Porous ceramic material prepared based on high internal phase emulsion template method and preparation method and application thereof

Abstract

The invention provides a porous ceramic material prepared based on a high internal phase emulsion template method and a preparation method and application thereof. The porous ceramic material is prepared from the following raw materials: a high internal phase emulsion and an adhesive, the high internal phase emulsion comprises a continuous phase and a dispersed phase; the continuous phase is a ceramic precursor aqueous solution; the dispersion phase is an emulsifier oil phase solution; the volume fraction of the dispersion phase in the high internal phase emulsion is 74-95%. According to the preparation method, the size of emulsion droplets is accurately regulated and controlled through a high internal phase emulsion template method, and accurate control over the pore diameter of the ceramic material is achieved, so that the porous ceramic material has high porosity and high strength, and is stable in structure, controllable in average pore diameter and wide in application range.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of porous ceramic materials, and particularly relates to a porous ceramic material prepared based on a high internal phase emulsion template method and a preparation method and application thereof. BACKGROUND

[0002] Porous ceramic materials have excellent high-temperature resistance, corrosion resistance, high specific surface area, light weight and other characteristics, and are in urgent demand in the fields of environment, energy, aerospace and the like.

[0003] However, the porous ceramic materials prepared by the existing preparation technology still have three core pain points.

[0004] 1. Difficulty in controlling pore size: Traditional processes (such as organic foam impregnation, direct foaming, sol-gel method, etc.) rely on random stacking of templates, and it is difficult to accurately control the pore size and distribution, resulting in a wide pore size distribution (50-1000 nm). The method for preparing the porous ceramic material disclosed in CN115231943B reduces the temperature for preparing the ceramic material, but due to the problem of substrate adhesion, problems such as falling off and agglomeration occur during the preparation process, making it difficult to uniformly control the pore size, and the pore size distribution CV=35%. When the obtained porous ceramic material is used as a catalyst carrier, insufficient large pores will result in low mass transfer efficiency; too few small pores will result in small specific surface area, insufficient adsorption sites, insufficient contact, and limited catalytic performance.

[0005] 2. Poor performance synergy: Existing materials cannot simultaneously achieve high porosity and high mechanical strength. To increase porosity, the amount of template needs to be increased, resulting in a loose ceramic skeleton that cannot meet the structural load requirements in industrial applications. The method disclosed in CN109553412B directly foams to prepare a porous ceramic, and the porosity can reach 75%-95%, but the strength is low and cannot meet the structural load requirements.

[0006] 3. Limited function and complex preparation: Traditional porous ceramics have limited functions and only have single physical properties such as adsorption and filtration. Functional porous ceramics (such as adsorption type and heat insulation type) need to be prepared in two steps (first prepare the ceramic matrix, then load the functional components), which is complicated and the functional components are easy to fall off.

[0007] Therefore, it is an urgent problem in the field to develop a porous ceramic material with controllable pore size, stable structure, high porosity and mechanical properties, and various functions, and a simple preparation method. SUMMARY

[0008] In view of the deficiencies of the prior art, the present application aims to provide a porous ceramic material prepared based on a high internal phase emulsion template method and a preparation method and application thereof.The porous ceramic material has high porosity and high strength, is stable in structure, has controllable pore size, and has a wide application range.

[0009] To achieve this purpose, the present application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a porous ceramic material, wherein the preparation raw material of the porous ceramic material comprises a high internal phase emulsion and a glue adhesive; the high internal phase emulsion comprises a continuous phase and a dispersed phase; the continuous phase is a ceramic precursor aqueous solution; the dispersed phase is an emulsifier oil phase solution; and the volume fraction of the dispersed phase in the high internal phase emulsion is 74-95%.

[0011] PolyHIPE (Polymer High Internal Phase Emulsion) is a kind of high polymer material with three-dimensional interconnected macroporous structure, which has great application potential in the fields of separation and adsorption, catalytic carrier, tissue engineering scaffold, etc. due to its high porosity, large specific surface area and excellent permeability. In the present application, the high internal phase emulsion formed by the continuous phase and the dispersed phase is used as the preparation raw material, the volume fraction of the dispersed phase is controlled in the range of 74-95%, the pore size is controlled by the emulsifier, and the emulsifier can also stabilize the oil-water interface; the stability of the ceramic precursor is maintained by the glue adhesive to avoid the collapse of the skeleton during sintering; and the size of the emulsion droplets can be controlled by combining with a specific emulsifier, so as to realize the controllable pore size; the structural stability of the ceramic skeleton is improved by the action of the glue adhesive while ensuring the high porosity of the material, so that the porous ceramic material has high porosity and high strength, is multifunctional, and the functional components such as adsorption active sites and heat insulation pores are uniformly distributed, the effect is stable and persistent, the pore size of the porous ceramic material is accurately controlled, the high porosity and high mechanical strength are coordinated, and the multifunctional characteristics are integrated, which greatly widens the application range of the porous ceramic material.

[0012] In the present application, the volume fraction of the dispersed phase in the high internal phase emulsion is 74-95%, for example, it can be 75%, 76%, 77%, 78%, 79%, 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, 85%, 85.5%, 86%, 86.5%, 87%, 87.5%, 88%, 88.5%, 89%, 89.5%, 90%, 91%, 92%, 93%, 94%, 95%, etc.

[0013] Preferably, the high internal phase emulsion is an oil-in-water emulsion. The oil-in-water system is selected in order to ensure the uniform dispersion of the ceramic precursor.

[0014] Preferably, the mass fraction of the ceramic precursor in the ceramic precursor aqueous solution is 10-40%, for example, it can be 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, etc.

[0015] In the present application, the mass fraction of the ceramic precursor is within a certain range, which can balance the density and porosity of the ceramic framework. When it is lower than 10%, the framework is too thin and easy to break; when it is higher than 40%, the porosity is easy to be filled and the porosity decreases.

[0016] Preferably, the ceramic precursor includes at least one of alumina, zirconia, silica, silicon nitride, and silicon carbide.

[0017] Preferably, the D50 of the ceramic precursor is 0.05-10 μm, for example, it can be 0.06 μm, 0.08 μm, 0.1 μm, 0.15 μm, 0.18 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, etc.

[0018] In the present application, the D50 of the ceramic precursor is within a certain range, which can obtain a porous ceramic material with uniform pore size distribution and dense distribution.

[0019] Preferably, the ceramic precursor aqueous solution further includes a dispersant.

[0020] Preferably, the dispersant includes at least one of trisodium citrate, polyvinylpyrrolidone, polyacrylic acid, and sodium hexametaphosphate.

[0021] Preferably, the mass of the dispersant is 2-20% of the mass of the ceramic precursor, for example, it can be 3%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, etc.

[0022] Preferably, the emulsifier oil phase solution includes an emulsifier and an organic solvent.

[0023] Preferably, the mass fraction of the emulsifier in the emulsifier oil phase solution is 2-15%, for example, it can be 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, etc.

[0024] In the present application, if the mass fraction of the emulsifier is too low, the emulsion is unstable; if the mass fraction is too high, there will be residues, affecting the pore size strength and the pore size is prone to shrinkage.

[0025] Preferably, the emulsifier comprises a complex of an organic compound and modified nanosilica.

[0026] Preferably, the mass ratio of the organic compound to the modified nanosilica is (1-6):1, wherein the specific value in (1-6) can be 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, etc.

[0027] Preferably, the organic compound comprises at least one of polyoxyethylene octyl phenyl ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and sodium dodecyl sulfonate.

[0028] Preferably, the modified nanosilica is nanosilica modified by a silane coupling agent.

[0029] In the present application, if the mass ratio of the organic compound to the modified nanosilica is <1, inorganic particle agglomeration will occur; if the mass ratio is >6, organic emulsifier residues will occur.

[0030] In the present application, by modifying the nanosilica, steric hindrance is formed, the interfacial strength is improved, and it is also beneficial to enhancing the compatibility of the emulsifier and the ceramic precursor, preventing the precursor from agglomerating, and improving the stability of the aqueous phase.

[0031] In the present application, the silane coupling agent includes but is not limited to KH550; the silane coupling agent hydrolyzes to generate a silanol group, which can react with the surface hydroxyl group formed in the aqueous solution of the ceramic precursor, dehydrates and condenses, and improves the interfacial strength.

[0032] Preferably, the organic solvent comprises at least one of n-hexane, cyclohexane, and xylene.

[0033] Preferably, the mass ratio of the adhesive to the ceramic precursor in the aqueous solution of the ceramic precursor is 1:(0.5~3), wherein the specific values ​​of (0.5~3) can be, for example, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, etc.

[0034] In this invention, if the proportion of adhesive is too small, the gel strength is insufficient and it is easy to break during sintering; if the proportion is too large, there is too much gel, which leads to easy shrinkage during sintering, resulting in cracks and defects.

[0035] Preferably, the adhesive comprises a combination of a first compound and an acid.

[0036] Preferably, the volume ratio of the first compound to the acid is (8~10):1, wherein the specific values ​​of (8~10) can be, for example, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, etc.

[0037] Preferably, the first compound includes at least one of ethyl silicate, silica sol, polyvinyl alcohol, and polyethylene glycol.

[0038] Preferably, the acid includes hydrochloric acid.

[0039] Preferably, the porosity of the porous ceramic is 80-95%, for example, it can be 82%, 84%, 86%, 88%, 90%, 92%, 94%, etc.

[0040] Preferably, the pore size of the porous ceramic is 0.5~100μm, for example, it can be 1μm, 2μm, 5μm, 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, 60μm, 70μm, 80μm, 90μm, 95μm, etc.

[0041] In a second aspect, the present invention provides a method for preparing the porous ceramic material described in the first aspect, the method comprising the following steps:

[0042] (1) Mix the high internal phase emulsion with the adhesive, let it stand, and obtain a ceramic emulsion gel;

[0043] (2) The ceramic emulsion gel is degreased and sintered to obtain the porous ceramic material.

[0044] In this invention, a high internal phase emulsion template method is used, with a high internal phase emulsion as a template, a ceramic precursor solution as the continuous phase, and an organic solvent containing a functional emulsifier as the dispersed phase, to construct a stable high internal phase emulsion with an internal phase volume fraction of 80-95%. By adjusting the emulsion droplet size, the pore size of the ceramic material is precisely controlled. Then, after adhesive curing, debinding and sintering, a ceramic material with a hierarchical porous structure is obtained. The resulting porous ceramic material has both high porosity and high strength.

[0045] Preferably, the method for preparing the high internal phase emulsion includes: adding the dispersed phase dropwise to the continuous phase under stirring conditions, and continuing to mix and stir after the dropwise addition is completed to obtain the high internal phase emulsion.

[0046] Preferably, the stirring speed is 200~1000 rpm, for example, it can be 220 rpm, 250 rpm, 300 rpm, 350 rpm, 420 rpm, 450 rpm, 480 rpm, 500 rpm, 520 rpm, 550 rpm, 580 rpm, 600 rpm, 620 rpm, 650 rpm, 680 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm, etc.

[0047] Preferably, the dripping rate is 1~15 mL / min, for example, it can be 1.2 mL / min, 1.5 mL / min, 1.8 mL / min, 2 mL / min, 2.2 mL / min, 2.5 mL / min, 2.8 mL / min, 3 mL / min, 3.2 mL / min, 3.5 mL / min, 3.8 mL / min, 4 mL / min, 4.2 mL / min, 4.5 mL / min, 4.8 mL / min, 5 mL / min, 6 mL / min, 8 mL / min, 10 mL / min, 12 mL / min, 14 mL / min, etc.

[0048] Preferably, the mixing and stirring time after the dripping is completed is 5 to 120 minutes, for example, 10 minutes, 15 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 62 minutes, 65 minutes, 68 minutes, 70 minutes, 72 minutes, 75 minutes, 78 minutes, 80 minutes, 82 minutes, 85 minutes, 88 minutes, 90 minutes, 100 minutes, 110 minutes, 115 minutes, etc.

[0049] In this invention, the method for preparing the continuous phase includes: ultrasonically dispersing a ceramic precursor with water and an optional dispersant at 100-500W for 30-75 minutes to obtain the continuous phase.

[0050] In this invention, the method for preparing the dispersed phase includes: mixing an emulsifier with an organic solvent and stirring at a speed of 400-700 rpm until completely dissolved to obtain the dispersed phase.

[0051] Preferably, the settling temperature is room temperature and the time is 0.5 to 10 hours, for example, 1 hour, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, etc.

[0052] Preferably, the step of drying the ceramic emulsion gel is further included before the degreasing and sintering.

[0053] In this invention, the drying process includes vacuum drying.

[0054] Preferably, the degreasing sintering includes a first heating, degreasing, a second heating, and sintering performed sequentially.

[0055] Preferably, the heating rate of the first heating is 0.5~15℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, etc.; the temperature is raised to 300~700℃, for example, it can be 350℃, 400℃, 450℃, 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃, 600℃, 650℃, 680℃, etc.

[0056] Preferably, the degreasing time is 1 to 6 hours, for example, 1.2 hours, 1.5 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, etc.

[0057] Preferably, the heating rate of the second heating is 0.5~15℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, etc.; the temperature is raised to 1000~1800℃, for example, it can be 1050℃, 1100℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃, 1700℃, 1750℃, etc.

[0058] Preferably, the sintering time is 1 to 8 hours, for example, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, 4 hours, 4.2 hours, 4.5 hours, 4.8 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, etc.

[0059] Thirdly, the present invention provides an application of the porous ceramic material prepared by the high internal phase emulsion template method described in the first aspect in the fields of environment, energy, and aerospace.

[0060] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] The porous ceramic material provided by this invention uses a high internal phase emulsion as a template, which can control the size of the emulsion droplets and achieve precise control of the pore size of the porous ceramic material. This results in a porous ceramic material with controllable average pore size and stable structure, thus expanding the application of porous ceramic materials.

[0063] In this invention, the porous ceramic material uses a high internal phase emulsion as a template, adds an adhesive, and forms a dense ceramic skeleton through gel curing and high-temperature sintering. This synergistic effect helps to improve the strength of the porous ceramic material. At the same time, the volume fraction of the dispersed phase is controlled within the range of 74-95% to form a high porosity foam, achieving the performance requirements of "high porosity-high strength".

[0064] In this invention, a composite emulsifier system of "organic compound and modified nano silica" is used. Compared with the single emulsifier or unmodified inorganic particulate emulsifier in the prior art, the amphiphilic properties of "hydrophobic segments anchoring the oil phase and hydrophilic segments stabilizing the aqueous phase" and the synergistic effect of modified nano silica achieve the stability of high internal phase emulsion.

[0065] In this invention, the porous ceramic material is integrally formed, with the ceramic powder and emulsion template being formed simultaneously. The functional components (such as adsorption active sites and heat insulation pores) are evenly distributed, requiring no subsequent loading, and the effect is stable and long-lasting. Attached Figure Description

[0066] Figure 1 This is a scanning electron microscope image of the porous ceramic material provided in Embodiment 1 of the present invention. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0068] All materials used in this invention are commercially available or prepared using conventional methods; unless otherwise specified, the materials used in this invention are as follows:

[0069] Polyoxyethylene octylphenyl ether: OP-10 from Haian Petrochemical Plant, Jiangsu Province.

[0070] Modified nano-silica (modified with silane coupling agent KH550): Aladdin reagent, particle size D50 20nm.

[0071] Polyvinylpyrrolidone: Maclean's reagent, PVP K30 grade.

[0072] Polyvinyl alcohol: Maclean's reagent, catalog number 767382

[0073] Trisodium citrate: Maclean's reagent, AR grade.

[0074] Alumina powder: Ningbo Jinlei Nanomaterials Technology Co., Ltd., D50 is 1μm, purity is 99.9%.

[0075] Zirconia powder: Ningbo Jinlei Nanomaterials Technology Co., Ltd., D50 is 1μm, purity is 99.9%.

[0076] Silica powder: Ningbo Jinlei Nanomaterials Technology Co., Ltd., D50 is 0.5μm, purity is 99.9%.

[0077] Ethyl silicate: Maclean's reagent, analytical grade.

[0078] Example 1

[0079] This embodiment provides a porous ceramic material, and the preparation method of the porous ceramic material includes the following steps:

[0080] (1) Weigh 20g of alumina powder and 2g of trisodium citrate, add them to 80mL of deionized water, and ultrasonically disperse at 200W for 45min to obtain an alumina precursor solution with a mass fraction of 20%, which is the continuous phase; the mass of sodium citrate is 10% of the mass of alumina powder.

[0081] (2) Weigh 3g of polyoxyethylene octylphenyl ether and 1g of modified nano silica (modified with silane coupling agent KH550), add them to 96mL of cyclohexane, and stir at 500rpm for 30min to obtain an emulsifier oil phase solution with a mass fraction of 4%, which is the dispersed phase; the mass ratio of polyoxyethylene octylphenyl ether to modified nano silica is 3:1;

[0082] (3) While stirring at 500 rpm, the dispersed phase was added dropwise to the continuous phase at a rate of 10 mL / min, where the continuous phase was 80 mL and a total of 400 mL of dispersed phase was added. After the addition was completed, stirring was continued for 20 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion was 83.3%.

[0083] (4) Add 20g of adhesive (18mL of ethyl silicate + 2mL of hydrochloric acid) to the high internal phase emulsion, let it stand at room temperature for 3h to allow the emulsion to solidify and obtain block alumina emulsion gel; the mass ratio of the adhesive to the alumina powder is 1:1.

[0084] (5) The alumina emulsion gel was vacuum dried at 70°C and -0.09 MPa for 18 hours, and then degreased in a muffle furnace at 5°C / min to 550°C for 2.5 hours, and then sintered at 1400°C for 4 hours. After cooling, the porous alumina ceramic was obtained, which is the porous ceramic material.

[0085] The morphology of the obtained porous ceramic material was characterized by scanning electron microscopy, and the results are as follows: Figure 1 As shown; by Figure 1 It can be seen that the porous ceramic material provided by the present invention has high porosity and uniform pore size distribution.

[0086] Example 2

[0087] This embodiment provides a porous ceramic material, and the preparation method of the porous ceramic material includes the following steps:

[0088] (1) Weigh 30g of zirconia powder and 3g of polyvinylpyrrolidone, add them to 70mL of deionized water, and ultrasonically disperse them at 300W for 60min to obtain a 30% zirconia precursor solution, which is the continuous phase; the mass of polyvinylpyrrolidone is 10% of the mass of zirconia powder.

[0089] (2) Weigh 5g of polyoxyethylene octylphenyl ether and 1.7g of modified nano silica (modified with silane coupling agent KH550), add them to 93.3mL of n-hexane, and stir at 600rpm for 40min to obtain an emulsifier oil phase solution with a mass fraction of 6.7%, which is the dispersed phase; the mass ratio of polyoxyethylene octylphenyl ether to modified nano silica is 2.94:1;

[0090] (3) While stirring at 600 rpm, the dispersed phase was added dropwise to the continuous phase at a rate of 14 mL / min, where the continuous phase was 70 mL and a total of 350 mL of dispersed phase was added. After the addition was completed, stirring was continued for 25 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion was 83.3%.

[0091] (4) Add 15g of adhesive (the volume ratio of ethyl silicate to hydrochloric acid is 9:1) to the high internal phase emulsion, let it stand at room temperature for 2.5h to allow the emulsion to solidify and obtain block zirconia emulsion gel; the mass ratio of the adhesive to the zirconia powder is 1:2.

[0092] (5) The zirconia emulsion gel was vacuum dried at 80°C and -0.09 MPa for 24 hours, then degreased in a muffle furnace at 5°C / min to 600°C for 2 hours, and then sintered at 1600°C for 5 hours. After cooling, zirconia porous ceramic was obtained, which is the porous ceramic material.

[0093] Example 3

[0094] This embodiment provides a porous ceramic material, and the preparation method of the porous ceramic material includes the following steps:

[0095] (1) Weigh 20g of silica powder and 2g of trisodium citrate, add them to 80mL of deionized water, and ultrasonically disperse at 200W for 45min to obtain a silica precursor solution with a mass fraction of 20%, which is the continuous phase; the mass of sodium citrate is 10% of the mass of silica powder.

[0096] (2) Weigh 3g of polyoxyethylene octylphenyl ether and 1g of modified nano silica (modified with silane coupling agent KH550), add them to 96mL of xylene, and stir at 500rpm for 30min to obtain an emulsifier oil phase solution with a mass fraction of 4%, which is the dispersed phase; the mass ratio of polyoxyethylene octylphenyl ether to modified nano silica is 3:1;

[0097] (3) While stirring at 500 rpm, the dispersed phase was added dropwise to the continuous phase at a rate of 10 mL / min, where the continuous phase was 80 mL and a total of 400 mL of dispersed phase was added. After the addition was completed, stirring was continued for 20 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion was 83.3%.

[0098] (4) Add 20g of adhesive (18mL of ethyl silicate + 2mL of hydrochloric acid) to the high internal phase emulsion, let it stand at room temperature for 3h to allow the emulsion to solidify and obtain blocky silica emulsion gel; the mass ratio of the adhesive to the silica powder is 1:1.

[0099] (5) The silica emulsion gel was vacuum dried at 70°C and -0.09 MPa for 18 hours, and then degreased in a muffle furnace at 5°C / min to 550°C for 2.5 hours, and then sintered at 1400°C for 4 hours. After cooling, the porous silica ceramic was obtained, which is the porous ceramic material.

[0100] Example 4

[0101] This embodiment provides a porous ceramic material, and the preparation method of the porous ceramic material includes the following steps:

[0102] (1) Weigh 10g of alumina powder, 10g of silica powder, and 2g of trisodium citrate, add them to 80mL of deionized water, and ultrasonically disperse at 200W for 45min to obtain an alumina-silica composite precursor solution with a mass fraction of 20%, which is the continuous phase; the mass of sodium citrate is 10% of the total mass of alumina and silica powder.

[0103] (2) Weigh 3g of polyoxyethylene octylphenyl ether and 1g of modified nano silica (modified with silane coupling agent KH550), add them to 96mL of cyclohexane, and stir at 500rpm for 30min to obtain an emulsifier oil phase solution with a mass fraction of 4%, which is the dispersed phase; the mass ratio of polyoxyethylene octylphenyl ether to modified nano silica is 3:1;

[0104] (3) While stirring at 500 rpm, the dispersed phase was added dropwise to the continuous phase at a rate of 10 mL / min, where the continuous phase was 80 mL and a total of 400 mL of dispersed phase was added. After the addition was completed, stirring was continued for 20 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion was 83.3%.

[0105] (4) Add 20g of adhesive (18mL of ethyl silicate + 2mL of hydrochloric acid) to the high internal phase emulsion, let it stand at room temperature for 3h to allow the emulsion to solidify and obtain blocky alumina-silica composite emulsion gel; the total mass ratio of the adhesive to the alumina and silica powder is 1:1.

[0106] (5) The alumina-silica composite emulsion gel was vacuum dried at 70°C and -0.09 MPa for 18 hours, and then degreased in a muffle furnace at 5°C / min to 550°C for 2.5 hours, and then sintered at 1400°C for 4 hours. After cooling, the alumina-silica composite porous ceramic was obtained, which is the porous ceramic material.

[0107] Example 5

[0108] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the ratio of polyoxyethylene octylphenyl ether to modified nano silica remains unchanged, and the content of both is increased so that the mass fraction of emulsifier in the emulsifier oil phase solution is 20%. That is, in step (2), 15g of polyoxyethylene octylphenyl ether and 5g of modified nano silica (modified with silane coupling agent KH550) are weighed and added to 80mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 20%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0109] Example 6

[0110] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the ratio of polyoxyethylene octylphenyl ether to modified nano silica remains unchanged, and the content of both is reduced so that the mass fraction of emulsifier in the emulsifier oil phase solution is 1%. That is, in step (2), 0.75g of polyoxyethylene octylphenyl ether and 0.25g of modified nano silica (modified with silane coupling agent KH550) are weighed and added to 99mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 1%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0111] Example 7

[0112] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the total mass of the polyoxyethylene octylphenyl ether and the modified nano silica remains unchanged, and the mass ratio is 0.5:1. That is, in step (2), 1.33g of polyoxyethylene octylphenyl ether and 2.67g of modified nano silica (modified with silane coupling agent KH550) are weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0113] Example 8

[0114] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the total mass of the polyoxyethylene octylphenyl ether and the modified nano silica remains unchanged, and the mass ratio is 7:1. That is, in step (2), 3.5g of polyoxyethylene octylphenyl ether and 0.5g of modified nano silica (modified with silane coupling agent KH550) are weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0115] Example 9

[0116] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the total mass of the polyoxyethylene octylphenyl ether and the modified nano silica remains unchanged, and there is no polyoxyethylene octylphenyl ether. That is, in step (2), 4g of modified nano silica (modified with silane coupling agent KH550) is weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0117] Example 10

[0118] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the total mass of the polyoxyethylene octylphenyl ether and the modified nano silica remains unchanged. That is, in step (2), 4g of polyoxyethylene octylphenyl ether is weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. There is no modified nano silica. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0119] Example 11

[0120] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the polyoxyethylene octylphenyl ether is replaced with an equal mass of lauryl alcohol polyoxyethylene ether. That is, in step (2), 3g of lauryl alcohol polyoxyethylene ether and 1g of modified nano silica (modified with silane coupling agent KH550) are weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. Other raw materials, dosages and preparation methods are the same as in Example 1.

[0121] Example 12

[0122] This embodiment provides a porous ceramic material, which differs from Example 1 only in that the modified nano-silica is replaced with an equal mass of modified alumina. Specifically, in step (2), 3g of polyoxyethylene octylphenyl ether and 1g of modified nano-alumina (modified with silane coupling agent KH550) are weighed and added to 96mL of cyclohexane to obtain an emulsifier oil phase solution with a mass fraction of 4%. Other raw materials, dosages, and preparation methods are the same as in Example 1.

[0123] Comparative Example 1

[0124] This comparative example provides a porous ceramic material, which is prepared by the sol-gel method, specifically including the following steps:

[0125] (1) Weigh 18 mL of ethyl silicate, 2 mL of hydrochloric acid, 5 mL of ethanol and 10 mL of deionized water, mix them and stir for 2 h to form silica sol;

[0126] (2) Add 5g of alumina powder to the silica sol and continue stirring for 1h to obtain a uniformly mixed sol;

[0127] (3) Heat the sol obtained in step (2) to 60°C and let it stand for 2.5 hours to allow the emulsion to solidify and form a gel;

[0128] (4) The gel was vacuum dried at 70°C and -0.09 MPa for 18 hours, and then degreased in a muffle furnace at 5°C / min to 550°C for 2.5 hours. After that, it was heated to 1400°C and sintered for 4 hours. After cooling, alumina porous ceramic was obtained, which is the porous ceramic material.

[0129] Comparative Example 2

[0130] This comparative example provides a porous ceramic material, which differs from Example 1 only in that the volume fraction of the dispersed phase in the high internal phase emulsion is 71.4%, that is, in step (3) of the preparation method, the continuous phase is 80 mL, and a total of 200 mL of dispersed phase is added dropwise. After the addition is completed, stirring is continued for 20 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion is 71.4%; other raw materials, dosages and preparation methods are the same as in Example 1.

[0131] Comparative Example 3

[0132] This comparative example provides a porous ceramic material, which differs from Example 1 only in that the volume fraction of the dispersed phase in the high internal phase emulsion is 96.8%, that is, in step (3) of the preparation method, the continuous phase is 80 mL, and a total of 2400 mL of dispersed phase is added dropwise. After the addition is completed, stirring is continued for 20 min to form a milky white and stable high internal phase emulsion, wherein the volume fraction of the dispersed phase in the high internal phase emulsion is 96.8%; other raw materials, dosages and preparation methods are the same as in Example 1.

[0133] Comparative Example 4

[0134] This comparative example provides a porous ceramic material, and the specific preparation method includes the following steps:

[0135] (1) Weigh 20g of alumina powder (D50=1μm), 2g of polyvinyl alcohol, and 1g of sodium dodecyl sulfate, add them to 80mL of water, and stir for 2h to form a slurry;

[0136] (2) Air is introduced into the slurry while stirring at 500 rpm for 30 min to obtain foam slurry;

[0137] (3) The foam slurry is dried at 60°C for 12 hours to obtain ceramic blank;

[0138] (4) The ceramic blank is heated to 550°C at 5°C / min in a muffle furnace for 2.5 hours to degrease, and then heated to 1400°C for 4 hours to sinter. After cooling, alumina porous ceramic is obtained, which is the porous ceramic material.

[0139] Performance testing

[0140] (1) Porosity: The porosity of the porous ceramic materials provided in the test examples and comparative examples was tested using the liquid displacement method. The dry porous ceramic material was weighed (m1), then immersed in anhydrous ethanol until saturated, and after being removed and dried, the surface of the ethanol was weighed (m2). The porosity P = (m2 - m1) / (ρ 乙醇 ×V 多孔陶瓷 The porosity of the open-pore porous ceramic material is required to be ≥70% (100%).

[0141] (2) Pore diameter: The cross-section of the porous ceramic material was observed using a scanning electron microscope (SEM). 100 pores were selected to measure the diameter and the average pore diameter D50 was calculated. The average pore diameter deviation was required to be ≤25%.

[0142] (3) Compressive strength: The MTS universal tensile tester was used to test the porous ceramic material. The porous ceramic material was cut into cubic specimens of 10mm×10mm×10mm and compressed at 25℃ and 1mm / min. The stress-strain curve was obtained and the compressive strength was obtained from the stress-strain curve. The test result was the average value of 3 parallel specimens.

[0143] (4) Pore size distribution: The porous ceramic material was cut into cuboids of 10mm×10mm×5mm, sputtered with gold, and observed with a scanning electron microscope (SEM). The diameter of 100 pores was counted. The average value d and standard deviation S of the diameter of 100 pores were calculated, and CV = S / d × 100%.

[0144] The specific test results are shown in Table 1.

[0145] Table 1

[0146]

[0147] As shown in Table 1, the porous ceramic material provided by this invention uses a high internal phase emulsion as a template, controlling the dispersed phase volume fraction within the range of 74-95%. This allows for control over the size of the emulsion droplets, achieving precise control over the pore size of the porous ceramic material. This results in a porous ceramic material with controllable average pore size and stable structure. Furthermore, the addition of an adhesive, followed by gel curing and high-temperature sintering, forms a dense ceramic framework, synergistically enhancing the strength of the porous ceramic material and achieving the performance requirements of "high porosity-high strength," with a uniform pore size distribution. The porous ceramic material exhibits a porosity ≥80%, compressive strength ≥6MPa, and CV value ≤12%.

[0148] In Example 9, the absence of polyoxyethylene octylphenyl ether (i.e., the absence of organic compounds) resulted in the emulsifier being unable to anchor the oil phase, causing the emulsion to separate into layers after standing. In Example 10, the lack of modified nano-silica led to a decrease in interfacial modulus, resulting in a compressive strength of only 7.1 MPa.

[0149] As can be seen from Comparative Examples 1 to 4, porous ceramic materials are not prepared using high internal phase emulsions as templates, or the volume fraction of the dispersed phase in the high internal phase emulsion is not within a specific range. As a result, the porosity of the obtained porous ceramic materials is reduced, and / or the compressive strength is reduced and the pore size distribution is uneven.

[0150] In Comparative Example 3, the dispersed phase volume fraction was too high, resulting in an excessively thin continuous phase that could not form a stable interfacial film. Consequently, the oil phase droplets coalesced directly, preventing the formation of an emulsion.

[0151] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A porous ceramic material prepared based on a high internal phase emulsion template method, characterized in that, The raw materials for preparing the porous ceramic material include a high internal phase emulsion and an adhesive. The high internal phase emulsion comprises a continuous phase and a dispersed phase; The continuous phase is an aqueous solution of a ceramic precursor. The dispersed phase is an emulsifier oil phase solution; The volume fraction of the dispersed phase in the high internal phase emulsion is 74-95%.

2. The porous ceramic material according to claim 1, characterized in that, The high internal phase emulsion is an oil-in-water emulsion; Preferably, the mass fraction of the ceramic precursor in the aqueous solution of the ceramic precursor is 10-40%. Preferably, the ceramic precursor includes at least one of alumina, zirconium oxide, silicon dioxide, silicon nitride, and silicon carbide; Preferably, the D50 of the ceramic precursor is 0.05~10μm.

3. The porous ceramic material according to claim 1 or 2, characterized in that, The aqueous solution of the ceramic precursor also includes a dispersant; Preferably, the dispersant comprises at least one of trisodium citrate, polyvinylpyrrolidone, polyacrylic acid, and sodium hexametaphosphate; Preferably, the mass of the dispersant is 2 to 20% of the mass of the ceramic precursor.

4. The porous ceramic material according to any one of claims 1 to 3, characterized in that, The emulsifier oil phase solution includes an emulsifier and an organic solvent; Preferably, the mass fraction of the emulsifier in the oil phase solution is 2-15%; Preferably, the emulsifier comprises a complex of an organic compound and modified nano-silica; Preferably, the mass ratio of the organic compound to the modified nano-silica is (1~6):1; Preferably, the organic compound includes at least one of polyoxyethylene octylphenyl ether, fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and sodium dodecyl sulfonate; Preferably, the modified nano-silica is silane coupling agent modified nano-silica; Preferably, the organic solvent includes at least one selected from hexane, cyclohexane, xylene, toluene, and petroleum ether.

5. The porous ceramic material according to any one of claims 1 to 4, characterized in that, The mass ratio of the adhesive to the ceramic precursor in the aqueous solution of the ceramic precursor is 1:(0.5~3); Preferably, the adhesive comprises a combination of a first compound and an acid; Preferably, the volume ratio of the first compound to the acid is (8~10):1; Preferably, the first compound includes at least one of ethyl silicate, silica sol, polyvinyl alcohol, polyethylene glycol, and carboxymethyl cellulose; Preferably, the acid includes hydrochloric acid.

6. The porous ceramic material according to any one of claims 1 to 5, characterized in that, The porosity of the porous ceramic is 80-95%; Preferably, the porous ceramic has a pore size of 0.5~100μm.

7. A method for preparing porous ceramic materials based on the high internal phase emulsion template method according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: (1) Mix the high internal phase emulsion with the adhesive, let it stand, and obtain a ceramic emulsion gel; (2) The ceramic emulsion gel is degreased and sintered to obtain the porous ceramic material.

8. The preparation method according to claim 7, characterized in that, The method for preparing the high internal phase emulsion includes: adding the dispersed phase dropwise to the continuous phase under stirring conditions, and continuing to mix and stir after the dropwise addition is completed to obtain the high internal phase emulsion; Preferably, the stirring speed is 200~1000 rpm; Preferably, the dropping rate is 1~15 mL / min; Preferably, the mixing and stirring time after the dripping is completed is 5 to 120 minutes.

9. The preparation method according to claim 7 or 8, characterized in that, The settling temperature is room temperature, and the time is 0.5~10h; Preferably, the step of drying the ceramic emulsion gel before degreasing and sintering is further included; Preferably, the degreasing sintering includes a first heating, degreasing, a second heating, and sintering performed sequentially; Preferably, the heating rate of the first heating is 0.5~15℃ / min, and the temperature is raised to 300~700℃; Preferably, the degreasing time is 1-6 hours; Preferably, the heating rate of the second heating is 0.5~15℃ / min, and the temperature is raised to 1000~1800℃; Preferably, the sintering time is 1 to 8 hours.

10. The application of a porous ceramic material prepared by the high internal phase emulsion template method according to any one of claims 1 to 6 in the fields of environment, energy, and aerospace.

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