Super-oleophobic low-temperature sintered silicon carbide ceramic membrane and preparation method thereof

Abstract

The invention provides a super-oleophobic low-temperature sintered silicon carbide ceramic membrane as well as a preparation method and application thereof. According to the silicon carbide ceramic membrane, a SiC-Al2O3-Y2O3 system is adopted, Y2O3 serves as a key low-temperature co-fluxing agent and forms a eutectic liquid phase with Al2O3 and the like, low-temperature sintering at the temperature of 1300-1400 DEG C is achieved, by means of the synergistic effect of a SiC core framework, Al2O3 and Y2O3, the bending strength of the prepared ceramic membrane can reach 60-100 MPa, and the ceramic membrane is high in density, excellent in chemical stability and good in thermal shock resistance; a PLA evanescent mode is adopted, and a dry-pressing integrated forming process is combined, so that the butterfly type ceramic membrane with a complex runner structure can be accurately prepared. The silicon carbide ceramic membrane prepared by the invention is specially adapted to a dynamic rotating disc type membrane system, and deeply cooperates with active shearing force generated during operation of the rotating disc type system, so that dual effects of oil stain adhesion resistance and easy stripping are realized, and the anti-pollution capacity of a membrane module and the stability of long-term operation flux are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane technology, and in particular to a superoleophobic low-temperature sintered silicon carbide ceramic membrane and its preparation method. Background Technology

[0002] Oily wastewater, a major source of pollution in industrial production and daily life, originates widely from various sectors including oil extraction, metal processing, food processing, and textile printing and dyeing. The oil phase in this type of wastewater exists in various forms, such as floating oil, dispersed oil, emulsified oil, and dissolved oil. Among these, emulsified oil, due to its extremely small droplet size (typically less than 20 μm) and high stability, is the most difficult type of oily wastewater to treat. Direct discharge of untreated oily wastewater not only causes severe water pollution and disrupts the balance of aquatic ecosystems but also wastes a large amount of recyclable oil resources. Furthermore, it can lead to a series of subsequent problems such as pipe blockage and equipment corrosion, posing a dual threat to environmental safety and the sustainability of industrial production. Therefore, developing efficient, stable, and economical oily wastewater treatment technologies has become a core technical challenge urgently needing to be addressed in the fields of environmental protection and industrial water conservation.

[0003] Membrane separation technology, with its significant advantages such as high separation efficiency, simple operation, small footprint, no need for chemical reagents, and ability to recover oil resources, is widely recognized as one of the most promising advanced treatment technologies. The core principle of this technology is to utilize the selective permeability of membrane materials to achieve efficient separation of the oil and water phases under the driving forces of pressure and concentration differences. However, in practical applications of membrane separation technology for oily wastewater treatment, its separation performance and long-term operational stability are highly dependent on the physicochemical properties of the membrane material itself and its suitability for oil-water separation conditions. Membrane fouling is the primary bottleneck restricting its large-scale industrial application.

[0004] Currently, membrane materials used for oily wastewater treatment are mainly divided into two categories: organic membranes and inorganic ceramic membranes. However, both types of materials have unavoidable technical drawbacks.

[0005] On the one hand, organic membranes (such as polyvinylidene fluoride (PVDF), polypropylene (PP), and polyethersulfone (PES)) have been widely used in the early treatment of oily wastewater due to their simple preparation process, low cost, and wide range of adjustable pore sizes. However, the inherent characteristics of these organic membranes make them highly susceptible to oil contamination during oil-water separation: organic membrane materials generally have high surface energy, and their surface hydrophilicity / hydrophobicity is difficult to precisely control, resulting in strong interfacial interactions with oil droplets, which easily lead to oil droplets adsorbing onto the membrane surface and pore walls; the pore size of organic membranes is easily swelled or contracted by the oil phase, further aggravating the aggregation and spreading of oil droplets in the membrane pores, eventually leading to irreversible pore blockage, resulting in a sharp decline in membrane flux and a significant decrease in separation efficiency; organic membranes have limited chemical resistance, and when treating industrial oily wastewater containing acids, alkalis, organic solvents, or oxidants, membrane material degradation or aging easily occurs; their mechanical strength and thermal stability are insufficient, making it difficult to withstand the scouring of solid particles in oily wastewater, high-shear operating conditions, and high-temperature wastewater treatment requirements, resulting in a short service life of membrane modules and increased actual operating costs.

[0006] On the other hand, traditional inorganic ceramic membranes, such as those made of alumina (Al2O3) and zirconium oxide (ZrO2), have shown certain advantages in treating oily wastewater under harsh conditions due to their excellent chemical stability, mechanical strength, and thermal stability, thus compensating for the shortcomings of organic membranes to some extent. However, these traditional ceramic membranes have not completely solved the oil pollution problem: their surfaces typically have high surface energy and strong hydrophilicity. During oil-water separation, the oil phase easily spreads on the membrane surface and wets the membrane pores, forming a dense oil film layer. This oil film layer is tightly bonded to the membrane surface and is difficult to remove through conventional physical cleaning or simple chemical cleaning, leading to a rapid decline in membrane flux. Furthermore, repeated cleaning further damages the membrane surface structure, shortens the membrane's lifespan, and limits its application in treating highly challenging oily wastewater.

[0007] To address the fouling issues of the aforementioned membrane materials, researchers have turned their attention to silicon carbide (SiC), a material with excellent physicochemical properties. As a novel inorganic non-metallic material, silicon carbide possesses several key advantages suitable for oily wastewater treatment: it exhibits extremely high chemical inertness, tolerating strong acids, strong alkalis, organic solvents, and high-temperature environments, making it suitable for treating oily wastewater under various harsh conditions; it possesses excellent mechanical strength and high thermal conductivity, able to withstand the scouring of wastewater with high shear and high solids content, and is not easily damaged by temperature changes; its surface energy can be precisely controlled through the preparation process, potentially allowing for the construction of surface structures with both hydrophilic and oleophobic properties, thus suppressing oil pollution at its source. Therefore, silicon carbide is considered an ideal candidate material for preparing high-performance, anti-fouling oil-water separation membranes.

[0008] However, existing silicon carbide membrane preparation technologies still face key bottlenecks that hinder their industrialization: the preparation of traditional pure silicon carbide ceramic membranes relies on high-temperature sintering processes exceeding 2000℃, which not only places extremely high demands on sintering equipment but also leads to a significant increase in energy consumption, substantially raising the production cost of membrane materials. Simultaneously, high-temperature sintering easily results in uneven membrane pore size distribution and decreased porosity, negatively impacting the membrane's separation performance. Although some researchers have lowered the sintering temperature by adding sintering aids, this often comes at the cost of sacrificing the core properties of silicon carbide membranes, such as mechanical strength and chemical stability, making it difficult to balance membrane performance and cost.

[0009] Furthermore, current improvements to membrane technologies for treating oily wastewater often focus on single-dimensional optimization: either enhancing the antifouling properties of membrane materials through surface modification (such as grafting hydrophilic groups or constructing micro / nano structures), or improving separation efficiency through optimizing separation processes (such as adjusting operating pressure and flow rate). Such single-dimensional improvements cannot fundamentally solve the problem of synergistic optimization between membrane fouling and separation efficiency. Even if the membrane material itself possesses certain antifouling characteristics, without a suitable and efficient dynamic separation method, oil droplets may still gradually accumulate on the membrane surface, leading to membrane fouling after long-term operation. Conversely, if only the separation process is optimized without fundamentally improving the intrinsic antifouling properties of the membrane material, it is difficult to achieve long-term stable separation results.

[0010] In summary, existing membrane materials for oily wastewater treatment still have many shortcomings: organic membranes have poor antifouling properties and stability; traditional ceramic membranes are prone to oil phase wetting and oil film adhesion; although silicon carbide membranes have excellent performance, their preparation cost is high and the process is not mature.

[0011] In view of this, it is necessary to improve the existing membrane materials for oil-water separation in order to solve the above problems. Summary of the Invention

[0012] The first objective of this invention is to disclose a superoleophobic ceramic film made with a specific ratio of SiC-Al2O3-Y2O3, which achieves low-temperature sintering of silicon carbide support by forming a eutectic liquid phase with multiple oxides at 1300-1400℃.

[0013] To achieve the above objectives, the present invention discloses a superoleophobic low-temperature sintered silicon carbide ceramic membrane, wherein the silicon carbide ceramic membrane comprises a support, an intermediate layer, and a separation layer; the support is composed of the following components by weight: 100 parts of silicon carbide powder, 10-30 parts of alumina powder, 2-7 parts of yttrium oxide powder, 1-5 parts of low-temperature additives, 2-10 parts of pore-forming agent, 0.5-1.5 parts of dispersant, 4-14 parts of plasticizer, and 8-26 parts of binder.

[0014] In some embodiments, the low-temperature additive is one or more of titanium oxide, magnesium oxide, silicon dioxide, and copper oxide.

[0015] In some embodiments, the pore-forming agent is one or more of starch, carbon powder, and cellulose.

[0016] In some embodiments, the silicon carbide powder has a particle size of 20-30 μm, the alumina powder has a particle size of 5-10 μm, and the yttrium oxide powder has a particle size of 1-5 μm.

[0017] In some embodiments, the dispersant is sodium hexametaphosphate dispersant, the plasticizer is polyethylene glycol, and the binder is polyvinyl alcohol.

[0018] In some embodiments, the average pore size of the support is 1-5 μm, the average pore size of the intermediate layer is 0.2-0.6 μm, and the average pore size of the separation layer is 0.05-0.1 μm; the support is a low-temperature sintered silicon carbide structure, and the underwater surface of the silicon carbide ceramic film is superoleophobic.

[0019] The second objective of this invention is to disclose a method for preparing silicon carbide ceramic membranes by low-temperature sintering. This method uses yttrium oxide low-temperature co-firing agent and low-temperature additives in synergy, and simultaneously uses PLA lost foam casting process to prepare an integrated ceramic membrane. The flow channel can be adjusted in various ways according to the PLA mold to achieve high mechanical strength, high throughput and underwater superoleophobic properties.

[0020] To achieve the above objectives, this invention discloses a method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film, comprising the following steps:

[0021] Step 1: Dry the silicon carbide, alumina, yttrium oxide, and low-temperature additives for later use;

[0022] Step 2: Add the above components and pore-forming agent to a mixing tank in a certain proportion, then add deionized water, dispersant, plasticizer, and binder and mix thoroughly, maintaining a total solids content of 50-60 wt%.

[0023] Step 3: Transfer the mixture to a ball mill for grinding to obtain a uniform, fine, and stable slurry;

[0024] Step 4: The slurry is fed into a spray drying tower for atomization and drying to obtain spherical composite powder;

[0025] Step 5: Sieve and proportion the spherical composite powder;

[0026] Step Six: Dry press the spherical composite powder together with the PLA mold to form a green body, and then dry and shape it to obtain a green body;

[0027] Step 7: Place the green body in a sintering furnace for degreasing and sintering to obtain a ceramic film support;

[0028] Step 8: Mix silicon carbide powder with grinding aid, dispersant, and binder and ball mill to obtain intermediate layer slurry;

[0029] Step 9: Coat the surface of the ceramic membrane support with an intermediate layer slurry, dry and sinter it to obtain the pre-finished ceramic membrane.

[0030] Step 10: Mix silicon carbide powder with binder and dispersant and ball mill to obtain film slurry;

[0031] Step 11: Coat the surface of the ceramic membrane pre-finished product with a membrane slurry, dry and sinter it to obtain an underwater superoleophobic low-temperature sintered silicon carbide ceramic membrane.

[0032] In some embodiments, in step one, silicon carbide, alumina, yttrium oxide and low-temperature additives are dried at 110°C for 4 hours for later use.

[0033] In some embodiments, in step three, zirconia balls are used as the grinding medium, the grinding speed is 300-400 rpm, and the grinding time is 4-8 hours.

[0034] In some embodiments, in step four, the atomization method is high-speed rotary atomization, and the drying temperature is 180℃-250℃.

[0035] In some embodiments, in step six, a layer of spherical composite powder is first laid, then a PLA mold is placed, and another layer of spherical composite powder is laid on the PLA mold, followed by dry pressing; wherein the thickness of the spherical composite powder laid on the surface of the PLA mold is uniform.

[0036] In some embodiments, in step seven, the temperature is first raised to 80-120°C at a rate of 1-2°C / min and held for 1-2 hours, then raised to 450-600°C at a rate of 0.5-1°C / min and held for 2-3 hours, and finally raised to 1300-1400°C at a rate of 3-5°C / min and held for 1-3 hours. After sintering, the temperature is controlled to drop to below 1000°C at a rate of 3-5°C / min, and then cooled to room temperature with the furnace.

[0037] In some embodiments, in step eight, the particle size of the silicon carbide powder is 2-5 μm; the grinding aid is 0.3-1.2 wt% ammonium polyacrylate, the dispersant is 1-2 wt% polyethylene glycol, and the binder is 0.2-0.5 wt% of a 2-5% polyvinyl alcohol solution.

[0038] In some embodiments, in step ten, the particle size of the silicon carbide powder is 0.1-1 μm; the binder is a 2-5 wt% polyvinyl alcohol solution with a concentration of 5-10%.

[0039] The third objective of this invention is to disclose the application of a superoleophobic low-temperature sintered silicon carbide ceramic membrane. The silicon carbide ceramic membrane of this invention is specifically designed for dynamic rotating disc membrane systems. In synergy with the shear force generated by the membrane, it achieves the dual effects of anti-adhesion and easy peeling, significantly improving the anti-fouling ability of the membrane material.

[0040] To achieve the above objectives, this invention discloses the application of a superoleophobic low-temperature sintered silicon carbide ceramic membrane, which is applied to a dynamic rotating disc membrane system.

[0041] In some embodiments, the superoleophobic low-temperature sintered silicon carbide ceramic membrane utilizes its own underwater superoleophobic properties combined with the high-speed shear force of the dynamic rotating disc membrane system to achieve high antifouling properties on the surface of the silicon carbide ceramic membrane.

[0042] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention adopts the SiC-Al2O3-Y2O3 system, with clear division of labor and synergistic effect of each component. Y2O3, as the key low-temperature eutectic agent, forms a low-temperature eutectic liquid phase with Al2O3 and other components, promoting the material to achieve low-temperature sintering at 1300-1400℃, effectively solving the technical difficulties of high-temperature sintering of traditional silicon carbide ceramic films, and greatly saving energy consumption; (2) PLA (polylactic acid) lost foam is prepared by injection molding or 3D printing process, combined with dry pressing integrated molding process, which can accurately prepare dish-shaped film green blanks with complex flow channel structure, solving the problem of It solves the technical problems of complex flow channels being difficult to form in traditional molding processes, and the blank being prone to delamination and uneven density; (3) Relying on the core skeleton of SiC and the synergistic effect of Al2O3 and Y2O3, the ceramic membrane prepared can achieve a bending strength of 60-100MPa, high density, excellent chemical stability, and can withstand the corrosion of complex media, while also having good thermal shock resistance; (4) The ceramic membrane support has underwater superoleophobic properties, a high porosity of 35%-45%, and 4000-5000L / m 2The high throughput of ·h·bar, and the formation of a reasonable pore size gradient structure by coating a micron-level intermediate layer and a nano-level separation layer on the low-temperature sintering support, effectively achieves high-precision oil-water separation and particulate matter interception under high throughput; (5) The silicon carbide ceramic membrane prepared by this invention is specially adapted to the dynamic rotating disc membrane system. It combines the intrinsic underwater superoleophobic passive anti-oil-fouling properties of the membrane body with the active shear force generated during the operation of the rotating disc system, achieving the dual effect of anti-adhesion and easy peeling of oil-fouling, significantly improving the anti-fouling ability of the membrane module and the stability of the long-term operating throughput, and solving the problems of easy fouling, fast throughput decay and high maintenance cost of the membrane module in the dynamic rotating disc membrane system. Attached Figure Description

[0043] Figure 1 This is a SEM image of the silicon carbide ceramic film support shown in this invention.

[0044] Figure 2 This is a SEM image of the intermediate layer of the silicon carbide ceramic film shown in this invention.

[0045] Figure 3 This is a SEM image of the silicon carbide ceramic membrane separation layer shown in this invention;

[0046] Figure 4 This is a SEM image of the cross-section of the silicon carbide ceramic membrane shown in this invention.

[0047] Figure 5 This is a schematic diagram of the underwater oil contact angle of the silicon carbide ceramic membrane shown in this invention;

[0048] Figure 6 This is a schematic diagram comparing the flux of the silicon carbide ceramic membrane shown in Example 4 and the alumina ceramic membrane shown in Comparative Example 1 in treating oily wastewater.

[0049] Figure 7 This is a schematic diagram showing the water flux change of the silicon carbide ceramic membrane shown in Examples 3-5 over an 8-hour period;

[0050] Figure 8 This is a table of performance test data for the silicon carbide ceramic membrane support, intermediate layer, and membrane separation layer shown in Examples 3-5;

[0051] Figure 9 The table below shows the performance test data of the silicon carbide ceramic films shown in Examples 3-5;

[0052] Figure 10 The table shows the performance test data of the silicon carbide ceramic membrane shown in Example 4 and the ceramic membranes shown in Comparative Examples 2-3. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Any equivalent substitutions or replacements in function, method, or structure made by those skilled in the art based on these embodiments are within the scope of protection of the present invention.

[0054] Example 1

[0055] This invention discloses a superoleophobic low-temperature sintered silicon carbide ceramic film, such as... Figure 1-5 As shown, the silicon carbide ceramic membrane includes a support, an intermediate layer, and a separation layer.

[0056] The support is composed of the following components by weight: 100 parts silicon carbide powder, 10-30 parts alumina powder, 2-7 parts yttrium oxide powder, 1-5 parts low-temperature additives, 2-10 parts pore-forming agent, 0.5-1.5 parts dispersant, 4-14 parts plasticizer, and 8-26 parts binder.

[0057] The low-temperature additive is one or more of titanium dioxide, magnesium oxide, silicon dioxide, and copper oxide, with titanium dioxide being preferred in this embodiment. The pore-forming agent is one or more of starch, carbon powder, and cellulose. The dispersant is sodium hexametaphosphate, the plasticizer is polyethylene glycol (PEG), and the binder is polyvinyl alcohol (PVA).

[0058] The silicon carbide powder has a particle size of 20-30 μm, the alumina powder has a particle size of 5-10 μm, and the yttrium oxide powder has a particle size of 1-5 μm.

[0059] The support has an average pore size of 1-5 μm, the intermediate layer has an average pore size of 0.2-0.6 μm, and the membrane separation layer has an average pore size of 0.05-0.1 μm. The support is a low-temperature sintered silicon carbide structure, and the underwater surface of the silicon carbide ceramic membrane is superoleophobic.

[0060] Compared with existing technologies, this invention mainly adopts the SiC-Al2O3-Y2O3 formulation system, which can realize the sintering process at low temperature.

[0061] Silicon carbide (SiC) powder, as the framework material of the ceramic membrane, mainly provides the structural strength and hardness of the membrane, endowing it with corrosion resistance, high temperature resistance, and shock resistance in extreme environments. Alumina (Al2O3) powder, as a sintering aid and reactive phase precursor, reacts partly with the SiO2 thin layer on the surface of SiC particles to form intergranular phases such as mullite. This forms continuous or semi-continuous bonding phases at grain boundaries, effectively inhibiting abnormal grain growth and improving the material's density and mechanical strength. Another part reacts with yttrium oxide (Y2O3) to form yttrium aluminum garnet (YAG) phase, which is crucial for forming a low-temperature liquid phase and promoting mass transport. Alumina powder also acts as a filler; its fine particles can fill the spaces between larger SiC particles, optimizing particle size distribution and increasing green body density. Y2O3, as a key low-temperature co-firing agent, plays a crucial role in forming a eutectic liquid phase and promoting densification.

[0062] Furthermore, the silicon carbide ceramic film also contains low-temperature additives such as titanium oxide, which form a lower-melting-point multi-element eutectic with the Y2O3-Al2O3 system, further optimizing the sintering window, refining the grain size of the final material, and forming a more uniform microstructure. Through solid solution and the formation of a second phase, the thermal shock resistance and mechanical strength of the material are optimized. In this invention, yttrium oxide (Y2O3) forms a eutectic liquid phase with Al2O3, TiO2, etc., at temperatures far below their respective melting points. This greatly accelerates atomic diffusion and particle rearrangement through a dissolution-precipitation mechanism, achieving densification sintering within a low-temperature range of 1300-1400℃.

[0063] The superoleophobic low-temperature sintered silicon carbide ceramic membrane of this invention can be used in dynamic rotating disc membrane systems. In dynamic rotating disc membrane systems, the superoleophobic low-temperature sintered silicon carbide ceramic membrane utilizes its underwater superoleophobic properties combined with the high-speed shear force of the dynamic rotating disc membrane system to achieve high antifouling properties on the silicon carbide ceramic membrane surface.

[0064] The dynamic rotating disc membrane system is existing technology, and its specific structure will not be described in detail here. Please refer to relevant Chinese patents CN210544403U, CN215463341U, or CN217795528U.

[0065] Example 2

[0066] This invention also discloses a method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film, comprising the following steps:

[0067] Step 1: Dry silicon carbide, alumina, yttrium oxide and low-temperature additives at 110°C for 4 hours for later use.

[0068] Step 2: Add the above components and pore-forming agent to a mixing tank according to the weight ratio in Example 1, and add deionized water, dispersant, plasticizer and binder to mix evenly, keeping the total solid content at 50-60 wt%.

[0069] Step 3: Transfer the mixture to a ball mill for grinding, using zirconia balls as the grinding medium, at a grinding speed of 300-400 rpm for 4-8 hours, to obtain a uniform, fine, and stable slurry.

[0070] Step 4: The slurry is pumped to the atomizer at the top of the spray drying tower. The slurry is atomized into numerous fine droplets under high-speed rotation. The droplets are dried in contact with hot air at 180℃-250℃ inside the tower. The binder and plasticizer are solidified during the droplet drying process, forming a dry, free-flowing, moisture-controlled, and relatively concentrated spherical composite powder.

[0071] Step 5: Sieve the spherical composite powder and classify it according to mesh size. Proportion the classified spherical composite powder so that when it is loaded into the mold, it achieves a higher initial filling density and more uniform filling. In the subsequent dry pressing process, these powder particles can effectively slide and rearrange, and the fine particles can fully fill the voids. This allows for the production of green bodies with high density, low porosity, and uniform strength at relatively low pressing pressure, effectively reducing defects such as delamination and density inconsistencies.

[0072] Step Six: Dry-press the spherical composite powder together with a removable mold, and then dry and shape it to obtain a green body. Specifically, first lay a layer of spherical composite powder, then place the removable mold, then lay another layer of spherical composite powder on the removable mold, and then dry-press it. The thickness of the spherical composite powder laid on the surface of the removable mold is uniform. The removable mold described in this invention can be starch, graphite, or engineering plastics such as PMMA and HDPE, but in this embodiment, a polylactic acid (PLA) mold is preferred.

[0073] Step 7: Place the green body in a sintering furnace for degreasing and sintering to obtain a ceramic membrane support. Specifically, first, heat to 80-120℃ at a rate of 1-2℃ / min and hold for 1-2 hours; then heat to 450-600℃ at a rate of 0.5-1℃ / min and hold for 2-3 hours; finally, heat to 1300-1400℃ at a rate of 3-5℃ / min and hold for 1-3 hours. After sintering, control the cooling rate to below 1000℃ at a rate of 3-5℃ / min, and then cool to room temperature with the furnace. Finally, a flexural strength of 60-100MPa, porosity of 35%-45%, and pure water flux of 4000-5000L / m³ are obtained. 2 Ceramic membrane support with an average pore size of 1-5 μm and a pressure of ·h·bar.

[0074] Step 8: Mix silicon carbide powder with grinding aid, dispersant and binder and ball mill to obtain intermediate layer slurry; wherein, the particle size of silicon carbide powder is 2-5μm; the grinding aid is 0.3-1.2wt% ammonium polyacrylate, the dispersant is 1-2wt% PEG, and the binder is 0.2-0.5wt% polyvinyl alcohol solution with a concentration of 2-5%.

[0075] Step 9: Uniformly coat the intermediate layer slurry onto the surface of the ceramic membrane support, then dry and sinter it to obtain a pore size of 0.2-0.6 μm and a pure water flux of 2800-3600 L / m³. 2 Ceramic membrane pre-finished product (i.e., intermediate layer) with a density of h·bar.

[0076] Step 10: Mix silicon carbide powder with binder and dispersant and ball mill to obtain film slurry; wherein the particle size of silicon carbide powder is 0.1-1μm; the binder is 2-5wt% of a 5-10% polyvinyl alcohol solution.

[0077] Step 11: Uniformly coat the ceramic membrane pre-finished product with a membrane slurry, then dry and sinter it to obtain a pore size of 0.05-0.1μm and a pure water flux of 1600-2500L / m. 2 ·h·bar underwater superoleophobic low-temperature sintered silicon carbide ceramic membrane.

[0078] In the above preparation method, during the heating process, Y2O3, Al2O3, and low-temperature additives first undergo a solid-phase reaction at the particle contact points, and then a viscous glassy phase or liquid phase begins to form at around 1300℃. This liquid phase encapsulates the SiC particles, and through extremely high atomic diffusion rates, it achieves particle rearrangement, dissolution of fine particles, and re-precipitation on the surface of coarse particles, thereby rapidly filling the voids between particles and enabling the material to achieve high density at a temperature far below the sintering temperature of pure SiC (>2000℃).

[0079] SiC particles themselves form a robust framework through liquid-phase sintering. On the other hand, Al₂O₃ reacts with Y₂O₃ to form YAG, and reacts with SiO₂ on the SiC surface to form intergranular phases such as mullite. These intergranular phases continuously and firmly bridge the SiC grains, providing strong bonding forces and inhibiting abnormal grain growth. This microscopically constructs a dual-reinforcement network combining a high-strength main crystalline phase and high-strength grain boundaries, achieving a leap in overall mechanical properties.

[0080] This invention employs a lost foam casting process for the support structure. A PLA mold, either injection molded or 3D printed, is embedded within spherical composite powder. After molding, the mold is sintered to form a disc-shaped membrane preform with a complex flow channel structure. This ensures structural integrity and reduces defects, laying the foundation for subsequent coating of the intermediate and separation layers. This guarantees that the final silicon carbide ceramic membrane material possesses high strength and high water flux. This integrated flow channel molding process allows for adjustments to the flow channel layout according to actual needs; this invention preferably uses an involute flow channel layout. This involute flow channel, combined with the rotating cross-flow mechanism of the dynamic rotating disc membrane system, achieves high flux and low cake deposition.

[0081] Example 3

[0082] A method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film includes the following steps:

[0083] Step 1: Dry 100 parts of silicon carbide powder with a purity ≥ 99.9% and a particle size of 20-30 μm, 10 parts of alumina with a purity ≥ 99.9% and a particle size of 5-10 μm, 2 parts of yttrium oxide with a purity ≥ 99.9% and a particle size of 1-5 μm, and 1 part of titanium oxide powder with a purity ≥ 99.9% and a particle size of 0.5-2 μm at 110℃ for 4 hours for later use.

[0084] Step 2: Add the above-mentioned components and 2 parts of starch pore-forming agent to a mixing tank and mix. Then add deionized water, 0.5 parts of sodium hexametaphosphate dispersant, 4 parts of polyethylene glycol (PEG) plasticizer and 8 parts of polyvinyl alcohol (PVA) binder and mix evenly to maintain a total solid content of 50 wt%.

[0085] Step 3: Transfer the mixture to a ball mill for grinding, using zirconia balls as the grinding medium, at a grinding speed of 300 rpm for 4 hours, to obtain a uniform, fine, and stable slurry.

[0086] Step 4: The slurry is pumped to the atomizer at the top of the spray drying tower and dried at 180°C to form a dry, free-flowing, moisture-controlled, and relatively concentrated spherical composite powder.

[0087] Step 5: Sieve the spherical composite powder and classify it according to mesh size. Proportion the classified spherical composite powder so that when it is loaded into the mold, it achieves a higher initial filling density and more uniform filling. In the subsequent dry pressing process, these powder particles can effectively slide and rearrange, and the fine particles can fully fill the voids. This allows for the production of green bodies with high density, low porosity, and uniform strength at relatively low pressing pressure, effectively reducing defects such as delamination and density inconsistencies.

[0088] Step 6: Dry press the spherical composite powder together with the PLA mold, and then dry and shape it to obtain a green body; specifically, first lay a layer of spherical composite powder, then place the PLA mold, then lay another layer of spherical composite powder on the PLA mold, then dry press it at 50MPa, and then transfer it to a drying oven for drying.

[0089] Step 7: Place the green body in a sintering furnace for degreasing and sintering to obtain a ceramic membrane support. Specifically, first, heat to 80℃ at a rate of 1℃ / min and hold for 1 hour, then heat to 450℃ at a rate of 0.5℃ / min and hold for 2 hours, and finally heat to 1300℃ at a rate of 3℃ / min and hold for 1 hour. After sintering, control the cooling rate to below 1000℃ at a rate of 3℃ / min, and then cool to room temperature with the furnace to produce a ceramic membrane support with a flexural strength of 68.25MPa, a porosity of 39%, and a pure water flux of 4480L / m³. 2 Ceramic membrane support of h bar.

[0090] Step 8: Mix silicon carbide powder with a particle size of 2μm with 0.3wt% ammonium polyacrylate, 1wt% PEG and 0.2wt% PVA solution with a concentration of 2%, and ball mill for 6 hours to prepare an intermediate layer slurry.

[0091] Step 9: Uniformly coat the intermediate layer slurry onto the surface of the ceramic membrane support, then dry and sinter it to obtain a pore size of 0.52 μm and a pure water flux of 3400 L / m³. 2 Ceramic membrane pre-finished product with a density of h bar.

[0092] Step 10: Mix 0.1μm silicon carbide powder with 2wt% of 5% PVA solution binder and dispersant and ball mill for 5h to obtain film slurry.

[0093] Step 11: Uniformly coat the ceramic membrane pre-finished product with membrane slurry, then dry and sinter it to obtain a pore size of 0.1 μm and a pure water flux of 2300 L / m. 2 ·h·bar underwater superoleophobic low-temperature sintered silicon carbide ceramic membrane.

[0094] Example 4

[0095] A method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film includes the following steps:

[0096] Step 1: Dry 100 parts of silicon carbide powder with a purity ≥ 99.9% and a particle size of 20-30 μm, 20 parts of alumina with a purity ≥ 99.9% and a particle size of 5-10 μm, 5 parts of yttrium oxide with a purity ≥ 99.9% and a particle size of 1-5 μm, and 3 parts of titanium oxide powder with a purity ≥ 99.9% and a particle size of 0.5-2 μm at 110℃ for 4 hours for later use.

[0097] Step 2: Add the above-mentioned components and 6 parts of toner pore-forming agent to a mixing tank and mix. Then add deionized water, 1 part of sodium hexametaphosphate dispersant, 9 parts of polyethylene glycol (PEG) plasticizer and 17 parts of polyvinyl alcohol (PVA) binder and mix evenly to maintain a total solid content of 55 wt%.

[0098] Step 3: Transfer the mixture to a ball mill for grinding, using zirconia balls as the grinding medium, at a grinding speed of 350 rpm for 6 hours, to obtain a uniform, fine, and stable slurry.

[0099] Step 4: The slurry is pumped to the atomizer at the top of the spray drying tower and dried at 200℃ to form a dry, free-flowing, moisture-controlled, and relatively concentrated spherical composite powder.

[0100] Step 5: Sieve the spherical composite powder and classify it according to mesh size. Proportion the classified spherical composite powder so that when it is loaded into the mold, it achieves a higher initial filling density and more uniform filling. In the subsequent dry pressing process, these powder particles can effectively slide and rearrange, and the fine particles can fully fill the voids. This allows for the production of green bodies with high density, low porosity, and uniform strength at relatively low pressing pressure, effectively reducing defects such as delamination and density inconsistencies.

[0101] Step 6: Dry press the spherical composite powder together with the PLA mold, and then dry and shape it to obtain a green body; specifically, first lay a layer of spherical composite powder, then place the PLA mold, then lay another layer of spherical composite powder on the PLA mold, then dry press it at 75MPa, and then transfer it to a drying oven for drying.

[0102] Step 7: Place the green body in a sintering furnace for degreasing and sintering to obtain a ceramic membrane support. Specifically, first, heat to 100℃ at a rate of 1.5℃ / min and hold for 1.5 hours, then heat to 525℃ at a rate of 0.8℃ / min and hold for 2.5 hours, and finally heat to 1350℃ at a rate of 4℃ / min and hold for 2 hours. After sintering, control the cooling rate to below 1000℃ at a rate of 4℃ / min, and then cool to room temperature with the furnace to produce a ceramic membrane support with a flexural strength of 85.82MPa, a porosity of 42%, and a pure water flux of 4960L / m³. 2 Ceramic membrane support of h bar.

[0103] Step 8: Mix silicon carbide powder with a particle size of 3μm with 0.75wt% ammonium polyacrylate, 1.5wt% PEG and 0.35wt% PVA solution with a concentration of 3.5%, and ball mill for 7 hours to prepare an intermediate layer slurry.

[0104] Step 9: Uniformly coat the intermediate layer slurry onto the surface of the ceramic membrane support, then dry and sinter it to obtain a pore size of 0.5 μm and a pure water flux of 3580 L / m³. 2 Ceramic membrane pre-finished product with a density of h bar.

[0105] Step 10: Mix 0.1μm silicon carbide powder with 3.5wt% of a 7.5% PVA solution binder and dispersant, and ball mill for 6.5h to obtain a film slurry.

[0106] Step 11: Uniformly coat the ceramic membrane pre-finished product with membrane slurry, then dry and sinter it to obtain a pore size of 0.1 μm and a pure water flux of 2500 L / m. 2 ·h·bar underwater superoleophobic low-temperature sintered silicon carbide ceramic membrane.

[0107] Example 5

[0108] A method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film includes the following steps:

[0109] Step 1: Dry 100 parts of silicon carbide powder with a purity ≥ 99.9% and a particle size of 20-30 μm, 30 parts of alumina with a purity ≥ 99.9% and a particle size of 5-10 μm, 7 parts of yttrium oxide with a purity ≥ 99.9% and a particle size of 1-5 μm, and 5 parts of titanium oxide powder with a purity ≥ 99.9% and a particle size of 0.5-2 μm at 110℃ for 4 hours for later use.

[0110] Step 2: Add the above-mentioned components and 10 parts of cellulose pore-forming agent to a mixing tank and mix. Then add deionized water, 1.5 parts of sodium hexametaphosphate dispersant, 14 parts of polyethylene glycol (PEG) plasticizer and 26 parts of polyvinyl alcohol (PVA) binder and mix evenly to maintain a total solid content of 60 wt%.

[0111] Step 3: Transfer the mixture to a ball mill for grinding, using zirconia balls as the grinding medium, at a grinding speed of 400 rpm for 8 hours, to obtain a uniform, fine, and stable slurry.

[0112] Step 4: The slurry is pumped to the atomizer at the top of the spray drying tower and dried at 250°C to form a dry, free-flowing, moisture-controlled, and relatively concentrated spherical composite powder.

[0113] Step 5: Sieve the spherical composite powder and classify it according to mesh size. Proportion the classified spherical composite powder so that when it is loaded into the mold, it achieves a higher initial filling density and more uniform filling. In the subsequent dry pressing process, these powder particles can effectively slide and rearrange, and the fine particles can fully fill the voids. This allows for the production of green bodies with high density, low porosity, and uniform strength at relatively low pressing pressure, effectively reducing defects such as delamination and density inconsistencies.

[0114] Step 6: Dry press the spherical composite powder together with the PLA mold, and then dry and shape it to obtain a green body; specifically, first lay a layer of spherical composite powder, then place the PLA mold, then lay another layer of spherical composite powder on the PLA mold, then dry press it at 100MPa, and then transfer it to a drying oven for drying.

[0115] Step 7: Place the green body in a sintering furnace for degreasing and sintering to obtain a ceramic membrane support. Specifically, first, heat to 120℃ at a rate of 2℃ / min and hold for 2 hours, then heat to 600℃ at a rate of 1℃ / min and hold for 3 hours, and finally heat to 1400℃ at a rate of 5℃ / min and hold for 3 hours. After sintering, control the cooling rate to below 1000℃ at a rate of 5℃ / min, and then cool to room temperature with the furnace to produce a ceramic membrane support with a flexural strength of 71.55MPa, a porosity of 34%, and a pure water flux of 4010L / m³. 2 Ceramic membrane support of h bar.

[0116] Step 8: Mix silicon carbide powder with a particle size of 5μm with 1.2wt% ammonium polyacrylate, 2wt% PEG and 0.5wt% PVA solution with a concentration of 5%, and ball mill for 8 hours to prepare an intermediate layer slurry.

[0117] Step 9: Uniformly coat the intermediate layer slurry onto the surface of the ceramic membrane support, then dry and sinter it to obtain a pore size of 0.45 μm and a pure water flux of 3080 L / m³. 2 Ceramic membrane pre-finished product with a density of h bar.

[0118] Step 10: Mix 1μm silicon carbide powder with 5wt% of 10% PVA solution binder and dispersant and ball mill for 8 hours to obtain film slurry.

[0119] Step 11: Uniformly coat the ceramic membrane pre-finished product with membrane slurry, then dry and sinter it to obtain a pore size of 0.09 μm and a pure water flux of 2150 L / m³. 2 ·h·bar underwater superoleophobic low-temperature sintered silicon carbide ceramic membrane.

[0120] Comparative Example 1

[0121] A ceramic membrane made of alumina was selected.

[0122] Comparative Example 2

[0123] Compared with Example 4, Comparative Example 2 directly used recrystallized SiC powder for sintering, without adding yttrium oxide and other low-temperature additives.

[0124] Comparative Example 3

[0125] Compared with Example 4, Comparative Example 3 uses clay-bonded SiC powder for sintering, and also does not add yttrium oxide and other low-temperature additives.

[0126] Comparative Example 4

[0127] Compared with Example 4, Comparative Example 4 no longer uses the lost foam casting process, but instead uses a traditional bonding process. First, a (disc-shaped) ceramic film support is prepared, then an intermediate layer and a release layer are coated on the upper surface in sequence, and then two identical ceramic films are bonded together to form a complete ceramic film. The flow channel is formed using a traditional process.

[0128] Comparative Example 5

[0129] Compared with Example 4, Comparative Example 5 uses starch or graphite as a sinterable additive to form internal flow channels in the ceramic membrane.

[0130] Comparative Example 6

[0131] Compared with Example 4, Comparative Example 6 uses PMMA or HDPE engineering plastics as sinterable additives to form internal flow channels in the ceramic membrane.

[0132] 1. Wastewater flux tests were conducted on Example 4 and Comparative Example 1.

[0133] II. The silicon carbide ceramic films, supports, intermediate layers, and separation layers prepared in Examples 3-5 were characterized as follows:

[0134] 1. Underwater contact angle test;

[0135] 2. Pure water flux test;

[0136] 3. Bending strength test;

[0137] 4. Average pore size test;

[0138] 5. Porosity test.

[0139] III. The following performance characterization was performed on the samples prepared in Example 4 and Comparative Examples 2-3:

[0140] 1. Sintering temperature monitoring;

[0141] 2. Underwater contact angle test;

[0142] 3. Bending strength test;

[0143] 4. Average pore size test;

[0144] 5. Pure water flux test.

[0145] from Figure 6-7 It can be seen that the silicon carbide ceramic membrane prepared by the present invention, due to its superoleophobic surface properties, can maintain a high water flux after 8 hours of operation when treating oily wastewater, with very little change compared to the initial flux. In contrast, the alumina ceramic membrane in Comparative Example 1, due to its hydrophilic properties, experienced a 50% decrease in flux after 8 hours of operation.

[0146] from Figure 8-9 As can be seen, the silicon carbide ceramic membrane prepared by this invention has excellent superoleophobic properties, with an underwater contact angle greater than 160°. Due to the SiC-Al2O3-Y2O3 formulation system, the silicon carbide ceramic membrane has a flexural strength of 60-100 MPa, a porosity of 35-45%, an average pore size of 0.05-0.1 μm, and a pure water flux of 1600-2500 L / m³. 2 ·h·bar.

[0147] from Figure 10 It can be seen that the silicon carbide ceramic membrane prepared by the present invention uses yttrium oxide as a low-temperature co-firing agent and low-temperature additives, resulting in a sintering temperature below 1400℃. Compared with the prior art, it can still maintain high flexural strength and water flux while sintering at low temperature, thus producing a silicon carbide ceramic membrane with good superoleophobic properties.

[0148] Comparative Example 4 uses a bonding process, which is relatively mature and simple, and does not require complex molds. However, it has poor molding ability, is difficult to form complex internal flow channels, has low green strength, is prone to deformation, and is prone to cracking, bubbling and deformation during firing, resulting in a low yield. Inorganic binders are used and will leave permanent residues, making it unsuitable for biomedical and sanitary ultra-clean working conditions.

[0149] Comparative Example 5 uses starch and graphite as sinterable additives, but the particle size and distribution of these additives need to be strictly controlled during the manufacturing process. During the preparation process, decomposition gases are released in a concentrated manner, and there is a high risk of bubbling and cracking. Graphite will also have residual ash, which needs to be cleaned and removed.

[0150] Comparative Example 6 uses engineering plastics such as PMMA and HDPE. However, PMMA and HDPE are complex to mold and are prone to elastic deformation during green body preparation, leading to internal stress. During the firing process, the decomposition temperature is relatively high, which eventually causes the green body to crack due to thermal expansion stress. Residual organic carbon or ash needs to be cleaned.

[0151] Examples 3-5 use PLA as a lost-wax mold. Precision molds can be pre-molded using injection molding or 3D printing as needed, then embedded in spherical composite powder and removed by sintering. This allows for complex flow channel designs, high green strength, and PLA's non-deformation during pressing, perfectly replicating the flow channel shape. Furthermore, PLA's decomposition temperature is mild and controllable, greatly reducing the risk of cracking and blistering. PLA can completely decompose, leaving the flow channel inner wall smooth and clean, requiring no cleaning and suitable for hygienic working conditions.

[0152] The method for preparing a superoleophobic low-temperature sintered silicon carbide ceramic film disclosed in this invention involves the following steps during the support sintering process: First, low-temperature pre-firing and physical adsorbent removal are used to thoroughly remove residual free moisture from the green body, preventing stress cracks caused by rapid moisture evaporation during the subsequent high-temperature sintering stage. Second, medium-temperature decomposition and binder removal are employed to ensure the full and gradual decomposition and oxidation of PLA lost foam and other additives, preventing rapid gas escape that could lead to defects such as cracking and blistering in the green body. Third, high-temperature sintering and densification are used to achieve solid-state sintering and full densification of the material, resulting in a stable microstructure and excellent mechanical and separation properties. Finally, programmed cooling effectively releases internal thermal stress in the green body, reducing the risk of internal stress cracking caused by excessively rapid cooling, stabilizing the microstructure of the ceramic film, and ensuring the integrity of the structural performance.

[0153] This invention employs a process of low-temperature sintering support, coated intermediate layer, and coated separation layer. On the low-temperature sintered support, a micron-level intermediate layer and a nano-level separation layer are sequentially constructed by coating, forming a reasonable pore size gradient and achieving a balance between high throughput and high precision separation, which is particularly suitable for oil-water separation scenarios.

[0154] This invention utilizes an Al2O3-Y2O3-based low-temperature eutectic system to simultaneously solve the sintering and grain boundary strengthening problems of silicon carbide at extremely low temperatures. Combined with pore-forming technology, it successfully manufactures an underwater superoleophobic silicon carbide ceramic membrane that simultaneously meets the requirements of low-temperature preparation, high strength, high throughput, and high stability, which can meet the application requirements of dynamic rotating disc membrane systems.

[0155] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

[0156] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An ultra-oleophobic, low-temperature sintered silicon carbide ceramic membrane, characterized by, The silicon carbide ceramic membrane comprises a support body, an intermediate layer and a separation layer; the support body is composed of 100 parts of silicon carbide powder, 10-30 parts of aluminum oxide powder, 2-7 parts of yttrium oxide powder, 1-5 parts of low-temperature additive, 2-10 parts of pore-forming agent and 0.5-1.5 parts of dispersing agent, 4-14 parts of plasticizer and 8-26 parts of binder.

2. The ultra-oleophobic, low temperature sintered silicon carbide ceramic membrane according to claim 1, wherein, The low-temperature additive is one or more of titanium oxide, magnesium oxide, silicon dioxide and copper oxide.

3. The ultra-oleophobic, low temperature sintered silicon carbide ceramic membrane of claim 1, wherein, The pore-forming agent is one or more of starch, carbon powder and cellulose.

4. The ultra-oleophobic, low temperature sintered silicon carbide ceramic membrane of claim 1, wherein, The particle size of the silicon carbide powder is 20-30 μm, the particle size of the aluminum oxide powder is 5-10 μm, and the particle size of the yttrium oxide powder is 1-5 μm.

5. The ultra-oleophobic, low temperature sintered silicon carbide ceramic membrane according to claim 1, wherein, The dispersing agent is sodium hexametaphosphate dispersing agent, the plasticizer is polyethylene glycol, and the binder is polyvinyl alcohol.

6. The ultra-oleophobic, low temperature sintered silicon carbide ceramic membrane according to claim 1, wherein The average pore size of the support body is 1-5 μm, the average pore size of the intermediate layer is 0.2-0.6 μm, and the average pore size of the separation layer is 0.05-0.1 μm; the support body is a low-temperature sintered silicon carbide structure, and the silicon carbide ceramic membrane has an underwater super-oil-repellent surface.

7. A method for preparing an ultra-oleophobic low-temperature sintered silicon carbide ceramic membrane, characterized by, The method comprises the following steps: Step one: dry silicon carbide, aluminum oxide, yttrium oxide and low-temperature additive for standby; Step two: add the above components and pore-forming agent into a mixing tank in a certain proportion, and then add deionized water, dispersing agent, plasticizer and binder to mix and stir uniformly, so that the total solid content is 50-60 wt%; Step three: transfer the mixture to a ball mill for grinding to obtain a uniform and fine stable slurry; Step four: send the slurry to a spray drying tower for atomization and drying to obtain spherical composite powder; Step five: screen and proportion the spherical composite powder; Step six: dry-press the spherical composite powder and PLA mold together to form a green body; Step seven: place the green body in a sintering furnace for debinding and sintering to obtain a ceramic membrane support body; Step eight: mix silicon carbide powder, grinding aid, dispersing agent and binder to obtain an intermediate layer slurry; Step nine: uniformly coat the intermediate layer slurry on the surface of the ceramic membrane support body and dry and sinter to obtain a ceramic membrane pre-product; Step ten: mix silicon carbide powder, binder and dispersing agent to obtain a membrane layer slurry; Step eleven: uniformly coat the membrane layer slurry on the surface of the ceramic membrane pre-product and dry and sinter to obtain an underwater super-oil-repellent low-temperature sintered silicon carbide ceramic membrane.

8. The method of claim 7, wherein the method is characterized by: In step one, the silicon carbide, aluminum oxide, yttrium oxide and low-temperature additive are dried at 110°C for 4h for standby.

9. The method of claim 7, wherein the method is characterized by: In step three, zirconium oxide balls are used as grinding medium, the grinding speed is 300-400 rpm, and the grinding time is 4-8h.

10. The method of claim 7, wherein the method is characterized by: In step four, the atomization method is high-speed rotary atomization, and the drying temperature is 180°C-250°C.

11. The method of claim 7, wherein the method is characterized by: In step six, first lay a layer of spherical composite powder, then place the PLA mold, then lay another layer of spherical composite powder on the PLA mold, and then dry-press; the thickness of the spherical composite powder laid on the surface of the PLA mold is uniform. In step one, the silicon carbide, aluminum oxide, yttrium oxide and low-temperature additive are dried at 110°C for 4h for standby.

12. The method of claim 11, wherein the method is characterized by: In the step seven, the temperature is first increased to 80-120℃ at a rate of 1-2℃ / min and kept for 1-2 hours, then increased to 450-600℃ at a rate of 0.5-1℃ / min and kept for 2-3 hours, and finally increased to 1300-1400℃ at a rate of 3-5℃ / min and kept for 1-3 hours; after sintering, the temperature is controlled to decrease to below 1000℃ at a rate of 3-5℃ / min, and then cooled to room temperature with the furnace.

13. The method of claim 7, wherein the method is characterized by: In the step eight, the particle size of the silicon carbide powder is 2-5μm; the grinding aid is 0.3-1.2wt% ammonium polyacrylate, the dispersant is 1-2wt% polyethylene glycol, and the binder is 0.2-0.5wt% polyvinyl alcohol solution with a concentration of 2-5%.

14. The method of claim 7, wherein the method is characterized by: In the step ten, the particle size of the silicon carbide powder is 0.1-1μm; the binder is 2-5wt% polyvinyl alcohol solution with a concentration of 5-10%.

15. Use of an ultra-oleophobic, low-temperature sintered silicon carbide ceramic membrane, characterized in that The super-oleophobic low-temperature sintered silicon carbide ceramic membrane is applied to a dynamic rotary butterfly membrane system.

16. Use of the superoleophobic, low-temperature sintered silicon carbide ceramic membrane according to claim 15, characterized in that The super-oleophobic low-temperature sintered silicon carbide ceramic membrane realizes high anti-fouling property on the surface of the silicon carbide ceramic membrane by using the underwater super-oleophobic property and the high-speed shearing force of the dynamic rotary butterfly membrane system.

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