A high-precision homogeneous metal membrane filter element and its preparation method

Abstract

The present invention is applicable to the technical field of metal membrane filter elements and provides a high-precision homogeneous metal membrane filter element and a preparation method thereof, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. The metal film layer comprises the following raw materials: nano-metal powder, modified mannitol, modified nano-graphene, and nano-alumina. The high-precision homogeneous metal membrane filter element provided by the present invention improves the dispersibility of nano-metal powder by adding modified mannitol, can prevent particle aggregation, and ensure uniform pore size distribution of the membrane layer. By adding modified nano-graphene, its interface bonding strength with nano-metal powder is improved. The modified graphene can serve as a reinforcing phase in the metal membrane layer to improve the mechanical properties of the membrane layer. Nano-alumina particles are added to improve hardness and wear resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal membrane filter elements, and in particular relates to a high-precision homogeneous metal membrane filter element and a preparation method thereof. Background Art

[0002] Metal membrane filter elements are high-precision filter components made from metal materials through a specialized process. They are primarily used for high-precision filtration of fluids (such as gases or liquids), effectively removing impurities, particles, and microorganisms while maintaining excellent mechanical properties and chemical stability. Due to their unique properties, metal membrane filter elements are widely used in various fields, including industry, healthcare, and environmental protection.

[0003] When using existing metal membrane filter elements, problems such as membrane shedding and mechanical strength reduction are prone to occur, which affect the service life and filtration performance of the filter element. Summary of the Invention

[0004] The present invention provides a high-precision homogeneous metal membrane filter element, aiming to solve the above-mentioned problems.

[0005] The present invention is achieved as follows: a high-precision homogeneous metal membrane filter element includes a metal substrate, a metal film layer and a protective layer. The metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 0.1-2 mm. The metal film layer includes the following raw materials in parts by weight: 90-100 parts of nano-metal powder, 5-10 parts of modified mannitol, 1-2 parts of modified nano-graphene, and 1-3 parts of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc.

[0006] Preferably, the metal film layer comprises the following raw materials in parts by weight: 92-98 parts of nano metal powder, 6-9 parts of modified mannitol, 1.3-1.7 parts of modified nano graphene, and 1.5-2.5 parts of nano alumina.

[0007] Preferably, the metal film layer comprises the following raw materials in parts by weight: 95 parts of nano metal powder, 7.5 parts of modified mannitol, 1.5 parts of modified nano graphene, and 2 parts of nano alumina.

[0008] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5-3 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide-zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside, so as to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0009] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:1-2, heated and stirred at 160-180°C, and reacted for 30-50 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is obtained by cooling and crystallization separation. The multiple hydroxyl groups of mannitol undergo esterification or etherification reaction with the hydroxyl groups of PEG to form a mannitol-PEG conjugated structure. The introduction of PEG increases the molecular weight and steric hindrance of mannitol, improves its dispersibility and stability, thereby improving the dispersibility of the nano-metal powder, preventing particle aggregation, and ensuring a uniform pore size distribution of the film layer. During the deposition process on the metal substrate surface, the modified mannitol can reduce the friction between the film layer and the substrate and improve the adhesion of the film layer.

[0010] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 0-5°C, and the reduction stage is carried out at 80-100°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:2-4, and then added to 10-15 times the weight and 70-80% ethanol solution, and reacted at 60-80°C for 2-4 hours, filtered, washed and dried to obtain modified nanographene, through the oxidation-reduction process, oxygen-containing functional groups (such as hydroxyl groups and carboxyl groups) are introduced on the surface of the graphene to improve its dispersibility and compatibility with the metal matrix, the reduced graphene restores its conductivity while retaining some functional groups to enhance the binding force with the metal powder, and through the grafting reaction of polyvinyl alcohol, active groups are introduced on the surface of the graphene to improve its interfacial bonding strength with the nanometal powder, and the modified graphene can serve as a reinforcing phase in the metal film layer to improve the mechanical properties of the film layer.

[0011] The present invention also provides a method for preparing the above-mentioned high-precision homogeneous metal membrane filter element, comprising the following steps:

[0012] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 10-100 microns and a porosity of 30-70%. 3D printing technology can achieve high-precision pore size control;

[0013] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0014] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide-zirconia gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0015] The metal membrane filter element is cleaned and dried, and the drying temperature can be 40-60°C.

[0016] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0017] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 10-30 minutes. The power of the low-temperature plasma device is 100-500W, the pressure is 10-100Pa, the gas is argon or oxygen, and the gas flow rate is 10-50 sccm (standard cubic centimeters per minute). Plasma treatment can clean the surface of the metal substrate, remove oxides and contaminants, and introduce active groups (such as hydroxyl groups, carboxyl groups, etc.) on the metal surface through plasma activation, thereby increasing the surface energy, enhancing the bonding strength between the metal film layer and the metal substrate, forming a micro-nanoscale rough structure on the metal surface, increasing the surface area, and improving the adhesion of the metal film layer.

[0018] Preferably, after the protective layer is coated on the surface of the metal membrane layer, the product is fermented. The fermentation method is as follows: soak the product in a culture medium, inoculate Acetobacter xylinum into the culture medium at an inoculation rate of 5-10%, place the fermentation container in a constant temperature fermentation box and ferment at 28-30°C for 3-5 days. After the fermentation is completed, take out the product. During the fermentation process, bacterial cellulose forms a uniform nano-scale porous structure on the surface of the product, further refines the filtration pore size, and improves the filtration performance. Bacterial cellulose has natural corrosion resistance and can be protected on the surface of the product. Bacterial cellulose has high strength and toughness, which can improve the tensile strength and impact resistance of the metal membrane. Bacterial cellulose is hydrophilic and can improve the wettability of the filter element surface, promote the uniform distribution of liquid on the membrane surface, and improve the filtration efficiency and flux.

[0019] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0020] The high-precision homogeneous metal membrane filter element provided by the present invention improves the mechanical properties and durability of the metal membrane filter element by adding modified mannitol, modified nano-graphene, and nano-alumina to the raw materials of the metal membrane layer. The addition of modified mannitol improves the dispersibility of the nano-metal powder, prevents particle aggregation, and ensures a uniform pore size distribution of the membrane layer. During the deposition process on the metal substrate surface, the modified mannitol can reduce the friction between the membrane layer and the substrate and improve the adhesion of the membrane layer. By adding modified nano-graphene, the interface bonding strength between it and the nano-metal powder is improved. The modified graphene can serve as a reinforcing phase in the metal membrane layer to improve the mechanical properties of the membrane layer. By adding nano-alumina particles, the hardness and wear resistance are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a preparation flow chart of a high-precision homogeneous metal membrane filter element provided by the present invention. DETAILED DESCRIPTION

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0023] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] Example 1

[0025] The embodiment of the present invention provides a high-precision homogeneous metal membrane filter element, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 1 mm, and the metal film layer comprises the following raw materials in parts by weight: 90 parts of nano-metal powder, 5 parts of modified mannitol, 1 part of modified nano-graphene, and 1 part of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc., such as Figure 1 As shown, the preparation method of the metal membrane filter element comprises the following steps:

[0026] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 10 microns and a porosity of 30%. 3D printing technology can achieve high-precision pore size control;

[0027] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0028] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide zirconium oxide gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0029] The metal membrane filter element is obtained by cleaning and drying.

[0030] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside, so as to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0031] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:1, heated and stirred at 160°C, and reacted for 30 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is separated by cooling, crystallization and other steps.

[0032] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 0°C, and the reduction stage is carried out at 80°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:2 and added to an ethanol solution with 10 times the weight and a mass fraction of 70%, and the reaction is carried out at 60°C for 2h, filtered, washed and dried to obtain the modified nanographene.

[0033] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0034] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 10 minutes. The power of the low-temperature plasma device is 100 W, the pressure is 10 Pa, the gas is argon or oxygen, and the gas flow rate is 10 sccm (standard cubic centimeters per minute).

[0035] Preferably, after the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, Acetobacter xylinum is inoculated into the culture medium at a 5% inoculation rate, the fermentation container is placed in a constant temperature fermentation box and fermented at 28° C. for 3 days. After the fermentation is completed, the product is taken out.

[0036] Example 2

[0037] The embodiment of the present invention provides a high-precision homogeneous metal membrane filter element, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 1 mm, and the metal film layer comprises the following raw materials in parts by weight: 92 parts of nano-metal powder, 6 parts of modified mannitol, 1.3 parts of modified nano-graphene, and 1.5 parts of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc., such as Figure 1As shown, the preparation method of the metal membrane filter element comprises the following steps:

[0038] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 10 microns and a porosity of 30%. 3D printing technology can achieve high-precision pore size control;

[0039] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0040] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide zirconium oxide gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0041] The metal membrane filter element is obtained by cleaning and drying.

[0042] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside, so as to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0043] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:1, heated and stirred at 160°C, and reacted for 30 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is separated by cooling, crystallization and other steps.

[0044] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 0°C, and the reduction stage is carried out at 80°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:2 and added to an ethanol solution with 10 times the weight and a mass fraction of 70%, and the reaction is carried out at 60°C for 2h, filtered, washed and dried to obtain the modified nanographene.

[0045] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0046] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 10 minutes. The power of the low-temperature plasma device is 100 W, the pressure is 10 Pa, the gas is argon or oxygen, and the gas flow rate is 10 sccm (standard cubic centimeters per minute).

[0047] Preferably, after the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, Acetobacter xylinum is inoculated into the culture medium at a 5% inoculation rate, the fermentation container is placed in a constant temperature fermentation box and fermented at 28° C. for 3 days. After the fermentation is completed, the product is taken out.

[0048] Example 3

[0049] The embodiment of the present invention provides a high-precision homogeneous metal membrane filter element, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 1 mm, and the metal film layer comprises the following raw materials in parts by weight: 95 parts of nano-metal powder, 7.5 parts of modified mannitol, 1.5 parts of modified nano-graphene, and 2 parts of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc., such as Figure 1 As shown, the preparation method of the metal membrane filter element comprises the following steps:

[0050] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 50 microns and a porosity of 50%. 3D printing technology can achieve high-precision pore size control;

[0051] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0052] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide-zirconia gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0053] The metal membrane filter element is obtained by cleaning and drying.

[0054] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide-zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0055] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:1.5, heated and stirred at 170°C, and reacted for 40 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is separated by cooling, crystallization and other steps.

[0056] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 3°C, and the reduction stage is carried out at 90°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:3 and added to an ethanol solution with 12 times the weight and a mass fraction of 75%, and the reaction is carried out at 70°C for 3h, filtered, washed and dried to obtain the modified nanographene.

[0057] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0058] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 20 minutes. The power of the low-temperature plasma device is 300W, the pressure is 50Pa, the gas is argon or oxygen, and the gas flow rate is 30 sccm (standard cubic centimeters per minute).

[0059] Preferably, after the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, Acetobacter xylinum is inoculated into the culture medium at an inoculation rate of 8%, the fermentation container is placed in a constant temperature fermentation box and fermented at 29° C. for 4 days. After the fermentation is completed, the product is taken out.

[0060] Example 4

[0061] The embodiment of the present invention provides a high-precision homogeneous metal membrane filter element, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 1 mm, and the metal film layer comprises the following raw materials in parts by weight: 98 parts of nano-metal powder, 9 parts of modified mannitol, 1.7 parts of modified nano-graphene, and 2.5 parts of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc., such as Figure 1 As shown, the preparation method of the metal membrane filter element comprises the following steps:

[0062] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 100 microns and a porosity of 70%. 3D printing technology can achieve high-precision pore size control;

[0063] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0064] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide zirconium oxide gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0065] The metal membrane filter element is obtained by cleaning and drying.

[0066] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside, so as to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0067] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:2, heated and stirred at 180°C, and reacted for 50 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is separated by cooling, crystallization and other steps.

[0068] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 5°C, and the reduction stage is carried out at 100°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:4 and added to an ethanol solution with 15 times the weight and a mass fraction of 80%, and the mixture is reacted at 80°C for 4 hours, filtered, washed and dried to obtain the modified nanographene.

[0069] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0070] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 30 minutes. The power of the low-temperature plasma device is 500W, the pressure is 100Pa, the gas is argon or oxygen, and the gas flow rate is 50 sccm (standard cubic centimeters per minute).

[0071] Preferably, after the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, Acetobacter xylinum is inoculated into the culture medium at a 10% inoculation rate, the fermentation container is placed in a constant temperature fermentation box and fermented at 30°C for 5 days. After the fermentation is completed, the product is taken out.

[0072] Example 5

[0073] The embodiment of the present invention provides a high-precision homogeneous metal membrane filter element, comprising a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, and the protective layer is located on the surface of the metal film layer. Preferably, the thickness of the metal film layer is 1 mm, and the metal film layer comprises the following raw materials in parts by weight: 100 parts of nano-metal powder, 10 parts of modified mannitol, 2 parts of modified nano-graphene, and 3 parts of nano-alumina. The nano-metal powder can be nickel, titanium, tantalum, etc., such as Figure 1 As shown, the preparation method of the metal membrane filter element comprises the following steps:

[0074] Using 3D printing technology, a metal matrix with a porous structure is printed, with a pore size range of 100 microns and a porosity of 70%. 3D printing technology can achieve high-precision pore size control;

[0075] Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer;

[0076] A protective layer is coated on the surface of the metal film layer. Aluminum oxide layer can be coated by ALD technology, and aluminum oxide zirconium oxide gradient layer and zirconium oxide layer can be coated by sol-gel method combined with heat treatment to improve the crystallinity and mechanical strength of the protective layer;

[0077] The metal membrane filter element is obtained by cleaning and drying.

[0078] Preferably, the protective layer is a multi-layer structure with a thickness of 0.5 mm. From the inside to the outside, it is an aluminum oxide layer, an aluminum oxide zirconium oxide gradient layer, and a zirconium oxide layer. The gradient material design is adopted so that the composition and structure of the protective layer gradually change from the inside to the outside, so as to improve the bonding strength and thermal shock resistance of the protective layer and the metal film layer.

[0079] Preferably, the preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reactor at a ratio of 1:2, heated and stirred at 180°C, and reacted for 50 minutes. After the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is separated by cooling, crystallization and other steps.

[0080] Preferably, the preparation method of the modified nanographene is as follows: the nanographene is oxidized by the Hummers method to generate graphene oxide, and then its conductivity is restored by chemical reduction, the oxidation stage is carried out at 5°C, and the reduction stage is carried out at 100°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:4 and added to an ethanol solution with 15 times the weight and a mass fraction of 80%, and the mixture is reacted at 80°C for 4 hours, filtered, washed and dried to obtain the modified nanographene.

[0081] Preferably, the process of depositing the mixed material on the surface of the metal substrate to form a metal film layer adopts magnetron sputtering, chemical vapor deposition or atomic layer deposition.

[0082] Preferably, before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 30 minutes. The power of the low-temperature plasma device is 500W, the pressure is 100Pa, the gas is argon or oxygen, and the gas flow rate is 50 sccm (standard cubic centimeters per minute).

[0083] Preferably, after the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, Acetobacter xylinum is inoculated into the culture medium at a 10% inoculation rate, the fermentation container is placed in a constant temperature fermentation box and fermented at 30°C for 5 days. After the fermentation is completed, the product is taken out.

[0084] Comparative Example 1: The difference from Example 3 is that modified mannitol is not contained.

[0085] Comparative Example 2: The difference from Example 3 is that the modified mannitol is replaced by ordinary mannitol.

[0086] Comparative Example 3: The difference from Example 3 is that the modified graphene is replaced by ordinary graphene.

[0087] Comparative Example 4: The difference from Example 3 is that the modified mannitol is replaced by ordinary mannitol and the modified graphene is replaced by ordinary graphene.

[0088] Comparative Example 5: The difference from Example 3 is that the product is not subjected to fermentation treatment.

[0089] Performance tests were performed on the metal membrane filter elements of Examples 1-5 and Comparative Examples 1-5.

[0090] 1. Tensile strength test

[0091] Test method: tensile test.

[0092] Standard: ISO 6892-1: Tensile test methods for metallic materials.

[0093] ASTM E8 / E8M: Standard Methods of Tensile Testing of Metallic Materials.

[0094] Equipment: Universal material testing machine.

[0095] Steps: Prepare a standard tensile specimen (e.g., dumbbell-shaped specimen, e.g., with a gauge length of 50 mm, a width of 10 mm, and a thickness of 1 mm); secure the specimen in the fixture of the testing machine; apply tension at a constant rate (usually 1 mm / min) until the specimen breaks; record the maximum tension and elongation at break, and calculate the tensile strength (maximum tension / cross-sectional area).

[0096] 2. Filtration accuracy test

[0097] Test method: Particle retention rate test.

[0098] Standard: ISO 16889: Hydraulic filter elements - Test methods for filtration performance.

[0099] ASTM F795: Test method for particle retention of filter elements.

[0100] Equipment: particle counter, filter test device.

[0101] Steps: Prepare a standard particle suspension (such as a latex particle suspension with a particle size of 0.1µm), install the metal membrane filter element in a filtration test device, filter the suspension at a constant pressure (0.1MPa), use a particle counter to measure the particle concentration in the filtrate, and calculate the retention rate.

[0102] The test results are shown in Table 1 below:

[0103]

[0104] It can be seen from the above results that the metal membrane filter element prepared by the present invention has good mechanical properties and filtration performance. By adding modified mannitol and modified nanographene to the metal membrane layer, the two have a synergistic effect and can further improve its performance. By fermenting the product to form a bacterial cellulose layer, a uniform nanoscale porous structure is formed on the surface of the product, the filtration pore size is further refined, and the filtration performance is improved. Bacterial cellulose has natural corrosion resistance and can be protected on the surface of the product. Bacterial cellulose has high strength and toughness, which can improve the tensile strength and impact resistance of the metal membrane. Bacterial cellulose is hydrophilic and can improve the wettability of the filter element surface, promote the uniform distribution of liquid on the membrane surface, and improve the filtration efficiency and flux.

[0105] It should be noted that, for the sake of simplicity, the aforementioned embodiments are described as a series of action combinations. However, those skilled in the art should be aware that the present invention is not limited by the order of the actions described, because according to the present invention, certain steps may be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also fall within the scope of protection of the present invention.

Claims

1. A high-precision homogeneous metal membrane filter element, characterized in that: The invention comprises a metal substrate, a metal film layer and a protective layer, wherein the metal film layer is located on the surface of the metal substrate, the protective layer is located on the surface of the metal film layer, and the metal film layer comprises the following raw materials in parts by weight: 90-100 parts of nano metal powder, 5-10 parts of modified mannitol, 1-2 parts of modified nano graphene, and 1-3 parts of nano alumina; The preparation method of the modified mannitol is as follows: mannitol and polyethylene glycol are added to a reaction kettle at a ratio of 1:1-2, heated and stirred at 160-180° C., reacted for 30-50 minutes, and after the reaction is completed, the water generated during the reaction is discharged under reduced pressure, and the modified mannitol is obtained by cooling and crystallization separation; The preparation method of the modified nanographene is as follows: oxidizing the nanographene by the Hummers method to generate graphene oxide, and then restoring its conductivity by chemical reduction, wherein the oxidation stage is carried out at 0-5°C and the reduction stage is carried out at 80-100°C, and then the oxidized and reduced nanographene is mixed with polyvinyl alcohol in a mass ratio of 1:2-4, and then added to an ethanol solution with a mass fraction of 10-15 times and a mass fraction of 70-80%, reacting at 60-80°C for 2-4 hours, filtering, washing and drying to obtain the modified nanographene.

2. The high-precision homogeneous metal membrane filter element according to claim 1, characterized in that: The metal film layer comprises the following raw materials in parts by weight: 92-98 parts of nano metal powder, 6-9 parts of modified mannitol, 1.3-1.7 parts of modified nano graphene, and 1.5-2.5 parts of nano alumina.

3. The high-precision homogeneous metal membrane filter element according to claim 2, characterized in that: The metal film layer includes the following raw materials in parts by weight: 95 parts of nano metal powder, 7.5 parts of modified mannitol, 1.5 parts of modified nano graphene, and 2 parts of nano alumina.

4. The high-precision homogeneous metal membrane filter element according to claim 1, characterized in that: The protective layer is a multi-layer structure, which includes an aluminum oxide layer, an aluminum oxide-zirconia gradient layer, and a zirconium oxide layer from the inside to the outside.

5. The method for preparing a high-precision homogeneous metal membrane filter element according to any one of claims 1 to 4, characterized in that: The steps include: Using 3D printing technology to print a metal matrix with a porous structure; Mixing raw materials of the metal film layer to obtain a mixture, and depositing the mixture on the surface of the metal substrate to form a metal film layer; Coating a protective layer on the surface of the metal film layer; The metal membrane filter element is obtained by cleaning and drying.

6. The method for preparing a high-precision homogeneous metal membrane filter element according to claim 5, characterized in that: The method of depositing the mixed material on the surface of the metal substrate to form a metal film layer is magnetron sputtering, chemical vapor deposition or atomic layer deposition.

7. The method for preparing a high-precision homogeneous metal membrane filter element according to claim 5, characterized in that: Before depositing the metal film layer, the metal substrate is placed in a low-temperature plasma device for low-temperature plasma treatment for 10-30 minutes.

8. The method for preparing a high-precision homogeneous metal membrane filter element according to claim 5, characterized in that: After the protective layer is coated on the surface of the metal film layer, the product is fermented. The fermentation method is as follows: the product is immersed in a culture medium, 5-10% of the inoculation amount of Acetobacter xylinum is inoculated into the culture medium, the fermentation container is placed in a constant temperature fermentation box and fermented at 28-30°C for 3-5 days. After the fermentation is completed, the product is taken out.

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