Ni-cu-fe porous material with gradient pore structure and preparation method thereof

Abstract

The application relates to a Ni-Cu-Fe porous material with a gradient pore structure and a preparation method thereof. The preparation method is as follows: firstly, fine-particle-diameter Ni powder, Cu powder and Fe powder are mechanically mixed uniformly, and the mass ratio is 5:3:2-8:1:1; secondly, coarse-particle-diameter Ni powder, Cu powder, Fe powder and ammonium bicarbonate powder are mechanically mixed uniformly, and the mass ratio is 5:3:2:1-8:1:1:1; stearic acid is added into the Ni-Cu-Fe mixed powder for granulation and drying; the Ni-Cu-Fe mixed powder and the Ni-Cu-Fe-ammonium bicarbonate mixed powder are laid in the mold layer by layer for cold forming, and vacuum pressureless sintering is adopted to obtain the Ni-Cu-Fe gradient pore structure porous material. The method has the advantages of low energy consumption, simple operation, low cost, almost no pollution, and self-control of pore size, porosity and thickness. The prepared filtering membrane has good acid corrosion resistance and heat resistance, the service life of the inorganic membrane is improved, and the filtering membrane can be widely applied to filtering, separation, purification and extraction in harsh environments, especially in high-temperature environments and HF acid corrosion environments.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of inorganic porous materials, and particularly relates to a Ni-Cu-Fe porous material with a gradient pore structure and a preparation method thereof. BACKGROUND

[0002] Porous metal material is composed of metal skeleton and pores, and a large number of internal pores make the porous metal material have the advantages of small specific gravity, large specific surface area, high heat exchange and dissipation capacity, and good permeability. Gradient porous metal material with gradient change in pore size and porosity has advantages that uniform porous metal material does not have due to its unique pore structure. In the field of filtration and separation, there are often situations where small molecular substances such as gas and liquid need to be separated from large molecular substances such as suspended solids, glue and microorganisms. A single-structure porous metal material filter membrane cannot guarantee a large filtration flux, so it cannot achieve good filtration efficiency. To solve this problem, a porous metal material with gradient pore size is often used as a filter membrane, so that small molecular substances (or liquid) can pass through the membrane, and large molecular substances (or solid) are intercepted by the large pore size end of the membrane, so as to achieve a large filtration flux, thereby improving the filtration precision and filtration efficiency.

[0003] In the current industrial filtration, there are often filtrations of acidic gases, especially HF acid. The porous metal filter membrane existing in the current industry will be corroded when filtering HF acid and other acidic gases, thereby resulting in the disadvantages of low filtration precision and short service life of the porous metal filter membrane. Ni-Cu-Fe alloy compound has excellent corrosion resistance to CO2, H2S / CO2, Cl - gas or ions, and the presence of Fe element improves the HF acid corrosion resistance of Ni-Cu-Fe alloy compound, so that it has obvious advantages in gas filtration and other aspects in an acidic environment. At the same time, the raw materials for preparing Ni-Cu-Fe alloy compound are low in price, so it has a wide application prospect in the field of filtration and separation.

[0004] The existing preparation methods for gradient-pore porous materials include: spraying or brushing method, which is completed manually, so that the coating thickness and uniformity are difficult to accurately control; sol-gel method, which can finely control the pore size and porosity, but has a large amount of organic matter, is difficult to completely remove when the material size is large, and has a relatively complex process. In order to solve the above problems, a certain particle size of ammonium bicarbonate can be added in the preparation process of the porous metal material, and the gradient porous metal material can be obtained through layering and cold pressing; the ammonium bicarbonate is a colorless or light granular, plate-like or columnar crystal, the particle size can be controlled, the chemical property is very unstable, and the ammonium bicarbonate is easy to decompose under heat to generate ammonia, water and carbon dioxide. The method for preparing the gradient porous metal material can effectively simplify the process, accurately control the pore size and porosity by controlling the particle size of the ammonium bicarbonate, and control the thickness of the large-pore layer and the small-pore layer in the process of layering and cold pressing, so that the gradient porous metal material with high filtration precision and filtration flux can be prepared, and the method has important theoretical guidance and practical significance for industrial production. SUMMARY

[0005] The present application aims to solve the problems of poor HF acid corrosion resistance, low service life and the fact that the porous material cannot simultaneously have high filtration precision and filtration flux, and provides a preparation method of Ni-Cu-Fe gradient-pore metal porous material.

[0006] The present application is a kind of Ni-Cu-Fe porous material with gradient-pore structure and its preparation method, which comprises the following steps:

[0007] (1) powder proportioning: the fine particle size Ni powder, Cu powder and Fe powder are weighed according to the mass ratio of 5:3:2 to 8:1:1, and the coarse particle size Ni powder, Cu powder, Fe powder and ammonium bicarbonate powder are weighed according to the mass ratio of 5:3:2:1 to 8:1:1:1;

[0008] (2) powder mixing: the fine particle size powder prepared in step (1) is uniformly mixed on a V-type powder mixer, and the coarse particle size powder is ball milled at the same time;

[0009] (3) granulation: the mixed Ni-Cu-Fe powder in step (2) is granulated, sieved and dried;

[0010] (4) cold pressing: two portions of Ni-Cu-Fe-ammonium bicarbonate mixed powder with a total mass percentage of 70% to 90% and Ni-Cu-Fe mixed powder with a total mass percentage of 10% to 30% are taken and laid in the mold layer by layer, and a complete green compact is obtained by cold pressing;

[0011] (5) vacuum sintering: the green compact prepared in step (4) is sintered at 2.0x10 -2~1.0 x 10 -3 sintering under vacuum condition: increasing temperature from room temperature to 100-150℃ at a rate of 5-10℃ / min, keeping temperature for 60-120min; increasing temperature to 320-450℃ at a rate of 2-5℃ / min, keeping temperature for 40-70min; increasing temperature to 450-650℃ at a rate of 3-8℃ / min, keeping temperature for 50-100min; increasing temperature to 760-850℃ at a rate of 5-10℃ / min, keeping temperature for 40-90min; increasing temperature to 900-950℃ at a rate of 3-7℃ / min, keeping temperature for 70-120min; then cooling down in the furnace to obtain the Ni-Cu-Fe porous material with gradient pore structure;

[0012] wherein the average particle size of the fine particle size Ni powder, Cu powder and Fe powder in step (1) is 3-5μm, the average particle size of the coarse particle size Ni powder, Cu powder and Fe powder is 40-65μm, and the particle size of the ammonium bicarbonate powder is 300-400mesh;

[0013] wherein the mixing time in step (2) is 10-14h, the ball milling treatment time is 6-10h, and the ball-to-material ratio is 15-30:1;

[0014] wherein the granulation in step (3) is mixed granulation by adding stearic acid, the content of the added stearic acid is 3%-5% of the total mass of the mixed powder, and the mesh size of the screen is 50-150mesh;

[0015] wherein the layering mode in step (4) is that the bottom layer is coarse particle size Ni-Cu-Fe-ammonium bicarbonate mixed powder with a thickness of 2-4mm, and the upper layer is fine particle size Ni-Cu-Fe mixed powder with a thickness of 0.1-1mm; the pressure for cold pressing is 50-150MPa, the pressing time is 40-50s, and the pressure maintaining time is 20-40s.

[0016] Compared with the prior art, the present application has the following advantages:

[0017] (1) The present application can synthesize multi-layer gradient metal porous material, and by designing the composition of the components, adjusting the particle size of the Ni powder, Cu powder, Fe powder and ammonium bicarbonate powder, and adjusting the sintering process and the pressure, a gradient pore structure metal porous material with different components, different pore sizes, different porosities and different thicknesses can be obtained.

[0018] (2) The present application only needs to be sintered once to obtain the Ni-Cu-Fe gradient pore structure metal porous material, which has low energy consumption, low cost and low price of raw materials.

[0019] (3) The ammonium bicarbonate powder added in the preparation of the Ni-Cu-Fe gradient pore structure metal porous material in the present application forms gas to run out in the sintering process, thereby forming large pores on the surface of the sample, and simplifying the process flow.

[0020] (4) The Ni-Cu-Fe gradient pore structure metal porous material prepared by using Ni, Cu and Fe as raw materials in the present application has excellent acid corrosion resistance, and has obvious advantages in gas filtration in an HF acid environment.

[0021] (5) The Ni-Cu-Fe gradient pore structure metal porous material prepared in the present application has high filtration precision and filtration flux, the maximum pore diameter of the large pore diameter end is 20-60 μm, the maximum pore diameter of the small pore diameter end is 1-6 μm, the air permeability is 100-500 m 3 ·m -2 ·s -1 ·KPa -1 . BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application. Among them:

[0023] Figure 1 SEM morphology of the cross section of the Ni-Cu-Fe gradient pore structure metal porous material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0024] The present application will be further specifically and concretely described below in combination with specific embodiments.

[0025] Example 1

[0026] The preparation of the Ni-Cu-Fe porous material with gradient pore structure described in the present embodiment uses Ni powder, Cu powder and Fe powder with a fine powder average particle size of 5 μm and a coarse powder average particle size of 50 μm, and ammonium bicarbonate powder with an average particle size of 300 mesh; first, the fine particle size Ni powder, Cu powder and Fe powder are weighed and mixed according to a mass ratio of 5:2:3, and then the coarse particle size Ni powder, Cu powder, Fe powder and ammonium bicarbonate powder are weighed and mixed according to a mass ratio of 5:2:3:1; the fine particle size powder is mixed on a V-type powder mixer for 12 h, and the coarse particle size powder is ball milled for 10 h with a ball-to-material ratio of 20:1; then the mixed fine particle size and coarse particle size Ni-Cu-Fe powder is added with 5% of stearic acid in total mass for granulation, and then sieved with 100 mesh and 60 mesh sieves respectively, and finally dried.

[0027] The Ni-Cu-Fe-ammonium bicarbonate mixed powder in the embodiment is laid on the bottom layer of a Φ25 mm mold, and a layer of fine-grained Ni-Cu-Fe mixed powder is laid on the top layer; the mass ratio of the powder in each layer is 4:1; the green body is pressed by a pressure of 100 MPa, a pressing time of 50 s, and a holding time of 20 s, wherein the thickness of the bottom layer of the green body is 2 mm, and the thickness of the top layer is 0.5 mm.

[0028] The pressed green body is placed in a vacuum furnace with a vacuum degree of 1.0 x 10 -3 Pa for sintering. The temperature is raised from room temperature to 120 °C at a rate of 8 °C / min, and the temperature is kept for 70 min; the temperature is raised to 400 °C at a rate of 5 °C / min, and the temperature is kept for 60 min; the temperature is raised to 550 °C at a rate of 5 °C / min, and the temperature is kept for 90 min; the temperature is raised to 850 °C at a rate of 8 °C / min, and the temperature is kept for 60 min; the temperature is raised to 900 °C at a rate of 5 °C / min, and the temperature is kept for 90 min; and then the furnace is cooled to obtain a Ni-Cu-Fe porous material with a gradient pore structure, wherein the bottom layer is a large pore, and the top layer is a small pore.

[0029] The cross-sectional pore structure of the prepared material is tested, and the cross-sectional SEN morphology of the prepared Ni-Cu-Fe gradient pore metal porous material is shown in FIG. 2. Figure 1 The air permeability of the prepared material reaches 432 m 3 ·m -2 ·s -1 ·KPa -1 , and the maximum pore diameter of the outermost layer of the Ni-Cu-Fe porous material is 58 μm.

[0030] Example 2

[0031] The preparation of the Ni-Cu-Fe porous material with a gradient pore structure in the embodiment uses Ni powder, Cu powder, and Fe powder with an average particle size of 4 μm and an average particle size of 48 μm, and ammonium bicarbonate powder with an average particle size of 350 mesh; the fine-grained Ni powder, Cu powder, and Fe powder are weighed and mixed in a mass ratio of 7:1:2, and the coarse-grained Ni powder, Cu powder, Fe powder, and ammonium bicarbonate powder are weighed and mixed in a mass ratio of 7:1:2:1; the fine-grained powder is mixed on a V-shaped powder mixer for 10 h, and the coarse-grained powder is ball milled for 8 h with a ball-to-powder ratio of 25:1; the mixed fine-grained and coarse-grained Ni-Cu-Fe powder is granulated with 4% of the total mass of stearic acid, and then sieved through a 120 mesh and a 70 mesh screen, and finally dried.

[0032] The Ni-Cu-Fe-ammonium bicarbonate mixed powder in the embodiment is laid on the bottom layer of a Φ25 mm mold, and a layer of Ni-Cu-Fe mixed powder is laid on the top layer. The mass ratio of the powder in each layer is 7:3. The green body is pressed by a pressure of 70 MPa, a pressing time of 40 s, and a holding time of 30 s. The thickness of the bottom layer of the green body is 2.5 mm, and the thickness of the top layer is 1 mm.

[0033] The pressed green body is placed in a vacuum furnace with a vacuum degree of 7.0 x 10 -2 Pa for sintering. The temperature is raised from room temperature to 130 °C at a rate of 8 °C / min, and the temperature is kept for 90 min. The temperature is raised to 380 °C at a rate of 4 °C / min, and the temperature is kept for 50 min. The temperature is raised to 600 °C at a rate of 4 °C / min, and the temperature is kept for 60 min. The temperature is raised to 800 °C at a rate of 6 °C / min, and the temperature is kept for 80 min. The temperature is raised to 920 °C at a rate of 4 °C / min, and the temperature is kept for 100 min. Then the furnace is cooled to obtain a Ni-Cu-Fe porous material with a gradient pore structure, in which the bottom layer is a large pore and the top layer is a small pore.

[0034] The cross-sectional pore structure of the prepared Ni-Cu-Fe gradient pore structure metal porous material is tested, and the air permeability thereof is up to 356 m 3 ·s -2 ·s -1 ·KPa -1 The maximum pore diameter of the outermost layer of the Ni-Cu-Fe porous material is 50 μm.

[0035] Example 3

[0036] The preparation of a Ni-Cu-Fe porous material with a gradient pore structure in the embodiment uses Ni powder, Cu powder, and Fe powder with an average particle size of 3 μm and an average particle size of 48 μm, and ammonium bicarbonate powder with an average particle size of 400 mesh. The fine particle size Ni powder, Cu powder, and Fe powder are weighed and mixed in a mass ratio of 6:1:3. The coarse particle size Ni powder, Cu powder, Fe powder, and ammonium bicarbonate powder are weighed and mixed in a mass ratio of 6:1:3:1. The fine particle size powder is mixed on a V-shaped powder mixer for 14 h, and the coarse particle size powder is ball milled for 6 h with a ball-to-material ratio of 15:1. The mixed fine particle size and coarse particle size Ni-Cu-Fe powder is granulated with 3% stearic acid, and then sieved through a 100 mesh and an 80 mesh screen, and finally dried.

[0037] The Ni-Cu-Fe-ammonium bicarbonate mixed powder in the embodiment is laid on the bottom layer of a Φ25mm mold, and a layer of Ni-Cu-Fe mixed powder is laid on the top layer, the mass ratio of the powder in each layer is 9:1, and the green body is pressed by a pressure of 80MPa, a pressing time of 45s, and a holding time of 25s, wherein the thickness of the bottom layer of the green body is 3mm, and the thickness of the top layer is 0.3mm.

[0038] The pressed green body is placed in a vacuum furnace with a vacuum degree of 5.0x10 -2 Pa for sintering. The temperature is raised from room temperature to 150℃ at a rate of 6℃ / min, and the temperature is kept for 100min; the temperature is raised to 350℃ at a rate of 5℃ / min, and the temperature is kept for 55min; the temperature is raised to 620℃ at a rate of 3℃ / min, and the temperature is kept for 100min; the temperature is raised to 780℃ at a rate of 8℃ / min, and the temperature is kept for 75min; the temperature is raised to 950℃ at a rate of 5℃ / min, and the temperature is kept for 120min; and then the furnace is cooled to obtain a Ni-Cu-Fe porous material with a gradient pore structure, wherein the bottom layer is a large pore, and the top layer is a small pore.

[0039] The cross-section pore structure of the prepared Ni-Cu-Fe gradient pore structure metal porous material is tested, and the air permeability thereof is up to 342m 3 ·s -2 ·s -1 ·KPa -1 , and the maximum pore diameter of the outermost layer of the Ni-Cu-Fe porous material is 42μm.

[0040] The above examples are only used to illustrate the technical solutions of the present application, and the embodiments of the present application are not limited by the above examples; although the present application is described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a Ni-Cu-Fe porous material with a gradient pore structure, characterized in that... Includes the following steps: (1) Powder ratio: Weigh fine-particle-size Ni powder, Cu powder, and Fe powder in a mass ratio of 5:3:2 to 8:1:1, with an average particle size of 3 to 5 μm. Weigh coarse-particle-size Ni powder, Cu powder, Fe powder, and ammonium bicarbonate powder in a mass ratio of 5:3:2:1 to 8:1:1:1, with an average particle size of 40 to 65 μm. The ammonium bicarbonate powder has a particle size of 300 to 400 mesh. (2) Powder mixing: The fine-particle-size powder prepared in step (1) is placed on a V-type powder mixer and mixed at a uniform speed. At the same time, the coarse-particle-size powder prepared is ball-milled. The mixing time is 10-14 hours, the ball-milling time is 6-10 hours, and the ball-to-material ratio is 15-30:

1. (3) Granulation: The Ni-Cu-Fe powder mixed in step (2) is granulated, sieved and dried. The granulation is mixed with stearic acid and the content of stearic acid is 3% to 5% of the total mass of the powder. The mesh size of the sieve is 50 to 150 mesh. (4) Cold pressing: Take two portions of Ni-Cu-Fe-ammonium bicarbonate mixed powder with a total mass percentage of 70% to 90% and Ni-Cu-Fe mixed powder with a total mass percentage of 10% to 30% and spread them layer by layer in the mold, and cold press to obtain a complete compact; (5) Vacuum sintering: The compact obtained in step (4) is sintered at 2.0 × 10⁻⁶ mm. -2 ~1.0×10 -3 Sintering was carried out under vacuum conditions of Pa: the temperature was increased from room temperature to 100–150°C at a heating rate of 5–10°C / min and held for 60–120 min; the temperature was increased to 320–450°C at a heating rate of 2–5°C / min and held for 40–70 min; the temperature was increased to 450–650°C at a heating rate of 3–8°C / min and held for 50–100 min; the temperature was increased to 760–850°C at a heating rate of 5–10°C / min and held for 40–90 min; the temperature was increased to 900–950°C at a heating rate of 3–7°C / min and held for 70–120 min; and then cooled in the furnace to obtain a Ni-Cu-Fe porous material with a gradient pore size structure.

2. The method for preparing a Ni-Cu-Fe porous material with a gradient pore structure according to claim 1, characterized in that... The layering method in step (4) is as follows: the bottom layer is a coarse-grained Ni-Cu-Fe-ammonium bicarbonate mixed powder with a thickness of 2-4 mm, and the upper layer is a fine-grained Ni-Cu-Fe mixed powder with a thickness of 0.1-1 mm; the cold pressing pressure is 50-150 MPa, the pressing time is 40-50 s, and the holding time is 20-40 s.

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