High-mesh ultrathin-wall honeycomb ceramic carrier and production method thereof

Abstract

The invention discloses a high-mesh ultrathin-wall honeycomb ceramic carrier and a production method thereof, the high-mesh ultrathin-wall honeycomb ceramic carrier comprises, by mass, 40-50% of modified kaolin, 15-40% of talc, 5-10% of alumina, 5-10% of nano powder, 8-12% of a graphite pore-forming agent, and 2-3% of carboxymethyl cellulose; wherein the modified kaolin is sieved by a sieve of 1200-1400 meshes, the talc is sieved by a sieve of 1200-1400 meshes, the aluminum oxide is sieved by a sieve of 1500-1600 meshes, and the particle size of the nano powder is less than or equal to 50nm. The use effect of the honeycomb ceramic carrier can be remarkably enhanced by using the modified kaolin, and the zirconium oxide nano powder is introduced into the high-mesh ultrathin-wall honeycomb ceramic carrier, so that the fracture toughness, bending strength and thermal shock resistance of the ultrathin-wall honeycomb ceramic carrier can be remarkably improved by compounding with other materials; and the cracking risk of the carrier under high temperature or mechanical stress is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic carriers, and specifically relates to a high-mesh ultra-thin-wall honeycomb ceramic carrier and a production method thereof. Background Art

[0002] Honeycomb ceramics is a new type of ceramic product with a honeycomb-like structure. It was first used in the purification of small car exhaust gases and is widely used in industries such as chemical engineering, electric power, metallurgy, petroleum, electronic appliances, and machinery, and is becoming more and more widespread, with quite promising development prospects. The ceramic honeycomb carrier was initially used in automotive exhaust catalytic converters.

[0003] Ceramic catalytic converters for automotive exhaust treatment are used to control automotive exhaust pollution and reduce the emissions of carbon monoxide, black smoke, and other toxic gases. Catalytic converters have been used in automobiles since the late 1970s. In the technological development over the past few decades, automobile manufacturers have used many different methods to reduce emission pollution, such as exhaust gas recirculation, fuel tank vapor recovery, and engine electronic control systems, etc. However, catalytic converters have always been the most effective method for reducing harmful exhaust emissions. In the chemical reaction of catalytic converters, noble metal atoms undergo various different transition reactions, reducing the overall reaction activation energy, thereby increasing the reaction probability of converting exhaust gases into generally harmless gases, and the catalyst itself remains in its original state after the chemical reaction, which is the biggest difference between catalytic converters and traditional smoke filters. Catalytic converters not only have a good service life but also avoid the possibility of being blocked after long-term use.

[0004] Most modern catalytic converters consist of two parts: a reducing honeycomb porcelain and an oxidizing honeycomb porcelain. When the exhaust gas passes through the reducing honeycomb porcelain, nitrogen oxides are first decomposed into nitrogen and oxygen. When the exhaust gas further passes through the oxidizing honeycomb porcelain, carbon monoxide and hydrocarbons are further oxidized into carbon dioxide and water. The oxygen generated in the previous stage also helps the progress of such oxidation reactions, especially for high-compression engines. Since the concentration of nitrogen oxides emitted is relatively high, the concentration of oxygen generated in the reduction reaction is also significantly increased. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a high-mesh ultra-thin-wall honeycomb ceramic carrier and a production method thereof.

[0006] The technical solution of the present invention is: a high-mesh ultra-thin-wall honeycomb ceramic carrier, by mass percentage, includes 40-50% of modified kaolin, 15-40% of talc, 5-10% of alumina, 5-10% of nano-powder, 8-12% of graphite pore-forming agent, and 2-3% of carboxymethyl cellulose; wherein, the modified kaolin is sieved through 1200-1400 meshes, the talc is sieved through 1200-1400 meshes, the alumina is sieved through 1500-1600 meshes, and the particle size of the nano-powder is ≤50 nm.

[0007] Further, the nano powder is any one of zirconia nano powder or alumina nano powder.

[0008] Explanation: By introducing zirconia nano powder into the high-mesh ultra-thin-walled honeycomb ceramic carrier, through compounding with other materials, the fracture toughness, flexural strength and thermal shock resistance of the honeycomb ceramic can be significantly improved, reducing the risk of cracking of the carrier under high temperature or mechanical stress. Moreover, the high melting point and high temperature resistance characteristics of zirconia can enhance the long-term stability of the carrier in high-temperature catalysis, heat exchange and other scenarios;

[0009] By introducing zirconia nano powder into the high-mesh ultra-thin-walled honeycomb ceramic carrier, the high specific surface area and chemical stability of alumina nano powder can improve the uniformity of the loading of catalytic active components and the reaction efficiency, and can increase the service life of the carrier in applications such as filtration and separation. Especially in acidic or corrosive environments, its good thermal conductivity can assist the honeycomb ceramic carrier to achieve efficient heat transfer in heat exchange scenarios;

[0010] At the same time, when using zirconia nano powder, its raw material contains alumina, which can utilize alumina to provide a high specific surface area to support catalytic active components, and zirconia strengthens the thermal shock resistance of the matrix, jointly improving the efficiency and durability of the carrier in catalytic reactions.

[0011] Further, the preparation method of the modified kaolin is as follows:

[0012] 1) Select kaolin raw ore with a purity > 95%, remove impurities through water washing and magnetic separation, make the content of iron oxide less than 0.5%, and then dry and grind it to a particle size less than 5 μm to ensure that the interlayer structure is fully exposed;

[0013] 2) Mix kaolin and potassium acetate in a mass ratio of 1:0.25 - 0.35 and perform microwave fluctuation irradiation treatment to obtain a preliminary mixture; microwave irradiation destroys the interlayer hydrogen bonds and pre-expands the interlayer spacing to more than 0.9 nm;

[0014] 3) Subsequently, add a mixed solution of formamide and oxalic acid to the preliminary mixture in a mass ratio of 1:0.7 - 1, and stir at 55 - 70 °C for 1 - 2 h to obtain a mixture, and use the synergistic effect of polar molecules to further expand the interlayer spacing to more than 1.2 nm; wherein, the volume ratio of formamide to oxalic acid is 3 - 5:2;

[0015] 4) Transfer the mixture to a ball mill, grind it at a rotation speed of 300 - 500 r / min with zirconia balls as the grinding medium for 3 - 4 h to obtain a product; mechanical shear force promotes complete peeling between layers, and the interlayer spacing is stabilized to more than 1.5 nm;

[0016] 5) Dry the product under vacuum at 70 - 85°C for 10 - 12 h, and then calcine it at 220 - 280°C for 30 min under nitrogen protection to obtain modified kaolin. Remove residual organic matter and fix the interlayer structure.

[0017] Note: By using modified kaolin, the service effect of the honeycomb ceramic carrier can be significantly enhanced. Through microwave fluctuation irradiation, the hydrogen bond strength can be reduced, subsequent mechanical energy consumption can be decreased, and kaolin particles can be activated. Meanwhile, through the synergistic effect of formamide and oxalic acid, the bonding ability between polar molecules and interlayer Al - O can be enhanced. And through high - energy ball milling combined with shear and compression forces, complete interlayer peeling can be achieved, so that the interlayer spacing of the modified kaolin can be increased from 0.72 nm to more than 1.5 nm, and the specific surface area can reach 380 m 2 / g after modification, which has a significant improvement compared with the traditional process (about 250 m 2 / g).

[0018] Furthermore, the microwave fluctuation irradiation treatment is as follows: Add 50 - 70% potassium acetate to kaolin in advance and stir well. Then apply microwaves with a power of 700 - 900 W and a frequency of 2.2 - 2.5 GHz. After treating for 3 - 5 min, add the remaining potassium acetate at a adding rate and keep stirring, and switch the power to a periodic fluctuation power. After treating for 7 - 12 min, obtain a preliminary mixture;

[0019] wherein, the periodic fluctuation power is The fluctuation frequency is 20 - 30 s / time; n is the percentage content of the remaining potassium acetate, and n ranges from 30% to 50%; T is the treatment time of the periodic fluctuation power table, and T ranges from 7 to 12 min; m is the microwave power, and m ranges from 700 to 900 W.

[0020] Note: By using a constant power for pretreatment and then a periodic fluctuation power for post - treatment, when adding potassium acetate gradually, irradiating the mixture of potassium acetate and kaolin with microwaves using the periodic fluctuation power can further enhance the destruction of interlayer hydrogen bonds, further pre - expand the interlayer spacing, thereby improving the adsorption and dispersion performance. And after the interlayer space increases, more transition metal oxides (such as Mn / Ce oxides) can be accommodated, enhancing the density of active sites for catalytic reactions, which is applicable to VOCs catalytic oxidation and chemical synthesis. At the same time, after the interlayer spacing expands, the friction between kaolin particles decreases, and the extrusion molding efficiency of the slurry increases by 20% - 30%, especially suitable for high - precision processing of honeycomb ceramics and nanocomposites.

[0021] The present invention also provides a production method for a high - mesh - number ultra - thin - wall honeycomb ceramic carrier, including the following steps:

[0022] S1. Mix the raw materials and deionized water at a mass ratio of 1:0.7 - 1, using zirconia balls as the grinding medium, and ball mill for 18 - 24 h until D50 ≤ 2 μm to obtain the abrasive;

[0023] S2. Control the water content of the abrasive to be 20 ± 1%, and perform degassing treatment for 20 - 30 min under a vacuum of -0.09 MPa to obtain the mud;

[0024] S3. Use a honeycomb mold to extrude the mud in a spiral manner, with a pressure of 18 - 22 MPa and an extrusion rate of 0.8 - 1.2 m / min. Monitor the plasticity index of the mud in real time to be 1.8 - 2.2, and immediately perform microwave-assisted drying after cutting the mud section to obtain the blank;

[0025] S4. Sinter the blank in stages to obtain the sintered body:

[0026] S5. Immerse the sintered body completely in molten potassium nitrate and treat it at 400 °C for 4 - 6 h to form a surface compressive stress layer through Na + / K + exchange; then immerse the sintered body completely in 5% HF solution for 10 - 20 min to etch the residual pore-forming agent by pickling and increase the open porosity to 50 - 65%.

[0027] Note: By using zirconia nanopowder in this method and based on the method of oriented growth of nanocrystals, the chemical bonding strength with the silicate matrix at high temperatures is improved. By adopting a dual-mode pore-forming mechanism, graphite pore-forming agent (macro pores) + pickling to expand pores (meso pores), a multi-level pore distribution is achieved. Through this method, the compressive strength of traditional honeycomb ceramics can be increased from 8 - 12 MPa to 25 - 30 MPa, while maintaining an open porosity of more than 55%, meeting the usage requirements of ultra-thin wall honeycomb ceramic carriers.

[0028] Further, the pore density of the mold is 1000 - 1200 cpsi.

[0029] Note: By using the above mold specifications to produce ultra-thin wall honeycomb ceramic carriers, the specifications requirements of ultra-thin wall honeycomb ceramic carriers can be met. At the same time, molds with other specification sizes can be selected for production according to actual needs to meet the requirements of different honeycomb ceramic carriers.

[0030] Further, the method of microwave-assisted drying is: keep drying at a constant temperature of 40 °C until the water content is 70 - 80% to prevent surface skinning; then, at a microwave power of 2 - 5 kW, increase the temperature gradient to 60 °C and dry until the water content ≤ 5%; the gradient temperature increase is: keep drying at a constant temperature until the water content ≤ 40% after rising to 50 °C, and keep drying at a constant temperature until the water content ≤ 15% after rising to 55 °C.

[0031] Note: By pre-drying the mud segment at a constant temperature of 40 °C, the surface skin formation can be prevented. By using the above-mentioned gradient heating, the drying effect of the mud segment can be improved, the risks of deformation and cracking can be avoided, and the above-mentioned gradient heating strategy can gradually regulate the water evaporation rate, reduce the micro-cracks generated in the pore structure of the green body due to rapid dehydration, ensure the stability of the porosity and specific surface area of the honeycomb ceramic, and moreover, the gradient heating reduces the thermal shock, avoids the collapse of thin-walled pores or surface caking, maintains the mechanical strength and geometric shape stability of the green body, and provides good matrix properties for subsequent sintering or coating of the catalytic layer.

[0032] Further, the method of staged sintering is as follows:

[0033] S4-1 Debinding stage: Sinter at 500 - 800 °C for 6 - 8 h in an air environment;

[0034] S4-2 Crystal nucleation stage: Sinter at 1000 - 1200 °C for 4 - 6 h in a nitrogen environment;

[0035] S4-3 Crystal growth stage: Sinter at 1500 - 1550 °C for 12 - 36 h in a mixed gas environment; wherein, the mixed gas is composed of 98 - 99.5% argon and 0.5 - 2% hydrogen;

[0036] S4-4 Slow cooling stage: Cool it from 1500 - 1550 °C to 800 °C within 36 h in a nitrogen environment, and then cool it to room temperature at a rate of 1 - 2 °C / min;

[0037] Among them, the heating rate in the S4-1, S4-2, and S4-3 stages is 1 - 3 °C / min; the zirconia crystal size can be adjusted by the holding time at 1500 °C, 12 h → 50 - 80 nm; 24 h → 100 - 150 nm; 36 h → 200 - 300 nm.

[0038] Note: Since the honeycomb ceramic of this product adopts an ultra-thin wall design, the risk of thermal stress and cracking can be reduced by using the above-mentioned staged sintering. For example, in the debinding stage, the pore-forming agent and organic matter can be effectively removed, in the crystal nucleation stage, the crystal skeleton can be initially formed, in the crystal growth stage, the nano-crystals can be bonded with the matrix, and in the slow cooling stage, the honeycomb ceramic carrier can eliminate the thermal stress. By using the staged regulation of temperature and time, the combination between particles can be promoted to be closer, the pores and defects can be reduced, the density and mechanical strength of the carrier can be improved, and the yield can be increased.

[0039] The beneficial effects of the present invention are:

[0040] The present invention provides a high-porosity ultra-thin-wall honeycomb ceramic carrier. The ultra-thin-wall design can significantly increase the honeycomb pore density per unit volume (such as 1200 CPSi), significantly improve the geometric surface area of the carrier, accelerate the catalytic reaction between harmful substances in the exhaust gas and the noble metal coating, and the thin-wall structure can reduce the gas flow resistance, reduce the exhaust back pressure, shorten the catalytic converter preheating time, and improve the cold start performance;

[0041] By introducing zirconia nanopowder into the high-porosity ultra-thin-wall honeycomb ceramic carrier of the present invention, through compounding with other materials, the fracture toughness, flexural strength and thermal shock resistance of the honeycomb ceramic can be significantly improved, reducing the risk of cracking of the carrier under high temperature or mechanical stress. By using modified kaolin, the use effect of the honeycomb ceramic carrier can be significantly enhanced. Detailed implementation mode

[0042] The following combines the specific implementation mode to further elaborate on the present invention in more detail to better reflect the advantages of the present invention.

[0043] Example 1: A high-porosity ultra-thin-wall honeycomb ceramic carrier, by mass percentage, includes 45% of modified kaolin, 27% of talc, 7% of alumina, 8% of nanopowder, 10% of graphite pore former, and 3% of carboxymethyl cellulose; among them, the modified kaolin is sieved through 1300 meshes, the talc is sieved through 1300 meshes, the alumina is sieved through 1600 meshes, and the particle size of the nanopowder is ≤50 nm. The nanopowder is zirconia nanopowder. The preparation method of the modified kaolin is as follows:

[0044] 1) Select kaolin raw ore with a purity > 95%, remove impurities through water washing and magnetic separation, make the content of iron oxide less than 0.5%, and then dry and grind it to a particle size less than 5 μm to ensure that the interlayer structure is fully exposed;

[0045] 2) Mix kaolin and potassium acetate in a mass ratio of 1:0.3 and perform microwave fluctuation irradiation treatment, applying microwave with a power of 800 W and a frequency of 2.4 GHz for 15 min to obtain a preliminary mixture; microwave irradiation destroys the interlayer hydrogen bonds and pre-expands the interlayer spacing to 0.9 nm;

[0046] 3) Subsequently, add a mixed solution of formamide and oxalic acid to the preliminary mixture in a mass ratio of 1:0.8, and stir at 60°C for 1.5 h to obtain a mixture, and further expand the interlayer spacing to 1.2 nm by the synergistic effect of polar molecules; among them, the volume ratio of formamide to oxalic acid is 2:1;

[0047] 4) Transfer the mixture to a ball mill, grind it at a rotational speed of 400 r / min with zirconia balls as the grinding medium for 3.5 h to obtain a product; mechanical shear force promotes complete delamination of the interlayer, and the interlayer spacing is stabilized above 1.5 nm;

[0048] 5) The product was dried in vacuum at 80 °C for 11 h, and then calcined at 260 °C for 30 min under nitrogen protection to obtain modified kaolin. Residual organic matter was removed and the interlayer structure was fixed.

[0049] The production method of the above high-mesh ultra-thin-wall honeycomb ceramic carrier includes the following steps:

[0050] S1. The raw materials and deionized water were mixed at a mass ratio of 1:0.8, and zirconia balls were used as the grinding medium. Ball milling was carried out for 20 h until D50 ≤ 2 μm to obtain the abrasive;

[0051] S2. The moisture content of the abrasive was controlled at 20 ± 1%, and degassing treatment was carried out for 25 min under a vacuum of -0.09 MPa to obtain the mud;

[0052] S3. The mud was subjected to spiral extrusion using a honeycomb mold at a pressure of 20 MPa and an extrusion rate of 1 m / min. The plasticity index of the mud was monitored in real time to be in the range of 1.8 - 2.2. After the mud section was cut, microwave-assisted drying was immediately carried out to obtain the blank. Specifically, it was dried at a constant temperature of 40 °C until the moisture content was 75% to prevent surface crusting; then dried at a microwave power of 4 kW with gradient heating to 60 °C until the moisture content was 5%; the gradient heating was as follows: after rising to 50 °C, it was dried at a constant temperature until the moisture content was 40%, and after rising to 55 °C, it was dried at a constant temperature until the moisture content was 15%; among them, the pore density of the mold was 1200 cpsi;

[0053] S4. The blank was sintered in stages to obtain the sintered body. The method of staged sintering was as follows:

[0054] S4-1 Debinding stage: Sintering at 600 °C for 7 h in an air environment;

[0055] S4-2 Crystal nucleation stage: Sintering at 1100 °C for 5 h in a nitrogen environment;

[0056] S4-3 Crystal growth stage: Sintering at 1550 °C for 24 h in a mixed gas environment; among them, the mixed gas was composed of 99% argon and 1% hydrogen;

[0057] S4-4 Slow cooling stage: Cooling it from 1550 °C to 800 °C in 36 h in a nitrogen environment, and then cooling to room temperature at a rate of 1 °C / min;

[0058] Among them, the heating rate in the S4-1, S4-2, and S4-3 stages was 2 °C / min;

[0059] S5. The sintered body was completely immersed in molten potassium nitrate and treated at 400 °C for 5 h, through Na + / K +Exchange to form a surface compressive stress layer; subsequently, the sintered body was completely immersed in a 5% HF solution for 18 min, and the open porosity was increased to 65% by pickling.

[0060] To verify the performance of the high-mesh ultra-thin-walled honeycomb ceramic carrier in this embodiment, the above-mentioned high-mesh ultra-thin-walled honeycomb ceramic carrier was experimentally explored. The experimental method is as follows:

[0061] I. Specimen preparation: Cut specimens from the inner area more than 5 mm away from the edge of the honeycomb ceramic carrier produced in the embodiment along three directions: the A-axis (axial direction), the B-axis (transverse direction), and the C-axis (radial direction); The shape of the specimen is a cylinder with a diameter and height of 20 ± 0.5 mm; At least 5 groups of effective specimens were prepared in the embodiment to ensure no defects such as cracks and edge defects.

[0062] II. Specimen treatment: The compression surface of the specimen needs to be machined to be flat and parallel to each other, and the specimen is placed in an oven at 110 °C for 2 h, and then transferred to a desiccator to cool to room temperature.

[0063] III. Test equipment parameters: A support is equipped to ensure uniform loading; The relative error of the indication is ≤ ±1%, and the failure load needs to be within the range of 20% - 90% of the full scale; Loading rate control: 1.5 - 2.5 MPa / s; Use a vernier caliper with a precision of ≥ 0.02 mm to measure the size of the compression surface of the specimen and calculate the actual compression area.

[0064] IV. Measurement steps:

[0065] 1) Dimension measurement: Measure the diameter of the compression surface of the specimen and calculate the compression area, unit mm 2 ;

[0066] 2) Specimen placement: Place the specimen at the center of the lower platen of the testing machine to ensure that the axial direction is consistent with the direction of the applied force;

[0067] 3) Loading and recording: Apply a compressive load at a rate of 1.5 - 2.5 MPa / s until the height changes by 10%, and record the maximum load value at the time of specimen failure, unit N.

[0068] 4) Strength calculation:

[0069]

[0070] Among them, σ is the compressive strength, MPa; F is the failure load, N; A is the compression area, mm 2 。

[0071] 5) Numerical statistics: Exclude abnormal data caused by eccentric compression or poor contact, and take the average value of each group of remaining values as the final result. The results are shown in Table 1 below:

[0072] Table 1 Compressive Strength Test of High Mesh Ultra-Thin Wall Honeycomb Ceramic Carrier in Example 1

[0073] Group Compressive strength in the A-axis direction Example 1 38.2 MPa

[0074] As can be seen from the results in Table 1 above, according to the standard requirements, the honeycomb ceramic carrier produced in this example far exceeds the standard requirement of ≥10.0 MPa. At the same time, the compressive strength of the honeycomb ceramic carrier in this example has been increased from 10 - 15 MPa of the traditional honeycomb ceramic carrier to 38 MPa. Therefore, this application can obtain a honeycomb ceramic carrier with excellent compressive strength.

[0075] At the same time, the thermal shock stability test was carried out on the honeycomb ceramic carrier produced in this example. The water-cooling cycle was carried out at 1100℃ → 25℃, and the number of cycles before cracking was tested. The results are shown in Table 2 below:

[0076] Table 2 Thermal Shock Stability Test of High Mesh Ultra-Thin Wall Honeycomb Ceramic Carrier in Example 1

[0077] Group Number of water-cooling cycles from 1100 °C to 25 °C Example 1 19 times

[0078] As can be seen from the results in Table 2 above, the honeycomb ceramic carrier produced by the process in this example has strong thermal shock stability and can withstand 19 water-cooling cycles at 1100℃ → 25℃ without cracking. Therefore, this application can obtain a honeycomb ceramic carrier with high thermal shock stability.

[0079] Furthermore, the specific surface area test was carried out on the honeycomb ceramic carrier produced in this example. The BET nitrogen adsorption method was used to test its specific surface area. The results are shown in Table 3 below:

[0080] Table 3 Specific Surface Area Test of High Mesh Ultra-Thin Wall Honeycomb Ceramic Carrier in Example 1

[0081] Group Specific surface area Example 1 <![CDATA[32m 2 / g]]>

[0082] As can be seen from the results in Table 3 above, the honeycomb ceramic carrier produced by the process in this example has a large specific surface area. Therefore, this application can obtain a honeycomb ceramic carrier with a high specific surface area.

[0083] Example 2: The difference between this example and Example 1 is that a high mesh ultra-thin wall honeycomb ceramic carrier, by mass percentage, includes 40% modified kaolin, 40% talc, 5% alumina, 5% zirconia nanoflour, 8% graphite pore former, and 2% carboxymethyl cellulose; among them, the modified kaolin is sieved through 1200 meshes, the talc is sieved through 1200 meshes, the alumina is sieved through 1500 meshes, and the particle size of the zirconia nanoflour ≤50 nm.

[0084] Example 3: The difference between this example and Example 1 lies in that a high-mesh ultra-thin-walled honeycomb ceramic carrier, calculated by mass percentage, comprises 50% of modified kaolin, 15% of talc, 10% of alumina, 10% of zirconia nanopowder, 12% of graphite pore former, and 3% of carboxymethyl cellulose; wherein, the modified kaolin is sieved through 1400 meshes, the talc is sieved through 1400 meshes, the alumina is sieved through 1600 meshes, and the particle size of the zirconia nanopowder is ≤50 nm.

[0085] Example 4: The difference between this example and Example 1 lies in that kaolin and potassium acetate are mixed in a mass ratio of 1:0.25 and subjected to microwave irradiation treatment.

[0086] Example 5: The difference between this example and Example 1 lies in that kaolin and potassium acetate are mixed in a mass ratio of 1:0.35 and subjected to microwave irradiation treatment.

[0087] Example 6: The difference between this example and Example 1 lies in that microwave with a power of 700 W and a frequency of 2.2 GHz is applied for 10 min.

[0088] Example 7: The difference between this example and Example 1 lies in that microwave with a power of 900 W and a frequency of 2.5 GHz is applied for 17 min.

[0089] Example 8: The difference between this example and Example 1 lies in that subsequently, a mixed solution of formamide and oxalic acid is added to the premix in a mass ratio of 1:0.7, wherein the volume ratio of the formamide to the oxalic acid is 3:2.

[0090] Example 9: The difference between this example and Example 1 lies in that subsequently, a mixed solution of formamide and oxalic acid is added to the premix in a mass ratio of 1:1, wherein the volume ratio of the formamide to the oxalic acid is 5:2.

[0091] Example 10: The difference between this example and Example 1 lies in that the mixture is transferred to a ball mill, and ground for 3 h at a rotation speed of 300 r / min with zirconia balls as the grinding medium to obtain a product.

[0092] Example 11: The difference between this example and Example 1 lies in that the mixture is transferred to a ball mill, and ground for 4 h at a rotation speed of 500 r / min with zirconia balls as the grinding medium to obtain a product.

[0093] Example 12: The difference between this example and Example 1 lies in that the product is vacuum dried at 70 °C for 10 h, and then calcined at 220 °C for 30 min under nitrogen protection to obtain modified kaolin.

[0094] Example 13: The difference between this example and Example 1 is that the product is dried in vacuum at 85°C for 12 h, and then calcined at 280°C for 30 min under nitrogen protection to obtain modified kaolin.

[0095] Example 14: The difference between this example and Example 1 is that the raw materials and deionized water are mixed at a mass ratio of 1:0.7, zirconia balls are used as grinding media, and ball milling is carried out for 18 h until D50≤2 μm.

[0096] Example 15: The difference between this example and Example 1 is that the raw materials and deionized water are mixed at a mass ratio of 1:1, zirconia balls are used as grinding media, and ball milling is carried out for 24 h until D50≤2 μm.

[0097] Example 16: The difference between this example and Example 1 is that the moisture content of the abrasive is controlled at 20±1%, degassing treatment is carried out under a vacuum of -0.09 MPa for 30 min to obtain a mud material, the mud material is subjected to screw extrusion using a honeycomb mold, the pressure is 18 MPa, the extrusion rate is 0.8 m / min, and the plasticity index of the mud material is monitored in real time at 1.8 - 2.2. The pore density of the mold is 1000 cpsi.

[0098] Example 17: The difference between this example and Example 1 is that the moisture content of the abrasive is controlled at 20±1%, degassing treatment is carried out under a vacuum of -0.09 MPa for 20 min to obtain a mud material, the mud material is subjected to screw extrusion using a honeycomb mold, the pressure is 22 MPa, the extrusion rate is 1.2 m / min, and the plasticity index of the mud material is monitored in real time at 1.8 - 2.2. The pore density of the mold is 1100 cpsi.

[0099] Example 18: The difference between this example and Example 1 is that it is dried at a constant temperature of 40°C until the moisture content is 70% to prevent surface crusting; then it is dried at a microwave power of 2 kW with gradient heating to 60°C until the moisture content is 5%; the gradient heating is as follows: after rising to 50°C, it is dried at a constant temperature until the moisture content is 35%, and after rising to 55°C, it is dried at a constant temperature until the moisture content is 12%.

[0100] Example 19: The difference between this example and Example 1 is that it is dried at a constant temperature of 40°C until the moisture content is 80% to prevent surface crusting; then it is dried at a microwave power of 5 kW with gradient heating to 60°C until the moisture content is 5%; the gradient heating is as follows: after rising to 50°C, it is dried at a constant temperature until the moisture content is 30%, and after rising to 55°C, it is dried at a constant temperature until the moisture content is 10%.

[0101] Example 20: The difference between this example and Example 1 is that the blank is sintered in stages to obtain a sintered body. The method of staged sintering is as follows: S4-1 Debinding stage: Sinter at 500 °C for 6 h in an air environment; S4-2 Crystal nucleation stage: Sinter at 1000 °C for 4 h in a nitrogen environment; S4-3 Crystal growth stage: Sinter at 1500 °C for 12 h in a mixed gas environment; where the mixed gas is composed of 98% argon and 2% hydrogen; S4-4 Slow cooling stage: In a nitrogen environment, cool it from 1500 °C to 800 °C within 36 h, and then cool it to room temperature at a rate of 2 °C / min; where the heating rates in the S4-1, S4-2, and S4-3 stages are all 3 °C / min.

[0102] Example 21: The difference between this example and Example 1 is that the blank is sintered in stages to obtain a sintered body. The method of staged sintering is as follows: S4-1 Debinding stage: Sinter at 800 °C for 8 h in an air environment; S4-2 Crystal nucleation stage: Sinter at 1200 °C for 6 h in a nitrogen environment; S4-3 Crystal growth stage: Sinter at 1550 °C for 36 h in a mixed gas environment; where the mixed gas is composed of 99.5% argon and 2% hydrogen; S4-4 Slow cooling stage: In a nitrogen environment, cool it from 1550 °C to 800 °C within 36 h, and then cool it to room temperature at a rate of 1 °C / min; where the heating rates in the S4-1, S4-2, and S4-3 stages are all 1 °C / min.

[0103] Example 22: The difference between this example and Example 1 is that the sintered body is completely immersed in molten potassium nitrate and treated at 400 °C for 4 h to form a surface compressive stress layer through Na + / K + exchange; then the sintered body is completely immersed in a 5% HF solution for 10 min.

[0104] Example 23: The difference between this example and Example 1 is that the sintered body is completely immersed in molten potassium nitrate and treated at 400 °C for 6 h to form a surface compressive stress layer through Na + / K + exchange; then the sintered body is completely immersed in a 5% HF solution for 20 min.

[0105] To verify the performance of the high-mesh ultra-thin-wall honeycomb ceramic carrier in the above examples, the above high-mesh ultra-thin-wall honeycomb ceramic carrier is now experimentally explored. Using the above test method, the compressive strength test results are shown in Table 4 below:

[0106] Table 4 Compressive strength test of the high-mesh ultra-thin-wall honeycomb ceramic carrier in each example

[0107]

[0108]

[0109] As can be seen from the results in Table 4 above, according to the standard requirements, the honeycomb ceramic carriers produced in each example are far greater than the standard requirement of ≥ 10.0 MPa. At the same time, the properties of the honeycomb ceramic carriers produced by the processes of different examples are different, and the analysis is as follows:

[0110] 1) Compared with Example 1, Examples 2 and 3 adopted different component formulations, and the compressive strengths of the honeycomb ceramic carriers prepared by them are different. Among them, the honeycomb ceramic carrier prepared with the component formulation of Example 1 has the best performance;

[0111] At the same time, to compare the use effect of the modified kaolin, a control is set up now. The unmodified kaolin is used to replace the modified kaolin in Example 1 in equal amount, and the prepared honeycomb ceramic carrier is tested. The results are shown in Table 5 below:

[0112] Table 5 Compressive strength test of the control high-mesh ultra-thin-wall honeycomb ceramic carrier

[0113] Group Compressive strength in the A-axis direction Control 31.6 MPa

[0114] It can be seen from the results in Table 5 that after the kaolin is used, the compressive strength in the A-axis direction has decreased significantly, from the original 38.2 MPa to 31.6 MPa. Therefore, after the modified kaolin is used, the compressive strength of the prepared honeycomb ceramic carrier has increased significantly.

[0115] 2) Compared with Example 1, Examples 4 and 5 have a certain impact on the use performance of the modified kaolin after using different mixing ratios of kaolin and potassium acetate. Among them, the modified kaolin prepared with the mixing ratio of Example 1 has the best performance.

[0116] 3) Compared with Example 1, Examples 6 and 7 have a certain impact on the use performance of the modified kaolin after using different microwave irradiation parameters. Among them, the modified kaolin prepared with the microwave irradiation parameters of Example 7 has the best performance. However, since there is no obvious change after Example 7 adopts higher microwave irradiation parameters, from the perspective of economy, the comprehensive effect of Example 1 is better.

[0117] 4) Compared with Example 1, Examples 8 and 9 have a certain impact on the use performance of the modified kaolin after using different mixing ratios of formamide and oxalic acid. Among them, the modified kaolin prepared with the mixing ratio of formamide and oxalic acid of Example 1 has the best performance.

[0118] 5) Compared with Example 1, in Examples 10 and 11, after using different grinding parameters, it had a certain impact on the performance of the modified kaolin. Among them, the performance of the modified kaolin prepared with the grinding parameters of Example 1 and Example 11 was the best. However, since there was no change after using higher grinding parameters in Example 11, from the economic perspective, the comprehensive effect of Example 1 was better.

[0119] 6) Compared with Example 1, in Examples 12 and 13, after using different vacuum drying and calcination parameters, it had a certain impact on the performance of the modified kaolin. Among them, the performance of the modified kaolin prepared with the vacuum drying and calcination parameters of Example 1 was the best.

[0120] 7) Compared with Example 1, in Examples 14 and 15, after grinding with different raw material water mixing ratios, it had a certain impact on the compressive strength of the honeycomb ceramic carrier. Among them, the performance of the honeycomb ceramic carrier prepared with the grinding parameters of Example 1 and Example 15 was the best. However, since there was no change after using higher grinding parameters in Example 15, from the economic perspective, the comprehensive effect of Example 1 was better.

[0121] 8) Compared with Example 1, in Examples 16 and 17, after using different mold manufacturing processes, it had a certain impact on the compressive strength of the honeycomb ceramic carrier. Among them, the compressive strength performance of the honeycomb ceramic carrier in Example 16 was the best. However, compared with Example 1, its pore density was small. Therefore, although it had relatively stronger compressive strength, its comprehensive performance was worse than that of the honeycomb ceramic carrier prepared in Example 1. Therefore, the comprehensive effect of Example 1 was better.

[0122] 9) Compared with Example 1, in Examples 18 and 19, after using different microwave-assisted drying parameters, it had a certain impact on the compressive strength of the honeycomb ceramic carrier. Among them, the performance of the honeycomb ceramic carrier prepared with the microwave-assisted drying parameters of Example 1 was the best.

[0123] 10) Compared with Example 1, in Examples 20 and 21, after using different staged sintering processes, it had a certain impact on the compressive strength of the honeycomb ceramic carrier. Among them, the performance of the honeycomb ceramic carrier prepared with the staged sintering process parameters of Example 21 was the best. However, since there was no obvious change after using higher staged sintering process parameters in Example 15, from the economic perspective, the comprehensive effect of Example 1 was better.

[0124] 11) Compared with Example 1, Example 22 and Example 23 have certain effects on the compressive strength of the honeycomb ceramic carrier after using different sintered body post-treatment processes. Among them, the honeycomb ceramic carrier prepared by the sintered body post-treatment processes of Example 1 and Example 23 has the best performance. However, since Example 23 uses a longer treatment time, the overall effect of Example 1 is better from an economic perspective.

[0125] Example 24: This example is different from Example 1 in that the microwave fluctuation irradiation treatment is as follows: 60% potassium acetate is pre-added to kaolin and stirred, and then microwaves with a power of 800 W and a frequency of 2.4 GHz are applied. After treating for 4 minutes, the remaining potassium acetate is added at a rate of 4% / min and stirred continuously, that is, 4% potassium acetate is added per minute, and the power is switched to periodic fluctuation power. After treating for 10 minutes, a primary mixture is obtained;

[0126] Among them, the periodic fluctuation power is n is the percentage of residual potassium acetate, and the value of n is 40%; T is the periodic fluctuation power table processing time, and the value of T is 10min; m is the microwave power, and the value of m is 800W;

[0127] It is calculated that the periodic fluctuation power is 800±80W, that is, the periodic fluctuation control is 720W→800W→880W→800W→720W, and the fluctuation frequency of the control is 25s / time.

[0128] Example 25: The microwave fluctuation irradiation treatment is as follows: 50% potassium acetate is pre-added to kaolin and stirred, and then microwaves with a power of 800 W and a frequency of 2.4 GHz are applied. After treating for 3 minutes, the remaining potassium acetate is added at an addition rate of 7.2% / min and stirred continuously (it should be noted that the addition rate is positive upward to ensure that the remaining potassium acetate can be completely added before the end of the treatment time), and the power is switched to periodic fluctuation power. After treating for 7 minutes, a primary mixture is obtained;

[0129] Among them, the periodic fluctuation power is n is the percentage of residual potassium acetate, and the value of n is 50%; T is the periodic fluctuation power table processing time, and the value of T is 7min; m is the microwave power, and the value of m is 800W;

[0130] It is calculated that the periodic fluctuation power is 800±115W (it should be noted that the periodic fluctuation power is rounded upward to ensure that the power can cover the calculated value), and the regulated fluctuation frequency is 20s / time.

[0131] Example 26: The microwave fluctuating irradiation treatment is as follows: 70% potassium acetate is pre-added to kaolin and stirred evenly. Subsequently, microwave with a power of 800 W and a frequency of 2.4 GHz is applied. After 5 minutes of treatment, the remaining potassium acetate is added at an addition rate of 5.9% / min while continuously stirring (it should be noted that the addition rate is rounded up to ensure that the remaining potassium acetate can be added completely before the end of the treatment time), and the power is switched to a periodic fluctuating power. After 12 minutes of treatment, a preliminary mixture is obtained;

[0132] Among them, the periodic fluctuating power is n is the percentage content of the remaining potassium acetate, and the value of n is 30%; T is the treatment time of the periodic fluctuating power table, and the value of T is 12 min; m is the microwave power, and the value of m is 800 W;

[0133] It is calculated that the periodic fluctuating power is 800 ± 67 W (it should be noted that the periodic fluctuating power is rounded up to ensure that the power can cover the calculated value), and the regulated fluctuation frequency is 30 s / time.

[0134] To verify the performance of the high-mesh ultra-thin-wall honeycomb ceramic carrier in the above examples, the high-mesh ultra-thin-wall honeycomb ceramic carrier is now experimentally explored. Using the above experimental method, the compressive strength test results are shown in Table 5 below:

[0135] Table 5 Compressive strength test of the high-mesh ultra-thin-wall honeycomb ceramic carrier in each example

[0136] Group Compressive strength in the A-axis direction Example 24 39.7 MPa Example 25 39.1 MPa Example 26 39.4 MPa

[0137] It can be seen from the results in Table 5 above that after using microwave fluctuating irradiation, the compressive strength of the high-mesh ultra-thin-wall honeycomb ceramic carrier in the A-axis direction is further enhanced, and its compressive strength is ≥ 39 MPa, which is better than the high-mesh ultra-thin-wall honeycomb ceramic carrier prepared in Example 1; at the same time, compared with Example 24, Examples 25 and 26 have certain effects on the compressive strength of the honeycomb ceramic carrier after adopting different microwave fluctuating irradiation parameters. Among them, the microwave fluctuating irradiation parameters of Example 24 are the best.

Claims

1. A high mesh number ultra-thin wall honeycomb ceramic carrier, characterized in that By mass percentage, it includes 40 - 50% of modified kaolin, 15 - 40% of talc, 5 - 10% of alumina, 5 - 10% of nano powder, 8 - 12% of graphite pore former, and 2 - 3% of carboxymethyl cellulose; among them, the modified kaolin is sieved through 1200 - 1400 mesh, the talc is sieved through 1200 - 1400 mesh, the alumina is sieved through 1500 - 1600 mesh, and the particle size of the nano powder ≤ 50nm.

2. The high-mesh ultra-thin-wall honeycomb ceramic carrier according to claim 1, wherein The nano powder is any one of zirconia nano powder or alumina nano powder, and the particle size of the zirconia nano powder ≤ 50nm.

3. The high-mesh ultra-thin-walled honeycomb ceramic carrier according to claim 1, wherein, The preparation method of the modified kaolin is as follows: 1) Select kaolin raw ore with a purity > 95%, remove impurities through water washing and magnetic separation to make the content of iron trioxide less than 0.5%, and then grind it to a particle size less than 5μm after drying. 2) Mix kaolin with potassium acetate in a mass ratio of 1:0.25 - 0.35 and perform microwave fluctuation irradiation treatment to obtain a preliminary mixture. 3) Then add a mixed solution of formamide and oxalic acid to the preliminary mixture in a mass ratio of 1:0.7 - 1, stir at 55 - 70°C for 1 - 2h to obtain a mixture, and use the synergistic effect of polar molecules to further expand the layer spacing to 1.2nm; among them, the volume ratio of formamide to oxalic acid is 3 - 5:

2. 4) Transfer the mixture to a ball mill, grind it for 3 - 4h at a rotation speed of 300 - 500r / min with zirconia balls as the grinding medium to obtain a product. 5) Vacuum dry the product at 70 - 85°C for 10 - 12h, and then calcine it at 220 - 280°C for 30min under nitrogen protection to obtain modified kaolin.

4. The high-mesh ultra-thin-walled honeycomb ceramic carrier according to claim 3, characterized in that, The microwave fluctuation irradiation treatment is as follows: 50-70% potassium acetate is pre-added to kaolin and stirred evenly, and then microwaves with a power of 700-900 W and a frequency of 2.2-2.5 GHz are applied. After 3-5 minutes of treatment, the remaining potassium acetate is added at a addition rate and continuously stirred, and the power is switched to a periodic fluctuation power. After 7-12 minutes of treatment, a preliminary mixture is obtained; wherein, the periodic fluctuation power is the fluctuation frequency is 20 - 30 s / time; n is the percentage content of the remaining potassium acetate, and the value of n is 30 - 50%; T is the processing time of the periodic fluctuation power meter, and the value of T is 7 - 12 min; m is the microwave power, and the value of m is 700 - 900 W.

5. The production method of a high mesh number and ultra-thin wall honeycomb ceramic carrier as claimed in claim 1, characterized in that, It includes the following steps: S1. Mix the raw materials with deionized water in a mass ratio of 1:0.7 - 1, use zirconia balls as the grinding medium, and ball mill for 18 - 24h until D50 ≤ 2μm to obtain a grinding material. S2. Control the moisture content of the grinding material at 20 ± 1%, and perform degassing treatment for 20 - 30min under a vacuum of -0.09MPa to obtain a mud material. S3. Use a honeycomb mold to perform screw extrusion on the mud material at a pressure of 18 - 22MPa and an extrusion rate of 0.8 - 1.2m / min, and continuously monitor the plasticity index of the mud material at 1.8 - 2.

2. Immediately perform microwave-assisted drying after cutting the mud section to obtain a blank. S4. Perform staged sintering on the blank to obtain a sintered body: S5. Immerse the sintered body completely in molten potassium nitrate and treat it at 400°C for 4 - 6h; then immerse the sintered body completely in 5% HF solution for 10 - 20min.

6. The production method of a high-mesh ultra-thin-walled honeycomb ceramic carrier as described in claim 5, characterized in that, The pore density of the mold is 1000 - 1200cpsi.

7. The production method of a high-mesh and ultra-thin-wall honeycomb ceramic carrier according to claim 5, characterized in that, The method of microwave-assisted drying is: Constantly dry at 40°C until the moisture content is 70 - 80%; then increase the temperature gradient to 60°C at a microwave power of 2 - 5kW and dry until the moisture content ≤ 5%; the gradient temperature increase is: Constantly dry at 50°C until the moisture content ≤ 40%, and constantly dry at 55°C until the moisture content ≤ 15%.

8. The production method of a high mesh number ultra-thin wall honeycomb ceramic carrier according to claim 5, characterized in that, The method of staged sintering is as follows: S4-1 Debinding stage: Sinter at 500 - 800°C for 6 - 8h in an air environment. S4-2 Crystal nucleation stage: sinter at 1000 - 1200 °C for 4 - 6 h in a nitrogen environment; S4-3 Crystal growth stage: sinter at 1500 - 1550 °C for 12 - 36 h in a mixed gas environment; wherein, the mixed gas is composed of 98 - 99.5% argon and 0.5 - 2% hydrogen; S4-4 Slow cooling stage: in a nitrogen environment, cool it from 1500 - 1550 °C to 800 °C within 36 h, and then cool it to room temperature at a rate of 1 - 2 °C / min; Among them, the heating rate in the S4-1, S4-2, and S4-3 stages is 1 - 3 °C / min.

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