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

Abstract

The application is a ceramic flat plate membrane and end seal integrated co-sintering forming process, comprising the following steps: S1, preparing a ceramic flat plate membrane support; S2, preparing an end seal; S3, preparing a bonding slurry; S4, combined sintering: after the bonding slurry is coated on both ends of the support mud body, drying is performed, then the end seal green body is combined, and an integrated structure is formed through one-time sintering, after sintering is completed, end seal drawing performance and end seal air tightness detection are performed; S5, preparing a flat plate membrane. After the plastic end seal is upgraded to a homogeneous ceramic end seal, the ceramic membrane product has full water quality applicability, and the risk of end seal cracking and falling off is completely solved. At the same time, in the ceramic membrane sintering process, the "integrated co-sintering forming" process is adopted, and the ceramic end seal and the ceramic membrane body are prepared synchronously. This process saves the complicated processes such as post-sintering installation, glue bonding and curing waiting required by the traditional plastic end seal, and significantly improves the product reliability and production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic membrane preparation, and particularly relates to a ceramic flat plate membrane and an end-sealing integrated co-sintering forming process. BACKGROUND

[0002] At present, in the field of water treatment (including industrial wastewater, production sewage and tap water purification, etc.), ceramic membranes have become the mainstream sewage purification technology due to their outstanding environmental protection and sustainable recyclability. However, the end-sealing components currently applied to ceramic flat plate membrane assemblies are generally made of plastic materials (such as PPO) and are bonded and packaged with ceramic membranes through epoxy resin glue or polyurethane glue. The defects in the prior art are as follows:

[0003] This packaging method has significant limitations: it has certain requirements for the water quality conditions of the treated water, and the water temperature generally cannot exceed 50 DEG C; the pH value is generally maintained within the range of 2 to 12. The reason is that when the water temperature is too high or the pH value is out of this range, the glue used as the bonding material and the plastic end-sealing itself are prone to aging, cracking and even falling off. At the same time, when the ceramic membrane product is operated in a relatively excellent water quality environment, the above problems may also occur due to the temperature difference between winter and summer, long-term contact with water and pressure during backwashing.

[0004] The risk brought by this is that during the ceramic membrane filtration process, impurity particles in the untreated sewage will directly penetrate into the clean water side along the cracks or falling-off end-sealing gaps, resulting in that the final effluent water quality cannot meet the standards. SUMMARY

[0005] The present application aims to solve the problem of cracking and falling off of glue or end-sealing during the operation of ceramic membrane products, and provides a ceramic flat plate membrane and end-sealing integrated co-sintering forming process, which does not need to be bonded with glue and can be applied to any water quality conditions to eliminate the phenomenon of end-sealing cracking and falling off.

[0006] To achieve the above-mentioned purpose, the following technical solution is adopted: a ceramic flat plate membrane and end-sealing integrated co-sintering forming process, comprising the following steps:

[0007] S1, preparing a ceramic flat plate membrane support: 100 parts of micron alumina, 2-4 parts of adhesion aid, 2-4 parts of pore former and 1-3 parts of sintering aid are mixed by weight, and then 18-25 parts of liquid auxiliary materials are added and kneaded into plastic clay, and then vacuum pugging, vacuum extrusion forming and drying treatment are sequentially performed to obtain a support clay body with a predetermined strength;

[0008] S2, end seal preparation: 100 parts of micron alumina, 2-4 parts of adhesion aid, 2-4 parts of pore forming agent and 1-3 parts of sintering aid are mixed, then 3-8 parts of liquid auxiliary is added and kneaded, and then dry pressing is performed to obtain an end seal green body with a predetermined strength after drying treatment;

[0009] S3, preparation of bonding slurry: 100 parts of nano alumina, 0.05-0.12 parts of dispersing agent, 4-8 parts of sintering aid and 50-80 parts of water are mixed and ground to obtain a bonding slurry with a predetermined viscosity;

[0010] S4, combined sintering: after the support body mud body is coated with the bonding slurry and dried, it is combined with the end seal green body, and then a one-time sintering is performed to form an integrated structure, and after sintering, the end seal drawing performance and the end seal air tightness are detected;

[0011] S5, preparation of flat plate membrane: 100 parts of nano alumina, 0.05-0.12 parts of dispersing agent, 4-8 parts of sintering aid and 150-200 parts of water are mixed and ground to obtain a membrane layer slurry with a predetermined viscosity, then the membrane layer slurry is sprayed on the surface of the support body after one-time sintering, dried and then subjected to two-time sintering to obtain a finished ceramic flat plate membrane, and finally the air tightness between the end seal and the flat plate membrane is detected.

[0012] In particular, in S1 and S2, the particle size of micron alumina is 5-10 μm, and the purity is ≥99%; the adhesion aid 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 powder, titanium white powder, magnesite and glass powder; the liquid auxiliary is one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerol and water.

[0013] In particular, in S3 and S5, the particle size of nano alumina is 70-100 nm, and the purity is ≥99%; the dispersing agent 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, aluminum sol and talc powder.

[0014] In particular, in the preparation process 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 to -0.08 MPa; the oven is heated to 90-110°C during drying treatment, and the temperature is maintained for 2-4 h, and after drying, the strength of the support body mud body is ≥5 MPa and the moisture content is ≤0.5%.

[0015] In particular, in the preparation process of S2, the mixing time is 30-60 min, the oven is heated to 90-110 DEG C during drying treatment, and the end-sealed green strength is greater than or equal to 5 MPa and the moisture is less than or equal to 0.5% after drying; the pressure is 50-80 MPa during final forming, and the dry pressing forming adopts a stepwise pressure increasing mode, including the following steps:

[0016] Pre-pressing: preliminary arrangement of powder, elimination of loose gas between particles, pressure is 10-30% of the final forming pressure, pre-pressing time is 0.5-2 s;

[0017] Medium pressure: further compacting the powder, continuing to eliminate the gas, the pressure is 30-70% of the final forming pressure, and the medium pressure stage is maintained for 0.5-2 s after reaching the medium pressure stage;

[0018] Short-term pressure relief: short-term release of pressure for 0.2-0.5 s after medium pressure ends;

[0019] High pressure: continue to compact the powder until the final green density of the product design requirement is reached, which is 2.5-3.0 g / cm 3 , the pressure is controlled at 50-80 MPa, and the pressure holding time is 5-20 s;

[0020] Pressure relief and demolding: after the high pressure holding ends, the pressure relief is carried out at a rate of 2-4 MPa / s, and the total pressure relief time is 10-40 s, and the end-sealed green body can be taken out after the pressure relief is completed.

[0021] In particular, in the preparation process of S3, the grinding speed is 80-100 rpm, the grinding time is 30-60 min, and the grinding target is the slurry viscosity, and the slurry viscosity is controlled at 1500-2000 mpa.s.

[0022] In particular, in the preparation process of S4, the bonding slurry coating thickness is 0.5-1 mm, the width is 15-20 mm, the drying temperature is 80-100 DEG C during drying treatment, and the drying time is 5-10 s; the highest temperature of the first sintering is 1250-1300 DEG C, and the total time of the first sintering is 20-25 h.

[0023] In particular, in the preparation process of S5, the grinding speed is 80-100 rpm, the grinding time is 30-60 min, and the grinding target is the slurry viscosity, and the slurry viscosity is controlled at 1500-2000 mpa.s; the drying temperature is 80-100 DEG C, the drying time is 5-10 s; the highest temperature of the second sintering is 1200-1250 DEG C, and the total time of the second 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] Fig. 1 This is a process flow diagram of the present invention;

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

[0027] Fig. 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 Figs. 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 auxiliary material is a key auxiliary material for powder kneading forming, and one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerol and water is adopted;

[0037] The preparation process is specifically as follows:

[0038] S11, homogenizing: after the solid powder is weighed according to the formula, it is poured into a homogenizer for homogenizing mixing, so that the raw materials are uniformly mixed, and the homogenizing time is 30-60 min;

[0039] S12, kneading: the mixed raw materials enter a kneader, and liquid auxiliary materials are added according to the formula ratio for kneading, so that the dry powder is kneaded into a mud mass under the action of the liquid auxiliary materials, and a mud material with certain plasticity is formed, and the kneading time is 30-60 min;

[0040] S13, vacuum mud conditioning: the kneaded mud material is subjected to a vacuum mud conditioning machine, so that the air in the mud material is completely removed, thereby forming a dense mud mass, and the vacuum degree is-0.06 to-0.08 MPa;

[0041] S14, vacuum extrusion: the mud material after mud conditioning enters a vacuum extruder, and the mud material is shaped through a customized mold to form a support body mud body, and the vacuum degree is-0.06 to-0.08 MPa;

[0042] S15, drying: the mud body is sent into an oven, and the temperature is raised to 90-110 DEG C, and the temperature is kept for 2-4 h, so that a certain amount of water in the mud body is removed, so that the mud body has a certain strength. After drying, the strength of the support body mud body is greater than or equal to 5 MPa, and the moisture content is less than or equal to 0.5%. If the strength is less than 5 MPa or the moisture content is greater than 0.5%, the mud body will be soft and easy to deform, which is not conducive to the subsequent combination with the ceramic end seal.

[0043] S2, preparation of end seal: according to the weight fraction, 100 parts of micron alumina, 2-4 parts of adhesion aid, 2-4 parts of pore forming agent and 1-3 parts of sintering aid are homogenized, and then 3-8 parts of liquid auxiliary material is added for kneading and dry pressing forming, and then drying treatment is performed to obtain an end seal green body with a predetermined strength;

[0044] The types and amounts of solid powder of the end seal formula are consistent with those of the support body formula, and the types of liquid auxiliary materials are consistent, but the amount needs to be reduced for subsequent dry pressing forming.

[0045] The preparation process is specifically as follows:

[0046] S21, homogenizing: after the solid powder is weighed according to the formula, it is poured into a homogenizer for homogenizing mixing, so that the raw materials are uniformly mixed, and the homogenizing time is 30-60 min;

[0047] S22, kneading: because less liquid auxiliary material is added during kneading, the mud material after kneading is in a scattered state and cannot form a mud mass like the support body.

[0048] S23, dry pressing: the kneaded bulk material is sent into a customized mold for dry pressing, the pressure during forming is 50-80 MPa (too low pressure will result in low green density and poor strength (easy to break, missing corners), difficult demolding and handling; too high pressure will result in too large elastic aftereffect, easy to crack and delamination (particles deform and accumulate elastic energy during pressure, part of which is recovered after pressure relief), aggravate the uneven density inside the body caused by mold wall friction (dense skin, loose center), and serious mold wear), in order to improve the uniformity of the end seal green body, a step-by-step pressure increasing method is used, including the following steps:

[0049] pre-pressing: preliminary arrangement of powder, elimination of loose gas between particles, establishment of preliminary inter-particle contact and bridging, to create a more uniform basis for subsequent high-pressure compaction, the pressure is 10-30% of the final forming pressure, the goal is to stably fill the powder into the mold cavity, and obtain a preliminary, relatively uniform but low-density body skeleton, the pre-pressing holding time is 0.5-2S;

[0050] medium pressure: further compacting the powder under higher pressure, continuing to eliminate gas, the pressure is 30%-70% of the final forming pressure, and the pressure is maintained for 0.5-2S after reaching the intermediate pressure stage;

[0051] short-term pressure relief: after the medium pressure is finished, the pressure is released for 0.2-0.5S; this small release action makes the powder body compressed at a lower pressure produce a small elastic expansion. This expansion forms a short-term local negative pressure or reduced pressure area in the body, which helps to "suck" or diffuse the residual gas (especially the gas in the deeper part) that has been driven into the interior but has not been completely discharged to the area with lower pressure (such as the mold wall or the powder surface), and then discharged through the exhaust passage of the mold. At the same time, this short-term stress release also helps to relieve the internal elastic stress accumulated during the early compression, reducing the risk of cracking caused by stress concentration when high pressure is immediately applied, especially for powders with high "elasticity". If the pressure release time is too long, the formed body will collapse or crack; if it is too short, the rebound effect will be poor;

[0052] high pressure: continue to compact the powder until the final green density of the product design requirement 2.5-3.0 g / cm 3 , the pressure is controlled at 50-80 MPa, and the pressure holding time is 5-20S. The green density calculation method: a cubic green body is pressed by the same dry pressing process, the green body weight M is recorded, the green body volume V is measured and calculated, and the green body density P=M / V is calculated. If the green density is less than 2.5 g / cm 3 , the green body will be loose and collapse, and the green density is greater than 3 g / cm 3, which will cause the green body to rebound and crack, and the rebound will cause the volume of the green body to expand, reducing the matching degree when combined with the ceramic membrane support, and the connection between the support and the end seal is prone to holes and gaps after sintering. Even if the green body density meets the requirements, if the pressure at each stage of the dry pressing process does not meet the requirements, the green body will still collapse, crack, and rebound;

[0053] Pressure relief demolding: after the high-pressure holding is completed, the pressure is released at a rate of 2-4 MPa / S, and the total pressure relief time is 10-40 S. The green body of the end seal can be taken out after the pressure relief is completed.

[0054] S24, drying: the green body is sent into an oven, the temperature is raised to 90-110°C, and the temperature is kept for 2-4 h to remove some water from the green body, so that the green body has a certain strength. After drying, the strength of the green body of the end seal is ≥5 MPa, and the moisture content is ≤0.5%.

[0055] S3, preparation of bonding slurry: 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 with a predetermined viscosity;

[0056] Among them, the bonding slurry is mainly nano alumina, the particle size of nano alumina is 70-100 nm (to reduce the sintering temperature and improve the bonding strength), and the purity is ≥99%;

[0057] The dispersant is used for the dispersion of nano alumina to ensure the uniformity of the slurry, and one or more of sodium hexametaphosphate, citric acid, ammonium polyacrylate, polyoxyethylene ether, and sodium polyacrylate is used. When the amount of dispersant added is small, the nano alumina powder is not uniformly dispersed, and the slurry is prone to clumping and settling. When the amount of dispersant added is large, the viscosity of the slurry will abnormally increase, the thickness of the slurry coated on the clay body is not easy to control, and holes exist between the end seal and the support after sintering;

[0058] The sintering aid is used to reduce the sintering temperature and improve the bonding strength after sintering, and one or more of kaolin, glass powder, silica sol, aluminum sol, and talc powder is used. When the amount of sintering aid is low, the bonding strength between the end seal and the support after sintering is reduced, and the tensile force when breaking is <5000 N. When the amount of sintering aid is large, the shrinkage during sintering increases, and the end seal or the support is prone to being cracked;

[0059] The preparation process is as follows:

[0060] S31, grinding: after weighing according to the formula, pour into the grinder for high-speed grinding, the grinding speed is 80~100r / min, the grinding time is 30~60min, the grinding target is the slurry viscosity, the slurry viscosity is controlled at 1500~2000mpa.s. If the viscosity is too large, the slurry coating thickness is uneven, if the viscosity is too low, the slurry fluidity is too large, resulting in less bonding slurry, finally causing holes between the end seal and the support after sintering;

[0061] S4, combined sintering: after coating the bonding slurry on both ends of the support mud blank, drying, then combining with the end seal green body, once sintering to form an integrated structure, after sintering, end seal drawing performance and end seal air tightness detection;

[0062] The preparation process is as follows:

[0063] S41, bonding combination: manually or mechanically scrape a layer of bonding slurry with a certain thickness on both ends of the support mud blank, the bonding slurry coating thickness is 0.5~1mm, the width is 15~20mm, after coating, drying treatment is carried out, the drying temperature is 80~100℃, the drying time is 5~10S; After drying, the end seal green body is smoothly sleeved on both ends of the support mud blank. Thickness measurement method: first test the thickness h1 of the support mud blank with a vernier caliper, then measure the dried size h2 after coating and drying the bonding slurry, the bonding slurry thickness h=h2-h1;

[0064] S42, once sintering: put the combined support and end seal into the shuttle kiln for high temperature sintering, the highest temperature of once sintering is 1250~1300℃, the total time of once sintering is 20~25h;

[0065] S43, end seal detection: after once sintering, end seal drawing performance and end seal air tightness detection. Drawing performance detection method: fix both ends of the ceramic membrane end seal on the drawing testing machine, one end is fixed, the other end is pulled with a certain pulling force to pull the ceramic membrane, when the ceramic membrane support is pulled off and the end seal and support connection is not pulled off, or the end seal and support connection is pulled off, the pulling force is ≥5000N, which indicates that the end seal and ceramic membrane support are firmly bonded.

[0066] End seal air tightness detection: block one end of the end seal, and inject a certain pressure of gas (pressure is 0.05~0.1MPa, too large bubble is too much, not easy to observe, too small pressure, can not form bubbles) into the other end, observe whether there is a large bubble at the connection between the end seal and the support. If there is no bubble, it indicates that the end seal and ceramic membrane support are well bonded, without unevenness.

[0067] S5, preparing flat sheet membrane: according to weight parts, 100 parts of nano-alumina, 0.05-0.12 parts of dispersing agent, 4-8 parts of sintering aid, 150-200 parts of water are mixed and ground to obtain a membrane layer slurry with a predetermined viscosity, then the membrane layer slurry is sprayed on the surface of the support after the first sintering, dried and sintered for the second time to obtain the finished ceramic flat sheet membrane, and finally the air tightness between the end seal and the flat sheet membrane is detected.

[0068] In the membrane layer formula, the water content is increased to 150-200 parts, and the rest is consistent with the adhesive slurry formula.

[0069] The preparation process is as follows:

[0070] S51, grinding: after weighing according to the formula, pour into the grinder for high-speed grinding, the grinding speed is 80-100 rpm, the grinding time is 30-60 min, the grinding target is 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 the first sintering is sent into the film spraying machine for spraying operation, and then dried at a temperature of 80-100℃ for 5-10s;

[0072] S53, second sintering: after spraying, put into the shuttle kiln for second sintering, the highest temperature of second sintering is 1200-1250℃, and the total time of second sintering is 20-25h;

[0073] S54, leak detection: the same as the air tightness detection method of end seal, but the test pressure needs to be increased to 0.2-0.3 MPa, because the particle size of the powder used in the membrane layer is smaller, the product aperture will be reduced by 2-5 times after spraying, therefore the test pressure needs to be increased, and the test judgment standard is the same as the air tightness detection of end seal.

[0074] Example 1

[0075] A ceramic flat sheet membrane and end seal integrated co-sintering forming process, comprising the following steps:

[0076] S1, preparing ceramic flat sheet membrane support: according to weight parts, 100 parts of micron alumina, 2 parts of HPMC fiber, 1 part of dextrin, 1.5 parts of baking soda, 0.5 parts of wood ash, 2 parts of kaolin are mixed, then 5 parts of silica sol, 4 parts of soybean oil and 14 parts of water are kneaded into plastic clay, and then vacuum kneading, vacuum extrusion molding and drying treatment are carried out in sequence to obtain a support clay body with a predetermined strength; the mixing and kneading time is 30 min, the vacuum degree is-0.08 MPa, the drying temperature is 100℃, the drying time is 3h, the clay body drying strength test is 6.7 MPa, and the moisture content is 0.2%, which meets the combination requirements with ceramic end seal.

[0077] S2, preparation of end seal: 100 parts of micron alumina, 2 parts of HPMC fiber, 1 part of dextrin, 1.5 parts of baking soda, 0.5 parts of wood ash, 2 parts of kaolin are uniformly mixed, then 1 part of silica sol, 1 part of soybean oil and 3 parts of water are kneaded into a bulk material, and then dry pressing is performed to form a green body, and then drying treatment is performed to obtain an end seal green body with a predetermined strength; the uniform mixing and kneading time is 30 min, the drying temperature is 100°C, and the drying time is 3h.

[0078] Dry pressing is performed according to the process parameters in Table 1, and the specific implementation is as follows:

[0079] Table 1 Process parameters of each stage of dry pressing of the embodiment

[0080]

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

[0082] Dry pressing is performed according to the process parameters in Table 2, and the comparative example is as follows:

[0083] Table 2 Process parameters of each stage of dry pressing of the comparative example

[0084]

[0085] As can be seen from Table 1 and Table 2, if the pre-pressing, intermediate-pressing, short-term pressure relief, high-pressure and pressure relief rates of dry pressing are not performed according to the process conditions, the green body will have problems such as collapse, cracking and rebound. Generally, (1) if the initial pressure, intermediate pressure and high pressure are low, the green body will be loose and collapsed; (2) if the initial pressure or intermediate pressure is low, even if the pressure is increased during high pressure, it is still impossible to ensure that the gas in the powder is excluded, resulting in volume expansion and rebound of the green body after molding; (3) if the initial pressure, intermediate pressure or high pressure is high, there is still a phenomenon that the gas in the powder cannot be discharged, resulting in volume expansion and rebound of the green body after molding, or even cracking; (4) if the short-term pressure relief is cancelled, the gas generated during the initial pressure and intermediate pressure cannot be dissipated, resulting in volume expansion and rebound of the green body after molding; (5) if the pressure relief rate is too fast, the green body after high pressure will have poor stability and be prone to collapse.

[0086] The dry pressing process is selected as No. 1 in Table 1, the remaining processes remain unchanged, only the liquid auxiliary material ratio in the end seal formula is adjusted, and the specific parameters are shown in Table 3.

[0087] Table 3 Related parameters involved in the embodiment after adjusting the liquid auxiliary material ratio of the end seal formula

[0088]

[0089] Liquid auxiliary material ratio adjustment, according to the process parameters in Table 4, the comparison is as follows:

[0090] Table 4 Related parameters involved in the comparative example of adjusting the liquid auxiliary material ratio of the end seal formula

[0091]

[0092] As shown in Table 3 and Table 4, the liquid auxiliary material ratio needs to be accurate, the addition amount of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol and glycerol (commonly known as oil) should not be too much, and the total addition amount should be controlled within 2-3%, otherwise it will lead to cracking during the subsequent sintering process. If the addition amount is too small, it is not conducive to dry pressing, and the green body is prone to collapse and cracking.

[0093] S3, preparing the bonding slurry: 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 with a predetermined viscosity; wherein the grinding speed is 100 rpm, the grinding time is 30 min, and the slurry viscosity is controlled within 1500-2000 mpa.s. The specific parameters of dispersant, sintering aid, water and slurry viscosity are shown in Table 5 and Table 6.

[0094] S4, combined sintering: after coating the bonding slurry on both ends of the support body mud body, drying, then combined with the end seal green body, once sintering to form an integrated structure, after sintering, end seal drawing performance and end seal air tightness detection; the coating thickness of the bonding slurry is 0.5-1 mm, the width is 15 mm, the drying temperature is 100℃, the drying time is 7s, the one-time sintering temperature is 1270℃, the total sintering time is 21h, and the air tightness detection pressure is 0.06MPa; the specific parameters of the coating thickness, bonding strength and air tightness test results are shown in Table 5 and Table 6.

[0095] Table 5 Related parameters involved in the preparation of bonding slurry and combined sintering process examples

[0096]

[0097] Note: According to this process parameter, it can ensure that the support body and the end seal are firmly connected, and the air tightness is good (the bubbles are uniform).

[0098] Adjusting the bonding slurry formula, according to the process parameters in Table 6, the comparison is as follows:

[0099] Table 6 Related parameters involved in the preparation of bonding slurry and combined sintering process examples

[0100]

[0101] From table 5 and table 6, (1) the dispersant is added too little, the slurry is not evenly dispersed, resulting in slurry deposition, which cannot proceed to subsequent process. If the dispersant is added too much, it will make the slurry viscosity abnormally increase, resulting in uneven slurry coating thickness, so that the sintering gap hole appears. Even if the amount of water is increased, the slurry viscosity is reduced, but the dispersant is seriously diluted, and uneven dispersion and slurry deposition also occur. (2) If the sintering additive is added too little, the sintering strength is low, and the fracture is easy to occur. At the same time, there are also gaps and holes after sintering. If the sintering additive is added too much, it will cause large shrinkage after sintering, so as to crack the end seal. (3) If the amount of water is small, the slurry viscosity is large, and uneven coating thickness will also occur. If the amount of water is large, it will cause the slurry layer of a certain thickness to be unable to form during coating, resulting in poor adhesion.

[0102] After the process of table 5, the ceramic membrane support and the ceramic end seal can be combined firmly, and the air tightness is good.

[0103] S5, preparing flat membrane: 100 parts of nano alumina, 0.05-0.12 parts of dispersant, 4-8 parts of sintering additive, 180 parts of water are mixed and ground to obtain a membrane layer slurry with a predetermined viscosity, then the membrane layer slurry is sprayed on the surface of the support after the first sintering, dried and sintered for the second time to obtain the finished ceramic flat membrane, and finally the air tightness between the end seal and the flat membrane is detected. The grinding speed is 100r / min, the grinding time is 30min, the specific parameters of the dispersant and the sintering additive are shown in table 3, the second sintering temperature is 1240℃, the total second sintering time is 20h, the leakage detection pressure is 0.25MPa, and no large bubble is found in the leakage detection, which indicates that the ceramic end seal and the ceramic membrane are combined firmly and can be used for filtration operation.

[0104] After the plastic end seal is upgraded to the homogeneous ceramic end seal, the ceramic membrane product has full water quality applicability, and the risk of end seal cracking and falling off is completely solved. At the same time, in the ceramic membrane sintering process, the "integrated co-sintering molding" process is adopted, and the ceramic end seal and the ceramic membrane body are prepared synchronously. This process saves the complicated processes such as installation, glue bonding and curing waiting required by the traditional plastic end seal, and significantly improves the product reliability and production efficiency.

[0105] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0106] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected or communicate with each other; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0107] The above is an exemplary description of the present application, and it is obvious that the specific implementation of the present application is not limited by the above manner, and various improvements using the method concept and technical scheme of the present application, or direct application to other occasions without improvement, are all within the protection scope of the present application.

Claims

1. A ceramic flat sheet membrane and end seal integrated co-firing forming process, characterized in that, The method comprises the following steps: S1, preparing a ceramic flat sheet membrane support: 100 parts of micron alumina, 2-4 parts of adhesion aid, 2-4 parts of pore former and 1-3 parts of sintering aid are uniformly mixed, then 18-25 parts of liquid auxiliary materials are added and kneaded into plastic clay, and the clay is subjected to vacuum pugging, vacuum extrusion molding and drying treatment in sequence to obtain a support green body with a predetermined strength; S2, preparing an end seal: 100 parts of micron alumina, 2-4 parts of adhesion aid, 2-4 parts of pore former and 1-3 parts of sintering aid are uniformly mixed, then 3-8 parts of liquid auxiliary materials are added and kneaded, and then dry pressing molding is performed, and the end seal green body with a predetermined strength is obtained after drying treatment; S3, preparing a bonding slurry: 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 with a predetermined viscosity; S4, combined sintering: the bonding slurry is coated on both ends of the support green body after drying, then the end seal green body is combined, and an integrated structure is formed after one-time sintering, and the end seal drawing performance and the end seal air tightness are detected after sintering is completed; S5, preparing a flat sheet membrane: 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 layer slurry with a predetermined viscosity, then the membrane layer slurry is sprayed on the surface of the support after one-time sintering, and the finished product ceramic flat sheet membrane is obtained after drying and two-time sintering, and finally the air tightness between the end seal and the flat sheet membrane is detected.

2. The process for integrated co-firing of ceramic flat sheet membrane and end cap according to claim 1, wherein In S1 and S2, the particle size of the micron alumina is 5-10 μm, and the purity is ≥99%; the adhesion aid is one or more of HPMC cellulose, CMC cellulose, dextrin, polyvinyl alcohol and carbon fiber; the pore former 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 powder, titanium white powder, magnesite and glass powder; and the liquid auxiliary material is one or more of rapeseed oil, soybean oil, tung oil, silica sol, aluminum sol, glycerol and water.

3. The process for integrated co-firing of ceramic flat sheet membrane and end cap according to claim 1, wherein In S3 and S5, the particle size of the nano alumina is 70-100 nm, and the purity is ≥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, aluminum sol and talc powder.

4. The process as claimed in claim 1, wherein the process is characterized by, In the preparation process of S1, the uniform mixing time is 30-60 min, the kneading time is 30-60 min, the vacuum degree during vacuum pugging and vacuum extrusion is-0.06--0.08 MPa, the oven is heated to 90-110 ℃ during drying treatment, and the temperature is maintained for 2-4 h, the strength of the support green body after drying is ≥5 MPa, and the moisture content is ≤0.5%.

5. The process as claimed in claim 1, wherein the process is characterized by, In the preparation process of S2, the uniform mixing time is 30-60 min, the oven is heated to 90-110 ℃ during drying treatment, and the temperature is maintained for 2-4 h, the strength of the end seal green body after drying is ≥5 MPa, the moisture content is ≤0.5%, and the pressure during final molding is 50-80 MPa; dry pressing molding is performed in a stepwise manner, comprising the following steps: Pre-pressing: preliminary arrangement of powder, to remove the loose gas between particles, the pressure is 10~30% of the final forming pressure, the pre-pressing time is 0.5~2S; Medium pressure: further compacting the powder, continue to remove the gas, the pressure is 30%~70% of the final forming pressure, keep for 0.5~2S after reaching the medium pressure stage; Short-term pressure relief: short-term release of pressure after medium pressure, 0.2~0.5S; High pressure: continue to compact the powder until the final green density of 2.5~3.0g / cm3 of the product design requirement is reached 3 , the pressure is controlled at 50~80MPa, and the pressure holding time is 5~20S; Pressure relief demolding: after the high pressure holding, release the pressure at the rate of 2~4MPa / S, the total pressure relief time is 10~40S, after the pressure relief, the end-sealed green body can be taken out.

6. The process as claimed in claim 1, wherein the process is characterized by, In the preparation process of S3, the grinding speed is 80~100r / min, the grinding time is 30~60min, and the grinding target is the slurry viscosity, which is controlled at 1500~2000mpa.s.

7. The process as claimed in claim 1, wherein the process is characterized by, In the preparation process of S4, the coating thickness of the bonding slurry is 0.5~1mm, the width is 15~20mm, the drying temperature is 80~100℃, the drying time is 5~10S; the highest temperature of the first sintering is 1250~1300℃, and the total time of the first sintering is 20~25h.

8. The process as claimed in claim 1, wherein the process is characterized by, In the preparation process of S5, the grinding speed is 80~100r / min, the grinding time is 30~60min, and the grinding target is the slurry viscosity, which is controlled at 1500~2000mpa.s; the drying temperature is 80~100℃, the drying time is 5~10S; the highest temperature of the second sintering is 1200~1250℃, and the total time of the second sintering is 20~25h.

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