Method for preparing high-strength porous ceramic material by blending multi-morphology inorganic ceramic particles

Abstract

The invention discloses a method for preparing a high-strength porous ceramic material by blending multi-morphology inorganic ceramic particles, and belongs to the technical field of porous ceramic material preparation. The method comprises the following steps: mixing angular inorganic ceramic particles with at least one of spherical inorganic ceramic particles and flaky inorganic ceramic particles to obtain a mixed base material; uniformly mixing the mixed base material with a binder, a pore forming agent, a sintering aid, a plasticizer and a solvent to obtain uniform ceramic pug; preparing the ceramic pug into a ceramic base material; and sintering the ceramic base material to obtain the porous ceramic material. The preparation method has the beneficial effects that through the synergistic effect of angular and spherical or flaky particles, the bending strength is improved by 25%-45% compared with that of a traditional single-morphology ceramic material, and the porosity is stabilized at 35%-45%; according to the method, the use amount of a pore-forming agent and a binder can be reduced by 10%-15%, the sintering temperature window is wide, the performance target can be achieved at the temperature of 1300-1600 DEG C, and the energy consumption cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of porous ceramic material preparation, and specifically relates to a method for preparing high-strength porous ceramic material by blending inorganic ceramic particles with multiple morphologies. Background Art

[0002] Porous ceramic materials have important application value in key fields such as industrial filtration, separation and purification, and catalytic carriers due to their unique high specific surface area, excellent temperature resistance, and chemical stability. Traditional preparation processes generally use single-morphology ceramic particles (angular, spherical, or flaky) as substrates, but there are significant performance defects: the multi-angular pore structure formed by the accumulation of angular particles is prone to stress concentration, resulting in low bending strength of the material; spherical particles (pure spherical, quasi-spherical, quasi-spherical) can increase the volume density through dense stacking, but the porosity drops sharply to below 20%; and the flaky particle system has the advantage of interlayer slip, but the anisotropic shrinkage can easily lead to structural instability. What is more noteworthy is that single-morphology particles are prone to non-uniform shrinkage during the sintering process due to differences in particle size distribution or morphological consistency, which in turn forms microcracks and leads to a wide pore size distribution.

[0003] The long-standing technical bottleneck in this field lies in the inverted relationship between the macroscopic properties of the material. The increase in porosity is often accompanied by a decrease in bending strength, while the enhancement of mechanical properties inevitably causes the degradation of the pore structure. Summary of the invention

[0004] The purpose of an embodiment of the present invention is to provide a method for preparing high-strength porous ceramic materials by blending inorganic ceramic particles of multiple morphologies, which fully utilizes the complementary advantages of particles of different morphologies, maintains a relatively high porosity, and significantly improves the bending strength of the material; this method not only solves the inverted contradiction between porosity and mechanical strength caused by traditional single-morphology particle systems, but also can achieve significant improvement in the performance of porous ceramic materials by optimizing the raw material ratio or preparation process of porous ceramic materials, thereby solving at least one technical problem involved in the background technology.

[0005] This is achieved specifically through the following technical solutions:

[0006] The embodiment of the present invention provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies, comprising the following steps:

[0007] Step S1, mixing angular inorganic ceramic particles with at least one of spherical inorganic ceramic particles and flaky inorganic ceramic particles according to mass percentage to obtain a mixed substrate;

[0008] Step S2, uniformly mixing the mixed substrate with a binder, a pore former, a sintering aid, a plasticizer and a solvent according to mass percentage to obtain a uniform ceramic mud;

[0009] Step S3, preparing the ceramic mud into a ceramic substrate with a preset morphology;

[0010] Step S4, sintering the ceramic substrate in a gas environment at a temperature of 1300° C. to 1600° C., and obtaining a porous ceramic material after cooling.

[0011] Optionally, in step S1, the inorganic ceramic particles are one of aluminum oxide, zirconium oxide, titanium dioxide and silicon dioxide.

[0012] Optionally, in step S1, the particle size of the angular inorganic ceramic particles is 1 to 50 μm, the particle size of the spherical inorganic ceramic particles is 0.5 to 30 μm, and the particle size ratio of the spherical inorganic ceramic particles to the angular inorganic ceramic particles is 1:1 to 1:3.

[0013] Optionally, in step S1, when the angular inorganic ceramic particles and the spherical inorganic ceramic particles are mixed, the mass proportion of the spherical inorganic ceramic particles in the mixed base material is 10% to 25%.

[0014] Optionally, in step S1, the spherical inorganic ceramic particles include pure spherical inorganic ceramic particles, quasi-spherical inorganic ceramic particles and quasi-spherical inorganic ceramic particles.

[0015] Optionally, in step S2, the binder is selected from at least one of polyvinyl alcohol, polyacrylic acid or its derivatives, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, ethyl cellulose, natural polysaccharides, and modified starch; the pore former is at least one of an organic pore former or an inorganic pore former; the sintering aid is at least one of magnesium oxide, calcium oxide, silicon dioxide, titanium dioxide, clay, and kaolin; the plasticizer is at least one of polyethylene glycol, ethylene glycol, glycerol, propylene glycol, oleic acid, tung oil, and vegetable oil; and the solvent is water.

[0016] Optionally, in step S2, the added amounts of the binder, pore former, sintering aid, plasticizer and solvent are 2% to 5%, 5% to 20%, 1% to 5%, 1% to 5% and 5% to 60% of the mass of the mixed substrate, respectively.

[0017] Optionally, in step S3, the preparation method adopts at least one of extrusion molding, slip casting molding, tape casting or dry powder pressing.

[0018] Optionally, in step S4, the gas is one of air, nitrogen, and argon; and a staged heating method is used for sintering, specifically including: in the first stage, the temperature is increased to 600°C at a rate of 1-5°C / min and kept warm for 1 to 2 hours to remove moisture and organic matter in the ceramic mud; in the second stage, the temperature is increased to a target temperature of 1300°C to 1600°C at a rate of 2-10°C / min and kept warm for 1 to 3 hours to promote particle neck growth and enhance grain boundary bonding; in the third stage, the temperature is reduced to 900°C at a rate of 2 to 5°C / min and then naturally cooled to avoid cracks caused by thermal stress.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention achieves synergistic enhancement of material strength and porosity by precisely controlling the compounding ratio of angular, spherical and flaky inorganic ceramic particles and optimizing the gradient sintering process. Its strengthening mechanism is embodied in a three-dimensional complementary effect or a synergistic effect of two-dimensional enhancement: the angular particles construct a rigid skeleton to maintain structural stability, and the spherical particles optimize the stress transfer path by filling the gaps to form a "truss-filling" structure, which significantly improves the mechanical strength while ensuring the porosity. The angular and flaky composite system forms a "truss-laminate" composite structure with the angular particles in an interlayer insertion manner through the two-dimensional plane constraint effect, and its crack deflection and bridging effect improve the fracture toughness, thereby promoting the improvement of mechanical strength. In addition, the size-morphology grading of the multimodal particles can effectively relieve the sintering interface stress, inhibit local shrinkage differences, and form a more uniform pore structure.

[0021] 2. The present invention improves the bending strength by 25%-45% compared with the traditional single-morphology ceramic materials through the synergistic effect of angular and spherical or flaky particles, and the porosity is stabilized at 35%-45%.

[0022] 3. Compared with the ceramic materials prepared from inorganic ceramic particles of single morphology, the porous ceramic materials prepared by the present invention can reduce the amount of pore-forming agents and binders (by 10% to 15%) while achieving the same bending strength, and the sintering temperature window is wide, and the performance targets can be achieved at 1300°C-1600°C, thereby reducing energy consumption costs.

[0023] 4. The present invention has a wide range of applications, and is suitable for filtration, separation, catalysis and other application fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, without paying creative work, the drawings of other embodiments can be obviously derived based on the technical solutions disclosed in these drawings, among which:

[0025] Figure 1 The SEM images of the alumina powders with different morphologies provided by the present invention are shown below;

[0026] Figure 2 The SEM surface images of the ceramic materials prepared in Examples 1 to 7;

[0027] Figure 3 The SEM surface images of the ceramic materials prepared in Comparative Examples 1 to 4 are shown;

[0028] Figure 4 The pore size distribution diagram of the ceramic materials prepared in Examples 1 to 7;

[0029] Figure 5 The pore size distribution diagram of the ceramic materials prepared in Comparative Examples 1 to 4;

[0030] Figure 6 The bending strength and porosity variation diagram of the ceramic materials prepared in Examples 1 to 7 and Comparative Examples 1 to 4;

[0031] Figure 7 This is a physical picture of the ceramic membrane provided by the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The terms "first", "second", etc. in the specification and claims of the present invention are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0034] The embodiment of the present invention provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies, comprising the following steps:

[0035] Step S1, mixing angular inorganic ceramic particles with at least one of spherical inorganic ceramic particles and flaky inorganic ceramic particles according to mass percentage to obtain a mixed substrate;

[0036] Step S2, uniformly mixing the mixed substrate with a binder, a pore former, a sintering aid, a plasticizer and a solvent according to mass percentage to obtain a uniform ceramic mud;

[0037] Step S3, preparing the ceramic mud into a ceramic substrate with a preset morphology;

[0038] Step S4, sintering the ceramic substrate in a gas environment at a temperature of 1300° C. to 1600° C., and obtaining a porous ceramic material after cooling.

[0039] In step S1, the inorganic ceramic particles are one of aluminum oxide, zirconium oxide, titanium dioxide and silicon dioxide.

[0040] The particle size of the angular inorganic ceramic particles is 1 to 50 μm, the particle size of the spherical inorganic ceramic particles is 0.5 to 30 μm, and the particle size ratio of the spherical inorganic ceramic particles to the angular inorganic ceramic particles is 1:1 to 1:3.

[0041] In a specific embodiment, when the angular inorganic ceramic particles are mixed with the spherical inorganic ceramic particles, the mass proportion of the spherical inorganic ceramic particles in the mixed matrix is ​​10% to 25%.

[0042] It should be additionally explained that the spherical inorganic ceramic particles include pure spherical inorganic ceramic particles, quasi-spherical inorganic ceramic particles and quasi-spherical inorganic ceramic particles.

[0043] In step S2, the binder is selected from at least one of polyvinyl alcohol, polyacrylic acid or its derivatives, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, ethyl cellulose, natural polysaccharides, and modified starch; the pore former is at least one of an organic pore former or an inorganic pore former; the sintering aid is at least one of magnesium oxide, calcium oxide, silicon dioxide, titanium dioxide, clay, and kaolin; the plasticizer is at least one of polyethylene glycol, ethylene glycol, glycerol, propylene glycol, oleic acid, tung oil, and vegetable oil; and the solvent is water.

[0044] In a specific embodiment, the added amounts of the binder, pore former, sintering aid, plasticizer and solvent are 2% to 5%, 5% to 20%, 1% to 5%, 1% to 5% and 5% to 60% of the mass of the mixed substrate, respectively.

[0045] In step S3, the preparation method adopts at least one of extrusion molding, slip casting molding, tape casting or dry powder pressing.

[0046] In step S4, the gas is one of air, nitrogen and argon; the sintering is carried out by a staged heating method, specifically including: in the first stage, the temperature is increased to 600°C at a rate of 1-5°C / min and kept warm for 1-2 hours to remove moisture and organic matter in the ceramic mud; in the second stage, the temperature is increased to the target temperature of 1300°C~1600°C at a rate of 2-10°C / min and kept warm for 1-3 hours to promote the growth of particle necks and enhance the grain boundary bonding strength; in the third stage, the temperature is reduced to 900°C at a rate of 2-5°C / min and then naturally cooled to avoid cracks caused by thermal stress.

[0047] The method for preparing high-strength porous ceramic materials by blending inorganic ceramic particles of various morphologies provided by the present invention is described in detail below with specific examples and comparative examples.

[0048] In the following examples, the angular, spherical and flaky inorganic ceramic particles used are Al 2 O 3 See also Figure 1 As shown in the figure, the particle size of the angular, spherical and flaky inorganic ceramic particles is 5μm, and the particle size ratio is 1:1. The morphology of the spherical inorganic ceramic particles is quasi-spherical and pure spherical. HPMC is selected as the binder, and the addition amount is 5% of the mass of the alumina substrate. The pore-forming agent is corn starch, and the addition amount is 10% of the mass of the alumina substrate. The sintering aid is clay, and the addition amount is 5% of the mass of the alumina substrate. The plasticizer (lubricant) is tung oil and soybean oil, and the addition amount is 1% and 5% of the mass of the alumina substrate, respectively. The solvent is water. Since the selected ceramic molding process is extrusion molding, the amount of water added is 24.5% of the mass of the alumina substrate. The specific amount of solvent needs to be appropriately adjusted according to the humidity and temperature on the day of production; the sintering atmosphere during the sintering process is air. Finally, a porous ceramic membrane is formed.

[0049] Example 1

[0050] Example 1 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies, and the specific steps are as follows:

[0051] (1) Raw material mixing and plasticization: Add angular alumina with a particle size of 5 μm (accounting for 95% of the mass of the alumina substrate) and quasi-spherical alumina (accounting for 5% of the mass of the alumina substrate) into a kneader, and simultaneously add 5% of the mass of the alumina substrate, 10% of corn starch and 10% of clay, and mix for 20 minutes. Then inject a plasticizer combination (1% of the mass of the alumina substrate, tung oil + 5% of the mass of the alumina substrate, soybean oil) and continue mixing for 10 minutes until the system is uniform. Finally, add 24.5% of the mass of the alumina substrate in three times by atomization spraying, and mix for 20 minutes to obtain a ceramic blank with good plasticity. During this period, pay attention to observe the plasticity of the mud, control the gradient of the amount of water added, and adjust the amount of water added appropriately.

[0052] (2) Billet aging and homogenization: The mixed billet was transferred to a constant temperature and humidity chamber (temperature 25°C, relative humidity 65%) for 24 hours of aging treatment, followed by three cycles of degassing treatment using a vacuum kneader (vacuum degree: -0.08MPa), and continued to age for 24 hours to eliminate internal stress.

[0053] (3) Extrusion molding process: A vertical or horizontal hydraulic extruder is used in combination with a porous plate (or tube) mold to prepare a wet-process ceramic blank with a specification of 72 mm wide × 6 mm thick × 150 mm long (the tube type has an outer diameter of 30 mm and 19 holes). For details, see Figure 7 shown.

[0054] (4) Shaping and drying: Using a microwave-hot air coupled drying system, pre-treat in a microwave oven at low power for 90 seconds to achieve rapid shaping, and then transfer to a drying oven for step-by-step drying: 40°C / 4h→50°C / 4h→60°C / 4h, with a final moisture content of ≤0.5%.

[0055] (5) Gradient sintering: The shaped ceramic blank is sintered using a multi-stage temperature-controlled sintering process. In the first stage (degreasing stage), the temperature is raised to 600°C at a rate of 1°C / min and kept at this temperature for 2 hours to remove organic matter; in the second stage (densification stage), the temperature is raised to the target temperature of 1400°C at a rate of 2.5°C / min and kept at this temperature for 2 hours to achieve grain boundary diffusion; in the third stage (structural stabilization stage), the temperature is lowered to 900°C at a rate of 2°C / min and then naturally cooled in the furnace to obtain a porous ceramic membrane.

[0056] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 38.1 MPa, a porosity of 37.6%, an average pore size d of 0.543±0.293 μm, and a pure water flux of 2709 L / (m 2·h·bar). Scanning electron microscopy analysis shows that compared with comparative example 1, after adding quasi-spherical particles, the ceramic material becomes denser and the mechanical properties are strengthened, but due to the small number of spherical particles, the bending strength does not increase much. At this time, the porosity is less affected and the ceramic membrane has a higher pure water flux.

[0057] Example 2

[0058] Example 2 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 1, except that in the alumina matrix, angular alumina accounts for 90% of the mass of the alumina substrate, and quasi-spherical alumina accounts for 10% of the mass of the alumina substrate.

[0059] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 38.7 MPa, a porosity of 36.8%, an average pore size d of 0.527±0.300 μm, and a pure water flux of 2233 L / (m 2 ·h·bar). Scanning electron microscopy analysis shows that compared with comparative example 1, the mechanical properties of the ceramic material are enhanced after adding quasi-spherical particles. When the mass ratio of quasi-spherical particles is increased to 10%, the bending strength increases by 2.4%. Here, the mechanism for improving the bending strength is the filling effect of quasi-spherical alumina, which reduces the gaps between angular particles and makes the structure more compact, thereby improving the bending strength; therefore, the porosity is reduced, but the degree of reduction is small, and the ceramic membrane still has a high pure water flux.

[0060] Example 3

[0061] Example 3 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 1, except that in the alumina matrix, angular alumina accounts for 85% of the mass of the alumina substrate, and quasi-spherical alumina accounts for 15% of the mass of the alumina substrate.

[0062] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 42.6 MPa, a porosity of 40.4%, an average pore size d of 0.516±0.243 μm, and a pure water flux of 2432 L / (m 2·h·bar). Scanning electron microscopy analysis shows that compared with comparative example 1, the ceramic material becomes denser and its mechanical properties are enhanced after adding quasi-spherical particles. When the mass ratio of quasi-spherical particles is increased to 15%, the filling degree increases, and the quasi-spherical particles disperse more stress in the stress field, which is beneficial to improve the toughness of the ceramic material, and then improve the bending strength, with an increase of 12.7%. However, the porosity is less affected, and the ceramic membrane can still maintain a high pure water flux.

[0063] Example 4

[0064] Example 4 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of multiple morphologies. The specific steps are the same as those of Example 1, except that in the alumina matrix, angular alumina accounts for 80% of the mass of the alumina substrate, and quasi-spherical alumina accounts for 20% of the mass of the alumina substrate.

[0065] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 54.9 MPa, a porosity of 37.5%, an average pore size d of 0.509±0.241 μm, and a pure water flux of 2469 L / (m 2 ·h·bar). Scanning electron microscopy analysis shows that compared with comparative example 1, the ceramic material becomes denser and its mechanical properties are enhanced after adding quasi-spherical particles. When the mass ratio of quasi-spherical particles is increased to 20%, a composite reinforcement structure of "angular main skeleton + spherical secondary network" is formed, which fills the gap and disperses the stress. The bending strength increases by 45.2%. Figure 6 It was observed that the mechanical properties of the ceramic membrane were optimal at this time. At the same time, the porosity was less affected and the ceramic membrane still maintained a high pure water flux.

[0066] Example 5

[0067] Example 5 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 1, except that in the alumina matrix, angular alumina accounts for 75% of the mass of the alumina substrate, and quasi-spherical alumina accounts for 25% of the mass of the alumina substrate.

[0068] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 46.2 MPa, a porosity of 39.7%, an average pore size d of 0.526±0.239 μm, and a pure water flux of 2705 L / (m 2·h·bar). Scanning electron microscope analysis shows that compared with comparative example 1, the ceramic material becomes denser and its mechanical properties are enhanced after adding quasi-spherical particles. When the mass ratio of quasi-spherical particles is increased to 25%, the bending strength increases by 22.2%. Figure 6 It was observed that the mechanical properties of the ceramic membrane decreased compared with Example 4. This is because too many quasi-spherical particles may cause agglomeration, resulting in insufficient compactness in local areas, defects, and decreased strength. Even so, its bending strength is still higher than that of the ceramic membrane prepared by single-morphology alumina, and the porosity is less affected. The ceramic membrane still has a high pure water flux.

[0069] Example 6

[0070] Example 6 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 3, except that the quasi-spherical alumina is replaced by pure spherical alumina, that is, in the alumina matrix, angular alumina accounts for 85% of the mass of the alumina substrate, and pure spherical alumina accounts for 15% of the mass of the alumina substrate.

[0071] Recombination Figure 2 , Figure 4 and Figure 6 As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 45.6 MPa, a porosity of 38.3%, an average pore size d of 0.434±0.184 μm, and a pure water flux of 2508 L / (m 2 ·h·bar). Scanning electron microscopy analysis shows that compared with comparative example 1, after adding quasi-spherical particles, the ceramic material becomes dense and the mechanical properties are enhanced. When the mass fraction of pure spherical particles added is 15%, the bending strength increases by 20.6%. Comparative Example 3, at the same amount of spherical alumina added, the bending strength of the ceramic film prepared by blending pure spherical alumina is higher than that of the quasi-spherical one. This is because the morphology uniformity of pure spherical alumina is high, and the contact points with the angular particles may be more or more uniform, which is conducive to stress transfer; at the same time, it is also more conducive to material diffusion during the sintering process, forming a stronger grain boundary bond.

[0072] Example 7

[0073] Example 7 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 3, except that the quasi-spherical alumina is replaced by flaky alumina, that is, in the alumina matrix, angular alumina accounts for 85% of the mass of the alumina substrate, and flaky alumina accounts for 15% of the mass of the alumina substrate.

[0074] Recombination Figure 2 , Figure 4 and Figure 6As shown, the porous ceramic membrane prepared in this embodiment has a three-point bending strength of 41.7 MPa, a porosity of 39.2%, an average pore size d of 0.447±0.200 μm, and a pure water flux of 2206 L / (m 2 ·h·bar). Scanning electron microscopy analysis shows that compared with Comparative Examples 1 and 4, the ceramic material prepared by mixing the two types of alumina particles is denser and has enhanced mechanical properties.

[0075] Comparative Example 1

[0076] Comparative Example 1 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 1, except that angular alumina accounts for 100% of the mass of the alumina substrate, and alumina of other morphologies is not blended.

[0077] Recombination Figure 3 and Figure 5 As shown, the porous ceramic membrane prepared in this comparative example has a three-point bending strength of 37.8 MPa, a porosity of 40.5%, an average pore size d of 0.448 ± 0.183 μm, and a pure water flux of 2061 L / (m 2 ·h·bar). Scanning electron microscopy shows that the ceramic material prepared from single angular particles has a loose structure, so the porosity is high, but it also leads to a low bending strength of the material.

[0078] Comparative Example 2

[0079] Comparative Example 2 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 1, except that quasi-spherical alumina accounts for 100% of the mass of the alumina substrate, and angular alumina is not blended.

[0080] Recombination Figure 3 and Figure 5 As shown, the porous ceramic membrane prepared in this comparative example has a three-point bending strength of 13.8 MPa, a porosity of 42.6%, an average pore size d of 0.453±0.189 μm, and a pure water flux of 2719 L / (m 2 ·h·bar). Scanning electron microscopy shows that the structure of the ceramic material formed by the single quasi-spherical particles is tighter than that of the comparative example 1, but its spherical shape leads to fewer contact points between particles and lack of interlocking structure. Therefore, the grain boundary area formed during sintering is insufficient, resulting in poor bending strength of the material.

[0081] Comparative Example 3

[0082] Comparative Example 3 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 6, except that pure spherical alumina accounts for 100% of the mass of the alumina substrate, and angular alumina is not blended.

[0083] Recombination Figure 3 and Figure 5 As shown, the porous ceramic membrane prepared in this comparative example has a three-point bending strength of 5.9 MPa, a porosity of 43.5%, an average pore size d of 0.380 ± 0.142 μm, and a pure water flux of 2264 L / (m 2 ·h·bar). Scanning electron microscopy shows that, compared with Comparative Examples 1, 2 and 4, the ceramic material prepared from pure spherical particles has a compact structure, but compared with quasi-spherical, angular and lamellar particles, it has fewer contact points between particles and lacks more interlocking structures, resulting in weak grain boundary bonding, and thus the worst bending strength.

[0084] Comparative Example 4

[0085] Comparative Example 4 provides a method for preparing a high-strength porous ceramic material by blending inorganic ceramic particles of various morphologies. The specific steps are the same as those of Example 7, except that flaky alumina accounts for 100% of the mass of the alumina substrate, and angular alumina is not blended.

[0086] Recombination Figure 3 and Figure 5 As shown, the porous ceramic membrane prepared in this comparative example has a three-point bending strength of 16.8 MPa, a porosity of 47.0%, an average pore size d of 0.536±0.203 μm, and a pure water flux of 2551 L / (m 2 ·h·bar). Scanning electron microscopy shows that compared with Comparative Example 1, the ceramic material prepared by the flaky particles has a compact structure, but it is easy to be arranged in parallel to form a layered structure, lacking an interlocking structure, resulting in interlayer peeling or slippage of the material when subjected to force; at the same time, when the flaky particles are sintered, the different shrinkage rates in different directions lead to the generation of internal stress, which in turn forms microcracks or pores, resulting in low bending strength.

[0087] It can be seen from the above embodiments and the above comparative examples that, on the premise of taking angular shape as the basic particle morphology, at least one of spherical and lamellar shapes is blended, and by adjusting the particle morphology ratio, the bending strength of the ceramic material can be effectively controlled to increase by 45%, and the porosity of the material can be maintained between 35% and 45%, thereby meeting the coordinated requirements of material mechanical properties and permeability characteristics in different application scenarios.

[0088] It should be noted that, in this article, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the method and device in the embodiment of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0089] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0090] In addition, it should be noted that the scope of the methods and systems in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0091] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for preparing high-strength porous ceramic materials by blending inorganic ceramic particles of various morphologies, characterized in that: The steps include: Step S1, mixing angular inorganic ceramic particles with at least one of spherical inorganic ceramic particles and flaky inorganic ceramic particles according to mass percentage to obtain a mixed substrate; Step S2, uniformly mixing the mixed substrate with a binder, a pore former, a sintering aid, a plasticizer and a solvent according to mass percentage to obtain a uniform ceramic mud; Step S3, preparing the ceramic mud into a ceramic substrate with a preset morphology; Step S4, sintering the ceramic substrate in a gas environment at a temperature of 1300° C. to 1600° C., and obtaining a porous ceramic material after cooling.

2. The method according to claim 1, characterized in that In step S1, the inorganic ceramic particles are one of aluminum oxide, zirconium oxide, titanium dioxide and silicon dioxide.

3. The method according to claim 2, characterized in that In step S1 , the particle size of the angular inorganic ceramic particles is 1 to 50 μm, the particle size of the spherical inorganic ceramic particles is 0.5 to 30 μm, and the particle size ratio of the spherical inorganic ceramic particles to the angular inorganic ceramic particles is 1:1 to 1:

3.

4. The method according to claim 3, characterized in that In step S1, when the angular inorganic ceramic particles and the spherical inorganic ceramic particles are mixed, the mass proportion of the spherical inorganic ceramic particles in the mixed base material is 10% to 25%.

5. The method according to claim 1 or 4, characterized in that: In step S1, the spherical inorganic ceramic particles include pure spherical inorganic ceramic particles, quasi-spherical inorganic ceramic particles and quasi-spherical inorganic ceramic particles.

6. The method according to claim 1, characterized in that In step S2, the binder is selected from at least one of polyvinyl alcohol, polyacrylic acid or its derivatives, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, sodium carboxymethyl cellulose, ethyl cellulose, natural polysaccharides, and modified starch; the pore former is at least one of an organic pore former or an inorganic pore former; the sintering aid is at least one of magnesium oxide, calcium oxide, silicon dioxide, titanium dioxide, clay, and kaolin; the plasticizer is at least one of polyethylene glycol, ethylene glycol, glycerol, propylene glycol, oleic acid, tung oil, and vegetable oil; and the solvent is water.

7. The method according to claim 6, characterized in that In step S2, the added amounts of the binder, pore former, sintering aid, plasticizer and solvent are 2% to 5%, 5% to 20%, 1% to 5%, 1% to 5% and 5% to 60% of the mass of the mixed substrate respectively.

8. The method according to claim 1, characterized in that In step S3, the preparation method adopts at least one of extrusion molding, slip casting molding, tape casting or dry powder pressing.

9. The method according to claim 1, characterized in that: In step S4, the gas is one of air, nitrogen and argon; the sintering is carried out by a staged heating method, specifically including: in the first stage, the temperature is increased to 600°C at a rate of 1-5°C / min and kept warm for 1-2 hours to remove moisture and organic matter in the ceramic mud; in the second stage, the temperature is increased to the target temperature of 1300°C~1600°C at a rate of 2-10°C / min and kept warm for 1-3 hours to promote the growth of particle necks and enhance the grain boundary bonding strength; in the third stage, the temperature is reduced to 900°C at a rate of 2-5°C / min and then naturally cooled to avoid cracks caused by thermal stress.

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