A method for preparing high flux feal intermetallic compound porous membranes

Abstract

The application discloses a method for preparing a large-flux FeAl intermetallic compound porous membrane, and first, a first FeAl alloy powder is prepared into a tubular green body; second, a dispersion liquid is prepared by using deionized water and an intermediate layer material, and the dispersion liquid is diluted; third, the diluted dispersion liquid is coated on the surface of the tubular green body to form an intermediate layer; then, a filter layer is prepared on the surface of the intermediate layer, and after sufficient drying, an intermetallic compound porous membrane layer composite is obtained; finally, the intermetallic compound porous membrane layer composite is subjected to one-time continuous sintering treatment, and the intermediate layer is decomposed and volatilized, so that the large-flux FeAl intermetallic compound porous membrane is obtained. The method solves the problem that the existing metal membrane filtering material cannot simultaneously have high precision and high permeability, and solves the problems of complex preparation process and high cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic porous membrane material preparation, and particularly relates to a method for preparing a large-flux FeAl intermetallic compound porous membrane. BACKGROUND

[0002] High-temperature filtration of metal porous membrane material is filtration and separation of high-temperature gas by using a specific pore structure of the membrane material, and has the advantages of high efficiency, energy saving, simplicity, small pollution and the like, and has been widely applied to various industrial fields, especially to steel, coal chemical industry, thermal power, waste incineration and the like. In some working conditions, hydrogen sulfide gas is contained, which causes strong corrosion to equipment and functional elements under high temperature and high pressure. The metal porous membrane has a large specific surface area, so that the corrosion rate is faster, and the pore channel is seriously blocked and the function is lost, which directly affects the stable operation of the entire production system.

[0003] FeAl-based alloy filter material has excellent room-temperature high-temperature strength, high-temperature oxidation resistance, sulfurization resistance, molten salt corrosion resistance and the like. Since the Fe-Al intermetallic compound has room-temperature brittleness, in order to achieve the required pressure resistance and shear resistance, the material must have a certain thickness, and the filtration precision and the permeation performance are contradictory, so how to improve the filtration precision and the element surface finish under the premise of guaranteeing the mechanical strength and the permeation performance, and reduce the filter cake adhesion and the renewability are problems to be solved for the Fe-Al alloy porous material at present. SUMMARY

[0004] The present application provides a method for preparing a large-flux FeAl intermetallic compound porous membrane, so as to solve the problem that the existing metal membrane filtration material cannot simultaneously have high precision and high permeation performance, and also solve the problem of complex preparation process and high cost.

[0005] The technical scheme provided by the present application is as follows:

[0006] A method for preparing a large-flux FeAl intermetallic compound porous membrane, comprising the following steps:

[0007] a. The first FeAl alloy powder is placed in a mold for isostatic pressing to prepare a tubular green body;

[0008] b. The intermediate layer material is dispersed by ultrasonic to form a uniform dispersion liquid, and the dispersion liquid is diluted by a solvent to facilitate surface film formation;

[0009] c. The diluted dispersion liquid is uniformly coated on the surface of the tubular green body, and dried at room temperature to form an intermediate layer;

[0010] d. Add the second FeAl alloy powder, binder and defoamer and mix well to form a metal film slurry. Spray the metal film slurry onto the surface of the intermediate layer to form a filter layer. After thorough drying, an intermetallic compound porous membrane composite is obtained.

[0011] e. Place the intermetallic compound porous membrane composite in a sintering furnace and perform a continuous sintering process to decompose and volatilize the intermediate layer, thereby obtaining a high-flux FeAl intermetallic compound porous membrane.

[0012] Further, in step a, the first FeAl alloy powder is a dendritic FeAl alloy powder with an average particle size of 50-500 μm, and the isostatic pressing pressure is 170 MPa-230 MPa.

[0013] Further, in step b, the intermediate layer material is one or more of graphene oxide, polyvinyl alcohol, boric acid, and polyvinylpyrrolidone; the volume ratio of deionized water to intermediate layer material in the dispersion is 1:0.5 to 5; when the solvent dilutes the dispersion, the volume ratio of the dispersion to the solvent is 1:1 to 10, and the solvent includes ethanol and deionized water.

[0014] Furthermore, in step c, the thickness of the intermediate layer is 5–50 μm.

[0015] Further, in step e, the specific process of the continuous sintering is as follows: the temperature is increased from room temperature to 380-490℃ at a rate of 3-6℃ / min and held for 30-60min, and then increased to 900-1300℃ at a rate of 5-10℃ / min and held for 60-180min.

[0016] Further, in step d, the adhesive includes polyvinylpyrrolidone and polyvinyl alcohol; the defoamer includes polydimethylsiloxane; and the second FeAl alloy powder is a dendritic FeAl alloy powder with an average particle size of 5-200 μm.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] (1) In the preparation process of the membrane, the present invention adds a burnable intermediate layer, which can prevent fine membrane particles from penetrating into the porous substrate and forming a thick transition zone on the substrate, resulting in low flux. Compared with membrane materials without an intermediate layer, the thickness of the metal membrane can be reduced to 10-100 μm while ensuring the integrity of the membrane, thus ensuring that the filtration accuracy and gas throughput are at a high level at the same time.

[0019] (2) The present invention adopts a one-time co-sintering of the substrate and the film layer, which reduces the preparation process, reduces costs, and avoids problems such as eccentricity, poor straightness, and large air permeability loss in the porous substrate after multiple sintering. Detailed Implementation

[0020] The present invention will now be described in detail with reference to specific embodiments.

[0021] This invention provides a method for preparing high-flux FeAl intermetallic compound porous membranes, comprising the following steps:

[0022] a. A tubular green body is prepared by isostatic pressing of dendritic FeAl alloy powder with an average particle size of 50-500 μm in a mold under a pressure of 170-230 MPa.

[0023] b. The intermediate layer material is ultrasonically dispersed using deionized water to form a uniform dispersion, and the dispersion is diluted with a solvent to facilitate surface film formation; the intermediate layer material is one or a combination of two or more of graphene oxide, polyvinyl alcohol, boric acid and polyvinylpyrrolidone; the volume ratio of deionized water to intermediate layer material in the dispersion is 1:0.5 to 5; when diluting the dispersion with a solvent, the volume ratio of dispersion to solvent is 1:1 to 10, and the solvent includes ethanol and deionized water.

[0024] c. Coat the diluted dispersion evenly on the surface of the tubular green body and dry at room temperature to form an intermediate layer with a thickness of 5 to 50 μm.

[0025] d. Add dendritic FeAl alloy powder with an average particle size of 5-200 μm, binder and defoamer and mix well to form a metal film slurry. Spray the metal film slurry onto the surface of the intermediate layer to form a filter layer. After thorough drying, a porous intermetallic compound membrane composite is obtained. The binder includes polyvinylpyrrolidone and polyvinyl alcohol, and the defoamer includes polydimethylsiloxane.

[0026] e. The intermetallic compound porous membrane composite is placed in a hydrogen sintering furnace for continuous sintering. The sintering process is as follows: the temperature is increased from room temperature to 380-490℃ at a rate of 3-6℃ / min and held for 30-60min. Then, the temperature is increased to 900-1300℃ at a rate of 5-10℃ / min and held for 60-180min. During the sintering process, the intermediate layer is completely decomposed and volatilized, thereby obtaining a high-flux FeAl intermetallic compound porous membrane.

[0027] For ease of distinction, the FeAl alloy powder added in step a is defined as the first FeAl alloy powder; and the FeAl alloy powder added in step d is defined as the second FeAl alloy powder.

[0028] Example 1

[0029] This embodiment provides a method for preparing high-flux FeAl intermetallic compound porous membranes, including the following steps:

[0030] Step 1: FeAl alloy powder with an average particle size of 50μm is placed in a mold and isostatically pressed at a pressure of 230MPa to obtain a tubular green blank with an outer diameter of 60mm and a length of 1500mm.

[0031] Step 2: Take 200 mL of deionized water and add 10 g of polyvinylpyrrolidone, stirring to form a homogeneous solution. Dissolve a certain amount of graphene oxide in the solvent at a volume ratio of 2:1 (solution to graphene oxide), stir thoroughly and ultrasonically disperse to form a homogeneous dispersion. Then, dilute with ethanol at a volume ratio of 1:1 (dispersion to ethanol) and stir thoroughly.

[0032] Step 3: Spray the diluted dispersion evenly onto the surface of the isostatically pressed tubular green body and dry it at room temperature to form an intermediate layer with a thickness of 5μm.

[0033] Step 4: Take 200 kg of FeAl alloy powder with an average particle size of 5 μm, 6 g of polyvinylpyrrolidone and 150 g of deionized water to prepare a membrane slurry. After stirring evenly, spray it onto the surface of the intermediate layer to form a filter layer. Dry at room temperature to obtain an intermetallic compound porous membrane composite.

[0034] Step 5: The obtained intermetallic compound porous membrane composite is placed in a hydrogen sintering furnace for sintering. The sintering process is as follows: the temperature is raised from room temperature to 380℃ at a rate of 3℃ / min and held for 30min; the temperature is raised from 380℃ to 900℃ at a rate of 5℃ / min and held for 120min. During the sintering process, the intermediate layer is completely decomposed and volatilized, resulting in a high-flux FeAl intermetallic compound porous membrane.

[0035] Testing revealed that the prepared high-flux FeAl intermetallic porous membrane had a pore size of 1 μm and a gas flux of 40 m³ / s. 3 / (hm 2 .kPa).

[0036] Example 2

[0037] This embodiment provides a method for preparing high-flux FeAl intermetallic compound porous membranes, including the following steps:

[0038] Step 1: FeAl alloy powder with an average particle size of 500μm is placed in a mold and isostatically pressed at a pressure of 170MPa to obtain a tubular green blank with an outer diameter of 60mm and a length of 1500mm.

[0039] Step 2: Take 200 mL of deionized water and add 10 g of polyvinylpyrrolidone, stirring to form a homogeneous solution. Dissolve a certain amount of graphene oxide in the solution at a volume ratio of 1:5, stir thoroughly and ultrasonically disperse to form a homogeneous dispersion. Then, dilute with ethanol at a volume ratio of 1:10 and stir thoroughly.

[0040] Step 3: Spray the diluted dispersion evenly onto the surface of the isostatically pressed tubular green body and dry it at room temperature to form an intermediate layer with a thickness of 50 μm.

[0041] Step 4: Take 200 kg of FeAl alloy powder with an average particle size of 90 μm, 6 g of polyvinylpyrrolidone and 150 g of deionized water to prepare a membrane slurry. After stirring evenly, spray it onto the surface of the intermediate layer to form a filter layer. Dry at room temperature to obtain an intermetallic compound porous membrane composite.

[0042] Step 5: The obtained intermetallic compound porous membrane composite is placed in a hydrogen sintering furnace for sintering. The sintering process is as follows: the temperature is raised from room temperature to 490℃ at a rate of 6℃ / min and held for 30min; the temperature is raised from 490℃ to 1300℃ at a rate of 10℃ / min and held at 1300℃ for 120min. During the sintering process, the intermediate layer is completely decomposed and volatilized, resulting in a high-flux FeAl intermetallic compound porous membrane.

[0043] Testing revealed that the prepared high-flux FeAl intermetallic porous membrane had a pore size of 18 μm and a gas flux of 550 m³ / h. 3 / (hm 2 .kPa).

[0044] Example 3

[0045] This embodiment provides a method for preparing high-flux FeAl intermetallic compound porous membranes, including the following steps:

[0046] Step 1: FeAl alloy powder with an average particle size of 250μm is placed in a mold and isostatically pressed at a pressure of 180MPa to obtain a tubular green blank with an outer diameter of 60mm and a length of 1500mm.

[0047] Step 2: Take 200 mL of deionized water and add 6 g of polyvinylpyrrolidone, stirring to form a homogeneous solution. Dissolve a certain amount of graphene oxide in the solution at a volume ratio of 1:2.5, stir thoroughly, and ultrasonically disperse to form a homogeneous dispersion. Then, dilute with deionized water at a volume ratio of 1:5 and stir thoroughly.

[0048] Step 3: Spray the diluted dispersion evenly onto the surface of the isostatically pressed tubular green body and dry it at room temperature to form an intermediate layer with a thickness of 25μm.

[0049] Step 4: Take 200 kg of FeAl alloy powder with an average particle size of 40 μm, 10 g of polyvinylpyrrolidone and 150 g of deionized water to prepare a membrane slurry. After stirring evenly, spray it onto the surface of the intermediate layer to form a filter layer. Dry at room temperature to obtain an intermetallic compound porous membrane composite.

[0050] Step 5: The obtained intermetallic compound porous membrane composite is placed in a hydrogen sintering furnace for sintering. The sintering process is as follows: the temperature is raised from room temperature to 450℃ at a rate of 5℃ / min and held for 30min; the temperature is raised from 450℃ to 1200℃ at a rate of 7℃ / min and held at 1200℃ for 120min. During the sintering process, the intermediate layer is completely decomposed and volatilized, resulting in a high-flux FeAl intermetallic compound porous membrane.

[0051] Testing revealed that the prepared high-flux FeAl intermetallic compound porous membrane had a pore size of 12 μm and a gas flux of 320 m³ / h. 3 / (hm 2 .kPa).

[0052] Example 4

[0053] This embodiment provides a method for preparing high-flux FeAl intermetallic compound porous membranes. The difference between this method and Example 1 is that in step two, polyvinyl alcohol and boric acid are used instead of polyvinylpyrrolidone and graphene oxide, and in step four, the FeAl alloy powder used has an average particle size of 200 μm.

[0054] Testing revealed that the prepared high-flux FeAl intermetallic compound porous membrane had a pore size of 1.8 μm and a gas flux of 53 m³ / s. 3 / (hm 2 .kPa).

[0055] In summary, this invention provides a method for preparing a high-flux FeAl intermetallic porous membrane. First, a FeAl alloy powder is prepared into a tubular green body. Second, a dispersion is prepared using deionized water and an intermediate layer material, and then the dispersion is diluted. Third, the diluted dispersion is coated onto the surface of the tubular green body to form an intermediate layer. Next, a filter layer is prepared on the surface of the intermediate layer, and after thorough drying, an intermetallic porous membrane composite is obtained. Finally, the intermetallic porous membrane composite is subjected to a single continuous sintering process to decompose and volatilize the intermediate layer, thus obtaining the high-flux FeAl intermetallic porous membrane. The high-flux FeAl intermetallic porous membrane prepared using this method solves the problem of existing metal membrane filter materials being unable to simultaneously possess high precision and high permeability. Furthermore, this method uses a single co-sintering of the substrate and membrane layer, reducing preparation steps, lowering costs, and avoiding problems such as eccentricity, poor straightness, and high air permeability loss associated with multiple sintering of the porous substrate.

[0056] 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 high-flux FeAl intermetallic compound porous membranes, characterized in that, Includes the following steps: a. The first FeAl alloy powder is placed in a mold and isostatically pressed to prepare a tubular green blank; b. The intermediate layer material is ultrasonically dispersed using deionized water to form a uniform dispersion, and the dispersion is diluted with a solvent to facilitate surface film formation; the intermediate layer material is one or a combination of two or more of graphene oxide, polyvinyl alcohol, boric acid and polyvinylpyrrolidone. c. The diluted dispersion is uniformly coated onto the surface of the tubular green body and dried at room temperature to form an intermediate layer; d. Add the second FeAl alloy powder, binder and defoamer and mix well to form a metal film slurry. Spray the metal film slurry onto the surface of the intermediate layer to form a filter layer. After thorough drying, an intermetallic compound porous membrane composite is obtained. e. The intermetallic compound porous membrane composite is placed in a sintering furnace and subjected to a single continuous sintering process to decompose and volatilize the intermediate layer, thereby obtaining a high-flux FeAl intermetallic compound porous membrane; the specific process of the single continuous sintering is as follows: the temperature is increased from room temperature to 380-490℃ at a rate of 3-6℃ / min and held for 30-60min, and then increased to 900-1300℃ at a rate of 5-10℃ / min and held for 60-180min.

2. The method for preparing high-flux FeAl intermetallic porous membranes according to claim 1, characterized in that, In step a, the first FeAl alloy powder is a dendritic FeAl alloy powder with an average particle size of 50~500μm, and the isostatic pressing pressure is 170MPa~230MPa.

3. The method for preparing high-flux FeAl intermetallic compound porous membranes according to claim 1, characterized in that, The volume ratio of deionized water to intermediate layer material in the dispersion is 1:0.5~5; when the solvent dilutes the dispersion, the volume ratio of the dispersion to the solvent is 1:1~10, and the solvent includes ethanol and deionized water.

4. The method for preparing high-flux FeAl intermetallic compound porous membranes according to claim 1, characterized in that, In step c, the thickness of the intermediate layer is 5~50μm.

5. The method for preparing high-flux FeAl intermetallic compound porous membranes according to any one of claims 1-4, characterized in that, In step d, the binder includes polyvinylpyrrolidone and polyvinyl alcohol; the defoamer includes polydimethylsiloxane; and the second FeAl alloy powder is a dendritic FeAl alloy powder with an average particle size of 5~200μm.