High-stability silicon carbide ceramic membrane and preparation method thereof
The silicon carbide ceramic film is prepared by combining modified carbon nanotubes and inorganic oxide toughening agents, combined with silicates and rare earth oxide additives, and low-temperature sintering is solved, which solves the problems of high energy consumption and insufficient mechanical strength in high temperature sintering, and achieves a high density and long-life silicon carbide ceramic film.
Patent Information
- Application Number
- CN202510710175.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-07-29
AI Technical Summary
The existing silicon carbide ceramic films have high energy consumption, poor chemical stability, easy oxidation and insufficient mechanical strength at high temperatures, resulting in short service life.
Modified carbon nanotubes and inorganic oxides are used as toughening agents, combined with silicates and rare earth oxides as sintering aids, and silicon carbide ceramic films are prepared by low-temperature sintering, and molded using silicon carbide whiskers and binders.
It reduces the sintering temperature, improves the density and mechanical strength of the silicon carbide ceramic film, enhances chemical stability, and extends service life.
Smart Images
Figure BDA0005426857830000051 
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Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of inorganic membrane separation materials, and particularly relates to a high-stability silicon carbide ceramic membrane and a preparation method thereof. Background Art
[0002] With the rapid development of industries such as petroleum, natural gas, petrochemical, pharmaceutical, metallurgical, and food, a large amount of high-temperature flue gas and oily wastewater are generated, posing a threat to human health and environmental protection. Most of the traditional treatment methods have problems that are contradictory to energy conservation and environmental protection. Therefore, the development of related technologies has become a key research direction.
[0003] Ceramic membranes are a type of separation membrane material and are often used in the fields of separation and purification. Due to their good thermal stability, chemical stability, and relatively high mechanical strength, they are more likely to adapt to harsh working environments. Currently, alumina, zirconia, titanium oxide, and silica ceramic membranes are relatively mature and dominate the ceramic membrane market. However, these ceramic membranes have problems such as low water flux and serious membrane fouling, which to a certain extent limit the further development of ceramic membranes.
[0004] Silicon carbide ceramic membranes have quickly become emerging materials in the membrane market due to their excellent hydrophilicity, mechanical stability, and chemical stability. However, due to the very strong covalent bond between silicon and carbon, it requires an extremely high temperature during the pressureless sintering process, which not only increases energy consumption but also raises production costs. In addition, during the high-temperature treatment process, the surface of silicon carbide is prone to oxidation to form silica, and the large generation of silica will weaken the chemical stability of silicon carbide. Moreover, in the process of flue gas filtration under some harsh working conditions, the support body and the membrane layer of the silicon carbide ceramic membrane will have brittle fracture due to poor material toughness, resulting in a low service life of the silicon carbide ceramic membrane.
[0005] Aiming at the problems existing in the prior art, how to provide a silicon carbide ceramic membrane with a low sintering temperature, good chemical stability, good mechanical properties, and a long service life is an urgent problem to be solved by the present invention. Summary of the Invention
[0006] The purpose of the present invention is to provide a high-stability silicon carbide ceramic membrane to solve the problems raised in the above background art.
[0007] To achieve the above purpose, the present invention provides a high-stability silicon carbide ceramic membrane, characterized in that the silicon carbide ceramic membrane comprises the following components in parts by weight: 70 - 90 parts of silicon carbide aggregate, 3 - 15 parts of toughening agent, 10 - 35 parts of sintering aid, 1 - 6 parts of binder, 30 - 50 parts of silicon carbide whiskers, and 1 - 5 parts of dispersant;
[0008] The toughening agent comprises modified carbon nanotubes and inorganic oxides.
[0009] As a further improvement, the synthesis of the modified carbon nanotubes comprises the following steps:
[0010] (1) Add carbon nanotubes to inorganic acid and ultrasonically disperse for 30 - 60 min, then stir and reflux at 60 - 100 °C for 1 - 3 h. After the reflux ends, continue ultrasonic treatment at room temperature. After the ultrasonic treatment ends, perform post-treatment to obtain acidified carbon nanotubes;
[0011] (2) Add trihydroxypropane and an organic solution to a flask, ultrasonically disperse for 20 - 50 min, then add a condensing agent and the acidified carbon nanotubes from step (1), continue ultrasonic dispersion to make them uniformly mixed, heat and reflux at 100 - 150 °C. After the reaction ends, perform post-treatment to obtain modified carbon nanotubes.
[0012] As a further improvement, in step (1), the diameter of the carbon nanotubes is 10 - 30 nm, and the tube length is 1 - 15 μm.
[0013] As a further improvement, the condensing agent in step (2) includes but is not limited to N,N'-diisopropylcarbodiimide and N,N'-dicyclohexylcarbodiimide.
[0014] As a further improvement, the inorganic oxide comprises at least one of silicon dioxide, zirconium oxide, and gallium oxide.
[0015] For better toughening effect, preferably, the inorganic oxide is silicon dioxide.
[0016] As a further improvement, the mass ratio of the added modified carbon nanotubes to the inorganic oxide is 3 - 5:1.
[0017] As a further improvement, the sintering aid comprises silicate and rare earth oxide.
[0018] As a further improvement, the silicate comprises at least one of sodium silicate, potassium silicate, bismuth silicate, and calcium silicate; the rare earth oxide comprises at least one of lanthanum oxide, cerium oxide, chromium trioxide, and yttrium oxide.
[0019] For a lower sintering temperature and reduced energy consumption, preferably, the sintering aid is sodium silicate and cerium oxide.
[0020] As a further improvement, the binder comprises at least one of carboxymethyl cellulose, hydroxypropyl cellulose, epoxy resin, and polyvinyl alcohol.
[0021] For better bonding performance, preferably, the binder is polyvinyl alcohol.
[0022] As a further improvement, the dispersant comprises at least one of sodium dodecyl sulfate, sodium citrate, and sodium polyacrylate.
[0023] For better dispersibility, preferably, the dispersant is sodium polyacrylate.
[0024] The present invention also provides a method for preparing a highly stable silicon carbide ceramic membrane, which is characterized by comprising the following steps:
[0025] (1) By weight, add silicon carbide aggregate, toughening agent, part of the sintering aid, and part of the binder into water, stir and mix them, dry at low temperature after extrusion molding, and then calcine at high temperature to obtain a silicon carbide support;
[0026] (2) Stir and mix silicon carbide whiskers, the remaining part of the sintering aid, the remaining part of the binder, the dispersant, and water, coat them on the silicon carbide support obtained in step (1), and then dry and calcine at high temperature to obtain a silicon carbide ceramic membrane.
[0027] As a further improvement, the addition amount of water in step (1) is 10% of the addition amount of silicon carbide aggregate; the addition amount of water in step (2) is 100% of the addition amount of silicon carbide whiskers.
[0028] Compared with the prior art, the beneficial effects of the present invention are:
[0029] The silicon carbide ceramic membrane prepared by the preparation method provided by the present invention has a lower apparent porosity, indicating high densification and good sintering effect. It has a lower mass loss rate of acid corrosion and a lower mass loss rate of alkali corrosion, indicating good corrosion resistance and strong chemical stability. It has a higher impact toughness and a higher number of thermal shock resistance, indicating that the silicon carbide ceramic membrane is not easily damaged by external force impact and has good stability under rapid temperature changes, with a long service life;
[0030] Among them, due to the high tensile strength, elastic modulus, and flexibility of the modified carbon nanotubes, their compounding with inorganic oxides as toughening agents can improve the mechanical properties of the silicon carbide ceramic membrane and can also improve the chemical stability to a certain extent; using silicate and rare earth oxide as sintering aids can reduce the sintering temperature of the silicon carbide ceramic membrane, reduce energy consumption, and improve the densification and strength of the material. Specific Embodiments
[0031] The following will illustrate the present invention in conjunction with specific implementation examples. It should be noted that the following examples are examples of the present invention and are only used to illustrate the present invention, rather than to limit the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.
[0032] In the following examples, except for the modified carbon nanotubes, all the compound monomers and related reagents used can be purchased from the market. Among them, the silicon carbide aggregate and silicon carbide whiskers are purchased from Nangong Jiuxin New Material Technology Co., Ltd., the carbon nanotubes are purchased from Shanghai Gaibang Industry Co., Ltd., and the polyvinyl alcohol is purchased from Shanxi Sanwei Shengtai New Material Technology Co., Ltd., with the model of 24-88. The sodium polyacrylate is purchased from Shandong Wanhua Environmental Protection New Material Co., Ltd.
[0033] The preparation method of the modified carbon nanotubes includes the following steps:
[0034] (1) Add 1 g of carbon nanotubes to a mixed solution of 20 mL of sulfuric acid with a mass fraction of 98% and 20 mL of nitric acid with a mass fraction of 65%, ultrasonically disperse for 40 min, then stir and reflux at 80 °C for 2 h. After the reflux ends, ultrasonically treat at room temperature for 1 h. After the ultrasonic treatment ends, filter and wash with deionized water until the washing liquid is neutral. Collect the solid and dry it at 85 °C for 12 h to obtain acidified carbon nanotubes;
[0035] (2) Add 2 g of trihydroxypropane and 80 mL of N,N-dimethylformamide to a flask, ultrasonically disperse for 30 min, then add 0.5 g of N,N'-diisopropylcarbodiimide, 0.5 g of N,N'-dicyclohexylcarbodiimide and the acidified carbon nanotubes obtained in step (1), continue to ultrasonically disperse for 1 h to make them uniformly mixed, heat and reflux at 135 °C for 3 h. After the reaction ends, cool to room temperature, centrifuge and separate, and dry the precipitate at 85 °C to obtain modified carbon nanotubes.
[0036] The preparation methods of Examples 1-5 and Comparative Examples 1-2 include the following steps:
[0037] (1) By weight, add the silicon carbide aggregate, toughening agent, 1 / 3 of the sintering aid, and 1 / 2 of the binder to water, stir and mix, extrude and mold, then dry at 80 °C for 2 h, and then calcine at 1000 °C for 3 h to obtain a silicon carbide support;
[0038] (2) Stir and mix the silicon carbide whiskers, 2 / 3 of the sintering aid, 1 / 2 of the binder, dispersant and water, coat them on the silicon carbide support obtained in step (1), then dry at 80 °C for 3 h, and calcine at 1100 °C at high temperature for 3 h to obtain a silicon carbide ceramic membrane.
[0039] The components and contents used in Examples 1-5 and Comparative Examples 1-2 are shown in Table 1 below:
[0040] Table 1
[0041]
[0042] The apparent porosity, mass loss rate of acid corrosion, mass loss rate of alkali corrosion, impact toughness, and number of thermal shock resistance of a highly stable silicon carbide ceramic membrane prepared in Examples 1-5 and Comparative Examples 1-2 were tested. The test methods are as follows:
[0043] Apparent porosity: Tested in accordance with GB / T 1966-1996;
[0044] Mass loss rate of acid corrosion: Tested in accordance with GB / T 1970-1996;
[0045] Mass loss rate of alkali corrosion: Tested in accordance with GB / T 1970-1996;
[0046] Impact toughness: Tested in accordance with GB / T 4742-1984;
[0047] Number of thermal shock resistance: Place the ceramic membrane specimen in a thyristor high-temperature box-type electric furnace, keep it at 120 °C in the furnace for 30 min, and then quickly take it out and cool it in cold air close to 0 °C, which is recorded as one thermal shock cycle. Repeat the above test until damage phenomena such as cracks, blisters, or peeling occur on the membrane layer. Record the change in the surface state of the membrane layer and the number of thermal shock resistance.
[0048] The measured results are shown in Table 2:
[0049] Table 2
[0050]
[0051] It can be seen from the test results of Example 2 and Comparative Examples 1-2 in Table 2 that compared with preparing a silicon carbide ceramic membrane by only using silica or using unmodified carbon nanotubes and silica composite as a toughening agent, using a modified carbon nanotube and silica composite as a toughening agent, the prepared silicon carbide ceramic membrane has a lower apparent porosity, indicating that the addition of modified carbon nanotubes can improve the densification and the sintering effect is good. It has a lower mass loss rate of acid corrosion and mass loss rate of alkali corrosion, indicating good corrosion resistance and strong chemical stability. It has a higher impact toughness and number of thermal shock resistance, indicating that the silicon carbide ceramic membrane is not easily damaged by external force impact and has good stability under rapid temperature changes and a long service life.
[0052] From the test results of Example 2 and Examples 4-5 in Table 2, it can be seen that compared with preparing silicon carbide ceramic membranes when the ratio of the addition amounts of modified carbon nanotubes to silica is in an inappropriate range, or preparing silicon carbide ceramic membranes using conventional sintering aids (such as cerium oxide and dolomite), when the ratio of the addition amounts of modified carbon nanotubes to silica is in a suitable range and using a composite of silicate and rare earth oxide as the sintering aid, the prepared silicon carbide ceramic membrane has a lower apparent porosity, acid corrosion mass loss rate, and alkali corrosion mass loss rate, indicating high densification, good corrosion resistance, high impact toughness, and high number of thermal shock resistance cycles, indicating good mechanical properties, high stability, and long service life.
[0053] From the test results of Examples 1-3, it can be seen that the silicon carbide ceramic membrane prepared by the preparation method provided by the present invention has a lower apparent porosity, indicating high densification and good sintering effect, has a lower acid corrosion mass loss rate and alkali corrosion mass loss rate, indicating good corrosion resistance and strong chemical stability, has high impact toughness and high number of thermal shock resistance cycles, indicating that the silicon carbide ceramic membrane is not easily damaged by external force impact and has good stability under rapid temperature changes, and has a long service life.
[0054] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it, and it cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.
Claims
1. A highly stable silicon carbide ceramic membrane, characterized in that, The silicon carbide ceramic membrane comprises the following components in parts by weight: 70-90 parts of silicon carbide aggregate, 3-15 parts of toughening agent, 10-35 parts of sintering aid, 1-6 parts of binder, 30-50 parts of silicon carbide whiskers, and 1-5 parts of dispersant; The toughening agent comprises modified carbon nanotubes and inorganic oxides.
2. A highly stable silicon carbide ceramic membrane according to claim 1, wherein The synthesis of the modified carbon nanotubes comprises the following steps: (1) Add carbon nanotubes into inorganic acid and ultrasonically disperse for 30-60 min, then stir and reflux at 60-100 °C for 1-3 h. After the reflux ends, continue ultrasonic treatment at room temperature. After the ultrasonic treatment ends, perform post-treatment to obtain acidified carbon nanotubes; (2) Add trihydroxypropane and an organic solution into a flask, ultrasonically disperse for 20-50 min, then add a condensing agent and the acidified carbon nanotubes obtained in step (1), continue ultrasonic dispersion to make them uniformly mixed, heat and reflux at 100-150 °C. After the reaction ends, perform post-treatment to obtain modified carbon nanotubes.
3. The highly stable silicon carbide ceramic membrane according to claim 2, wherein, In step (1), the carbon nanotubes have a tube diameter of 10-30 nm and a tube length of 1-15 μm.
4. A highly stable silicon carbide ceramic membrane according to claim 1, wherein The inorganic oxides comprise at least one of silicon dioxide, zirconium oxide, and gallium oxide.
5. A highly stable silicon carbide ceramic membrane according to claim 1, characterized in that, The mass ratio of the addition of the modified carbon nanotubes to the inorganic oxides is 3-5:
1.
6. The high-stability silicon carbide ceramic membrane according to claim 1, wherein The sintering aid comprises silicate and rare earth oxide.
7. The highly stable silicon carbide ceramic membrane according to claim 6, characterized in that, The silicate comprises at least one of sodium silicate, potassium silicate, bismuth silicate, and calcium silicate; the rare earth oxide comprises at least one of lanthanum oxide, cerium oxide, chromium trioxide, and yttrium oxide.
8. The highly stable silicon carbide ceramic membrane according to claim 1, wherein The binder comprises at least one of carboxymethyl cellulose, hydroxypropyl cellulose, epoxy resin, and polyvinyl alcohol.
9. The high-stability silicon carbide ceramic membrane according to claim 1, wherein The dispersant comprises at least one of sodium dodecyl sulfate, sodium citrate, and sodium polyacrylate.
10. A method for preparing a high-stability silicon carbide ceramic membrane according to any one of claims 1-9, characterized in that, It includes the following steps: (1) According to the parts by weight, add silicon carbide aggregate, toughening agent, part of the sintering aid, and part of the binder into water, stir and mix, extrude and mold, dry at low temperature, and then calcine at high temperature to obtain a silicon carbide support; (2) Stir and mix silicon carbide whiskers, the remaining part of the sintering aid, the remaining part of the binder, the dispersant, and water, coat them on the silicon carbide support obtained in step (1), and then dry and calcine at high temperature to obtain a silicon carbide ceramic membrane.