Ceramic flat sheet membrane and end seal integrated co-firing molding process

Abstract

The invention relates to a ceramic flat sheet membrane and end seal integrated co-firing molding process. The process comprises the following steps: S1, preparing a ceramic flat sheet membrane support body; s2, preparing an end seal; s3, preparing bonding slurry; the two ends of the supporting body mud blank are coated with bonding slurry and then dried, then the supporting body mud blank is combined with an end seal green body, an integrated structure is formed through one-time sintering, and after sintering is completed, the end seal drawing performance and the end seal air tightness are detected; and S5, preparing the flat sheet membrane. After a plastic end seal is upgraded into a homogeneous ceramic end seal, a ceramic membrane product has full water quality applicability, and the risk that the end seal cracks and falls off is thoroughly solved. Meanwhile, an integrated co-firing forming process is adopted in the sintering process of the ceramic membrane, and the ceramic end seal and the ceramic membrane body are synchronously prepared. According to the technology, tedious procedures of installation after sintering, glue bonding, curing waiting and the like needed by a traditional plastic end seal are omitted, and the product reliability and the production efficiency are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane preparation technology, and in particular to a ceramic flat sheet membrane and an integrated co-firing process for end sealing. Background Technology

[0002] Currently, in the water treatment field (including industrial wastewater, production sewage, and tap water purification), ceramic membranes have become the mainstream wastewater purification technology due to their outstanding environmental friendliness and sustainable recyclability. However, the end-sealing components currently used in ceramic flat-sheet membrane modules are generally made of plastic materials (such as PPO) and are bonded to the ceramic membrane using epoxy resin adhesives or polyurethane adhesives. The shortcomings of existing technologies include:

[0003] This encapsulation method has significant limitations: it requires specific water quality conditions, with the water temperature typically not exceeding 50°C and the pH generally maintained within the range of 2 to 12. This is because when the water temperature is too high or the pH exceeds this range, the adhesive and plastic end seals used as bonding materials are prone to aging, cracking, or even detachment. Furthermore, ceramic membrane products operating in relatively high-quality water environments also experience these problems due to temperature differences between winter and summer, prolonged contact with water, and the pressure during backwashing.

[0004] The risk associated with this is that during the ceramic membrane filtration process, impurities from the untreated wastewater will seep directly into the filtered clean water side through cracks or detached end seals, resulting in the final effluent water quality failing to meet standards. Summary of the Invention

[0005] This invention aims to solve the problem of adhesive or end seal cracking and detachment during the operation of ceramic membrane products, and provides an integrated co-firing molding process for ceramic flat sheet membrane and end seal. This process does not require adhesive bonding, is applicable to any water quality conditions, and eliminates the phenomenon of end seal cracking and detachment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an integrated co-firing process for ceramic flat sheet film and end-sealing, comprising the following steps:

[0007] S1. Preparation of ceramic flat film support: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and 18-25 parts of liquid auxiliary material are added to knead into plastic clay. The clay is then subjected to vacuum kneading, vacuum extrusion molding and drying to obtain a support blank with a predetermined strength.

[0008] S2. Preparation of end seals: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and then 3-8 parts of liquid additives are added, kneaded and dry-pressed into shape. After drying, an end seal green blank with a predetermined strength is obtained.

[0009] S3. Preparation of bonding slurry: By weight, mix and grind 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 50~80 parts of water to obtain a bonding slurry of the predetermined viscosity.

[0010] S4. Combined sintering: After coating the two ends of the support body clay blank with bonding slurry and drying it, it is combined with the end-sealing green blank and sintered once to form an integrated structure. After sintering, the end-sealing pull-out performance and end-sealing air tightness are tested.

[0011] S5. Preparation of flat sheet membrane: By weight, 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 150~200 parts of water are mixed and ground to obtain a membrane slurry of predetermined viscosity. The membrane slurry is then sprayed onto the surface of the support after the first sintering. After drying, the finished ceramic flat sheet membrane is obtained by a second sintering. Finally, the airtightness between the end seal and the flat sheet membrane is tested.

[0012] Specifically, in S1 and S2, the micron-sized alumina particles are 5~10μm in size and have a purity ≥99%; the binder is one or more of HPMC cellulose, CMC cellulose, dextrin, polyvinyl alcohol and carbon fiber; the pore-forming agent is one or more of baking soda, wood ash, carbon powder, calcium carbonate, starch and soda ash; the sintering aid is one or more of kaolin, talc, titanium dioxide, magnesite and glass powder; and the liquid additive is one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerin and water.

[0013] Specifically, in S3 and S5, the nano-alumina particles have a size of 70~100nm and a purity of ≥99%; the dispersant is one or more of sodium hexametaphosphate, citric acid, ammonium polyacrylate, polyoxyethylene ether, and sodium polyacrylate; and the sintering aid is one or more of kaolin, glass powder, silica sol, alumina sol, and talc.

[0014] Specifically, during the preparation of S1, the mixing time is 30~60 min; the kneading time is 30~60 min; the vacuum degree during vacuum kneading and vacuum extrusion is -0.06~-0.08 MPa; during the drying process, the oven temperature is raised to 90~110℃ and kept at that temperature for 2~4 h. After drying, the strength of the support body clay blank is ≥5 MPa and the moisture content is ≤0.5%.

[0015] Specifically, during the preparation of S2, the homogenization time is 30-60 minutes, the drying oven temperature is raised to 90-110℃ and held for 2-4 hours, and the end-sealed green body strength is ≥5MPa and the moisture content is ≤0.5% after drying; the final molding pressure is 50-80MPa, and the dry pressing adopts a staged pressure method, including the following steps:

[0016] Pre-compression: Initially arrange the powder and remove loose gas between particles. The pressure is 10-30% of the final molding pressure, and the pre-compression time is 0.5-2 seconds.

[0017] Medium pressure: Further compact the powder and continue to expel gas. The pressure is 30% to 70% of the final molding pressure. After reaching the intermediate pressure stage, maintain it for 0.5 to 2 seconds.

[0018] Brief pressure relief: After the medium pressure is released, briefly release the pressure for 0.2~0.5 seconds;

[0019] High pressure: Continue compacting the powder until the final green body density of 2.5~3.0 g / cm³, as required by the product design, is achieved. 3 The pressure is controlled at 50~80MPa, and the pressure holding time is 5~20S;

[0020] Depressurization and demolding: After the high pressure holding is completed, depressurize at a rate of 2~4MPa / S, with a total depressurization time of 10~40S. After depressurization is completed, the end-sealed green blank can be removed.

[0021] Specifically, during the preparation of S3, the grinding speed is 80~100 rpm, the grinding time is 30~60 min, and the grinding target is based on the slurry viscosity, which is controlled at 1500~2000 mPa·s.

[0022] Specifically, during the preparation of S4, the thickness of the adhesive slurry coating is 0.5~1mm, the width is 15~20mm, the drying temperature is 80~100℃, and the drying time is 5~10S; the maximum temperature for one sintering is 1250~1300℃, and the total sintering time is 20~25h.

[0023] Specifically, during the preparation of S5, the grinding speed is 80~100 rpm, the grinding time is 30~60 min, the grinding target is based on the slurry viscosity, and the slurry viscosity is controlled at 1500~2000 mPa·s; the drying temperature is 80~100℃, the drying time is 5~10 s; the maximum temperature for secondary sintering is 1200~1250℃, and the total duration of secondary sintering is 20~25 h.

[0024] The beneficial effects of this invention are as follows: By upgrading the plastic end seal to a homogeneous ceramic end seal, the ceramic membrane product becomes suitable for all water qualities, completely eliminating the risk of end seal cracking and detachment. Simultaneously, the "integrated co-firing molding" process is adopted during the ceramic membrane sintering process, ensuring that the ceramic end seal and the ceramic membrane body are prepared simultaneously. This process eliminates the cumbersome steps required by traditional plastic end seals, such as post-sintering installation, adhesive bonding, and curing waiting, significantly improving product reliability and production efficiency. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the present invention;

[0026] Figure 2 This is a schematic diagram of the support structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the end-cap structure of the present invention;

[0028] The following will describe in detail, with reference to the accompanying drawings, embodiments of the present invention. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments:

[0030] like Figures 1-3 As shown, a co-firing process for an integrated ceramic flat film and end-sealing includes the following steps:

[0031] S1. Preparation of ceramic flat film support: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and 18-25 parts of liquid auxiliary material are added to knead into plastic clay. The clay is then subjected to vacuum kneading, vacuum extrusion molding and drying to obtain a support blank with a predetermined strength.

[0032] Among them, micron-sized alumina is used as the main raw material for the support, with a particle size of 5~10μm and a purity of ≥99%;

[0033] The binder improves the plasticity of ceramic clay during molding and prevents cracking during molding. It is made of one or more of HPMC cellulose, CMC cellulose, dextrin, polyvinyl alcohol and carbon fiber.

[0034] Pore-forming agents are used to improve the pore size and porosity of ceramic membranes and increase water treatment efficiency. They are made from one or more of the following: baking soda, wood ash, carbon powder, calcium carbonate, starch, and soda ash.

[0035] Sintering aids have the function of lowering the sintering temperature of ceramic films and improving their strength. They are made of one or more of the following: kaolin, talc, titanium dioxide, magnesite, and glass powder.

[0036] Liquid additives are key additives for the kneading and molding of powders, and they include one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerin, and water.

[0037] The specific preparation process is as follows:

[0038] S11. Homogenization: After weighing the solid powder according to the formula, pour it into the homogenizer for homogenization and mixing to make the raw materials evenly mixed. The homogenization time is 30~60 minutes.

[0039] S12. Kneading: The mixed raw materials are fed into the kneader, and liquid additives are added according to the formula ratio for kneading. The dry powder is kneaded into a mud ball under the action of the liquid additives to form a mud material with a certain plasticity. The kneading time is 30~60 minutes.

[0040] S13. Vacuum mud refining: The kneaded mud is subjected to a vacuum mud refining machine to remove the air from the mud, thereby forming a dense mud lump with a vacuum degree of -0.06~-0.08MPa.

[0041] S14. Vacuum extrusion: After kneading, the clay material enters the vacuum extruder. The clay material is shaped by a customized mold to form a support body clay blank. The vacuum degree is -0.06~-0.08MPa.

[0042] S15. Drying: Place the clay blank in an oven, heat it to 90~110℃, and keep it at that temperature for 2~4 hours to remove some moisture from the clay blank, thereby giving it a certain strength. After drying, the strength of the support clay blank should be ≥5MPa and the moisture content ≤0.5%. If the strength is <5MPa or the moisture content is >0.5%, the clay blank will be too soft and easily deformed, which is not conducive to subsequent assembly with ceramic end seals.

[0043] S2. Preparation of end seals: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and then 3-8 parts of liquid additives are added, kneaded and dry-pressed into shape. After drying, an end seal green blank with a predetermined strength is obtained.

[0044] The types and amounts of solid powder in the end-sealing formulation are the same as those in the support formulation, and the types of liquid additives are the same, but the amounts need to be reduced to facilitate subsequent dry pressing.

[0045] The specific preparation process is as follows:

[0046] S21. Homogenization: After weighing the solid powder according to the formula, pour it into the homogenizer for homogenization and mixing to make the raw materials evenly mixed. The homogenization time is 30~60 minutes.

[0047] S22. Kneading: Due to the small amount of liquid additives added during kneading, the clay material becomes loose after kneading and cannot form a clay lump like the support.

[0048] S23. Dry Pressing: The kneaded loose clay material is fed into a custom mold for dry pressing. The pressure during molding is 50~80MPa (too low pressure will result in low density and poor strength of the green body (easy to break, missing corners), making demolding and handling difficult; too high pressure will result in excessive elastic aftereffect, making it easy to crack and delaminate (particles deform and accumulate elastic energy under pressure, and partially recover after pressure is released), exacerbating the uneven density inside the green body caused by friction from the mold wall (dense on the surface, loose in the center), and causing severe wear on the mold). To improve the uniformity of the end-sealed green body, a staged pressing method is adopted, including the following steps:

[0049] Pre-compression: Initially arranges the powder, removes loose gas between particles, and establishes initial contact and bridging between particles, creating a more uniform foundation for subsequent high-pressure compaction. The pressure is 10-30% of the final molding pressure. The goal is to stably fill the powder into the mold cavity to obtain a preliminary, relatively uniform but low-density green body skeleton. The pre-compression holding time is 0.5-2 seconds.

[0050] Medium pressure: The powder is further compacted under higher pressure to continue to expel gas. The pressure is 30% to 70% of the final forming pressure. After reaching the intermediate pressure stage, it is maintained for 0.5 to 2 seconds.

[0051] Brief pressure relief: After the medium-pressure phase ends, briefly release the pressure for 0.2~0.5 seconds. This small release causes a slight elastic expansion of the powder compact compressed under lower pressure. This expansion creates a brief localized negative pressure or decompression zone within the compact, which helps to "draw in" or diffuse residual gas (especially gas from deeper areas) that has been driven into the interior but not completely expelled to areas with lower pressure (such as the mold wall or powder surface), and then discharge it through the mold's venting channels. Simultaneously, this brief stress relief also helps alleviate the internal elastic stress accumulated during the initial compression, reducing the risk of cracking due to stress concentration when high pressure is immediately applied, especially for powders with high elasticity. Excessive pressure release time can cause the formed compact to collapse or crack, while insufficient release time results in poor rebound.

[0052] High pressure: Continue compacting the powder until the final green body density of 2.5~3.0 g / cm³, as required by the product design, is achieved. 3 The pressure is controlled at 50~80MPa, and the holding time is 5~20s. The method for calculating the green billet density is as follows: Press a cube-shaped green billet using the same dry pressing process, record the green billet weight M, measure and calculate the green billet volume V, and calculate the green billet density P=M / V. The green billet density is <2.5g / cm³. 3 This will lead to loose green bodies that collapse and crack, with a green body density > 3 g / cm³. 3If the green body is not properly compressed, it will be prone to springback and cracking. Springback will cause the green body to expand in volume, reducing the compatibility when combined with the ceramic film support. After sintering, the connection between the support and the end seal is prone to holes and gaps. Even if the green body density meets the requirements, if the pressure at each stage of dry pressing is not sufficient, it will still lead to the green body collapsing, cracking and springback.

[0053] Depressurization and demolding: After the high pressure holding is completed, depressurize at a rate of 2~4MPa / S, with a total depressurization time of 10~40S. After depressurization is completed, the end-sealed green blank can be removed.

[0054] S24. Drying: The green blank is placed in an oven and heated to 90~110℃, and held for 2~4 hours to remove some moisture from the green blank, thereby giving it a certain strength. After drying, the end-sealed green blank strength is ≥5MPa and the moisture content is ≤0.5%.

[0055] S3. Preparation of bonding slurry: By weight, mix and grind 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 50~80 parts of water to obtain a bonding slurry of the predetermined viscosity.

[0056] The bonding slurry is mainly composed of nano-alumina with a particle size of 70~100nm (to reduce sintering temperature and improve bonding strength) and a purity of ≥99%.

[0057] Dispersants are used to disperse nano-alumina and ensure the uniformity of the slurry. One or more of sodium hexametaphosphate, citric acid, ammonium polyacrylate, polyoxyethylene ether, and sodium polyacrylate are used. Insufficient dispersant leads to uneven dispersion of the nano-alumina powder, causing the slurry to easily agglomerate and settle. Excessive dispersant leads to an abnormal increase in slurry viscosity, making it difficult to control the thickness of the slurry when coated onto the clay blank, resulting in voids between the end-sintering seal and the support.

[0058] Sintering aids are used to lower the sintering temperature and improve the bond strength after sintering. They are typically one or more of kaolin, glass powder, silica sol, alumina sol, and talc. When the amount of sintering aid is low, the bond strength between the end seal and the support decreases after sintering, resulting in a tensile strength of <5000N at break. When the amount of sintering aid is high, it leads to increased shrinkage during sintering, making the end seal or support prone to tearing.

[0059] The preparation process is as follows:

[0060] S31. Grinding: After weighing according to the formula, pour the mixture into a grinding machine for high-speed grinding. The grinding speed is 80~100 rpm, and the grinding time is 30~60 minutes. The grinding target is based on the slurry viscosity, which should be controlled at 1500~2000 mPa·s. If the viscosity is too high, the slurry coating thickness will be uneven. If the viscosity is too low, the slurry will be too fluid, resulting in insufficient bonding slurry and ultimately causing voids between the end seal and the support after sintering.

[0061] S4. Combined sintering: After coating the two ends of the support body clay blank with bonding slurry and drying it, it is combined with the end-sealing green blank and sintered once to form an integrated structure. After sintering, the end-sealing pull-out performance and end-sealing air tightness are tested.

[0062] The preparation process is as follows:

[0063] S41. Bonding Assembly: Apply a layer of bonding slurry of a certain thickness to both ends of the support clay blank manually or by machine. The thickness of the bonding slurry is 0.5~1mm, and the width is 15~20mm. After application, allow it to dry at a temperature of 80~100℃ for 5~10 seconds. After drying, smoothly insert the end-sealing green blank into both ends of the support clay blank. Thickness Measurement Method: First, use a vernier caliper to measure the thickness h1 of the support clay blank. After the bonding slurry has dried, measure the dried dimension h2. The bonding slurry thickness h = h2 - h1.

[0064] S42. First sintering: The assembled support and end seals are placed in a shuttle kiln for high-temperature sintering. The maximum temperature for the first sintering is 1250~1300℃, and the total sintering time is 20~25h.

[0065] S43. End-seal testing: After the first sintering is completed, the end-seal pull-out performance and end-seal airtightness are tested. Pull-out performance testing method: Fix both ends of the ceramic membrane end seal on the pull-out testing machine. With one end fixed, apply a certain tensile force to the other end to pull the ceramic membrane. If the ceramic membrane support breaks but the connection between the end seal and the support does not break, or if the connection between the end seal and the support breaks, and the tensile force is ≥5000N, it can be said that the end seal and the ceramic membrane support are firmly bonded.

[0066] End-seal airtightness test: Block one end of the end seal and inject gas at a certain pressure (0.05~0.1MPa; too high a pressure will result in too many bubbles, making it difficult to observe; too low a pressure will prevent the formation of bubbles). Observe whether there are large bubbles at the connection between the end seal and the support. If there are no large bubbles, it indicates that the end seal and the ceramic membrane support are well bonded and there is no unevenness.

[0067] S5. Preparation of flat sheet membrane: By weight, 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 150~200 parts of water are mixed and ground to obtain a membrane slurry of predetermined viscosity. The membrane slurry is then sprayed onto the surface of the support after the first sintering. After drying, the finished ceramic flat sheet membrane is obtained by a second sintering. Finally, the airtightness between the end seal and the flat sheet membrane is tested.

[0068] The membrane formulation is identical to the adhesive slurry formulation, except that the water content is increased to 150-200 parts.

[0069] The preparation process is as follows:

[0070] S51. Grinding: After weighing according to the formula, pour into a grinding machine for high-speed grinding. The grinding speed is 80~100 rpm, and the grinding time is 30~60 min. The grinding target is based on the viscosity of the slurry, and the viscosity of the slurry is controlled at 1500~2000 mPa·s.

[0071] S52. Spraying: The semi-finished product after one sintering is sent into the spraying machine for spraying. After spraying, it is dried. The drying temperature is 80~100℃ and the drying time is 5~10S.

[0072] S53, Secondary sintering: After the coating is completed, the coating is placed in a shuttle kiln for secondary sintering. The maximum temperature of the secondary sintering is 1200~1250℃, and the total time of the secondary sintering is 20~25h.

[0073] S54. Leak detection: The test method is the same as that for end seal air tightness, but the test pressure needs to be increased to 0.2~0.3MPa. This is because the particle size of the powder used in the film layer is smaller, and the pore size of the product will be reduced by 2~5 times after spraying. Therefore, the test pressure needs to be increased. The test judgment criteria are the same as those for end seal air tightness.

[0074] Example 1

[0075] A co-firing process for an integrated ceramic flat sheet membrane and end-sealing includes the following steps:

[0076] S1. Preparation of ceramic flat sheet membrane support: By weight, 100 parts of micron-sized alumina, 2 parts of HPMC fiber, 1 part of dextrin, 1.5 parts of baking soda, 0.5 parts of wood ash, and 2 parts of kaolin are mixed evenly, and then 5 parts of silica sol, 4 parts of soybean oil, and 14 parts of water are added and kneaded into a plastic clay. The clay is then subjected to vacuum kneading, vacuum extrusion molding, and drying to obtain a support clay blank with a predetermined strength. The mixing and kneading time is 30 min, the vacuum degree is -0.08 MPa, the drying temperature is 100℃, and the drying time is 3 h. The dry strength test of the clay blank is 6.7 MPa, and the moisture content is 0.2%, which meets the requirements for combination with ceramic end seals.

[0077] S2. Preparation of end seals: By weight, 100 parts of micron-sized alumina, 2 parts of HPMC fiber, 1 part of dextrin, 1.5 parts of baking soda, 0.5 parts of wood ash, and 2 parts of kaolin are mixed evenly, and then 1 part of silica sol, 1 part of soybean oil, and 3 parts of water are added and kneaded into a loose material. The material is then dry-pressed and dried to obtain an end seal green body with a predetermined strength. The mixing and kneading time is 30 min, the drying temperature is 100℃, and the drying time is 3 h.

[0078] Dry pressing is performed according to the process parameters in Table 1. Specific examples are as follows:

[0079] Table 1 Parameters for each stage of dry pressing in the embodiment

[0080]

[0081] Note: The density of the green body after dry pressing meets the requirements, but the initial pressing should not be too high, otherwise the density of the green body will be close to or even lower than the lower limit.

[0082] Dry pressing is performed according to the process parameters in Table 2. A comparison is shown below:

[0083] Table 2 Parameters for each stage of comparative dry pressing molding

[0084]

[0085] As shown in Tables 1 and 2, if the pre-pressing, intermediate pressure, brief pressure release, high pressure, and pressure release rate of dry pressing are not performed according to the process conditions, problems such as collapse, cracking, and springback of the green body will occur. Generally speaking, (1) if the pressure is too low during the initial, intermediate, and high pressure, the green body will become loose and collapse; (2) if the initial or intermediate pressure is too low, even if the pressure is increased during the high pressure, it will still be impossible to ensure that the gas in the powder is removed, resulting in the green body expanding and springback after molding; (3) if the initial, intermediate, or high pressure is too high, there will still be a phenomenon that the gas in the powder cannot be removed, resulting in the green body expanding and springback after molding, or even cracking; (4) if the brief pressure release is canceled, the gas generated during the initial and intermediate pressure cannot be released, resulting in the green body expanding and springback after molding; (5) if the pressure release rate is too fast, the green body will be less stable after the high pressure is completed and is prone to collapse.

[0086] Select number 1 in Table 1 for the dry pressing process, keep the other processes unchanged, and only adjust the liquid auxiliary material ratio in the end-seal formulation. The specific parameters are shown in Table 3.

[0087] Table 3. Relevant parameters involved in the examples after adjusting the liquid excipient ratio of the end-sealing formulation.

[0088]

[0089] The liquid excipient ratio should be adjusted according to the process parameters in Table 4. A comparison is shown below:

[0090] Table 4 shows the relevant parameters involved in the comparative examples after adjusting the liquid excipient ratio of the end-sealing formulation.

[0091]

[0092] As shown in Tables 3 and 4, the proportions of liquid additives must be accurate. The amounts of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, and glycerin (commonly known as oils) should not be excessive; the total amount added should be controlled between 2% and 3%. Adding too much will lead to cracking during the subsequent sintering process. Adding too little will hinder dry pressing and cause the green body to collapse and crack.

[0093] S3. Preparation of bonding slurry: By weight, 100 parts of nano-alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 50~80 parts of water are mixed and ground to obtain a bonding slurry of a predetermined viscosity; wherein, the grinding speed is 100 rpm, the grinding time is 30 min, and the slurry viscosity is controlled at 1500~2000 mPa·s. For specific parameters of dispersant, sintering aid, water, and slurry viscosity, see Table 5 for examples and Table 6 for comparative examples.

[0094] S4. Combined sintering: After coating both ends of the support body clay blank with bonding slurry and drying, it is combined with the end-sealing green blank and sintered once to form an integrated structure. After sintering, the end-sealing pull-out performance and end-sealing air tightness are tested. The bonding slurry coating thickness is 0.5~1mm, the width is 15mm, the drying temperature is 100℃, the drying time is 7S, the first sintering temperature is 1270℃, the total sintering time is 21h, and the air tightness test pressure is 0.06MPa. For specific parameters of coating thickness, bonding strength and air tightness test results, see Table 5 for the example and Table 6 for the comparative example.

[0095] Table 5. Relevant parameters involved in the examples of preparing the binder slurry and the combined sintering process.

[0096]

[0097] Note: Following these process parameters will ensure a firm connection between the support and the end seal, and good airtightness (uniform air bubbles).

[0098] The adhesive mortar formulation was adjusted according to the process parameters in Table 6. A comparison is shown below:

[0099] Table 6. Relevant parameters involved in the comparative examples of binder slurry preparation and combined sintering processes.

[0100]

[0101] As shown in Tables 5 and 6, (1) if the amount of dispersant added is too small, the slurry will be unevenly dispersed, resulting in slurry deposition and making it impossible to proceed with subsequent processes. If the amount of dispersant added is too large, the viscosity of the slurry will increase abnormally, resulting in uneven slurry coating thickness, which will lead to gaps and pores after sintering. Even if the amount of water is increased to reduce the viscosity of the slurry, the dispersant will be severely diluted, resulting in uneven dispersion and slurry deposition. (2) If the amount of sintering aid added is too small, the strength after sintering will be low, and it will be easy to break when bumped. At the same time, gaps and pores will also exist after sintering. If the amount of sintering aid added is too large, the shrinkage after sintering will be large, which will cause the end seal to crack. (3) If the amount of water added is small, the viscosity of the slurry will be large, which will also lead to uneven coating thickness. If the amount of water added is large, it will be impossible to form a slurry layer of a certain thickness during coating, resulting in weak adhesion.

[0102] After the process described in Table 5, the ceramic membrane support and ceramic end seal can be firmly bonded together, resulting in good airtightness.

[0103] S5. Preparation of the flat sheet membrane: By weight, 100 parts of nano-alumina, 0.05-0.12 parts of dispersant, 4-8 parts of sintering aid, and 180 parts of water are mixed and ground to obtain a membrane slurry of a predetermined viscosity. The membrane slurry is then sprayed onto the surface of the support after the first sintering. After drying, a second sintering is performed to obtain the finished ceramic flat sheet membrane. Finally, the airtightness between the end seal and the flat sheet membrane is tested. The grinding speed is 100 rpm, the grinding time is 30 min, and the specific parameters of the dispersant and sintering aid are shown in Table 3. The second sintering temperature is 1240℃, the total second sintering time is 20 h, and the leak test pressure is 0.25 MPa. No large bubbles were found during the leak test, indicating a strong bond between the ceramic end seal and the ceramic membrane, suitable for filtration.

[0104] This invention upgrades plastic end seals to homogeneous ceramic end seals, making the ceramic membrane product suitable for all water qualities and completely eliminating the risk of end seal cracking and detachment. Simultaneously, the "integrated co-firing molding" process is used during the ceramic membrane sintering process, ensuring that the ceramic end seal and the ceramic membrane body are prepared simultaneously. This process eliminates the cumbersome steps required by traditional plastic end seals, such as post-sintering installation, adhesive bonding, and curing, significantly improving product reliability and production efficiency.

[0105] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0106] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0107] The present invention has been described above by way of example. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made by adopting the inventive concept and technical solution of the present invention, or direct application to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A co-firing process for an integrated ceramic flat film and end-sealing, characterized in that, Includes the following steps: S1. Preparation of ceramic flat film support: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and 18-25 parts of liquid auxiliary material are added to knead into plastic clay. The clay is then subjected to vacuum kneading, vacuum extrusion molding and drying to obtain a support blank with a predetermined strength. S2. Preparation of end seals: By weight, 100 parts of micron-sized alumina, 2-4 parts of adhesive, 2-4 parts of pore-forming agent and 1-3 parts of sintering aid are mixed together, and then 3-8 parts of liquid additives are added, kneaded and dry-pressed into shape. After drying, an end seal green blank with a predetermined strength is obtained. S3. Preparation of bonding slurry: By weight, mix and grind 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 50~80 parts of water to obtain a bonding slurry of the predetermined viscosity. S4. Combined sintering: After coating the two ends of the support body clay blank with bonding slurry and drying it, it is combined with the end-sealing green blank and sintered once to form an integrated structure. After sintering, the end-sealing pull-out performance and end-sealing air tightness are tested. S5. Preparation of flat sheet membrane: By weight, 100 parts of nano alumina, 0.05~0.12 parts of dispersant, 4~8 parts of sintering aid, and 150~200 parts of water are mixed and ground to obtain a membrane slurry of predetermined viscosity. The membrane slurry is then sprayed onto the surface of the support after the first sintering. After drying, the finished ceramic flat sheet membrane is obtained by a second sintering. Finally, the airtightness between the end seal and the flat sheet membrane is tested.

2. The integrated co-firing process for ceramic flat film and end-sealing as described in claim 1, characterized in that, In S1 and S2, the micron-sized alumina particles are 5~10μm in size and have a purity of ≥99%; the binder is one or more of HPMC cellulose, CMC cellulose, dextrin, polyvinyl alcohol and carbon fiber; the pore-forming agent is one or more of baking soda, wood ash, carbon powder, calcium carbonate, starch and soda ash; the sintering aid is one or more of kaolin, talc, titanium dioxide, magnesite and glass powder; and the liquid additive is one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerin and water.

3. The integrated co-firing process for ceramic flat film and end-sealing as described in claim 1, characterized in that, In S3 and S5, the nano-alumina particles have a size of 70~100nm and a purity of ≥99%; the dispersant is one or more of sodium hexametaphosphate, citric acid, ammonium polyacrylate, polyoxyethylene ether, and sodium polyacrylate; the sintering aid is one or more of kaolin, glass powder, silica sol, alumina sol, and talc.

4. The integrated co-firing process for ceramic flat film and end-sealing according to claim 1, characterized in that, During the preparation of S1, the mixing time is 30~60min; the kneading time is 30~60min; the vacuum degree during vacuum kneading and vacuum extrusion is -0.06~-0.08MPa; during the drying process, the oven temperature is raised to 90~110℃ and kept at that temperature for 2~4h. After drying, the strength of the support body clay blank is ≥5MPa and the moisture content is ≤0.5%.

5. The integrated co-firing process for ceramic flat sheet film and end-sealing according to claim 1, characterized in that, During the preparation of S2, the homogenization time is 30-60 min. During drying, the oven temperature is raised to 90-110℃ and held for 2-4 h. After drying, the end-sealed green body strength is ≥5 MPa, and the moisture content is ≤0.5%. The final molding pressure is 50-80 MPa. Dry pressing uses a staged pressure application method, including the following steps: Pre-compression: Initially arrange the powder and remove loose gas between particles. The pressure is 10-30% of the final molding pressure, and the pre-compression time is 0.5-2 seconds. Medium pressure: Further compact the powder and continue to expel gas. The pressure is 30% to 70% of the final molding pressure. After reaching the intermediate pressure stage, maintain it for 0.5 to 2 seconds. Brief pressure relief: After the medium pressure is released, briefly release the pressure for 0.2~0.5 seconds; High pressure: Continue compacting the powder until the final green body density of 2.5~3.0 g / cm³, as required by the product design, is achieved. 3 The pressure is controlled at 50~80MPa, and the pressure holding time is 5~20S; Depressurization and demolding: After the high pressure holding is completed, depressurize at a rate of 2~4MPa / S, with a total depressurization time of 10~40S. After depressurization is completed, the end-sealed green blank can be removed.

6. The integrated co-firing process for ceramic flat film and end-sealing according to claim 1, characterized in that, During the preparation of S3, the grinding speed is 80~100 rpm, the grinding time is 30~60 min, and the grinding target is based on the slurry viscosity, which is controlled at 1500~2000 mPa·s.

7. The integrated co-firing process for ceramic flat film and end-sealing according to claim 1, characterized in that, During the preparation of S4, the thickness of the adhesive slurry coating is 0.5~1mm and the width is 15~20mm. The drying temperature is 80~100℃ and the drying time is 5~10S. The maximum temperature for the first sintering is 1250~1300℃ and the total sintering time is 20~25h.

8. The integrated co-firing process for ceramic flat film and end-sealing according to claim 1, characterized in that, During the preparation of S5, the grinding speed is 80~100 rpm, the grinding time is 30~60 min, the grinding target is based on the slurry viscosity, and the slurry viscosity is controlled at 1500~2000 mPa·s; the drying temperature is 80~100℃, the drying time is 5~10 s; the maximum temperature for secondary sintering is 1200~1250℃, and the total duration of secondary sintering is 20~25 h.

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