Binder, application and method for producing large-size super-high-porosity dense alumina honeycomb ceramics

Abstract

The present application relates to the technical field of honeycomb ceramics, in particular to a bonding material, application and preparation method of large-specification super-high-pore-density dense alumina honeycomb ceramics. The composition of the bonding material comprises low-melting-point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol and water. The bonding material can realize low-temperature sintering, significantly reduce energy consumption and avoid the unit block cracking problem of super-high-pore-density dense alumina honeycomb ceramics caused by secondary high-temperature sintering; and make the bonding material have an ultra-long shelf life without using organic suspending agents; the method can realize the preparation of super-large-specification products, sinter a plurality of unit blocks at one time, and significantly reduce production cost.

Description

Technical Field

[0001] This invention relates to the field of honeycomb ceramic technology, and more specifically, to adhesives, applications, and methods for preparing large-format, ultra-high porosity dense alumina honeycomb ceramics. Background Technology

[0002] Ultra-high porosity dense alumina honeycomb ceramics possess ultra-high geometrical surface area, making them suitable for a wide range of applications, including gas-to-gas, gas-to-liquid, gas-to-solid, and liquid-to-solid contact exchange. Furthermore, with the development of new technologies and new energy sources, there is an increasing demand for contact exchange applications with even larger geometrical surface areas, such as various ultra-high-channel microreactors used in the pharmaceutical industry, environmental protection, fuel cells, thermoacoustic refrigeration, and thermoacoustic power generation.

[0003] Because the plastic molding of ultra-high pore density dense alumina honeycomb ceramics requires extremely high molding pressure, the extrusion equipment cannot directly extrude products with large cross-sectional areas. It can only extrude small cross-sectional area unit blocks, which are then bonded and processed according to the usage requirements to form the required specifications.

[0004] The ribs of ultra-high porosity dense alumina honeycomb ceramics are dense and have high strength. After bonding, they need to withstand great force when mechanically processed, which can easily lead to cracking at the bonding site.

[0005] Currently, there are no adhesives specifically designed for ultra-high porosity dense alumina honeycomb ceramics. Ordinary ceramic adhesives require high sintering temperatures, which not only leads to significant costs and energy consumption, but also makes it easy for ultra-high porosity dense alumina honeycomb ceramics to crack due to repeated high-temperature sintering. In addition, it is difficult to bond and fire multiple unit blocks at once, which can easily cause misalignment and collapse during the firing process. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an adhesive, its application, and a method for preparing large-scale, ultra-high porosity dense alumina honeycomb ceramics.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: Based on the above technical solution, the present invention can be further improved as follows.

[0008] The present invention provides an adhesive comprising low melting point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol and water.

[0009] Furthermore, the initial melting temperature of the low-melting-point glass powder is 280℃-350℃, and the complete melting temperature is 430-500℃. 50 It is 10-15 μm.

[0010] Furthermore, in the composition of the adhesive, the inorganic gel is magnesium aluminum silicate or magnesium lithium silicate.

[0011] Furthermore, in the composition of the adhesive, the mass ratio of the low melting point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol and water is 20-40:20-40:1-3:1-3:17-19:17-19.

[0012] The present invention also provides the application of the above-described binder in the preparation of large-format, ultra-high porosity dense alumina honeycomb ceramics.

[0013] Furthermore, the specifications of the honeycomb ceramic are as follows: the diameter is greater than 100 mm, and the pore density of the honeycomb ceramic is 3000 cpsi-70000 cpsi.

[0014] The present invention also provides a method for preparing large-size ultra-high porosity dense alumina honeycomb ceramic, characterized in that the outer walls of multiple honeycomb ceramic unit blocks are bonded together with the adhesive as described above, and the honeycomb ceramic is obtained after drying and sintering.

[0015] Furthermore, the drying process is a two-stage gradient heating drying process. The temperature of the first stage of drying is 75-95℃ and the time is 4-8 hours. The temperature of the second stage of drying is 105-120℃ and the time is 12-24 hours.

[0016] Furthermore, the sintering temperature is 400-550℃ and the time is 4-8h.

[0017] The present invention also provides a large-size, ultra-high porosity dense alumina honeycomb ceramic, which is prepared by the method described above.

[0018] The beneficial effects of this invention are as follows: (1) The adhesive of the present invention uses low melting point glass powder with an initial melting temperature of 280-350℃ and a full melting temperature of 430-500℃, inorganic gel, and palygorskite powder to work together to achieve low temperature sintering at 400-550℃, which significantly reduces energy consumption and avoids the problem of unit block cracking caused by secondary high temperature sintering of ultra-high pore density dense alumina honeycomb ceramic. (2) The adhesive of the present invention has an ultra-long shelf life without the use of organic suspending agents by using a compound thickening and suspension mechanism of inorganic gel and palygorskite powder; (3) The adhesive of the present invention, with the synergistic effect of low melting point glass powder and spherical alumina powder, combined with the solid network structure formed after the silica sol is dried, can provide excellent bonding strength, ensuring that the bonding seam of large-size products does not crack during mechanical processing and cutting, while avoiding the problems of melt adhesion misalignment caused by excessive glass powder or insufficient bonding strength caused by excessive alumina powder. (4) The method for preparing large-size ultra-high porosity dense alumina honeycomb ceramics of the present invention adopts a two-stage gradient heating process, which allows the moisture to evaporate slowly and uniformly and promotes the full condensation of silica sol. The resulting stable network structure continues to solidify the glass melt during the sintering process at 400-550℃, effectively preventing the spliced ​​products from misaligning, collapsing or deforming under the action of gravity. (5) The method for preparing large-size ultra-high porosity dense alumina honeycomb ceramics of the present invention achieves reliable preparation of ultra-large-size products through the combination of low-temperature sintering and inorganic bonding system. Multiple unit blocks can be bonded and sintered at one time, significantly reducing production costs. It is suitable for microreactor application scenarios where gas-to-gas, gas-to-liquid, gas-to-solid, and liquid-to-solid contact exchange occurs. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart illustrating a method for preparing large-size, ultra-high porosity dense alumina honeycomb ceramics in one embodiment of the present invention. Detailed Implementation

[0020] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0021] The adhesive of the present invention comprises low melting point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol and water.

[0022] The binder of this invention has the advantages of simple operation, low sintering temperature, environmental friendliness, and high strength, and is particularly suitable for the preparation of large-size ultra-high porosity dense alumina honeycomb ceramics.

[0023] Specifically, low-melting-point glass powder can achieve melting and bonding at lower temperatures. At the same time, the use of spherical alumina powder and palygorskite powder avoids the problems caused by the melting and flowing of low-melting-point glass powder during sintering, such as poor bonding, end-face clogging, and product adhesion to the kiln plate. Spherical alumina powder and fibrous palygorskite powder reduce the flow of glass melt during sintering. Furthermore, during cooling, spherical alumina powder reduces the expansion difference between the glass melt and the dense alumina honeycomb ceramic. The unique fibrous structure of palygorskite powder further prevents the glass melt from tearing the ribs of the ultra-high porosity dense alumina honeycomb ceramic during cooling.

[0024] In addition, organic suspending agents generally require 650℃ to be completely removed, and the slurry is prone to spoilage over time. This invention does not use organic suspending agents, but uses inorganic gel and palygorskite powder to achieve thickening and suspension of the binder, which can give the slurry good suspension properties and an ultra-long shelf life. At the same time, it will not pollute the environment during the sintering process, and there will be no organic residue after sintering at 400-550℃ that will affect the use of the product.

[0025] Meanwhile, the use of silica sol, inorganic gel, and palygorskite powder can ensure that the bonded large blocks do not crack during processing and transportation, and can also maintain a good bonding effect during sintering. The products will not be misaligned, collapsed, or deformed under gravity due to the melting of low-melting-point glass powder.

[0026] Preferably, the initial melting temperature of the low-melting-point glass powder is 280℃-350℃, and the complete melting temperature is 430-500℃. 50 It is 10-15 μm.

[0027] Traditional glazes generally require high-temperature sintering (above 1000℃), while this low melting point characteristic allows the binder to melt and bond at a low temperature of 400-550℃, significantly reducing the sintering temperature and avoiding the problem of unit block cracking caused by secondary high-temperature sintering in ultra-high pore density dense alumina honeycomb ceramics. At the same time, it greatly reduces energy consumption and production costs. The above-mentioned particle size ensures uniform dispersion of powder in the binder system and suitable sintering activity.

[0028] Preferably, the inorganic gel is magnesium aluminum silicate or lithium magnesium silicate. Using magnesium aluminum silicate or lithium magnesium silicate as the inorganic gel can have a good synergistic effect with palygorskite powder and silica sol.

[0029] Preferably, the mass ratio of low melting point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol and water is 20-40:20-40:1-3:1-3:17-19:17-19.

[0030] The above-mentioned mass ratio effectively achieves multiple synergistic effects of each component. The balanced ratio of 20-40 parts low-melting-point glass powder to spherical alumina powder ensures that sufficient melt is formed for effective bonding during low-temperature sintering. At the same time, the appropriate amount of spherical alumina powder can adjust the coefficient of thermal expansion, avoiding excessive melt, misalignment, adhesion, and cracking of the rib walls caused by excessive glass powder. It can also prevent insufficient bonding strength and processing cracking caused by excessive spherical alumina powder. The precise addition of inorganic gel and palygorskite powder, combined with silica sol and water, achieves excellent thickening and suspension properties without the use of organic suspending agents, giving the slurry an ultra-long shelf life and avoiding the risk of high-temperature removal of organic matter and spoilage.

[0031] The adhesive described above in this invention can be used to prepare large-size, ultra-high porosity dense alumina honeycomb ceramics.

[0032] Preferably, the specifications of the honeycomb ceramic are as follows: the diameter is greater than 100 mm and the pore density of the honeycomb ceramic is 3000 cpsi-70000 cpsi.

[0033] The method for preparing large-size ultra-high porosity dense alumina honeycomb ceramic of the present invention involves bonding the outer walls of multiple honeycomb ceramic unit blocks together with the adhesive as described above, and then drying and sintering to obtain the honeycomb ceramic.

[0034] Preferably, the drying process is a two-stage gradient heating drying process. The temperature of the first stage of drying is 75-95℃ and the time is 4-8 hours. The temperature of the second stage of drying is 105-120℃ and the time is 12-24 hours.

[0035] The two-stage gradient heating and drying process described above involves first drying at a mild temperature of 75-95℃ for 4-8 hours, allowing the moisture in the bonding joints of large-sized, ultra-high porosity, dense alumina honeycomb ceramic unit blocks to evaporate slowly and evenly, effectively avoiding stress concentration and cracking of the bonding layer caused by rapid dehydration. Then, drying is extended at 105-120℃ for 12-24 hours, completely removing residual free water and allowing the silica sol to fully condense and form a robust solid network structure. This structure can continuously solidify the low-melting-point glass melt during the subsequent low-temperature sintering process at 400-550℃, ensuring that the assembled products do not misalign, collapse, or deform due to gravity. Simultaneously, the gradient heating method matches the final low-temperature sintering regime, avoiding the unit block cracking problem caused by high-temperature sintering in traditional processes, and ensuring the structural integrity and joint strength of large-sized products during machining and transportation.

[0036] Preferably, the sintering temperature is 400-550℃ and the time is 4-8h.

[0037] Preferably, the adhesive is applied manually or automatically, and automatic application can be performed using conventional coating equipment.

[0038] Preferably, in order to prevent the adhesive from entering the pores of the honeycomb ceramic during the coating process, the open ends of the honeycomb ceramic need to be sealed before bonding, which can be done using tape.

[0039] like Figure 1 As shown, in one embodiment of the present invention, the preparation method specifically includes the following steps: S1. Prepare the adhesive material; Preferably, when preparing the adhesive, the powder and liquid are first mixed evenly separately, and then the powder and liquid are mixed evenly.

[0040] S2. Seal both ends of each alumina honeycomb ceramic unit block with tape; S3. Apply adhesive to the outer wall of the unit block, and then bond multiple alumina honeycomb ceramic unit blocks together according to the required specifications. S4. Perform two-stage gradient heating drying and sintering; S5. Perform machining to obtain large-size, ultra-high pore density, dense alumina honeycomb ceramics with the required shape and size.

[0041] The large-size, ultra-high porosity dense alumina honeycomb ceramic of the present invention is prepared by the method described above.

[0042] The effects of the present invention will be illustrated below through specific embodiments and comparative examples.

[0043] Example 1 This embodiment uses the binder of the present invention to prepare large-size, ultra-high porosity dense alumina honeycomb ceramics.

[0044] The adhesive composition of this embodiment, by mass percentage, is: 30% spherical alumina powder, 30% low-melting-point glass powder, 1% magnesium aluminum silicate inorganic gel powder, 1% palygorskite powder, 19% silica sol, and 19% deionized water. The initial melting temperature of the low-melting-point glass powder is 280°C, and the total melting temperature is 430°C. 50 It is 15μm.

[0045] The specific preparation method of the adhesive in this embodiment is as follows: Weigh the above components, mix spherical alumina powder, low melting point glass powder, magnesium aluminum silicate inorganic gel powder, and palygorskite powder evenly to obtain a dry powder mixture; mix deionized water and silica sol in liquid form to obtain a mixture; then mix the dry powder mixture and the mixture evenly to obtain the adhesive.

[0046] The preparation process of the large-scale, ultra-high porosity dense alumina honeycomb ceramic in this comparative example is as follows: The two ends of the dense alumina honeycomb ceramic cell block were sealed with tape. The cell block pore density used in this embodiment is 10000 cpsi.

[0047] Multiple unit blocks were manually bonded together using adhesive to form a large-sized product, which was then dried at 75°C for 4 hours and then at 120°C for 16 hours. After drying, the adhesive tape was removed, and the product was sintered at 400°C.

[0048] After sintering, the ceramic is processed by cutting, grinding and other mechanical processes to obtain large-size, ultra-high pore density, dense alumina honeycomb ceramics with adhesive material in the required shape and size.

[0049] Example 2 This embodiment is the same as Embodiment 1, except that the adhesive composition in this embodiment, by mass percentage, is: 40% spherical alumina powder, 20% low-melting-point glass powder, 1% magnesium aluminum silicate inorganic gel powder, 1% palygorskite powder, 19% silica sol, and 19% deionized water. The initial melting temperature of the low-melting-point glass powder is 280℃, and the total melting temperature is 430℃.

[0050] Example 3 This embodiment is the same as Embodiment 1, except that the adhesive composition in this embodiment, by mass percentage, is: 20% spherical alumina powder, 40% low-melting-point glass powder, 1% magnesium aluminum silicate inorganic gel powder, 1% palygorskite powder, 19% silica sol, and 19% deionized water. The initial melting temperature of the low-melting-point glass powder is 280℃, and the total melting temperature is 430℃.

[0051] Example 4 This embodiment is the same as Embodiment 1, except that the adhesive composition in this embodiment, by mass percentage, is: 30% spherical alumina powder, 30% low-melting-point glass powder, 2% magnesium aluminum silicate inorganic gel powder, 2% palygorskite powder, 18% silica sol, and 18% deionized water. The initial melting temperature of the low-melting-point glass powder is 280℃, and the total melting temperature is 430℃.

[0052] Example 5 This embodiment is the same as Embodiment 1, except that the adhesive composition in this embodiment, by mass percentage, is: 30% spherical alumina powder, 30% low-melting-point glass powder, 3% magnesium aluminum silicate inorganic gel powder, 3% palygorskite powder, 17% silica sol, and 17% deionized water. The initial melting temperature of the low-melting-point glass powder is 280℃, and the total melting temperature is 430℃.

[0053] Example 6 This embodiment is the same as Embodiment 1, except that the initial melting temperature of the low-melting-point glass powder is 400°C and the total melting temperature is 550°C. Simultaneously, the sintering temperature is 550°C.

[0054] Example 7 This embodiment is the same as Embodiment 1, except that the sintering temperature is 450℃.

[0055] Example 8 This embodiment is the same as Embodiment 1, except that the sintering temperature is 500℃.

[0056] Example 9 This embodiment is the same as Embodiment 6, except that the sintering temperature is 500℃.

[0057] Example 10 This embodiment is the same as Embodiment 6, except that the sintering temperature is 450℃.

[0058] Example 11 This embodiment is the same as Embodiment 1, except that the inorganic gel used is lithium magnesium silicate inorganic gel.

[0059] Example 12 This embodiment is the same as Embodiment 1, except that the pore density of the dense alumina honeycomb ceramic unit block is 3000 cpsi.

[0060] Example 13 This embodiment is the same as Embodiment 1, except that the pore density of the dense alumina honeycomb ceramic unit block is 30000cpsi.

[0061] Example 14 This embodiment is the same as Embodiment 1, except that the pore density of the dense alumina honeycomb ceramic unit block is 70,000 cpsi.

[0062] Comparative Example 1 This comparative example is the same as Example 1, except that the adhesive composition of this comparative example, by mass percentage, is: 10% spherical alumina powder, 50% low-melting-point glass powder, 1% magnesium aluminum silicate inorganic gel powder, 1% palygorskite powder, 19% silica sol, and 19% deionized water. The initial melting temperature of the low-melting-point glass powder is 280°C, and the total melting temperature is 430°C.

[0063] Comparative Example 2 This comparative example is the same as Example 1, except that the adhesive composition of this comparative example, by mass percentage, is: 50% spherical alumina powder, 10% low-melting-point glass powder, 1% magnesium aluminum silicate inorganic gel powder, 1% palygorskite powder, 19% silica sol, and 19% deionized water. The initial melting temperature of the low-melting-point glass powder is 280°C, and the total melting temperature is 430°C.

[0064] Comparative Example 3 This comparative example is the same as Example 1, except that the adhesive composition of this comparative example, by mass percentage, is: 35% spherical alumina powder, 35% low-melting-point glass powder, and 30% deionized water. The initial melting temperature of the low-melting-point glass powder is 280°C, and the total melting temperature is 430°C.

[0065] Comparative Example 4 The binder used in this comparative example has the following composition: 150g silica powder, 200g feldspar powder, 110g white gangue, 50g ash clay, 50g barium carbonate, and 20g limestone powder.

[0066] The preparation process of the adhesive in this comparative example is as follows: After the above components are mixed evenly, they are placed in an agate mortar and ball-milled, and then passed through a 300-mesh sieve to obtain a premix; 300g of deionized water and 1.6g of ammonium citrate are added to 200g of premix, stirred for 5min, and ultrasonically vibrated for 50min under constant temperature conditions; 40g of acrylamide and 0.3g of ammonium persulfate are added, stirred for 5min, and ultrasonically vibrated for 15-20min under constant temperature conditions to obtain the adhesive.

[0067] The preparation process of the large-scale ultra-high porosity dense alumina honeycomb ceramic in this comparative example is as follows: The two ends of the ultra-high porosity dense alumina honeycomb ceramic unit blocks are sealed with adhesive tape. Using the aforementioned adhesive, multiple unit blocks are manually bonded together to form a large-scale product. The product is then dried at 75℃ for 4 hours, followed by drying at 120℃ for 16 hours. After attaching the adhesive tape, it is sintered at 1260-1270℃. Following machining processes such as cutting and grinding, the large-scale ultra-high porosity dense alumina honeycomb ceramic with the required shape and size, containing the adhesive material, is obtained.

[0068] The performance of the large-size ultra-high porosity dense alumina honeycomb ceramics obtained in the above embodiments and comparative examples was tested, and the test results are shown in Table 1.

[0069] To facilitate a proper comparison between the embodiments and comparative examples, all final products were identical in specifications, specifically a diameter of 200 mm and a height of 100 mm. Of course, in practical applications, the diameter, height, and pore density of honeycomb ceramics are not limited to these values.

[0070] Table 1. Results of use for each embodiment and comparative example The test results in Table 1 show that low-melting-point glass powder can achieve melting and bonding at a relatively low temperature of 400-550℃. However, if too much spherical alumina powder is used, such as in Comparative Example 1, the bonding strength is low after sintering, which will cause the bond seam to crack during cutting and machining. If too much low-melting-point glass powder is used, such as in Comparative Example 2, there will be slight adhesion and misalignment. At the same time, because the amount of spherical alumina powder is small, its thermal expansion difference is large. During the cooling process, a large amount of glass melt shrinks and tears the wall of the unit block.

[0071] The use of low-melting-point glass powder, spherical alumina powder, palygorskite powder, inorganic gel, and silica sol avoids the problems caused by the melting and flowing of low-melting-point glass powder during sintering, such as poor adhesion, end-face clogging, and product adhesion to the kiln plate. Spherical alumina powder and fibrous palygorskite powder reduce the flow of glass melt during sintering, and during cooling, spherical alumina powder reduces the expansion difference between glass melt and dense alumina honeycomb ceramic. The unique fibrous structure of palygorskite powder further prevents the glass melt from tearing the walls of the ultra-high porosity dense alumina honeycomb ceramic during cooling. The solid network structure formed after the silica sol dries further solidifies the glass melt, maintaining good adhesion during sintering. The products will not be misaligned, collapsed, or deformed under gravity due to the melting of low-melting-point glass powder. When palygorskite powder, inorganic gel and silica sol are not used, such as in Comparative Example 3, the glass softens and melts during the sintering process. The bonded products are misaligned and collapse under the action of gravity, and the melt flows out and adheres to the kiln plate. Some end holes are blocked by the melt.

[0072] In addition, organic suspending agents generally need to be removed completely at 650℃, and the slurry is prone to spoilage over time. This invention does not use organic suspending agents, but uses inorganic gel and palygorskite powder to achieve thickening and suspension of the binder, which can give the slurry good suspension properties. At the same time, it will not pollute the environment during the sintering process, and there will be no organic residue after sintering at 400-550℃ that will affect the use of the product.

[0073] Examples 1-11 can all achieve low-temperature sintering at 400-550℃, while ceramic bonding using traditional glazes, such as Comparative Example 4, requires high-temperature sintering at 1260-1270℃. After secondary high-temperature sintering, the ultra-high porosity dense alumina unit blocks crack.

[0074] The large-format, ultra-high porosity dense alumina honeycomb ceramic containing binder of the present invention can be applied to, but is not limited to, scenarios where gas-to-gas, gas-to-liquid, gas-to-solid, and liquid-to-solid contact exchange can be carried out, such as various ultra-high channel microreactors used in the pharmaceutical industry, environmental protection, fuel cells, thermoacoustic refrigeration, and thermoacoustic power generation.

[0075] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An adhesive, characterized in that, The adhesive comprises low-melting-point glass powder, spherical alumina powder, inorganic gel, palygorskite powder, silica sol, and water.

2. The adhesive according to claim 1, characterized in that, The initial melting temperature of the low-melting-point glass powder is 280℃-350℃, and the complete melting temperature is 430-500℃. 50 It is 10-15 μm.

3. The adhesive according to claim 1, characterized in that, In the composition of the adhesive, the inorganic gel is magnesium aluminum silicate or magnesium lithium silicate.

4. An adhesive according to any one of claims 1-3, characterized in that, In the composition of the adhesive, the mass ratio of the low melting point glass powder, the spherical alumina powder, the inorganic gel, the palygorskite powder, the silica sol and water is 20-40:20-40:1-3:1-3:17-19:17-19.

5. The application of the binder as described in any one of claims 1-4 in the preparation of large-format ultra-high porosity dense alumina honeycomb ceramics.

6. The application of the adhesive according to claim 5 in the preparation of large-format, ultra-high porosity dense alumina honeycomb ceramics, characterized in that, The specifications of the honeycomb ceramic are as follows: the diameter is greater than 100 mm, and the pore density of the honeycomb ceramic is 3000 cpsi-70000 cpsi.

7. A method for preparing large-format, ultra-high porosity dense alumina honeycomb ceramics, characterized in that, The outer walls of multiple honeycomb ceramic unit blocks are bonded together using the adhesive as described in any one of claims 1-4, and then dried and sintered to obtain the honeycomb ceramic.

8. The method for preparing large-size ultra-high porosity dense alumina honeycomb ceramics according to claim 7, characterized in that, The drying process is a two-stage gradient heating drying process. The temperature of the first stage of drying is 75-95℃ and the time is 4-8 hours. The temperature of the second stage of drying is 105-120℃ and the time is 12-24 hours.

9. The method for preparing large-size ultra-high porosity dense alumina honeycomb ceramics according to claim 7, characterized in that, The sintering temperature is 400-550℃ and the time is 4-8h.

10. A large-format, ultra-high porosity, dense alumina honeycomb ceramic, characterized in that, It is prepared by the method described in any one of claims 7-9.

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