A method for preparing a single-layer metal porous membrane based on nano-preprocessing

Abstract

The application discloses a preparation method of a single-layer metal porous membrane based on nano pretreatment. The method utilizes a chemical alkaline oxidation method, performs nano pretreatment on the surface of a metal wire mesh by placing the metal wire mesh in an alkaline oxidation liquid heated to a certain temperature, forms a nano porous oxidation layer on the surface of the metal wire mesh by chemical reaction, directly rolls and forms a single-layer metal porous membrane when the metal wire mesh is combined with powder, and the single-layer metal porous membrane has high strength and integrity. The method is simple and easy to implement, is different from traditional direct rolling and film coating of a metal wire mesh, greatly solves the problems of powder loss and wire diameter exposure in the rolling and forming process of the metal wire mesh, greatly improves the yield of the film coating of the metal wire mesh under the premise of ensuring the strength of the metal wire mesh, and does not need additives or binders and the like. The whole process is environment-friendly and can realize mass production.

Description

Technical Field

[0001] This invention relates to the field of inorganic porous membrane preparation technology, and specifically to a method for preparing a single-layer metal porous membrane based on nano-pretreatment. Background Technology

[0002] Metal porous membranes possess advantages such as high mechanical strength, good thermal conductivity, high membrane flux, and large specific surface area, and are widely used in filtration industries such as coal chemical industry, polycrystalline silicon filtration, dust removal in thermal power plants, and dust removal in cement plants. However, in practical applications, it is necessary to consider various factors, not only meeting filtration requirements but also taking cost into account.

[0003] Currently, porous metal membranes are generally prepared using powder metallurgy. Although powder metallurgy has advantages such as simple operation, low cost, and controllable pore size and membrane structure, the smooth surface of the metal wires often leads to powder shortages and exposed wires during the direct rolling process to achieve metal powder-wire mesh composites. This results in problems such as complex forming process, high forming difficulty, and low yield when using powder metallurgy. Summary of the Invention

[0004] This invention provides a method for preparing a single-layer porous metal membrane based on nano-pretreatment. This method utilizes a chemical alkaline oxidation process, where a metal mesh is placed in an alkaline oxidation solution heated to a specific temperature to perform a nano-pretreatment on the mesh surface. A chemical reaction forms a nano-porous oxide layer on the mesh surface. By reducing the amount of additives required, the metal mesh is directly rolled into a single-layer porous metal membrane during composite processing with powder, resulting in a membrane with high strength and a complete membrane layer. This method solves the problems of low yield, complex forming process, and high difficulty encountered in existing technologies.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for preparing a single-layer porous metal membrane based on nano-pretreatment includes the following steps:

[0007] Step 1: Ultrasonic cleaning and drying of the metal wire mesh; uniform mixing of metal powders of different mesh sizes; addition of deionized water within the first mass percentage range; stirring and mixing evenly.

[0008] Step 2: Mix sodium hypochlorite, sodium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2–5:5–6:9–10:100 to obtain a metal oxidation solution; or mix potassium hypochlorite, potassium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2–5:5–6:9–10:100 to obtain a metal oxidation solution.

[0009] Step 3: Place the dried metal wire mesh in the metal oxide solution for oxidation. After oxidation is complete, rinse with deionized water and then air dry to obtain the pretreated metal wire mesh.

[0010] Step 4: After the pretreated metal wire mesh is leveled by a leveling machine, it is fed into the rolling mill together with the metal powder that was mixed evenly in Step 1. The rolling pressure, rolling speed and roll gap are adjusted to roll the composite metal film blank.

[0011] Step 5: The composite metal membrane preform is sintered and cured to obtain a composite metal porous membrane.

[0012] Further, in step one, the material of the metal wire mesh is one of 310s, 304, 304L, 316L, 316L, 2205 duplex stainless steel, nickel-based, titanium-based, Hastelloy, and Monel alloy wire mesh, and the weaving type of the metal wire mesh is one of woven mesh, expanded metal mesh, perforated mesh, and woven mesh.

[0013] The metal powder is selected from stainless steel powder, nickel powder, titanium powder, and tungsten powder, and the particle size distribution range of the metal powder is between 60 and 500 mesh.

[0014] The first mass percentage range is 0.01% to 2.00%.

[0015] Further, in step two, the step of placing the dried metal wire mesh in the metal oxide solution for oxidation, and then rinsing it with deionized water after oxidation is complete, specifically involves:

[0016] The dried metal wire mesh is placed in the metal oxide solution, and the oxidation temperature is kept constant between 30 and 90 degrees Celsius for 20 to 60 minutes. After oxidation is complete, it is ultrasonically rinsed with deionized water for 10 to 60 minutes.

[0017] Furthermore, in step four, the rolling pressure is 5–25t, the rolling speed is 3–15rad / min, and the roll gap is 100–200μm.

[0018] Furthermore, in step five, the parameters for sintering and solidifying the composite metal film blank are: sintering temperature of 1000-1250°C, holding time of 120-180 min, and heating rate of 2-8 / min.

[0019] Furthermore, in step four, the composite metal film blank has a length of 100–1000 mm, a thickness of 1.0–1.5 mm, and a width of 100–220 mm.

[0020] Furthermore, in step five, the thickness of the obtained composite metal porous membrane is 0.8–2.5 mm, and the gas permeability is ≥400 μm. 3 / m 2 • h·kpa, average pore size is 5~12μm, surface flatness ≤0.1mm.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] This invention provides a method for preparing a single-layer porous metal membrane based on nano-pretreatment. The method uses a metal oxide solution to perform nano-pretreatment on the surface of a metal wire mesh. This method is simple and easy to implement, and is the first to be used for metal wire mesh coating. Unlike the traditional method of directly rolling and coating metal wire mesh, it greatly solves the problems of powder shortage and wire diameter leakage that occur during the rolling process of metal wire mesh. While ensuring the strength of the metal wire mesh, it greatly improves the yield of metal wire mesh coating. In addition, no additives or binders are required, the whole process is environmentally friendly, and it can realize mass production. Attached Figure Description

[0023] Figure 1 A flowchart illustrating the method for preparing a single-layer porous metal membrane based on nano-pretreatment provided by the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0025] Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is intended merely to illustrate selected embodiments of this application and is not intended to limit the scope of protection claimed by this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0026] Metal oxidation treatment is divided into three main categories: thermal oxidation, chemical oxidation, and electrochemical oxidation. Commonly used chemical treatment methods include acid washing oxidation and alkaline washing oxidation. The principle of metal oxidation liquid treatment is to utilize the reaction between metal and oxygen liquid to form a layer of oxide on the surface of the metal wire mesh, which greatly improves the corrosion resistance, wear resistance, and hardness of the metal wire mesh. At the same time, it can also change the appearance and texture of the metal.

[0027] See Figure 1This invention provides a method for preparing a single-layer porous metal membrane based on nano-pretreatment, comprising the following steps:

[0028] Step 1: Ultrasonically clean and dry the metal wire mesh, mix the metal powders of different mesh sizes evenly, add deionized water within the first mass percentage range, and stir to mix evenly.

[0029] Step 2: Mix sodium hypochlorite, sodium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2–5:5–6:9–10:100 to obtain a metal oxidation solution. Alternatively, mix potassium hypochlorite, potassium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2–5:5–6:9–10:100 to obtain a metal oxidation solution.

[0030] The metal oxidation solution is prepared from sodium hypochlorite (NaClO), sodium hydroxide (NaOH), trisodium phosphate (Na3PO4), and deionized water, or from potassium hypochlorite, potassium hydroxide, trisodium phosphate, and deionized water, with a mass ratio of 2–5:5–6:9–10:100. The metal oxidation solution is a strongly oxidizing compound. Na3PO4, in particular, has a strongly alkaline aqueous solution and almost completely decomposes in water, producing a significant amount of Na+ in the solution. + OH - Ions are used to achieve oxidation, forming a nano-porous rough structure on the surface of the metal mesh without damaging its internal structure.

[0031] Step 3: Place the dried metal wire mesh in a metal oxide solution for oxidation. After oxidation is complete, rinse with deionized water and then air dry to obtain the pretreated metal wire mesh.

[0032] Step 4: After the pre-treated metal wire mesh from Step 3 is leveled by a leveling machine, it is fed into the rolling mill along with the uniformly mixed metal powder from Step 1. The rolling pressure, rolling speed and roll gap are adjusted to roll the composite metal film blank.

[0033] Step 5: Sinter and solidify the composite metal membrane preform to obtain a porous composite metal membrane.

[0034] Optionally, in step one, the material of the wire mesh is one of the following: 310s, 304, 304L, 316L, 316L, 2205 duplex stainless steel, nickel-based, titanium-based, Hastelloy, and Monel alloy wire mesh. The weaving type of the wire mesh is one of the following: woven mesh, expanded metal mesh, perforated mesh, and braided mesh.

[0035] The metal powder is selected from stainless steel powder, nickel powder, titanium powder, and tungsten powder, and the particle size distribution range of the metal powder is between 60 and 500 mesh.

[0036] The first mass percentage of deionized water added ranges from 0.01% to 2.00%. The purpose of adding deionized water is to reduce the flowability of the metal powder.

[0037] Optionally, in step two, the dried metal wire mesh is placed in a metal oxide solution for oxidation, and after oxidation is complete, it is rinsed with deionized water. Specifically:

[0038] The dried metal wire mesh is placed in a metal oxidation solution, and the oxidation temperature is kept constant between 30 and 90 degrees Celsius for 20 to 60 minutes. After oxidation is complete, it is ultrasonically rinsed with deionized water for 10 to 60 minutes.

[0039] Optionally, in step four, the rolling pressure is 5–25t, the rolling speed is 3–15 rad / min, and the roll gap is 100–200 μm.

[0040] Optionally, in step five, the parameters for sintering and curing the composite metal film preform are: sintering temperature of 1000-1250°C, holding time of 120-180 min, and heating rate of 2-8 / min.

[0041] Optionally, in step four, the composite metal film blank has a length of 100–1000 mm, a thickness of 1.0–1.5 mm, and a width of 100–220 mm.

[0042] Optionally, in step five, the thickness of the resulting composite metal porous membrane is 0.8–2.5 mm, and the gas permeability is ≥400 μm. 3 / m 2 • h·kpa, average pore size is 5~12μm, surface flatness ≤0.1mm.

[0043] The preparation method of the single-layer metal porous membrane based on nano-pretreatment provided by the present invention will be further described below with reference to specific embodiments.

[0044] Example 1

[0045] This embodiment provides a method for preparing a single-layer metal porous membrane based on nano-pretreatment. The method includes the following steps: (1) taking non-spherical stainless steel powder with particle size distributions of 100 / 160 mesh and 200 / 300 mesh, mixing them in a 1:1 ratio, and adding 0.03% deionized water to reduce the fluidity of the metal powder; (2) selecting a stainless steel wire mesh, ultrasonically cleaning and drying it for later use; (3) preparing a metal oxide solution by mixing sodium hypochlorite, sodium hydroxide, trisodium phosphate and deionized water in a mass ratio of 4.25:3.75:5.5:100, and placing the metal wire mesh in a temperature... (3) Soak the metal wire mesh in a 60℃ metal oxide solution for 30 min, and then wash it with deionized water for 40 min; (4) After the treated metal wire mesh is flattened by a flattening machine, it is fed into a powder mill together with the metal powder. The rolling pressure is 12-13t, the rotation speed is 5rad / min, and the roll gap is 90μm to obtain a composite metal film blank. The size of the composite metal film blank is 200mm×1000mm and the thickness is 1.0mm; (5) The composite metal film blank is sintered on a stainless steel sintering plate. The sintering temperature is 1240℃, the holding time is 120min, and the heating rate is 6 / min to obtain a single-layer metal porous membrane.

[0046] The single-layer porous metal membrane obtained in this embodiment has a thickness of 0.9 mm and an air permeability of 530 μm. 3 / m 2 • h·kPa, average pore size 10 μm.

[0047] Example 2

[0048] This embodiment provides a method for preparing a single-layer porous metal membrane based on nano-pretreatment. The method includes the following steps: (1) taking non-spherical stainless steel powder with particle sizes of 60 / 100 mesh and 200 / 300 mesh, mixing them in a 1:1 ratio, mechanically mixing them evenly, and adding 0.025% deionized water to reduce the fluidity of the metal powder; (2) using stainless steel to weave a single-layer mesh, ultrasonically cleaning and drying it for later use; (3) using sodium hypochlorite, sodium hydroxide, trisodium phosphate and deionized water in a mass ratio of 3.75:4.55:5.5:100 to obtain a metal oxide solution, and placing the metal mesh in a heating temperature of (3) Soak in 80℃ metal oxide solution for 45 min, then wash with deionized water for 25 min; (4) After the treated metal wire mesh is flattened by a flattening machine, it is fed into the powder mill together with the metal powder. The rolling pressure is adjusted to 13~14t, the rotation speed is 3rad / min, and the roll gap is 100μm to obtain a composite metal film blank. The size of the composite metal film blank is 200mm×1000mm and the thickness is 1.0mm; (5) The composite metal film blank is sintered on a stainless steel sintering plate. The sintering temperature is 1200℃, the holding time is 120min, and the heating rate is 5 / min to obtain a single-layer metal porous membrane.

[0049] The single-layer metal porous membrane obtained in this embodiment has a thickness of 1.0 mm and an air permeability of 422 μm. 3 / m 2 • h·kPa, average pore size 11 μm.

[0050] Example 3

[0051] This embodiment provides a method for preparing a single-layer metal porous membrane based on nano-pretreatment. The method includes the following steps: (1) taking non-spherical stainless steel powder with particle sizes of 60 / 100 mesh and 200 / 300 mesh, mixing them in a 1:1 ratio, mechanically mixing them evenly, and adding 0.025% deionized water to reduce the fluidity of the metal powder; (2) using stainless steel to weave a single-layer mesh, ultrasonically cleaning and drying it for later use; (3) using potassium hypochlorite, potassium hydroxide, tripotassium phosphate and deionized water in a mass ratio of 3.75:4.55:5.5:100 to obtain a metal oxide solution, and placing the metal mesh in a heating temperature of 6 (3) Soak in a metal oxide solution at 0℃ for 45 min, then wash with deionized water for 25 min; (4) After the treated metal wire mesh is flattened by a flattening machine, it is fed into a powder mill together with the metal powder. The rolling pressure is adjusted to 13-14t, the rotation speed is 3rad / min, and the roll gap is 100μm to obtain a composite metal film blank. The size of the composite metal film blank is 200mm×1000mm and the thickness is 1.0mm; (5) The composite metal film blank is sintered on a stainless steel sintering plate. The sintering temperature is 1200℃, the holding time is 120min, and the heating rate is 5 / min to obtain a single-layer metal porous membrane.

[0052] The single-layer metal porous membrane obtained in this embodiment has a thickness of 1.0 mm and an air permeability of 417 μm. 3 / m 2 • h·kPa, average pore size 13 μm.

[0053] The present invention provides a method for preparing a single-layer porous metal membrane based on nano-pretreatment. The method uses a metal oxide solution to perform nano-pretreatment on the surface of a metal wire mesh. This method is simple and easy to implement, and is the first to be used for metal wire mesh coating. Unlike the traditional method of directly rolling and coating metal wire mesh, this method greatly solves the problems of powder shortage and wire diameter leakage that occur during the rolling process of metal wire mesh. While ensuring the strength of the metal wire mesh, it greatly improves the yield of metal wire mesh coating. In addition, no additives or binders are required, the whole process is environmentally friendly, and it can achieve mass production.

[0054] The above description is merely the preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for preparing a single-layer porous metal membrane based on nano-pretreatment, characterized in that, Includes the following steps: Step 1: Ultrasonic cleaning and drying of the metal wire mesh; uniform mixing of metal powders of different mesh sizes; addition of deionized water within the first mass percentage range; stirring and mixing evenly. Step 2: Mix sodium hypochlorite, sodium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2~5:5~6:9~10:100 to obtain a metal oxidation solution; or mix potassium hypochlorite, potassium hydroxide, trisodium phosphate, and deionized water in a mass ratio of 2~5:5~6:9~10:100 to obtain a metal oxidation solution. Step 3: Place the dried metal wire mesh in the metal oxide solution for oxidation. After oxidation is complete, rinse with deionized water and then air dry to obtain the pretreated metal wire mesh. Step 4: After the pretreated metal wire mesh is leveled by a leveling machine, it is fed into the rolling mill together with the metal powder that was mixed evenly in Step 1. The rolling pressure, rolling speed and roll gap are adjusted to roll the composite metal film blank. Step 5: The composite metal membrane preform is sintered and cured to obtain a composite metal porous membrane.

2. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to claim 1, characterized in that: In step one, the material of the metal wire mesh is one of 310s, 304, 304L, 316L, 2205 duplex stainless steel, nickel-based, and titanium-based wire mesh, and the type of the metal wire mesh is one of expanded metal mesh, perforated mesh, and woven mesh. The metal powder is selected from stainless steel powder, nickel powder, titanium powder, and tungsten powder, and the particle size distribution range of the metal powder is between 60 and 500 mesh. The first mass percentage range is 0.01% to 2.00%.

3. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to claim 1, characterized in that, In step two, the dried metal wire mesh is placed in the metal oxide solution for oxidation, and then rinsed with deionized water after oxidation is complete. Specifically: The dried metal wire mesh is placed in the metal oxide solution, and the oxidation temperature is maintained at a constant temperature between 30 and 90°C for 20 to 60 minutes. After oxidation is complete, it is ultrasonically rinsed with deionized water for 10 to 60 minutes.

4. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to claim 1, characterized in that: In step four, the rolling pressure is 5~25 t, the rolling speed is 3~15 rad / min, and the roll gap is 100~200 μm.

5. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to any one of claims 1-4, characterized in that: In step five, the parameters for sintering and solidifying the composite metal film blank are: sintering temperature of 1000~1250, holding time of 120~180 min, and heating rate of 2~8 / min.

6. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to claim 5, characterized in that: In step four, the composite metal film blank has a length of 100~1000 mm, a thickness of 1.0~1.5 mm, and a width of 100~220 mm.

7. The method for preparing a single-layer porous metal membrane based on nano-pretreatment according to claim 5, characterized in that: In step five, the resulting composite metal porous membrane has a thickness of 0.8~2.5 mm and a gas permeability ≥400 μm. 3 / m 2 • h·kpa, average pore size is 5~12 μm, surface flatness ≤0.1 mm.

Images