Preparation method of ultrathin-wall large-specification honeycomb ceramic carrier
By optimizing the mixing and processing methods of raw materials, ultra-thin wall large-size honeycomb ceramic carriers were prepared, which solved the problems of easy cracking of the carrier and high mold cost in the existing technology, and achieved efficient and low-cost carrier preparation, meeting the needs of the National VI emission standards for diesel vehicles.
Patent Information
- Application Number
- CN202411871665.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-03-18
AI Technical Summary
The existing large-sized cordierite ceramic carriers are prone to wall fracture problems during the production process, and the mold production cost is high when making ultra-thin-wall honeycomb ceramic carriers, which is difficult to meet the needs of the National VI emission standards for diesel vehicles.
By optimizing the selection and mixing ratio of raw materials, the stirring of alumina source and water and the addition of nitric acid to form a gelatinous form, kneading of methyl and silica, and finally extruded and fired using a mold to prepare an ultra-thin wall large-sized honeycomb ceramic carrier.
It has achieved efficient preparation of ultra-thin wall honeycomb ceramic carriers, with product wall thickness up to 110 μm, sintering pass rate reaching more than 90%, mold manufacturing cost is reduced, and yield is increased by 50%.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of honeycomb ceramic carrier preparation, and in particular relates to a method for preparing an ultra-thin-wall large-size honeycomb ceramic carrier. Background Art
[0002] As we all know, diesel engines emit exhaust gases containing hydrocarbons, carbon monoxide and nitrogen oxides (nitrogen dioxide and nitric oxide) due to the combustion of fossil fuels, which can cause air pollution. In order to achieve exhaust purification of diesel engines, a three-way catalytic converter based on a honeycomb ceramic catalyst carrier needs to be installed in the exhaust system. Under the dual constraints of ultra-low pollutant emission limits and fuel consumption limits, the honeycomb ceramic catalyst carrier must have a higher pore density and a thinner lattice wall thickness.
[0003] The existing large-scale cordierite ceramic carrier production requires a thin-walled structure with a wall thickness requirement of less than 85 microns to meet the National VI emission requirements. During production, this thin-walled honeycomb ceramic carrier is prone to wall cracks. The cracks occur because one or more particles in the extruded material block the slit in the extrusion die head, restricting the flow of mud in this area. The number of cracks increases with the decrease in the slit width. If the slit width is very narrow, the number of blocked channels will be so large that the extrudates cannot be gathered together and multiple strands of material will be extruded. At the same time, the molds, drilling and grooving used in the production of this ultra-thin-wall honeycomb ceramic carrier have high requirements, which significantly increases the cost of mold production. Therefore, it is necessary to further improve the existing honeycomb ceramic carrier preparation technology and to produce a method for manufacturing ultra-thin-wall cordierite honeycomb ceramic carriers. Summary of the invention
[0004] The technical problem solved by the present invention is to provide a method for preparing an ultra-thin-wall large-size honeycomb ceramic carrier. The carrier prepared by the method has an ultra-thin wall and a large pore size, and can meet the use requirements of the National VI emission standards for diesel vehicles.
[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing an ultra-thin-wall large-size honeycomb ceramic substrate, the specific steps are as follows:
[0007] 1) Inspection and screening of raw materials; the average particle size of talc is 8-10 μm, the average particle size of silica is 2-4 μm, the average particle size of kaolin is 2-4 μm, and the average particle size of alumina source is 1-3 μm;
[0008] 2) Mix the alumina source and water and stir, adding nitric acid continuously until a gel is formed;
[0009] 3) Mix methyl and water and stir to knead into a plasticized state for later use; mix silicon dioxide and coupling agent and stir, then add the plasticized methyl and knead;
[0010] 4) kneading the aluminum source gelled in step 2) and the silicon dioxide plasticized in step 3);
[0011] 5) mixing talc and kaolin, and then kneading with the aluminum source and plasticized silica mixture;
[0012] 6) Extrusion molding is performed using a mold, and firing is performed to obtain a cordierite honeycomb ceramic carrier.
[0013] In the step 1), the alumina source is selected from any one of aluminum hydroxide, hydrated alumina, boehmite, pseudo-boehmite, hyperfluid alumina, γ-alumina, β-alumina, and θ-alumina.
[0014] In the step 2), the mass ratio of the aluminum source to water is 1:1.5; the mass ratio of the aluminum source to nitric acid is 1:0.05%-0.2%.
[0015] In the step 2), the pH of the aluminum source gelation is adjusted to 4-7.
[0016] In the step 3), the mass ratio of methyl to water is 1:4.
[0017] In step 3), the methyl group is selected from hydroxymethyl cellulose, propyl cellulose and methyl cellulose.
[0018] In the step 3), the coupling agent is selected from phthalate coupling agent or γ-aminopropyltriethoxysilane.
[0019] In the step 3), the mass ratio of silicon dioxide to coupling agent is 1:0.1%-0.5%.
[0020] The amount of each raw material used in step 5) is 39.5-41.5 parts of talc, 17-26.5 parts of silicon dioxide, 3-18 parts of kaolin, and 25-31 parts of aluminum source.
[0021] In step 6), at 280-350°C, the corresponding heating rate is 2°C / h; at 1300-1400°C, the corresponding heating rate is 5°C / h; and the temperature is kept at 1400°C for 10-12 hours.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] (1) In terms of productivity, the present invention can produce 1,200 pieces per shift for products with a wall thickness of 110 μm (taking products with a diameter of 190.5 mm as an example). If the product has a wall thickness of 85 μm, 300 to 500 pieces can be produced per shift. If the extrusion pressure of the equipment is increased from the current 10 to 15 MPa to at least 20 to 30 MPa, the productivity can be increased by at least 50%.
[0024] (2) In terms of quality, the 110 μm products produced by the present invention can have a firing qualification rate of more than 90%.
[0025] (3) In the present invention, the manufacturing cost of the mold is such that the manufacturing cost of a mold with a wall thickness of 110 μm is only 60-70% of the manufacturing cost of a mold with a wall thickness of 85 μm. DETAILED DESCRIPTION
[0026] The present invention is further illustrated below in conjunction with specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.
[0027] Example 1
[0028] A method for preparing an ultra-thin-wall large-size honeycomb ceramic substrate, the specific steps are as follows:
[0029] 1) Inspect, screen and prepare raw materials according to Table 1.
[0030] Table 1 Raw material specifications
[0031]
[0032] The total amount of talc, silicon dioxide, kaolin and alumina source used is 100 parts.
[0033] 2) Mix boehmite and water in a ratio of 1:4 and stir, adding nitric acid continuously during the process until a gel is formed with a pH of 4.
[0034] 3) Stir and knead the hydroxymethyl cellulose and water into a plasticized state for use; mix silica and phthalate coupling agent TM-385 in a ratio of 1:0.1%~0.5%, stir at high speed for 10 minutes, and then add the plasticized methyl to knead.
[0035] 4) The aluminum source gelled in step 2) and the silicon dioxide plasticized in step 3) are kneaded.
[0036] 5) Mix talc and kaolin, stir at high speed for 5 minutes, and then knead with the mixture of aluminum source and plasticized silica; the specific amount of each raw material is shown in Table 2.
[0037] 6) A honeycomb ceramic carrier was extruded using a conventional wall thickness (110 μm) die. The firing temperature control program was as follows: at 280-350°C, the corresponding heating rate was 2°C / h; at 1300-1400°C, the corresponding heating rate was 5°C / h; and the temperature was kept at 1400°C for not less than 10 h to obtain a cordierite honeycomb ceramic carrier.
[0038] The product components, dosage and test results were also tested in accordance with relevant product performance standards (test standard: GB / T 25994-2010). The results are shown in Table 2.
[0039] Table 2 Product components and dosage (in parts) and test results
[0040]
[0041] Example 2
[0042] According to the parameter formula and preparation method of product 1 in Table 2, the same as in Example 1, the difference lies in the pH value of the aluminum source gelation in step 2). The specific results are shown in Table 3.
[0043] Table 3 Results of products with different pH values
[0044]
[0045] It can be seen from Table 3 that the gelation degree of aluminum source plus nitric acid has an impact on the shrinkage of the product, but has little effect on the cracking of the product.
[0046] Example 3
[0047] According to the parameter formula and preparation method of product 1 in Table 2, the same as in Example 1, except for the aluminum oxide in step 2). The specific results are shown in Table 4.
[0048] Table 4 Product results of different alumina sources
[0049]
[0050] It can be seen from Table 4 that the aluminum source has little effect on the wall thickness of the product, but has a greater impact on the number of cracks in the product.
[0051] Comparative Example 1
[0052] The parameter formula and preparation method of product 1 in Table 2 are the same as those of Example 1, except that in step 3), the silicon dioxide is not plasticized and extruded, and the total shrinkage of the product after sintering in step 6) is 30%.
[0053] Comparative Example 2
[0054] The parameter formula and preparation method of product 1 in Table 2 are the same as those in Example 1, except that in step 5), water is added for mixing and stirring, and then the extruded product is sintered in step 6, and the total shrinkage of the product is 29%.
[0055] Comparative Example 3
[0056] According to product 1 in Table 2, all raw materials were replaced, water was added and kneaded, and the product was extruded and sintered according to step 6). The total shrinkage of the product was 9.2%.
[0057] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing an ultra-thin-wall large-size honeycomb ceramic carrier, characterized in that: The specific steps are as follows: 1) Inspection and screening of raw materials; the average particle size of talc is 8-10 μm, the average particle size of silica is 2-4 μm, the average particle size of kaolin is 2-4 μm, and the average particle size of alumina source is 1-3 μm; 2) Mix the alumina source and water and stir, adding nitric acid continuously until a gel is formed; 3) Mix methyl and water and stir to knead into a plasticized state for later use; mix silicon dioxide and coupling agent and stir, then add the plasticized methyl and knead; 4) kneading the aluminum source gelled in step 2) and the silicon dioxide plasticized in step 3); 5) mixing talc and kaolin, and then kneading with the aluminum source and plasticized silica mixture; 6) Extrusion molding is performed using a mold, and firing is performed to obtain a cordierite honeycomb ceramic carrier.
2. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: In the step 1), the alumina source is selected from any one of aluminum hydroxide, hydrated alumina, boehmite, pseudo-boehmite, superfluid alumina, γ-alumina, β-alumina, and θ-alumina.
3. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 2, characterized in that: In the step 2), the mass ratio of the aluminum source to water is 1:1.5; the mass ratio of the aluminum source to nitric acid is 1:0.05%-0.2%.
4. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 2, characterized in that: In the step 2), the pH of the aluminum source gelation is adjusted to 4-7.
5. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 2, characterized in that: In the step 3), the mass ratio of methyl to water is 1:
4.
6. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: In step 3), the methyl group is selected from hydroxymethyl cellulose, propyl cellulose and methyl cellulose.
7. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: In the step 3), the coupling agent is selected from phthalate coupling agent or γ-aminopropyltriethoxysilane.
8. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: In the step 3), the mass ratio of silicon dioxide to coupling agent is 1:0.1%-0.5%.
9. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: The amount of each raw material used in step 5) is 39.5-41.5 parts of talc, 17-26.5 parts of silicon dioxide, 3-18 parts of kaolin, and 25-31 parts of aluminum source.
10. The method for preparing the ultra-thin-wall large-size honeycomb ceramic carrier according to claim 1, characterized in that: In step 6), at 280-350°C, the corresponding heating rate is 2°C / h; at 1300-1400°C, the corresponding heating rate is 5°C / h; and the temperature is kept at 1400°C for 10-12 hours.