Silicon carbide composite ceramic membrane with gradient pore structure
By using a composite sintering aid system of germanium-containing optical fiber waste with carbon powder and iron oxide powder, combined with a gradient pore structure, the problem of high-temperature sintering of silicon carbide ceramic films was solved, achieving low-temperature sintering and cost reduction, and improving film density and mass transfer efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG JIANMO TECH CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-06-26
Smart Images
Figure CN122006516B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of silicon carbide ceramic membrane technology, and in particular relates to a silicon carbide composite ceramic membrane with a gradient pore size structure. Background Technology
[0002] Silicon carbide ceramic membranes have broad application prospects in high-temperature filtration, catalyst support, and separation due to their excellent high-temperature stability, chemical inertness, and mechanical strength. Traditional silicon carbide composite ceramic membranes typically consist of a macroporous support layer, an intermediate transition layer, and a surface microporous separation layer. The transition and separation layers are formed by high-temperature sintering after impregnation or spraying with a coating solution. Because of the high covalent bond energy between carbon and silicon in silicon carbide, ceramic membrane sintering usually requires temperatures exceeding 1800°C, resulting in high energy consumption, stringent equipment requirements, and significantly increased production costs.
[0003] Current research has attempted to reduce the sintering temperature of silicon carbide ceramic films by adding sintering aids. However, commonly used aids such as alumina, magnesium oxide, and yttrium oxide are costly, while organic sintering aids pose a risk of introducing organic matter, which may reduce the pore formation and film quality of silicon carbide. The effects of these methods are difficult to meet the application requirements of silicon carbide ceramic films.
[0004] Therefore, developing a method for preparing silicon carbide composite ceramic films that can reduce sintering temperature and industrial costs is of great industrial significance. Summary of the Invention
[0005] To address the aforementioned issues and further reduce the sintering temperature of silicon carbide ceramic membranes while lowering production costs, this application provides a silicon carbide composite ceramic membrane with a gradient pore size structure.
[0006] A silicon carbide composite ceramic membrane with a gradient pore size structure comprises a support layer, a transition layer, and a separation layer, arranged sequentially from the inside out; the transition layer and the separation layer are formed by sintering after being treated with a coating solution.
[0007] The preparation steps of the coating liquid include the following:
[0008] S01. Take germanium-containing optical fiber waste, grind it, then mix it with carbon powder and iron oxide powder, and continue ball milling to obtain mixed micro powder;
[0009] S02. Add silicon carbide micro powder and mixed micro powder to the dispersion, stir, then add silane coupling agent, continue stirring, let stand to degas, and obtain the product;
[0010] The transition layer uses silicon carbide micropowder with an average particle size of 2-2.8 micrometers;
[0011] The separation layer uses silicon carbide micropowder with an average particle size of 0.8-1.3 micrometers;
[0012] In step S01, the germanium-containing optical fiber waste comprises the following components by mass percentage: SiO2 96.2%-98.1%, Na2O 0.9%-2.2%, GeO2 0.5%-1.5%, K2O 0.03%-0.04%, SnO2 0.01%-0.02%, and In and Ti impurities <0.02%.
[0013] By adopting the above technical solution, germanium-containing optical fiber waste is mixed with carbon powder and iron oxide powder. During the sintering process, the main phase silicon dioxide component in the waste is carbothermally reduced to obtain silicon carbide. The introduction of supplementary silicon carbide can promote mass transfer and densification between silicon carbide particles and promote the ceramic film consolidation process. During the recrystallization sintering process of silicon carbide, the germanium element in the waste replaces silicon atoms in the silicon carbide lattice through the near-circle structure and induces lattice distortion, promoting silicon carbide phase transformation and gas phase migration, so that silicon carbide recrystallization can be carried out at a lower temperature.
[0014] Furthermore, in step S01, the mass ratio of germanium-containing optical fiber waste to carbon powder is (5-5.25):(3.1-3.3); the iron oxide powder is added at a rate of 3%-3.5% of the total mass of germanium-containing optical fiber waste and carbon powder.
[0015] Furthermore, in step S02, the preparation step of the dispersion includes the following: taking methylcellulose and polyacrylic acid, mixing them, adding water to disperse them, stirring at a constant temperature to dissolve them, and thus obtaining the dispersion.
[0016] The mass-to-volume ratio of the methylcellulose, polyacrylic acid, and water used is (0.3-0.5)g:(0.5-0.6)g:(75-80)mL, and the constant temperature stirring temperature is set to 60-80℃.
[0017] In step S02, the silane coupling agent is KH550.
[0018] Furthermore, the preparation steps of the silicon carbide composite ceramic film include the following:
[0019] M01. Take a porous silicon carbide ceramic support, wash it with water and dry it for later use;
[0020] M02. The support is placed in the coating liquid, immersed and pulled, and then sintered to obtain the ceramic membrane transition layer and separation layer respectively;
[0021] In step M02, the immersion and lifting process is as follows: the support is immersed in the coating liquid at a speed of 0.5-1.5 cm / s, and the immersion time is maintained for 30-90 seconds. Then, it is lifted out of the liquid surface at a speed of 1-3 cm / s and dried for later use.
[0022] In step M02, sintering is performed by heating at 0.5-1.3℃ / min to 1150-1220℃, holding at that temperature for 1-2 hours, and then heating at 3.2-3.5℃ to 1385-1420℃ and holding at that temperature for 2-2.5 hours.
[0023] Compared with the prior art, this application has the following beneficial effects:
[0024] 1. This application introduces a composite sintering aid system composed of germanium-containing optical fiber waste, carbon powder, and iron oxide. During the sintering process, the supplementary silicon carbide obtained by the carbothermic reduction reaction can improve the film density, promote mass transfer and densification between silicon carbide particles, and the germanium element in the waste can induce silicon carbide lattice distortion, promote its phase transformation and gas phase migration, and reduce the recrystallization sintering temperature of silicon carbide ceramic film.
[0025] 2. This application realizes the resource utilization of optical fiber waste, reduces raw material costs, and has good economic benefits. Attached Figure Description
[0026] Figure 1 The XRD diffraction patterns of the silicon carbide composite ceramic membrane separation layer in Examples 1-2 of this application are shown.
[0027] Figure 2 This is a SEM image of the silicon carbide composite ceramic membrane separation layer in Example 1 of this application.
[0028] Figure 3 This is a SEM image of the transition layer of the silicon carbide composite ceramic film in Example 1 of this application.
[0029] Figure 4 This is the pore size distribution data of the silicon carbide composite ceramic membrane separation layer in Example 1 of this application.
[0030] Figure 5 This is the pore size distribution data of the transition layer of the silicon carbide composite ceramic membrane in Example 1 of this application. Detailed Implementation
[0031] To make the inventive purpose, technical solution, and beneficial technical effects of this application clearer, the following detailed description of this application is provided in conjunction with embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0032] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.
[0033] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.
[0034] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.
[0035] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.
[0036] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0037] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.
[0038] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.
[0039] In this application, room temperature refers to 0~40℃, including but not limited to 10~40℃, or further to 20~30℃.
[0040] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.
[0041] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.
[0042] Example 1
[0043] (1) The germanium-containing optical fiber waste was ground through a 200-mesh sieve to obtain fine material. Then, it was mixed with carbon powder at a mass ratio of 5:3.1. Iron oxide with a total mass ratio of 3% was added, and the ball-to-material ratio was set to 3:1. The mixture was ball-milled for 2 hours to obtain mixed micro powder.
[0044] (2) Dissolve 0.3g of methylcellulose and 0.5g of polyacrylic acid in 75mL of deionized water at 60℃, stir to dissolve, then stop heating, add 20g of silicon carbide micro powder (particle size 2 micrometers) and 3g of mixed micro powder, then add 0.5mL of KH550 silane coupling agent, stir for 2h, and then let stand to degas, to obtain the transition layer coating liquid;
[0045] (3) Repeat step (2) to prepare the separation layer coating liquid using silicon carbide micro powder (particle size 0.8 micrometers);
[0046] (4) Clean and dry the tubular silicon carbide support, immerse the support in the transition layer coating liquid at a speed of 0.5 cm / s, keep the immersion time for 30 seconds, and then pull it out of the liquid surface at a speed of 1 cm / s. Then dry it at room temperature for 0.5 h and then dry it in an oven at 80℃ for 2 h.
[0047] (5) In a muffle furnace, the temperature is increased to 1150℃ at 0.5℃ / min and held for 1h. Then, the temperature is increased to 1385℃ at 3.2℃ / min and held for 2h. Then, the heating is stopped and the transition layer is obtained after cooling with the furnace.
[0048] (6) Repeat steps (4) and (5), and sinter after applying the separation layer coating liquid to the dip plate to obtain a silicon carbide composite ceramic membrane with a pure water flux of 2896.8 L·m. -2 ·h -1 ·bar -1 It has a water contact angle of 1.2° and a porosity of 40.1%.
[0049] The germanium-containing optical fiber waste is composed of the following components by mass percentage: SiO2 96.2%, Na2O 2.2%, GeO2 1.5%, K2O 0.03%, SnO2 0.01%, and In and Ti impurities <0.02%.
[0050] Example 2
[0051] (1) The germanium-containing optical fiber waste was ground through a 200-mesh sieve to obtain fine material. Then, it was mixed with carbon powder at a mass ratio of 5.25:3.3. Iron oxide with a total mass ratio of 3.5% was added, and the ball-to-material ratio was set to 3:1. The mixture was ball-milled for 2 hours to obtain mixed micro powder.
[0052] (2) Dissolve 0.5g of methylcellulose and 0.6g of polyacrylic acid in 80mL of deionized water at 80℃, stir until dissolved, then stop heating, add 30g of silicon carbide micro powder (particle size 2.8 micrometers) and 5g of mixed micro powder, then add 0.8mL of KH550 silane coupling agent, stir for 3h, and then let stand to degas, to obtain the transition layer coating liquid;
[0053] (3) Repeat step (2) to prepare the separation layer coating liquid using silicon carbide micro powder (particle size 1.3 micrometers);
[0054] (4) Clean and dry the tubular silicon carbide support, immerse the support in the transition layer coating liquid at a speed of 1.5 cm / s, keep the immersion time for 90 seconds, and then pull it out of the liquid surface at a speed of 3 cm / s. Then dry it at room temperature for 1 hour and then dry it in an oven at 80°C for 2 hours.
[0055] (5) The temperature is increased to 1220℃ in a muffle furnace at 1.3℃ / min and held for 2h. Then the temperature is increased to 1420℃ at 3.5℃ / min and held for 2.5h. Then the heating is stopped and the transition layer is obtained after cooling with the furnace.
[0056] (6) Repeat steps (4) and (5), and sinter after applying the separation layer coating liquid to the membrane to obtain a silicon carbide composite ceramic membrane with a pure water flux of 3105.3 L·m. -2 ·h -1 ·bar -1 The water contact angle is 0.7°, and the porosity is 38.7%.
[0057] The germanium-containing optical fiber waste is composed of the following components by mass percentage: SiO2 98.1%, Na2O 0.9%, GeO2 0.5%, K2O 0.04%, SnO2 0.02%, and In and Ti impurities <0.02%.
[0058] Take Examples 1-2 and Figures 1-5 It can be concluded that the XRD peak positions of the prepared composite ceramic membrane are basically consistent with the silicon carbide peak positions of the standard card PDF#75-0524, indicating that the silica component mixed in the coating solution is almost completely converted into silicon carbide during the carbothermic reduction process, and a silicon carbide-dominated composite ceramic membrane separation layer and transition layer are obtained. From the SEM image of the silicon carbide composite ceramic membrane in Example 1, it can be seen that the silicon carbide particles on the separation layer and transition layer after sintering are relatively uniform, and there are no obvious defects induced by insufficient sintering, indicating that membrane sintering can be carried out at a low temperature. Combined with the pore size distribution data of the silicon carbide composite ceramic membrane, after sintering, the pore size concentration areas of the separation layer and transition layer of the composite ceramic membrane are different, and a gradient pore size structure is formed together with the macropore structure of the support column.
[0059] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A silicon carbide composite ceramic membrane with a gradient pore size structure, characterized in that, The method comprises, from the inside out, a support, a transition layer, and a separation layer; the transition layer and the separation layer are formed by sintering after being treated with a coating solution; the transition layer uses silicon carbide micro powder with an average particle size of 2-2.8 micrometers; the separation layer uses silicon carbide micro powder with an average particle size of 0.8-1.3 micrometers. The preparation steps of the coating liquid include the following: S01. Take germanium-containing optical fiber waste, grind it, then mix it with carbon powder and iron oxide powder, and continue ball milling to obtain mixed micro powder; S02. Add silicon carbide micro powder and mixed micro powder to the dispersion, stir, then add silane coupling agent, continue stirring, and let stand to degas, and the product is obtained.
2. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, characterized in that, In step S01, the germanium-containing optical fiber waste comprises the following components by mass percentage: SiO2 96.2%-98.1%, Na2O 0.9%-2.2%, GeO2 0.5%-1.5%, K2O 0.03%-0.04%, SnO2 0.01%-0.02%, and In and Ti impurities <0.02%.
3. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, characterized in that, In step S01, the mass ratio of germanium-containing optical fiber waste to carbon powder is (5-5.25):(3.1-3.3); the iron oxide powder is added at a rate of 3%-3.5% of the total mass of germanium-containing optical fiber waste and carbon powder.
4. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, characterized in that, In step S02, the preparation steps of the dispersion include the following: take methylcellulose and polyacrylic acid, mix them, add water to disperse them, stir and dissolve them at a constant temperature, and the dispersion is obtained.
5. A silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 4, characterized in that, The mass-to-volume ratio of the methylcellulose, polyacrylic acid, and water used is (0.3-0.5)g:(0.5-0.6)g:(75-80)mL, and the constant temperature stirring temperature is set to 60-80℃.
6. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, characterized in that, In step S02, the silane coupling agent is KH550.
7. The silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 1, characterized in that, The preparation steps include the following: M01. Take a porous silicon carbide ceramic support, wash it with water and dry it for later use; M02. The support is placed in the coating liquid, immersed and pulled, and then sintered to obtain the ceramic membrane transition layer and separation layer respectively.
8. A silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 7, characterized in that, In step M02, the immersion and lifting process is as follows: the support is immersed in the coating liquid at a speed of 0.5-1.5 cm / s, and the immersion time is maintained for 30-90 seconds. Then, it is lifted out of the liquid surface at a speed of 1-3 cm / s and dried for later use.
9. A silicon carbide composite ceramic membrane with a gradient pore size structure according to claim 7, characterized in that, In step M02, sintering is performed by heating at 0.5-1.3℃ / min to 1150-1220℃, holding at that temperature for 1-2 hours, and then heating at 3.2-3.5℃ to 1385-1420℃ and holding at that temperature for 2-2.5 hours.