WO2021168737A1 - 一种制备高分散高结晶纳米镍粉的方法 - Google Patents

一种制备高分散高结晶纳米镍粉的方法 Download PDF

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WO2021168737A1
WO2021168737A1 PCT/CN2020/076964 CN2020076964W WO2021168737A1 WO 2021168737 A1 WO2021168737 A1 WO 2021168737A1 CN 2020076964 W CN2020076964 W CN 2020076964W WO 2021168737 A1 WO2021168737 A1 WO 2021168737A1
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nickel
organosol
water
soluble salt
powder
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PCT/CN2020/076964
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English (en)
French (fr)
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董岩
罗心怡
徐勤勤
蒋建清
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东南大学
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Priority to PCT/CN2020/076964 priority Critical patent/WO2021168737A1/zh
Priority to CN202080094056.1A priority patent/CN115087506A/zh
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
    • B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G53/00—Compounds of nickel
    • C01G53/04—Oxides; Hydroxides

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  • the invention relates to a technique for preparing highly dispersed and highly crystalline nano nickel powder, and belongs to the technical field of metal nanoparticle preparation.
  • Nano-metal nickel powder has excellent electrical and magnetic properties, and has broad application prospects in the fields of magnetic properties, electrode materials, catalysts, and magnetic fluids. especially.
  • MLCC multilayer ceramic capacitors
  • the demand for nano-nickel powder has been increasing, and the research on its preparation technology has become more extensive.
  • MLCC is moving towards ultra-thin layer development.
  • the thickness of the inner electrode has reached the thinnest 0.6-0.7 ⁇ m, and the particle size of the corresponding nano-nickel powder is about 100nm.
  • the particle size of nano-nickel powder needs to be further reduced in the future.
  • the nano-nickel powder for internal electrodes of MLCC not only the particle size is small, but also the dispersibility and crystallinity of the nano-particles have high requirements.
  • MLCC internal electrodes need to go through the process of debinding and sintering.
  • the nano-nickel powder needs to have good crystallinity to have sufficient oxidation resistance, and the highly crystalline nickel particles have high density and shrinkage after sintering.
  • the nano-nickel powder also needs to have good dispersibility, otherwise the particle agglomeration will cause problems such as discontinuity of the internal electrode and leakage.
  • the nano-nickel powder prepared by the existing method generally has the problems of large particle size, poor dispersibility, or low oxidation resistance temperature.
  • the oxidation resistance of nano-nickel powder depends on its crystallinity, and the crystallinity depends heavily on the preparation temperature.
  • Highly crystalline nano-metallic nickel needs to be prepared at a higher temperature, and nano-particles are difficult to avoid agglomeration and sintering at high temperatures, so it is difficult to achieve the unity of high crystallinity, high dispersion and small particle size.
  • methods such as liquid phase reduction and electrolytic precipitation can prepare nano-nickel powder with a particle size of less than 100nm, due to the low preparation temperature ( ⁇ 100°C) and poor crystallinity, oxidation will occur at room temperature.
  • nano-nickel powder for commercial MLCC adopts chemical vapor condensation or physical vapor condensation, which can prepare nano-nickel powder with a thickness of about 100-300nm. It has good oxidation resistance and high dispersibility, but it is difficult to prepare a larger particle size. Small nano-nickel powder, and the preparation process is complicated, the equipment is expensive, and the production cost is extremely high.
  • the present invention provides a method for quickly synthesizing highly crystalline and highly dispersed nano nickel powder, which can prepare nano nickel powder with a particle size of less than 50 nm, uniform particle size and good dispersibility on a large scale.
  • the preparation technology is used in conductive paste Materials, magnetic fluid and microwave absorbing materials have good application prospects.
  • the method for preparing highly crystalline and highly dispersed nano nickel powder of the present invention includes the following steps:
  • the organic solvent is ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, ethanol, n-propanol, and isopropyl alcohol.
  • the water-soluble salt coated with the dry gel film is calcined at a temperature above 400°C and below the salt melting point.
  • the dry gel film is converted into nickel oxide nanoparticles, which are dispersed and attached to the surface of the water-soluble salt particles to form a calcined product;
  • the calcined product is reduced at 400°C to 600°C in a reducing atmosphere, and the nickel oxide nanoparticles dispersed and attached to the surface of the water-soluble salt particles are converted into nickel nanoparticles;
  • the water-soluble salt in step 2) is potassium sulfate, sodium sulfate, potassium chloride or sodium chloride.
  • the molar concentration of nickel is between 0.01M and 1M, and the molar ratio of nickel nitrate and citric acid is 1:0.1-1.
  • the nickel salt is nickel nitrate, nickel acetate or nickel chloride.
  • the present invention has the following advantages:
  • the nano-nickel powder prepared by the liquid-phase reduction method and the electrolytic precipitation method has poor crystallinity and is easy to oxidize.
  • the nano-nickel powder prepared by chemical vapor condensation or physical vapor condensation has the disadvantages of too large particle size, complicated process, expensive equipment and high production cost.
  • the project team tried various methods such as water-soluble sulfate co-precipitation method, water-soluble salt nanoparticle isolation method and metal acetylacetonate solution impregnation method to prepare nano-nickel powder in the early stage, but these methods still have complex processes and particle size. Disadvantages such as unevenness make it difficult to prepare highly crystalline and highly dispersed nano-nickel powder on a large scale.
  • the present invention uses nickel-containing organosol to impregnate the water-soluble salt.
  • the organosol undergoes a sol-gel transition during the subsequent heat preservation process.
  • the organic solvent in the gel evaporates, the gel shrinks and can be dissolved in water after being completely dried.
  • the surface of the salt particles is coated with a dry gel film.
  • the organic matter in the dry gel film is calcined and decomposed to generate nickel oxide nanoparticles, and the generated nickel oxide nanoparticles are dispersed and attached to the water-soluble salt.
  • the surface of the particles is then reduced in a reducing atmosphere at 400°C to 600°C to convert the nickel oxide nanoparticles dispersed and attached to the surface of the water-soluble salt particles into nickel nanoparticles.
  • the salt is removed by washing with water to obtain a good dispersion.
  • Metallic nickel nanoparticles that are both flexible and crystalline.
  • the invention utilizes the shrinkage characteristic of the gel when it is dried to form a uniform dry gel film on the surface of the water-soluble salt particles.
  • organic matter decomposes, and this xerogel film becomes nickel oxide nanoparticles dispersed on the surface of the water-soluble salt particles.
  • Our research shows that these nanoparticles are closely attached to the surface of the salt particles and have a strong binding force with the water-soluble salt particles. When they are reduced to nickel nanoparticles again, they will not fall off the surface of the salt particles. At the same time, since these nickel nanoparticles are not in contact with each other, diffusion and mass transfer will not occur, and agglomeration and sintering will not occur.
  • the reduction temperature of the present invention can be as high as 800°C, the nickel nano-particles are crystallized perfectly, and there are almost no crystal defects inside the particles. Therefore, the present invention can obtain highly crystalline and highly dispersed nano-nickel powder.
  • the present invention uses potassium sulfate (melting point 1067°C), sodium sulfate (melting point 884°C), sodium chloride (melting point 801°C), potassium chloride (melting point 770°C) these four water-soluble salts to prepare nano-nickel pink.
  • surfactants include polyethylene glycol, polyvinylpyrrolidone, carboxylic acid surfactants and the like.
  • the preparation method of the invention has simple process and easy mass production, and can quickly prepare high-crystalline and highly-dispersed nano nickel powder in batches, and the particle size is less than 50 nm.
  • Figure 1 shows the nano nickel powder prepared by reduction at 600°C using the method of the present invention, with a particle size of about 30-50 nm and good dispersibility.
  • Example 1 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 2 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and sodium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of sodium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano-nickel powder.
  • Example 3 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, where the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate to citric acid was 1:0.5.
  • the organosol is mixed with potassium chloride, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium chloride, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano-nickel powder.
  • Example 4 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol is mixed with sodium chloride, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of sodium chloride, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano-nickel powder.
  • Example 5 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.01M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 6 The organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano-nickel powder.
  • Example 7 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.1.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 8 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol methyl ether, where the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:1. The organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate. The mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 9 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 10 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol butyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 11 An organosol was prepared by dissolving nickel nitrate and citric acid in ethanol, where the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate to citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 75°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 12 An organosol was prepared by dissolving nickel nitrate and citric acid in n-propanol, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 90°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 13 An organosol was prepared by dissolving nickel nitrate and citric acid in isopropanol, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 75°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano-nickel powder.
  • Example 14 An organosol was prepared by dissolving nickel nitrate and citric acid in n-butanol, where the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate to citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 110°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 15 An organosol was prepared by dissolving nickel nitrate and citric acid in ethylene glycol, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate and citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 16 An organosol was prepared by dissolving nickel nitrate and citric acid in propylene glycol, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel nitrate to citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 17 An organosol was prepared by dissolving nickel acetate and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel acetate to citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.
  • Example 18 An organosol was prepared by dissolving nickel chloride and citric acid in ethylene glycol methyl ether, wherein the molar concentration of nickel was 0.1M, and the molar ratio of nickel chloride to citric acid was 1:0.5.
  • the organosol and potassium sulfate are mixed, and the excess organosol is poured out after sedimentation to obtain a mixture of organosol and potassium sulfate.
  • the mixture is kept at 60°C to 120°C, and a loose powder is obtained after drying.
  • the powder is calcined at 400°C to below the melting point of potassium sulfate, and then reduced in a reducing atmosphere at 400°C to 600°C, and the reduced product is washed with water and dried to obtain highly crystalline and highly dispersed nano nickel powder.

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Abstract

提供一种高结晶高分散纳米镍粉的制备方法，包括：1）将镍盐和柠檬酸溶解于有机溶剂中，制成有机溶胶；2）将该有机溶胶与水溶性盐混合，静置或离心，使水溶性盐沉降，去除上部多余的有机溶胶，得到含金属镍的有机溶胶与水溶性盐的混合物；3）保温，使有机溶胶转变为凝胶，得到水溶性盐颗粒表面包覆的干凝胶膜；4）在400℃以上和盐熔点以下煅烧，形成煅烧产物；5）将煅烧产物在400-600℃还原性气氛中煅烧，将氧化镍转化为镍纳米颗粒；6）水洗、干燥，得到纳米镍粉。该方法可以快速批量生产，制得的产品具有良好的分散性和结晶性，颗粒尺寸小于50nm，适用于制备导电浆料等材料。

Description

一种制备高分散高结晶纳米镍粉的方法 技术领域
本发明涉及一种制备高分散高结晶纳米镍粉的技术，属于金属纳米颗粒制备技术领域。
背景技术
纳米金属镍粉具有优良的电学和磁学性能，在磁学性能，在电极材料、催化剂、磁流体等领域有有广泛的应用前景。特别是。特别是近年来随着多层陶瓷电容器(MLCC)的快速发展，对纳米镍粉的需求不断增长，对其制备技术的研究也愈加广泛。MLCC正在朝着超薄层化发展，目前内电极的厚度最薄已达0.6-0.7μm，相对应的纳米镍粉的颗粒尺寸在100nm左右。随着MLCC层数的不断增加和内电极厚度的不断减薄，未来纳米镍粉的颗粒尺寸还需要进一步减小。
对MLCC内电极用纳米镍粉来说，不仅要求粒径小，还对纳米颗粒的分散性和结晶性有很高的要求。MLCC内电极制作时需要经过排胶和烧结过程，需要纳米镍粉具有良好的结晶性，才能具备足够的抗氧化性能，而且高结晶的镍颗粒具有高的致密度，烧结后的收缩程度也较轻；同时，纳米镍粉还需要具有良好的分散性，否则颗粒团聚将导致出现内电极不连续、漏电等问题。
现有方法制备的纳米镍粉普遍存在着颗粒尺寸偏大、分散性差或抗氧化温度低等问题。纳米镍粉的抗氧化性能取决于其结晶性，而结晶性又严重依赖于制备温度。高结晶的纳米金属镍需要在较高温度下制备，而纳米颗粒在高温下很难避免团聚和烧结，因此难以达到高结晶、高分散和小粒径的统一。液相还原和电解沉淀等方法虽然可以制备出粒径小于100nm的纳米镍粉，但由于制备温度低(<100℃)，结晶性差，室温就会发生氧化。目前商用MLCC用纳米镍粉采用的是化学气相冷凝或物理气相冷凝法，可以制备出100-300nm左右的纳米镍粉，具有良好的抗氧化性和高的分散性，但难以制备出颗粒尺寸更小的纳米镍粉，而且制备工艺复杂、设备昂贵、生产成本极高。
使用高熔点水溶性盐作为隔离相可以防止高温下纳米颗粒的团聚和烧结，且水溶性盐易于水洗清除，有利于制备高结晶高分散的纳米颗粒。本项目组前期采用水溶性硫酸盐共沉淀法(中国专利CN201810037875.7)、水溶性盐纳米颗粒隔离法(中国专利CN201810037620.0)和金属乙酰丙酮盐溶液浸渍法(2019101041603)等多种方法来研制纳米镍粉，但这些方法仍存在工艺复杂、颗粒尺寸不均匀等缺点，难以规模化制备出高结晶高分散纳米镍粉。
发明内容
技术问题：本发明提供了一种能快速合成高结晶高分散纳米镍粉的方法，可规模化制备 出粒径小于50nm、粒径均匀、分散性好的纳米镍粉，该制备技术在导电浆料、磁流体和微波吸收材料等领域具有良好的应用前景。
技术方案：本发明的制备高结晶高分散纳米镍粉的方法，包括以下步骤：
1)将镍盐和柠檬酸溶解于有机溶剂中，配制含有镍的有机溶胶，所述有机溶剂为乙二醇甲醚、乙二醇乙醚，乙二醇丁醚，乙醇，正丙醇，异丙醇、正丁醇、乙二醇和丙二醇中的一种；
2)将含有镍的有机溶胶与水溶性盐混合，静置或离心，使水溶性盐沉降，去除上部多余的有机溶胶，得到含有金属元素的有机溶胶与水溶性盐的混合物；
3)将该混合物在60℃至120℃保温，发生溶胶-凝胶转变，凝胶干燥后在水溶性盐颗粒表面包覆一层干凝胶膜；
4)将包覆有干凝胶膜的水溶性盐在400℃以上、盐熔点以下煅烧，干凝胶膜转变为氧化镍纳米颗粒，并分散附着在水溶性盐颗粒表面，形成煅烧产物；
5)将煅烧产物在还原性气氛中400℃至600℃还原，将分散附着在水溶性盐颗粒的表面的氧化镍纳米颗粒转变为镍纳米颗粒；
6)将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
进一步的，本发明方法中，步骤2)中的水溶性盐为硫酸钾、硫酸钠、氯化钾或氯化钠。
进一步的，本发明方法中，步骤1)中的含有镍的有机溶胶中，镍的摩尔浓度在0.01M至1M之间，硝酸镍和柠檬酸的摩尔比为1:0.1-1。
进一步的，本发明方法中，步骤1)中的含有镍的有机溶胶中，镍盐为硝酸镍、乙酸镍或氯化镍。
有益效果：本发明与现有技术相比，具有以下优点：
现有的纳米镍粉制备方法难以同时获得高结晶性、高分散性和小的粒径。液相还原法和电解沉淀法制备出的纳米镍粉结晶性太差、容易氧化。化学气相冷凝或物理气相冷凝法制备的纳米镍粉又存在粒径太大、工艺复杂、设备昂贵和生产成本高的缺点。本项目组前期尝试过使用水溶性硫酸盐共沉淀法、水溶性盐纳米颗粒隔离法和金属乙酰丙酮盐溶液浸渍法等多种方法来制备纳米镍粉，但这些方法仍存在工艺复杂、颗粒尺寸不均匀等缺点，难以规模化制备出高结晶高分散纳米镍粉。
本发明使用含有镍的有机溶胶来浸渍水溶性盐，有机溶胶在后续的保温过程中发生溶胶-凝胶转变，当凝胶中的有机溶剂蒸发时，凝胶发生收缩，彻底干燥后可在水溶性盐颗粒表面包覆一层干凝胶膜，在后续的高温煅烧过程中，干凝胶膜中的有机物煅烧分解，生成 氧化镍纳米颗粒，而且生成的氧化镍纳米颗粒分散附着在水溶性盐颗粒的表面，然后在400℃至600℃还原气氛中还原，将分散附着在水溶性盐颗粒的表面的氧化镍纳米颗粒转变为镍纳米颗粒，冷却后水洗将盐去除，即可得到具有良好分散性和结晶性的金属镍纳米颗粒。
本发明利用了凝胶干燥时的收缩特性，在水溶性盐颗粒表面生成一层均匀的干凝胶膜。高温煅烧时，有机物发生分解，这层干凝胶膜变成氧化镍纳米颗粒分散在水溶性盐颗粒的表面。我们的研究表明，这些纳米颗粒紧密附着在盐颗粒表面，与水溶性盐颗粒有较强的结合力，再次还原成镍纳米颗粒时，也不会从盐颗粒表面脱落。同时这些镍纳米颗粒之间由于相互不接触，因此不会发生扩散传质，也就不会发生团聚和烧结。而且，本发明的还原温度可高达800℃，镍纳米颗粒结晶完善，颗粒内部几乎没有晶体缺陷。因此，本发明可以得到高结晶高分散的纳米镍粉。
经过优选后，本发明使用硫酸钾(熔点1067℃)、硫酸钠(熔点884℃)、氯化钠(熔点801℃)、氯化钾(熔点770℃)这四种水溶性盐来制备纳米镍粉。
如果在有机溶胶中加入表面活性剂，将能进一步改善纳米镍粉的颗粒尺寸均匀性。表面活性剂包括聚乙二醇、聚乙烯吡咯烷酮、羧酸类表面活性剂等。
本发明的制备方法工艺简便，易于大规模生产，可以快速批量制备出高结晶高分散的纳米镍粉，颗粒尺寸小于50nm。
附图说明
图1为使用本发明方法在600℃还原制备的纳米镍粉，粒径约30-50nm，分散性良好。
具体实施方式
下面结合实施例和说明书附图对本发明作进一步的说明。
实施例1：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例2：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钠混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钠熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例3：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和氯化钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至氯化钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例4：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和氯化钠混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至氯化钠熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例5：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.01M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例6：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例7：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.1。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例8：将硝酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:1。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例9：将硝酸镍、柠檬酸溶于乙二醇乙醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例10：将硝酸镍、柠檬酸溶于乙二醇丁醚配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例11：将硝酸镍、柠檬酸溶于乙醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至75℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例12：将硝酸镍、柠檬酸溶于正丙醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至90℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例13：将硝酸镍、柠檬酸溶于异丙醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至75℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例14：将硝酸镍、柠檬酸溶于正丁醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至110℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例15：将硝酸镍、柠檬酸溶于乙二醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例16：将硝酸镍、柠檬酸溶于丙二醇配制有机溶胶，其中镍的摩尔浓度为0.1M，硝酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例17：将乙酸镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，乙酸镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。
实施例18：将氯化镍、柠檬酸溶于乙二醇甲醚配制有机溶胶，其中镍的摩尔浓度为0.1M，氯化镍和柠檬酸的摩尔比为1:0.5。用该有机溶胶和硫酸钾混合，沉降后倒掉多余的有机溶胶，得到有机溶胶和硫酸钾的混合物。将该混合物在60℃至120℃保温，干燥后得到松散粉末。将粉末在400℃至硫酸钾熔点以下煅烧，再在400℃至600℃还原气氛中还原，将还原产物用水洗涤、干燥，得到高结晶高分散纳米镍粉。

Claims (4)

  1. 一种制备高结晶高分散纳米镍粉的方法，其特征在于，该方法包括以下步骤：
    1)将镍盐和柠檬酸溶解于有机溶剂中，配制含有镍的有机溶胶，所述有机溶剂为乙二醇甲醚、乙二醇乙醚，乙二醇丁醚，乙醇，正丙醇，异丙醇、正丁醇、乙二醇和丙二醇中的一种；
    2)将含有镍的有机溶胶与水溶性盐混合，静置或离心，使水溶性盐沉降，去除上部多余的有机溶胶，得到含有金属元素的有机溶胶与水溶性盐的混合物；
    3)将该混合物在60℃至120℃保温，发生溶胶-凝胶转变，凝胶干燥后在水溶性盐颗粒表面包覆一层干凝胶膜；
    4)将包覆有干凝胶膜的水溶性盐在400℃以上、盐熔点以下煅烧，干凝胶膜转变为氧化镍纳米颗粒，并分散附着在水溶性盐颗粒表面，形成煅烧产物；
    5)将煅烧产物在还原性气氛中400℃至600℃煅烧，将分散附着在水溶性盐颗粒的表面的氧化镍纳米颗粒转变为镍纳米颗粒；
    6)将还原产物用水洗涤、干燥，得到高结晶纳米镍粉。
  2. 根据权利要求1所述的制备高结晶高分散纳米镍粉的方法，其特征在于，所述水溶性盐为硫酸钾、硫酸钠、氯化钾或氯化钠。
  3. 根据权利要求1所述的一种制备高结晶高分散纳米镍粉的方法，其特征在于，所述含有镍的有机溶胶中，镍的摩尔浓度在0.01M至1M之间，镍盐和柠檬酸的摩尔比为1:0.1-1。
  4. 根据权利要求1、3所述的一种制备高结晶高分散纳米镍粉的方法，其特征在于，所述含有镍的有机溶胶中，镍盐为硝酸镍、乙酸镍或氯化镍。
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