A method for preparing a porous Ni / Ni-Al composite material with a micron Ni skeleton

Abstract

The application discloses a preparation method of a porous Ni / Ni-Al composite material with a micron Ni skeleton, and the method comprises the following steps: firstly, dispersing nickel-aluminum alloy powder in a deionized water solution containing polyethylene glycol, then adding flocculent nickel carbonyl powder, mixing, and drying to obtain mixed powder; secondly, pressing the mixed powder to obtain a compact; thirdly, sintering the compact to obtain a porous Ni / Ni-Al composite material sintered body; and fourthly, performing oil bath boiling and dissolving treatment on the sintered body. The porous composite material prepared by adopting the powder metallurgy combined with the dissolving post-treatment method has a nickel carbonyl sintered body as a three-dimensional interconnected skeleton and a nickel-aluminum alloy as a filling body, the strength and plasticity of the porous composite material are improved, the micron pores formed by the flocculent nickel carbonyl powder and the nanometer pores formed by the in-situ Al element removal in the nickel-aluminum alloy in the core are effectively coupled, the specific surface area and porosity of the porous composite material are improved, and the porous composite material is suitable for the fields of filtration and separation, catalysts, fuel cell electrodes and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of porous material preparation, and particularly relates to a preparation method of a porous Ni / Ni-Al composite material with a micron Ni skeleton. BACKGROUND

[0002] Porous materials have unique pore structures, and their pore morphologies can be regulated to control their functional characteristics according to requirements. According to the distribution and scale of the pores, the porous materials can be used in different fields such as filtration separation, catalysis industry, thermal management and new energy, and have broad application prospects.

[0003] Porous nickel not only continues the excellent characteristics of porous materials, but also enriches the application fields of the functional pores. In particular, porous nickel with high porosity and small pore size has great application potential in fuel cells, noise reduction, heat insulation, heat exchange and other fields. Porous nickel also retains the characteristics of nickel metal itself, such as good oxidation resistance and acid and alkali corrosion resistance of its compounds, which can be used for filtration elements in high-temperature and acid and alkali environments, and has high-precision filtration efficiency. For the energy battery industry, porous nickel is often used as an electrode material for various types of batteries and has been widely used.

[0004] In addition, for the catalyst industry, nickel has excellent catalytic activity as a transition metal, and its pore structure provides a larger specific surface area and abundant active sites, which has good catalytic potential in the field of hydrogenation catalysis. However, the commonly used hydrogenation reaction such as methanation catalyst often uses powdered porous nickel for catalysis. However, powdered porous nickel has two significant problems in use: (1) due to the small size and high surface activity of the powder, agglomeration and sintering phenomena easily occur, resulting in reduced catalytic activity; (2) porous nickel used for methanation catalysis is prepared by alloy smelting, crushing and leaching, and the uneven size of the powder particles can cause uneven heat transfer, brittle particle collision and breakage. The commonly used solution in industry is to use a carrier to improve the thermal stability and provide certain mechanical strength. However, the use of carriers is generally inert components that occupy a part of the catalytically active volume, and the preparation method is complex. Powder metallurgy is a commonly used method for preparing metal products from raw powders, which is simple in process, easy to operate and suitable for batch production. And there is no report on the method of directly preparing monolithic porous nickel composite materials by powder metallurgy. SUMMARY

[0005] The technical problem solved by the present application is to provide a preparation method of porous Ni / Ni-Al composite material with micron Ni skeleton, aiming at the deficiencies of the prior art.

[0006] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of porous Ni / Ni-Al composite material with micron Ni skeleton, characterized in that the method comprises the following steps:

[0007] Step one: disperse nickel-aluminum alloy powder with a nickel-aluminum mass ratio of 1:1 in a deionized water solution containing polyethylene glycol, then add flocculent carbonyl nickel powder for mixing, and obtain mixed powder after drying;

[0008] Step two: press the mixed powder obtained in step one to obtain a compact;

[0009] Step three: place the compact obtained in step two into a hydrogen sintering furnace, and sinter in a hydrogen atmosphere to obtain a porous Ni / Ni-Al composite material sintered body;

[0010] Step four: place the porous Ni / Ni-Al composite material sintered body obtained in step three into a NaOH solution with a mass concentration of 20% to 35% for oil bath boiling dissolution treatment to partially remove the soluble component Al, then wash with deionized water until the washing water has a pH of 7, and then place in a vacuum oven for vacuum drying to obtain a porous Ni / Ni-Al composite material with micron Ni skeleton and a porosity of 45% to 65%.

[0011] The present application mixes nickel-aluminum alloy powder with flocculent carbonyl nickel powder, then presses into a green compact, so that the fine carbonyl nickel powder is coated around the nickel-aluminum alloy powder to form a three-dimensional interconnected skeleton, then sintering in a hydrogen atmosphere, so that the three-dimensional interconnected skeleton is fully developed and forms a metallurgical bond, obtaining a Ni / Ni-Al sintered compact with a stable structure and micron carbonyl nickel as the skeleton and nickel-aluminum alloy as the filler, then placing it in an alkaline solution for rapid corrosion and dissolution treatment to partially remove the soluble component Al, in-situ forming a fine nano-porous structure, obtaining a porous Ni / Ni-Al composite material with a micron Ni skeleton. The porous composite material uses carbonyl nickel sintered body as the skeleton and nickel-aluminum alloy as the filler, and the carbonyl nickel skeleton is coated on the nickel-aluminum alloy filler to form a three-dimensional interconnected skeleton, which plays a connecting role and effectively improves the strength and plasticity of the porous composite material, while the nickel-aluminum alloy filler can provide functional effects such as catalysis; at the same time, the pores of the porous composite material include micron-level stacking pores formed by the combination of fine carbonyl nickel powder and nano-pores formed in-situ in the nickel-aluminum alloy core, which improves the specific surface area and porosity of the porous composite material.

[0012] The flocculent carbonyl nickel powder used in the present application is usually prepared by a carbonyl pyrolysis method, and forms a flocculent structure by bridging with individual fine nickel particles. The nickel powder with this morphology has a high porosity and specific surface area after subsequent pressing and sintering, which not only forms a stable three-dimensional interconnected micron skeleton and improves the strength of the composite material, but also further increases the specific surface area of the composite material.

[0013] The preparation method of the porous Ni / Ni-Al composite material with a micron Ni skeleton, wherein the phase composition of the nickel-aluminum alloy powder in step one is NiAl3 and Ni2Al3, and has an irregular morphology, the particle size of the nickel-aluminum alloy powder is 60-74 μm, and the particle size of the flocculent carbonyl nickel powder is 1-5 μm. Among the five common phases of nickel-aluminum alloy, NiAl3 and Ni2Al3 are the most easily removed by corrosion and dissolution in an alkaline solution, so the present application limits the phase composition of the nickel-aluminum alloy powder to NiAl3 and Ni2Al3, which ensures that the soluble component Al is partially removed by oil bath boiling dissolution treatment, and a porous Ni / Ni-Al composite material is obtained. At the same time, the present application preferably uses flocculent carbonyl nickel powder with a particle size of 1-5 μm, which on the one hand is easy to form a flocculent bridge to provide a three-dimensional interconnected skeleton structure, and on the other hand, the skeleton structure formed by the sintering of the flocculent carbonyl nickel powder with a small particle size has smaller average pores and larger specific surface area, and the micron skeleton structure with high porosity and small pore size can provide greater capillary force, which is beneficial to the subsequent oil bath boiling dissolution treatment process using an alkaline solution.

[0014] The preparation method of the porous Ni / Ni-Al composite material with micron Ni skeleton has the characteristics that the mass percentage of the flocculent nickel carbonyl powder in the mixed powder in step one is 45% to 60%. The present application limits the amount of the flocculent nickel carbonyl powder to be added to ensure that the flocculent nickel carbonyl powder effectively covers the nickel-aluminum alloy powder to form a better coating effect, and ensures the content of the nickel-aluminum alloy to avoid the loss of its functionality.

[0015] The preparation method of the porous Ni / Ni-Al composite material with micron Ni skeleton has the characteristics that the molecular weight of the polyethylene glycol in step one is 1000 to 6000, and the mixing time is more than 4 hours. The polyethylene glycol with the above-mentioned molecular weight is used as a suspending agent to promote the dispersion of the nickel-aluminum alloy powder, so that the nickel-aluminum alloy powder is uniformly mixed with the flocculent nickel carbonyl powder, and the carbon-based nickel powder forms a uniform three-dimensional interconnected structure after pressing and sintering.

[0016] The preparation method of the porous Ni / Ni-Al composite material with micron Ni skeleton has the characteristics that the pressing method in step two is isostatic pressing, and the pressure of the isostatic pressing is 50 MPa±10 MPa, and the pressure holding time is 60 seconds. The present application can also use the method of die pressing to press.

[0017] The preparation method of the porous Ni / Ni-Al composite material with micron Ni skeleton has the characteristics that the sintering process in step three is: first heated to 350℃ at a heating rate of 2℃ / min and kept for 4 hours, and then heated to 600℃ to 850℃ at a heating rate of 10℃ / min and kept for 2 hours, and taken out when the furnace temperature is less than 60℃; the composition of the sintered body of the porous Ni / Ni-Al composite material is composed of NiAl3, Ni2Al3 and Ni. The present application first slowly heats to 350℃ and keeps for 4 hours to make the organic matter in the compact completely volatilize and remove, and then quickly heats to 600℃ to 850℃ and keeps for 2 hours to make the components in the compact metallurgically combine and form a high porosity structure. At the same time, the sintering process ensures the stability of the phase composition, so that the purpose porous composite material is prepared under the rapid sintering process.

[0018] The preparation method of the porous Ni / Ni-Al composite material with the micron Ni skeleton has the following characteristics: the oil bath temperature of the oil bath boiling dissolution treatment in step four is 100-120 DEG C, and the solution is replaced every 15 minutes during the treatment process, and the solution is observed every 15 minutes, and the porous Ni part of the porous Ni / Ni-Al composite sintered body is observed when the NaOH solution is cooled to about 90 DEG C, and then the solution is taken out. Compared with the conventional corrosion treatment at 100 DEG C, especially at about 90 DEG C, the oil bath boiling dissolution treatment temperature of 100-120 DEG C is used in the present application, so that the boiling bubbles are formed in the alkali solution, thereby accelerating the corrosion process. At the same time, by controlling the solution replacement frequency, the boiling corrosion effect of the alkali NaOH is ensured.

[0019] The preparation method of the porous Ni / Ni-Al composite material with the micron Ni skeleton has the following characteristics: the oil bath temperature of the oil bath boiling dissolution treatment in step four is 100-120 DEG C, and the solution is replaced every 15 minutes during the treatment process, and the solution is observed every 15 minutes, and the porous Ni part of the porous Ni / Ni-Al composite sintered body is observed when the NaOH solution is cooled to about 90 DEG C, and then the solution is taken out. Compared with the conventional corrosion treatment at 100 DEG C, especially at about 90 DEG C, the oil bath boiling dissolution treatment temperature of 100-120 DEG C is used in the present application, so that the boiling bubbles are formed in the alkali solution, thereby accelerating the corrosion process. At the same time, by controlling the solution replacement frequency, the boiling corrosion effect of the alkali NaOH is ensured. -2 Pa below, the temperature is 100 DEG C, and the time is 30 minutes. By controlling the process parameters of the vacuum drying, the oxidation of the product composite material is avoided, and the purity of the composite material is ensured.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] 1. The porous Ni / Ni-Al composite material with the micron Ni skeleton is prepared by adopting the powder metallurgy combined with the dissolution post-treatment method, the three-dimensional interconnected skeleton structure formed by the carbonyl nickel improves the strength and plasticity of the porous composite material, the micron pores formed by the carbonyl nickel powder and the nanometer pores formed in situ in the nickel-aluminum alloy core are effectively coupled, the specific surface area and porosity of the porous composite material are improved, and the adsorption and catalytic potential are improved.

[0022] 2. The three-dimensional interconnected network skeleton structure of the composite material is formed by sintering the carbonyl nickel powder, which not only improves the overall strength of the composite material, but also plays a self-supporting role between the same elements for the nickel-aluminum alloy, does not introduce other impurities, and effectively avoids the problems of low temperature, poor bonding force and phase separation during high-temperature sintering of the single Ni-Al intermetallic compound, and ensures the phase composition of the porous composite material.

[0023] 3、The porous Ni / Ni-Al composite sintered body prepared by the method has micron-level pores and forms a continuous network structure, and the active component Al in the sintered body is dissolved and corroded, the capillary force provided by the micron-level interconnected pores is used to make the corrosion alkali solution quickly reach the central position to be corroded, and the nano-scale pores are efficiently prepared, so that the specific surface area of the material as a whole is further improved, the problem of single size of the traditional porous nickel composite material is broken through, and the application of the porous nickel composite material in the functional environment is greatly enriched.

[0024] 4、The porous Ni / Ni-Al composite material prepared by the method has rich pore structure and high specific surface area, and meets the requirements of material strength and toughness and thermal stability under working conditions, and is not only suitable for the field of filtration and separation, but also is an ideal fuel cell electrode and industrial catalyst material.

[0025] The technical solutions of the present application will be further described in detail through the following examples. DETAILED DESCRIPTION

[0026] Example 1

[0027] The embodiment includes the following steps:

[0028] Step one, 2g of polyethylene glycol with a molecular weight of 1000 is dissolved in 100mL of deionized water to form a suspending agent solution, 5.5g of nickel-aluminum alloy powder with a particle size of 60μm and a nickel-aluminum mass ratio of 1:1 is uniformly dispersed in the suspending agent solution, then 4.5g of flocculent carbonyl nickel powder with a particle size of 1μm is mixed for 4h, and after washing, it is placed on a heating table to be dried at 100℃, to obtain a mixed powder; the phase composition of the nickel-aluminum alloy powder is NiAl3 and Ni2Al3, and has an irregular morphology; the mass percentage of the flocculent carbonyl nickel powder in the mixed powder is 45%;

[0029] Step two, the mixed powder obtained in step one is loaded into a mold bag, fixed with a steel bag and placed in a cold isostatic pressing machine for pressing, the pressing pressure is 50MPa±10MPa, and the pressure holding time is 60s, and after the pressing is completed, the compact is taken out from the bag to obtain a compact;

[0030] Step three, the compact obtained in step two is placed in a hydrogen sintering furnace, a hydrogen atmosphere is introduced, after the gas flow is stable, the temperature is raised to 350℃ at a rate of 2℃ / min and kept for 4h, then the temperature is raised to 850℃ at a rate of 10℃ / min and kept for 2h, and the furnace is cooled to less than 60℃, and the porous Ni / Ni-Al composite sintered body is obtained; the composition of the porous Ni / Ni-Al composite sintered body is composed of NiAl3, Ni2Al3 and Ni, and the porosity is 34.9%;

[0031] Step four, the porous Ni / Ni-Al composite sintered body obtained in step three is put into a beaker containing a 20% mass concentration NaOH solution, and the beaker is put into an oil bath at 100°C for oil bath boiling dissolution treatment to partially remove the soluble component Al. The NaOH solution is replaced every 15 minutes during the treatment, and the porous Ni / Ni-Al composite sintered body is taken out for observation every 15 minutes. When no reaction bubbles are observed in the porous Ni part of the porous Ni / Ni-Al composite sintered body after the NaOH solution is cooled to about 90°C, the porous Ni / Ni-Al composite sintered body is taken out, washed with deionized water until the pH of the washing water is 7, and then placed in a vacuum oven at a vacuum degree of 1.0 x 10 -2 Pa, and vacuum dried at 100°C for 30 minutes to obtain a porous Ni / Ni-Al composite material with a micrometer Ni skeleton and a porosity of 47.8%.

[0032] Example 2

[0033] This example includes the following steps:

[0034] Step one, 2g of polyethylene glycol with a molecular weight of 3000 is dissolved in 100mL of deionized water to form a suspending agent solution, 5g of nickel-aluminum alloy powder with a particle size of 65μm and a nickel-aluminum mass ratio of 1:1 is uniformly dispersed in the suspending agent solution, then 5g of flocculent nickel carbonyl powder with a particle size of 3μm is added and mixed for 5h, and after washing, it is placed on a heating table and dried at 100°C to obtain a mixed powder; the phase composition of the nickel-aluminum alloy powder is NiAl3 and Ni2Al3, and has an irregular morphology; the mass percentage of the flocculent nickel carbonyl powder in the mixed powder is 50%;

[0035] Step two, the mixed powder obtained in step one is loaded into a mold bag and fixed with a steel bag, and then put into a cold isostatic pressing machine for pressing, the pressing pressure is 50MPa±10MPa, and the pressure holding time is 60s, and after the pressing is completed, the compact is taken out from the bag to obtain a compact;

[0036] Step three, the compact obtained in step two is placed in a hydrogen sintering furnace, a hydrogen atmosphere is introduced, and after the gas flow is stable, the temperature is raised to 350°C at a rate of 2°C / min and held for 4h, and then the temperature is raised to 700°C at a rate of 10°C / min and held for 2h, and the furnace is cooled to less than 60°C, and the porous Ni / Ni-Al composite sintered body is taken out; the composition of the porous Ni / Ni-Al composite sintered body is composed of NiAl3, Ni2Al3 and Ni, and the porosity is 41.8%;

[0037] Step four, the porous Ni / Ni-Al composite sintered body obtained in step three is put into a beaker containing a 25% mass concentration NaOH solution, and the beaker is put into an oil bath at 110°C for oil bath boiling dissolution treatment to partially remove the soluble component Al. The NaOH solution is replaced every 15 minutes during the treatment, and the porous Ni / Ni-Al composite sintered body is observed every 15 minutes. The solution replacement and observation operations are repeated a total of 4 times. When no reaction bubbles are observed in the porous Ni part of the porous Ni / Ni-Al composite sintered body after the NaOH solution is cooled to about 90°C, the porous Ni / Ni-Al composite sintered body is taken out, washed with deionized water until the pH of the washing water is 7, and then placed in a vacuum oven at a vacuum degree of 1.0 x 10 -2 The porous Ni / Ni-Al composite material with a micrometer Ni skeleton and a porosity of 56.2% is obtained by vacuum drying at a temperature of 100°C and a pressure of 1.0 x 10

[0038] Example 3

[0039] This example includes the following steps:

[0040] Step one, 2g of polyethylene glycol with a molecular weight of 6000 is dissolved in 100mL of deionized water to form a suspending agent solution, 4g of nickel-aluminum alloy powder with a particle size of 74μm and a nickel-aluminum mass ratio of 1:1 is uniformly dispersed in the suspending agent solution, then 6g of flocculent nickel carbonyl powder with a particle size of 5μm is added and mixed for 6h, and after washing, it is placed on a heating table and dried at 100°C to obtain a mixed powder; the phase composition of the nickel-aluminum alloy powder is NiAl3 and Ni2Al3, and has an irregular morphology; the mass percentage of the flocculent nickel carbonyl powder in the mixed powder is 60%;

[0041] Step two, the mixed powder obtained in step one is loaded into a mold bag and fixed with a steel bag, and then put into a cold isostatic pressing machine for pressing, the pressing pressure is 50MPa±10MPa, and the pressure holding time is 60s. After the pressing is completed, the compact is taken out from the bag to obtain a compact;

[0042] Step three, the compact obtained in step two is placed in a hydrogen sintering furnace, a hydrogen atmosphere is introduced, and after the gas flow is stable, the temperature is raised to 350°C at a rate of 2°C / min and held for 4h, and then the temperature is raised to 600°C at a rate of 10°C / min and held for 2h. The furnace is cooled to less than 60°C, and the porous Ni / Ni-Al composite sintered body is taken out. The composition of the porous Ni / Ni-Al composite sintered body is composed of NiAl3, Ni2Al3 and Ni, and the porosity is 46.9%;

[0043] Step four, the porous Ni / Ni-Al composite sintered body obtained in step three is put into a beaker containing 35% mass concentration NaOH solution, and the beaker is put into an oil bath at 120°C for oil bath boiling and dissolving treatment to partially remove the soluble component Al. The NaOH solution is replaced every 15 minutes during the treatment, and the porous Ni / Ni-Al composite sintered body is taken out for observation every 15 minutes. The solution replacement and observation operations are repeated for a total of 6 times. When the NaOH solution is cooled to about 90°C and no reaction bubbles are observed in the porous Ni part of the porous Ni / Ni-Al composite sintered body, the sintered body is taken out, washed with deionized water until the pH of the washing water is 7, and then placed in a vacuum oven at a vacuum degree of 1.0 x 10 -2 Pa, dried in vacuum at 100°C for 30 minutes, and a porous Ni / Ni-Al composite material with a micrometer Ni skeleton and a porosity of 64.5% is obtained.

[0044] The above description is only a preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change, and equivalent change made to the above embodiment according to the technical essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing a porous Ni / Ni-Al composite material having a micron Ni skeleton, characterized in that, The method comprises the following steps: Step one, disperse the nickel-aluminum alloy powder with a mass ratio of 1:1 into a deionized water solution containing polyethylene glycol, then add flocculent nickel carbonyl powder for mixing, and obtain a mixed powder after drying; the phase composition of the nickel-aluminum alloy powder is NiAl3 and Ni2Al3, the particle size of the flocculent nickel carbonyl powder is 1-5 μm, and the mass percentage of the flocculent nickel carbonyl powder in the mixed powder is 45-60%; Step two, press the mixed powder obtained in step one to obtain a compact; Step three, place the compact obtained in step two into a hydrogen sintering furnace, and sinter in a hydrogen atmosphere to obtain a porous Ni / Ni-Al composite sintered body; the sintering process is as follows: first, heat to 350°C at a heating rate of 2°C / min and keep for 4 h, then heat to 600-850°C at a heating rate of 10°C / min and keep for 2 h, and take out when the furnace temperature is less than 60°C; the composition of the porous Ni / Ni-Al composite sintered body is composed of NiAl3, Ni2Al3 and Ni; Step four, place the porous Ni / Ni-Al composite sintered body obtained in step three into a NaOH solution with a mass concentration of 20-35% for oil bath boiling dissolution treatment to partially remove the soluble component Al, then wash with deionized water until the pH of the washing water is 7, and then place in a vacuum oven for vacuum drying to obtain a porous Ni / Ni-Al composite material with a micrometer Ni skeleton and a porosity of 45-65%; the oil bath temperature of the oil bath boiling dissolution treatment is 100-120°C, and the solution is replaced every 15 min during the treatment process, and the porous Ni / Ni-Al composite sintered body is taken out for observation every 15 min; when no reaction bubbles are observed in the porous Ni part of the porous Ni / Ni-Al composite sintered body when the NaOH solution is cooled to about 90°C, the porous Ni / Ni-Al composite sintered body is taken out.

2. The method for preparing a porous Ni / Ni-Al composite material with a micron-sized Ni framework according to claim 1, characterized in that, The nickel-aluminum alloy powder in step one has an irregular morphology, and the particle size of the nickel-aluminum alloy powder is 60-74 μm.

3. The method for preparing a porous Ni / Ni-Al composite material with a micron-sized Ni framework according to claim 1, characterized in that, The molecular weight of the polyethylene glycol in step one is 1000-6000, and the mixing time is more than 4 h.

4. The method for preparing a porous Ni / Ni-Al composite material with a micron-sized Ni framework according to claim 1, characterized in that, The pressing method in step two is isostatic pressing, and the pressure of the isostatic pressing is 50 MPa±10 MPa, and the pressure holding time is 60 s.

5. The method for preparing a porous Ni / Ni-Al composite material with a micron-sized Ni framework according to claim 1, characterized in that, The vacuum degree of the vacuum drying in step four is 1.0 x 10 -2 Pa, temperature is 100°C, and time is 30 min.