Honeycomb ceramic carrier with high strength and low thermal expansion coefficient and preparation method thereof

Abstract

The invention discloses a honeycomb ceramic carrier with high strength and low thermal expansion coefficient and a preparation method thereof, and belongs to the technical field of honeycomb ceramic materials. The honeycomb ceramic carrier prepared by the method is prepared by firing coarse and fine talc, kaolin, alumina and silica powder with different particle sizes together with a pore-forming agent and a cosolvent. According to the preparation method, the particle size grading of the inorganic raw materials is optimized, and the fluxing agent is added, so that the honeycomb ceramic carrier which is relatively denser and higher in strength is obtained. Besides, the water absorption rate can be regulated and controlled to the required level by additionally adding the pore-forming agent, and the high-strength low-thermal-expansion-coefficient honeycomb ceramic carrier can meet the use requirements of the national sixth emission standard of gasoline cars.

Description

Technical Field

[0001] This invention belongs to the field of honeycomb ceramic materials technology, and more specifically, relates to a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier and its preparation method. Background Technology

[0002] As a key component of three-way catalytic converters, honeycomb ceramic supports face increasingly stringent emission regulations. Currently, aftertreatment devices meeting China VI emission standards generally require honeycomb ceramic supports with a wall thickness of 2.5 mil to 4 mil. While a thinner wall thickness increases the specific surface area of ​​the honeycomb ceramic support, allowing for the coating of more catalyst, it also reduces its strength. This reduced strength increases the difficulty of encapsulating the honeycomb ceramic support and may weaken its thermal shock resistance, increasing the risk of breakage during subsequent assembly and use.

[0003] Patent CN117720334A discloses a high-porosity, thin-walled, high-strength honeycomb ceramic, its preparation method, and its applications. By replacing silicon dioxide with metallic silicon, it achieves the goal of reducing the wall thickness of the honeycomb ceramic, increasing porosity, and simultaneously improving the strength of the carrier. This solution proposes a method to improve the strength of the honeycomb ceramic carrier; however, this method mainly targets the particle trapping filter (GPF), which differs microscopically from the TWC carrier. Furthermore, since water absorption rate is a crucial parameter determining the coating process, the solution does not conduct experiments targeting a specific water absorption rate range.

[0004] Patent CN119591394A discloses a method for preparing a honeycomb ceramic carrier for gasoline vehicles with an ultra-low coefficient of thermal expansion. This method replaces the magnesium source in talc and part of the aluminum source in α-alumina with more reactive materials such as boehmite and magnesium oxide. A sol is formed through a complexation reaction with citric acid, which is then mixed with silica and alumina particles. This enhances the reactivity of the solid-phase reaction at the same firing temperature. This method improves the reactivity of the raw materials through complexation, and can increase the strength of the honeycomb ceramic carrier to a certain extent under the same firing regime. However, this method suffers from excessively high costs in large-scale production.

[0005] Patent CN115819108A ​​discloses a high-strength, high-porosity honeycomb ceramic carrier and its preparation method, which is obtained by sintering raw materials containing narrow-particle-size flake talc, ultrafine fumed alumina, and spherical silica dust-absorbing powder. This method improves the specific surface area of ​​the raw materials through optimized raw material selection, resulting in a honeycomb ceramic carrier with uniform, microporous structures. This carrier can meet the water absorption requirements for coating. However, this method requires selection of the morphology of the talc raw material, thus limiting its applicability. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the technical problem to be solved by the present invention is to provide a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier. This honeycomb ceramic carrier has high strength and a low thermal expansion coefficient, which can meet the thermal shock resistance requirements for use in gasoline vehicles meeting the China VI emission standards. Another technical problem to be solved by the present invention is to provide a method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier. This method prepares a cordierite honeycomb ceramic carrier by combining two inorganic raw materials with different particle sizes (coarse and fine) and supplementing them with a flux. This results in a more dense cordierite, thereby improving the strength of the honeycomb ceramic carrier.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier includes the following steps:

[0009] 1) Coarse talc, coarse alumina, coarse silica powder, coarse kaolin and fine talc, fine alumina, fine silica powder, fine kaolin are mixed separately to obtain two inorganic mixed raw materials with different particle sizes;

[0010] 2) Dry-mix two inorganic mixed raw materials with different particle sizes, hydroxypropyl methylcellulose, stearic acid, oleic acid, pore-forming agent, and flux;

[0011] 3) After dry mixing, deionized water is added for wet mixing, and the mixture is then kneaded, coarsely smelted, and refined in a kneader to obtain clay.

[0012] 4) The clay is extruded, microwave dried and shaped, cut and fired to finally obtain cordierite honeycomb ceramic carrier.

[0013] Further, in step 1), the average particle size (D50) of coarse talc is 15~20μm, the average particle size (D50) of fine talc is 2~3μm, the average particle size (D50) of coarse kaolin is 8~12μm, the average particle size (D50) of fine kaolin is 1~2μm, the average particle size (D50) of coarse alumina is 15±0.5μm, the average particle size (D50) of fine alumina is 2±1μm, the average particle size (D50) of coarse silica powder is 18±1μm, and the average particle size (D50) of fine silica powder is 3±1μm.

[0014] Further, in step 1), there are 26-30 parts of coarse talc, 19.5-22.5 parts of coarse alumina, 13-15 parts of coarse silica powder, and 6.5-7.5 parts of coarse kaolin.

[0015] Further, in step 1), there are 10-14 parts of fine talc, 7.5-10.5 parts of fine alumina, 5-7 parts of fine silica powder, and 2.5-3.5 parts of fine kaolin.

[0016] Further, in step 2), the pore-forming agent is starch with an average particle size (D50) of 20±5μm.

[0017] Furthermore, in step 2), the flux is selected from either ammonium chloride or magnesium chloride hexahydrate.

[0018] Further, in step 2), 0.2 parts of hydroxypropyl methylcellulose, 0.3 parts of stearic acid, 0.5 parts of oleic acid, 5-12 parts of pore-forming agent, and 0.8 parts of flux are used.

[0019] Furthermore, in step 3), the hardness of the clay is controlled at 21~23 kg / cm² during the clay preparation process. 2 .

[0020] Furthermore, in step 3), the firing temperature is 1420℃ and the firing time is 18h.

[0021] Furthermore, the honeycomb ceramic carrier prepared by the aforementioned method for preparing high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier is also described.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention prepares cordierite honeycomb ceramic carriers by combining two inorganic raw materials with different particle sizes (coarse and fine). A flux is used to make the generated cordierite more compact, thereby improving the strength of the honeycomb ceramic carrier. At the same time, a pore-forming agent is used to form a microporous structure and control the water absorption rate of the honeycomb ceramic carrier to meet the requirements of practical applications. Attached Figure Description

[0024] Figure 1 This is a SEM image of the product axis in this application;

[0025] Figure 2 This is a SEM diagram of the axial direction of the existing product, which is Comparative Example 2 of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described below with reference to specific embodiments. Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0027] The raw material parameters used in the examples are shown in Table 1.

[0028] Table 1. Specific parameters of raw materials

[0029]

[0030] The following are the detection methods used in the examples:

[0031] Compressive strength and thermal shock resistance: GB / T 25994-2010;

[0032] Water absorption rate: GB / T 1966-1996;

[0033] Porosity: GB / T 21650.1-2008;

[0034] Coefficient of thermal expansion: GB / T 7320-2018.

[0035] Example 1

[0036] A high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier and its preparation method are disclosed. The honeycomb ceramic carrier has a diameter of 118.4 mm and a wall thickness of 3 mil. The specific steps include:

[0037] 1) Mix coarse talc, coarse alumina, coarse silica powder, and coarse kaolin separately with fine talc, fine alumina, fine silica powder, and fine kaolin. The specific amounts of each raw material are shown in Table 2.

[0038] 2) Then mix the coarse and fine inorganic raw materials with hydroxypropyl methylcellulose, stearic acid, oleic acid and flux magnesium chloride hexahydrate by adding 0.2 parts, 0.3 parts, 0.5 parts and 0.8 parts respectively for every 100 parts of inorganic material.

[0039] 3) Add a certain proportion of deionized water for wet mixing, and then knead, coarsely refining, and refining the clay in a kneader. Control the clay hardness to 21~23 kg / cm². 2 .

[0040] 4) The clay material is extruded and shaped in an extruder, and the temperature of the extruded clay blank is controlled to be ≤28 ℃ to obtain the honeycomb ceramic carrier clay blank.

[0041] 5) The honeycomb ceramic carrier blank is microwave dried and shaped, and the weight ratio of the blank after drying to the blank before drying is controlled at 0.8:1.

[0042] 6) The dried carrier is cut and fired at 1420℃ for 18 hours to obtain cordierite honeycomb ceramic carrier. The final product is obtained through post-processing.

[0043] Table 2. Dosage and test results of coarse and fine inorganic mixed raw materials (in parts).

[0044]

[0045] Examples 2-4

[0046] The honeycomb ceramic carrier was prepared according to the method of product 3 in Example 1, except that starch was added as a pore-forming agent in step 1), and the amount added was 5 parts, 8 parts, and 12 parts respectively.

[0047] Comparative Example 1

[0048] The honeycomb ceramic carrier was prepared according to the method of product 3 in Example 1, except that 15 parts of starch were added as a pore-forming agent in step 1) of the mixture.

[0049] Comparative Example 2

[0050] 1) Raw material selection: the average particle size of talc is 11±1μm, the average particle size of alumina is 5±0.5μm, the average particle size of silica is 13±1μm, and the average particle size of kaolin is 4±0.5μm.

[0051] 2) Mix 40 parts talc, 30 parts alumina, 20 parts silica powder and 10 parts kaolin with 0.2 parts hydroxypropyl methylcellulose, 0.3 parts stearic acid, 0.5 parts oleic acid and starch.

[0052] 3) Add a certain proportion of deionized water for wet mixing, and then knead, coarsely refining, and refining the clay in a kneader. Control the clay hardness to 21~23 kg / cm². 2 .

[0053] 4) The clay material is extruded and shaped in an extruder, and the temperature of the extruded clay blank is controlled to be ≤28 ℃ to obtain the honeycomb ceramic carrier clay blank.

[0054] 5) The honeycomb ceramic carrier blank is microwave dried and shaped, and the weight ratio of the blank after drying to the blank before drying is controlled at 0.8:1.

[0055] 6) The dried carrier is cut and fired at 1420℃ for 18 hours to obtain cordierite honeycomb ceramic carrier. The final product is obtained through post-processing.

[0056] The specific ratio of coarse and fine inorganic mixed raw materials, starch usage, product properties, etc. are shown in Table 3.

[0057] Table 3 Specific product formulations (in parts) and performance indicators

[0058]

[0059] From Table 2-3 and Figure 1-2Compared to conventional cordierite honeycomb ceramic carrier manufacturing processes, this application achieves a denser and stronger honeycomb ceramic carrier by improving the particle size distribution of inorganic raw materials and using flux. With the addition of starch as a pore-forming agent, the water absorption rate gradually approaches that of normal products, although the product strength decreases to some extent. By adjusting the particle size and dosage of the pore-forming agent to meet different needs, a balance can be found between product strength and water absorption performance.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier, characterized in that: Includes the following steps: 1) Coarse talc, coarse alumina, coarse silica powder, coarse kaolin and fine talc, fine alumina, fine silica powder, fine kaolin are mixed separately to obtain two inorganic mixed raw materials with different particle sizes; 2) Dry-mix two inorganic mixed raw materials with different particle sizes, hydroxypropyl methylcellulose, stearic acid, oleic acid, pore-forming agent, and flux; 3) After dry mixing, deionized water is added for wet mixing, and the mixture is then kneaded, coarsely smelted, and refined in a kneader to obtain clay. 4) The clay is extruded, microwave dried and shaped, cut and fired to finally obtain cordierite honeycomb ceramic carrier.

2. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 1), the average particle size (D50) of coarse talc is 15~20μm, the average particle size (D50) of fine talc is 2~3μm, the average particle size (D50) of coarse kaolin is 8~12μm, the average particle size (D50) of fine kaolin is 1~2μm, the average particle size (D50) of coarse alumina is 15±0.5μm, the average particle size (D50) of fine alumina is 2±1μm, the average particle size (D50) of coarse silica powder is 18±1μm, and the average particle size (D50) of fine silica powder is 3±1μm.

3. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 1), there are 26-30 parts of coarse talc, 19.5-22.5 parts of coarse alumina, 13-15 parts of coarse silica powder, and 6.5-7.5 parts of coarse kaolin.

4. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 1), there are 10-14 parts of fine talc, 7.5-10.5 parts of fine alumina, 5-7 parts of fine silica powder, and 2.5-3.5 parts of fine kaolin.

5. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 2), the pore-forming agent is starch with an average particle size (D50) of 20±5μm.

6. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 2), the flux is selected from either ammonium chloride or magnesium chloride hexahydrate.

7. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 2), 0.2 parts of hydroxypropyl methylcellulose, 0.3 parts of stearic acid, 0.5 parts of oleic acid, 5-12 parts of pore-forming agent, and 0.8 parts of flux are used.

8. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 3), the hardness of the clay is controlled at 21~23 kg / cm² during the clay preparation process. 2 .

9. The method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to claim 1, characterized in that: In step 3), the firing temperature is 1420℃ and the firing time is 18h.

10. The honeycomb ceramic carrier prepared by the method for preparing a high-strength, low-thermal-expansion-coefficient honeycomb ceramic carrier according to any one of claims 1 to 9.

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