm, the side length L1 of the first forming hole cross-section is 1.36 mm, the side length L2 of the second forming hole cross-section is 1.09 mm, R1 / R2=2.21, L1 / L2=1.25.

[0142] 1) 38 parts talc, 13 parts kaolin, 19 parts silica, 18 parts alumina, 12 parts aluminum hydroxide, 25 parts pore-forming agent (of which PMMA accounts for 10% by mass), 1 part stearic acid lubricant, 5 parts methyl cellulose binder (added), and 38 parts water (added).

[0143] 2) Add the inorganic raw materials (talc, kaolin, silica, alumina, aluminum hydroxide) from step 1) above, along with the pore-forming agent and stearic acid lubricant, into the mixer and dry mix at 10 Hz for 15 minutes.

[0144] 3) Add methylcellulose binder and water, and wet mix at 45 Hz for 8 minutes.

[0145] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 30 minutes.

[0146] 5) After kneading the clay, knead it further, then put it into an extruder and use the above-mentioned mold to extrude a honeycomb ceramic blank with a diameter of 7.5 inches and a height of 6 inches.

[0147] 6) Dry the raw blank.

[0148] 7) Plug the holes in the dried green blank.

[0149] 8) The green blank after plugging is sintered to obtain a wall-flow honeycomb ceramic filter.

[0150] Cordierite Example 10 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.104 mm, the radius of curvature R2 of the second forming hole cross-section is 0.047 mm, the side length L1 of the first forming hole cross-section is 1.36 mm, the side length L2 of the second forming hole cross-section is 1.09 mm, R1 / R2=2.21, L1 / L2=1.25.

[0151] 1) 38 parts talc, 13 parts kaolin, 19 parts silica, 18 parts alumina, 12 parts aluminum hydroxide, 25 parts pore-forming agent (of which PMMA accounts for 10% by mass), 1 part stearic acid lubricant, 5 parts methyl cellulose binder, and 38 parts water.

[0152] 2) Add all the raw materials from step 1) above into the mixer and dry mix at 10Hz for 15 minutes.

[0153] 3) Add methylcellulose binder and water, and wet mix at 45 Hz for 8 minutes.

[0154] 4) Add the raw material mixture obtained in step 3) into a biaxial kneader and knead for 30 minutes.

[0155] 5) After kneading the clay, knead it further and put it into an extruder to extrude a honeycomb ceramic blank with a diameter of 7.5 inches and a height of 6 inches using the above-mentioned mold.

[0156] 6) Dry the raw blank.

[0157] 7) Plug the holes in the dried green blank.

[0158] 8) The green blank after plugging is sintered to obtain a wall-flow honeycomb ceramic filter.

[0159] Comparative Example 1 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.45 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.1 mm, the side length L2 of the second forming hole cross-section is 0.86 mm, R1 / R2=4.5, L1 / L2=1.28.

[0160] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0161] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0162] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0163] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0164] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0165] 6) Microwave drying to obtain unit blanks.

[0166] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0167] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0168] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0169] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0170] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0171] Comparative Example 2 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.15 mm, the radius of curvature R2 of the second forming hole cross-section is 0.065 mm, the side length L1 of the first forming hole cross-section is 1.6 mm, the side length L2 of the second forming hole cross-section is 0.9 mm, R1 / R2=2.31, L1 / L2=1.78.

[0172] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0173] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0174] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0175] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0176] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0177] 6) Microwave drying to obtain unit blanks.

[0178] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0179] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0180] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0181] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0182] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0183] Comparative Example 3 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.45 mm, the radius of curvature R2 of the second forming hole cross-section is 0.08 mm, the side length L1 of the first forming hole cross-section is 1.3 mm, the side length L2 of the second forming hole cross-section is 0.7 mm, R1 / R2=5.625, L1 / L2=1.86.

[0184] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0185] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0186] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0187] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0188] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0189] 6) Microwave drying to obtain unit blanks.

[0190] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0191] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0192] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0193] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0194] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0195] Comparative Example 4 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.15 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.6 mm, the side length L2 of the second forming hole cross-section is 0.9 mm, R1 / R2=1.5, and L1 / L2=1.78.

[0196] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0197] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0198] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0199] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0200] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0201] 6) Microwave drying to obtain unit blanks.

[0202] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0203] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0204] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0205] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0206] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0207] Comparative Example 5 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.25 mm, the radius of curvature R2 of the second forming hole cross-section is 0.1 mm, the side length L1 of the first forming hole cross-section is 1.0 mm, the side length L2 of the second forming hole cross-section is 1.07 mm, R1 / R2=2.5, and L1 / L2=0.93.

[0208] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0209] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0210] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0211] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0212] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0213] 6) Microwave drying to obtain unit blanks.

[0214] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0215] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0216] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0217] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0218] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0219] Comparative Example 6 The first forming hole in the forming plate of the extrusion die has no rounded corners, the radius of curvature R2 of the cross-section of the second forming hole is 0.3 mm, the side length L1 of the cross-section of the first forming hole is 1.37 mm, the side length L2 of the cross-section of the second forming hole is 1.07 mm, and L1 / L2=1.28.

[0220] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0221] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0222] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0223] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0224] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0225] 6) Microwave drying to obtain unit blanks.

[0226] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0227] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0228] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0229] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0230] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0231] Comparative Example 7 The radius of curvature R1 of the first forming hole cross-section in the forming plate of the extrusion die is 0.35 mm, the second forming hole has no rounded corner, the side length L1 of the first forming hole cross-section is 1.37 mm, the side length L2 of the second forming hole cross-section is 1.07 mm, and L1 / L2=1.28.

[0232] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0233] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0234] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0235] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0236] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0237] 6) Microwave drying to obtain unit blanks.

[0238] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0239] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0240] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0241] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0242] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0243] Comparative Example 8 In the forming plate of the extrusion die, the side length L1 of the first forming hole cross-section is 1.54 and there is no chamfer. The side length L2 of the second forming hole cross-section is 1.1 and there is no chamfer. L1 / L2=1.4.

[0244] 1) 80 parts silicon carbide powder, 18 parts metallic silicon powder, 1.5 parts magnesium oxide, 0.8 parts kaolin, 10 parts hydroxymethyl cellulose, 5 parts polyvinyl alcohol, 3 parts glycerol, 2.5 parts potassium laurate, 10 parts starch, and 5 parts walnut powder.

[0245] 2) Add all the raw materials from step 1) above to a high-speed mixer and mix at high speed for 15 minutes.

[0246] 3) Add 23wt% water and 3.5 parts polyacrylamide solution, which is the total mass of the solid raw materials, and continue to mix at high speed for 5 minutes.

[0247] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 15 minutes.

[0248] 5) Add the raw material mixture obtained in step 4) into the extruder and extrude it through the above-mentioned die.

[0249] 6) Microwave drying to obtain unit blanks.

[0250] 7) Place the plugging material obtained in step 1 into the storage area of ​​the automatic plugging equipment. The automatic plugging equipment performs staggered plugging on the unit blank obtained in step 6) (i.e., alternately plugging the two ends of adjacent honeycomb channels). After plugging, the unit blank is subjected to oxygen-free sintering and oxidation sintering to obtain the sintered unit.

[0251] 8) Assemble the fired unit bodies obtained in step 7) and build them into a blank body of appropriate size according to the carrier specifications.

[0252] 9) Add splicing material to the splicing seam of the blank obtained in step 8) to obtain the unit body as a whole. The splicing material is any splicing material known to those skilled in the art.

[0253] 10) Grind the outer periphery and end face of the unit obtained in step 9) to obtain a silicon carbide honeycomb ceramic blank with a height of 7.5 inches and a diameter of 6 inches.

[0254] 11) The polished silicon carbide honeycomb ceramic blank is skinned and dried to obtain a wall-flow honeycomb ceramic filter.

[0255] Cordierite Comparative Example 9 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.125 mm, the side length L1 of the first forming hole cross-section is 1.40 mm, the second forming hole cross-section has no chamfer, the side length L2 of the second forming hole cross-section is 1.05 mm, and L1 / L2=1.33.

[0256] 1) 38 parts talc, 13 parts kaolin, 19 parts silica, 18 parts alumina, 12 parts aluminum hydroxide, 25 parts pore-forming agent (of which PMMA accounts for 10% by mass), 1 part stearic acid lubricant, 5 parts methyl cellulose binder (added), and 38 parts water (added).

[0257] 2) Add the inorganic raw materials (talc, kaolin, silica, alumina, aluminum hydroxide) from step 1) above, along with the pore-forming agent and stearic acid lubricant, into the mixer and dry mix at 10 Hz for 15 minutes.

[0258] 3) Add methylcellulose binder and water, and wet mix at 45 Hz for 8 minutes.

[0259] 4) Add the raw material mixture obtained in step 3) to a biaxial kneader and knead for 30 minutes.

[0260] 5) After kneading the clay, knead it further, then put it into an extruder and use the above-mentioned mold to extrude a honeycomb ceramic blank with a diameter of 7.5 inches and a height of 6 inches.

[0261] 6) Dry the raw blank.

[0262] 7) Plug the holes in the dried green blank.

[0263] 8) The green blank after plugging is sintered to obtain a wall-flow honeycomb ceramic filter.

[0264] Cordierite Comparative Example 10 In the forming plate of the extrusion die, the radius of curvature R1 of the first forming hole cross-section is 0.125 mm, the radius of curvature R2 of the second forming hole cross-section is 0.115 mm, the side length L1 of the first forming hole cross-section is 1.33 mm, the side length L2 of the second forming hole cross-section is 1.12 mm, R1 / R2=1.09, L1 / L2=1.19.

[0265] 1) 38 parts talc, 13 parts kaolin, 19 parts silica, 18 parts alumina, 12 parts aluminum hydroxide, 25 parts pore-forming agent (of which PMMA accounts for 10% by mass), 1 part stearic acid lubricant, 5 parts methyl cellulose binder, and 38 parts water.

[0266] 2) Add all the raw materials from step 1) above into the mixer and dry mix at 10Hz for 15 minutes.

[0267] 3) Add methylcellulose binder and water, and wet mix at 45 Hz for 8 minutes.

[0268] 4) Add the raw material mixture obtained in step 3) into a biaxial kneader and knead for 30 minutes.

[0269] 5) After kneading the clay, knead it further and put it into an extruder to extrude a honeycomb ceramic blank with a diameter of 7.5 inches and a height of 6 inches using the above-mentioned mold.

[0270] 6) Dry the raw blank.

[0271] 7) Plug the holes in the dried green blank.

[0272] 8) The green blank after plugging is sintered to obtain a wall-flow honeycomb ceramic filter. Test Example The performance of the honeycomb ceramic filters obtained in the above embodiments and comparative examples was tested in the following manner, and the results are recorded in Table 1 below: 1. Test the side length L1 and the radius of curvature R1 of the square cross-section of the first channel of the honeycomb ceramic filter, as well as the side length L2 and the radius of curvature R2 of the square cross-section of the first channel. L1 and L2 are measured directly using vernier calipers, while R1 and R2 are measured using an image measuring instrument with image analysis function (such as Novator432). After taking pictures, the rounded corners are directly captured and measured using software measurement tools.

[0273] 2. Test method for mold wear After each 5000m of product is extruded from the mold, the wear condition of the mold is observed using an image instrument.

[0274] 3. Test method for thermal shock resistance The thermal shock resistance of cellular ceramics was tested using the test method in Appendix C of GB / T 25994-2010 ("Cellular Ceramics") standard.

[0275] 4. Test method for voltage drop The pressure drop of the test carrier was measured using the SuperFlow SF-1020 pressure drop test bench. The test was conducted in inlet mode at room temperature (25±1℃), using an air bladder to secure and seal the carrier on the test bench. Parameters were input via the control panel, and the test flow rate was controlled at 600 CMH based on the carrier dimensions. The system automatically detected the test pressure drop and temperature, achieving precise digital airflow measurement and control, and outputting calibrated flow rate data. The pressure drop value displayed after reaching the set flow rate is the pressure drop value of the test carrier.

[0276] 5. Test method for lattice distortion rate Take a wall-flow honeycomb ceramic filter, cut off the end face and place it under a digital microscope (such as Keyence VHX-7000) to acquire an image of the entire end face. Observe the shape of each pore cell, and classify pore cells that meet any of the following conditions as distorted pore cells: (1) The shape of the lattice deviates from the design shape, and the angle deviation is >1°; (2) The offset of the center position of the grid is greater than 0.1 mm; (3) Obvious non-linear bending appears on the hole wall; (4) The holes are not connected or are blocked.

[0277] Count the number of distorted pores and the total number of pores on the end face, and calculate the pore distortion rate using the following formula: Pore distortion rate = (Number of distorted pores / Total number of pores on the end face) × 100%. At least three samples must be measured, and the average value should be taken as the final result.

[0278] The mold structures and performance of Examples 1-8 and Comparative Examples 1-10 are shown in Table 1 below: Table 1

[0279] As shown in Table 1, when the R1 / R2 ratio in the mold is the same as that in the honeycomb ceramic filter, and the L1 / L2 ratio in the mold is the same as that in the honeycomb ceramic filter, and 1≤L1 / L2≤1.6, 3≥R1 / R2≥2, for silicon carbide, based on a mold wear limit of 5 micrometers, its service life is ≥55000m, and the product's thermal shock resistance (°C) is ≥500°C. In contrast, Comparative Examples 1-3 show reduced mold service life and decreased thermal shock resistance, with back pressure greater than in Examples 1-6. Compared to the conventional chamfer-free mold in Comparative Example 8, its service life is only 30000m, and the product's thermal shock resistance (°C) is ≥400°C.

[0280] Compared to Comparative Example 8, Examples 1-6 show that, compared to the un-beveled honeycomb ceramic, the pressure drop increase is less than 5%, but the pore distortion rate is significantly reduced. Compared to Comparative Examples 6 and 7, the single-bevel structure is inferior in both pressure drop and pore distortion rate, and the mold wear of the three comparative examples is also increased. Comparative Examples 2-5 involve L1 / L2 not being between 1 and 1.6. When L1 / L2 < 1, the area of ​​the first channel and multiple second channels through which the airflow passes is entirely controlled by R2 of the second forming hole, reducing the filtration area, hindering gas flow, and increasing the pressure drop. When L1 / L2 > 1.6, the airflow needs to travel a longer distance after entering from the inlet end face to reach the outlet end face, thus increasing the pressure drop of Comparative Examples 2-4.

[0281] In Comparative Example 1, the L1 / L2 value is in the range of 1 to 1.6, but its R1 / R2 value is 4.5, which exceeds 3. Compared with Examples 1 to 10, the pressure drop of the honeycomb ceramic filter in Comparative Example 1 is higher, the thermal shock performance is lower, and the pore distortion rate is larger.

[0282] Compared with Comparative Example 9 and Example 9, the single-bevel structure has reduced thermal shock performance and a significantly increased thermal shock performance lattice distortion rate.

[0283] Compared with Example 10, the value of R1 / R2 in Comparative Example 10 is 1.09, which is less than 2, indicating that the pressure drop of the honeycomb ceramic filter in Comparative Example 10 is higher.

[0284] The above demonstrates that the wall-flow honeycomb ceramic filter provided by this invention can achieve a balance between high strength and low back pressure.

[0285] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims. Furthermore, specific examples have been used in the specification to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention, and the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A wall-flow honeycomb ceramic filter, characterized in that, Its honeycomb ceramic structure has multiple first channels and multiple second channels. The plurality of first channels extend axially in the honeycomb ceramic structure, opening at the air inlet end face and being sealed at the air outlet end face; the plurality of second channels extend axially in the honeycomb ceramic structure, opening at the air outlet end face and being sealed at the air inlet end face; and the first channels and the second channels are in communication. The first channel has a cross-section that is a square with a radius of curvature R1 and a side length of L1, and the second channel has a cross-section that is a square with a radius of curvature R2 and a side length of L2, wherein L1>L2 and R1 / R2≥2.

2. The wall-flow honeycomb ceramic filter according to claim 1, characterized in that, 0.15mm<R1≤0.4mm, R2≤0.15 mm.

3. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, 2≤R1 / R2≤3.

4. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, 0.7mm≤L1≤1.6mm, 0.7mm≤L2≤1.25mm.

5. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, 1 < L1 / L2 ≤ 1.

6.

6. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The honeycomb ceramic structure is a cylinder with an axial height H of 120mm ≤ H ≤ 300mm and a cross-sectional diameter Z of 140mm ≤ Z ≤ 350mm.

7. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The plurality of first channels and the plurality of second channels are separated by partitions, the partitions having a wall thickness of 5 mil to 14 mil.

8. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The total number density of the plurality of first channels and the plurality of second channels is 100 to 500 per square inch on the interface perpendicular to the axis of the cellular ceramic structure.

9. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The honeycomb ceramic structure is a honeycomb ceramic structure whose crystalline phase is mainly composed of cordierite or silicon carbide.

10. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, According to GB / T25994-2010, the thermal shock resistance temperature of the wall-flow honeycomb ceramic filter is greater than or equal to 500℃.

11. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The pressure drop of the wall-flow honeycomb ceramic filter is less than 10 kPa. The pressure drop was measured on a SuperFlow SF-1020 pressure drop test bench in intake mode, at a room temperature of 24℃~26℃, a flow rate of 600 CMH, with the airbag sealed and in a clean state.

12. The wall-flow honeycomb ceramic filter according to claim 1 or 2, characterized in that, The pore distortion rate of the aforementioned wall-flow honeycomb ceramic filter is less than 1%.

13. An extrusion die for manufacturing a wall-flow honeycomb ceramic filter as described in any one of claims 1 to 12, comprising a forming plate, characterized in that, The molding plate includes a first molding hole and a second molding hole, wherein the first molding hole is used to form the first channel and the second molding hole is used to form the second channel; The first forming hole has a cross-section that is a square with a radius of curvature R1 and a side length of L1, and the second forming hole has a cross-section that is a square with a radius of curvature R2 and a side length of L2, wherein L1>L2 and R1>R2.

14. The extrusion die according to 13, characterized in that, R2≤ 0.15 mm.

15. The extrusion die according to claim 13 or 14, characterized in that, 3≥R1 / R2≥2.

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