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超细铜粉的制备方法Preparation of ultrafine copper powder

来源: 时间:2019-03-05 15:53:53 次数:

1、常规制备方法
传统的电解铜粉由于颗粒较大,一般在10um以上,不适合用于制作纳米级超细铜粉;雾化法由于抗氧化问题难以解决,难以推广。除了传统的电解法和雾化法外,现有制备方法很多,如:物理法(球磨法、气相蒸汽法、等离子法、y射线辐照一水热结晶联合法、冷冻干燥法等)和液相化学还原法。前者成本高,设备昂贵,工艺复杂;目前研究较多的是液相化学还原法。
1.1、球磨法
以粗颗粒铜粉为试样,采用改进型振动球磨,高能球磨。高能球磨法产量较高、工艺简单,能制备常规方法难以制备的高熔点金属、互不相溶体系的固溶体、纳米金属间化合物及纳米金属,陶瓷复合材料,缺点是晶粒不均匀、球磨过程中易引入杂质。
国外有人使用机械化学法合成了超细铜粉。将氯化铜和钠粉混合进行机械粉碎,发生固态取代反应,生成铜及氯化钠的纳米晶混合物,清洗去除研磨混合物中的氯化钠,得到超细铜粉。若仅以氯化铜和钠为初始物机械粉碎,混合物将发生燃烧。如在反应混合物中加入氯化钠可避免燃烧,且生成的铜粉颗粒较细,粒径在20—50 nm之间。
1.2、气相蒸发法
该方法是制备金属超微粉末直接、有效的方法,法国的L’air liquid公司采用感应加热法,用改进的气相蒸气法制粉技术制备了铜超微粉末,产率为0.5 kg/h感应加热法是将盛放在陶瓷坩锅内的金属料在高频或中频电流感应下靠自身发热而蒸发,这种加热方式具有强烈的诱导搅拌作用,加热速度快、温度高。
1.3、等离子体法
等离子体温度高、反应速度快,可获得均匀、小颗粒的纳米粉体。易于实现批量生产,几乎可制备纳米材料l。等离子体法分为直流电弧等离子体(DC)法、高频等离子体(nv)法及混合等离子体(Hybrid plasma)法。DC法使用设备简单、易操作,生产速度快。几乎可制备纯金属超细粉,但高温下电易于熔化或蒸发而污染产物;RF法无电污染、反应速度快、反应区大,广泛应用于生产超细粉。其缺点是能量利用率低、稳定性差;混合等离子体法将DC法与RF法结合起来,既有较大的等离子体空间、较高的生产效率和纯度,也有好的稳定性。
1.4、7射线辐照一水热结晶联合法
陈祖耀等人利用co源强r射线辐照制备金属超微粒子,采用r射线辐照一水热结晶联合法获得了平均粒径约50 nlTl的纳米铜粉。
1.5、超声电解法
朱学彬等以分析纯硫酸铜配制成较低浓度0.20—0.25 M的溶液,并加入1.8~2.0M硫酸调配成电解液。在室温下将电解装置引入超声装置中(超声波频率20~60 kHz),电解过程中加入适量的有机溶剂以防氧化,如乙醇、甲苯、油酸等(均为分析纯)。电解完成后的溶液在进行高速离心、真空抽滤、酒精洗涤和真空干燥后,得到粉末产物。
李森利用超声电沉积法制备金属纳米铜粉,平均粒径30 nm,分散性较好;利用XRD、TEM等进行了成分、粒度、形貌及结构分析,对影响纳米粉末制备的主要工艺因素进行分析和优化。试验表明,电流密度对纳米粉末形成起控制作用,表面活性剂和超声场对粉末分散更为重要。
1.6、超临界流体干燥法(SCFD)
用均相溶液化学还原法与超临界流体干燥法相结合的组合技术,制备高纯度、高分散性、高抗氧化性的立方晶系纳米级铜粉。粉体颗粒为球形,粒径约为25 nm;与普通干燥法比较,超临界流体干燥法实现了粉体干燥与表面改性一步完成。
2、化学还原法制备纳米级超细铜粉
2.1、甲醛法
廖戎等人,用甲醛直接还原硫酸铜,得到的铜粉颗粒粗大,均匀性差。采用葡萄糖预还原硫酸铜,在碱性条件下,用甲醛还原得到紫红色超细铜粉,粒径在20一400 nm。
温传庚等人用甲醛做还原剂,采用液相沉淀法制备铜钠米粒子。经TEM和XRD表征,粒子形貌为球形,平均粒径为30nm左右,粒径分布窄,粒子分布均匀,无硬团聚,为立方晶系单质铜粉。该铜粉表面经钝化处理。提高了抗氧化的能力。可以在空气中保存。
2.2、水合肼法
高扬等人将溶有分散剂的硫酸铜溶液和水合肼溶液反应,制得粒径为10nm左右铜粉,粒度分布均匀.
赵斌等人以水合肼为还原剂,分别制备了不同粒径的超细铜粉(50—500/lm),研究了铜粉的制备工艺和不同粒径的铜粉在空气中的稳定性。采用葡萄糖还原法改善了以水合肼直接还原得到铜粉的均匀性。该作者认为明胶作为分散剂,有防止粒子凝聚作用,可控制铜粉粒径。
SanoI 等用水合肼还原铜盐得到铜粉,加入高分子保护剂聚乙烯吡咯(PVP)烷酮有利于稳定晶粒、防止团聚。Lisicecki等采用微乳液法,以水合肼为还原剂,制备出平均粒径为50 nm、单分散性好的纳米铜粉。
2.3、次亚磷酸钠法
张志梅等人,用NaH2PO2还原CuSO4的络合溶液,得到粒径30~50 nm单质铜。将一定浓度的次亚磷酸钠溶液以一定的速率加入一定浓度的硫酸铜溶液中搅拌,使二者发生氧化还原反应,生成单质铜。
2.4、硼氢化物法
黄钧声等人,用KBH4还原CuSO4,加入KOH和EDTA制得纳米级铜粉,调整反应物浓度可消除Cu:O等杂质,制备的纳米铜粉仍有一定团聚,试验需加入分散剂来改善。
张虹等用KBH4溶液还原CuCI2的络合溶液,得到红黑色的铜粉,粒径约为20-40nm。
2.5、锌粉还原法
钟莲云等采用化学合成法可低成本制备超细铜粉。以金属锌和五水硫酸铜为原料,用氨水调节pH值,研究了硫酸铜浓度、氨水加入量、反应温度等对超细铜粉粒径大小的影响,获得密度较小的0.1μm超细铜粉。
2.6、抗坏血酸法

肖寒 等人,以CuSO4·5H2O为原料,以抗坏血酸为还原剂,聚乙烯吡咯烷酬为保护剂,制得20~40 nm铜粉,并探讨 CuSO 和抗坏血酸的比例,保护剂(分散剂)用量及其对铜粉颗粒的控制作用。



1. Conventional preparation method
The traditional electrolytic copper powder is generally over 10um due to its large particle size, which is not suitable for the production of nanometer ultra-fine copper powder; the atomization method is difficult to solve the problem of oxidation resistance, so it is difficult to promote. In addition to the traditional electrolysis method and atomization method, there are many existing preparation methods, such as: physical method (ball milling method, gas-phase steam method, plasma method, y-ray irradiation hydrothermal crystallization method, freeze-drying method, etc.) and liquid-phase chemical reduction method. The former is of high cost, expensive equipment and complex process, and the liquid-phase chemical reduction method is more studied at present.
1.1 ball milling
In this paper, the coarse copper powder was used as the sample, and the improved vibration ball milling and high energy ball milling were used. The high-energy ball milling method has the advantages of high yield, simple process, and can prepare high melting point metals, solid solutions of mutually insoluble systems, nano intermetallic compounds, nano metals and ceramic composites which are difficult to be prepared by conventional methods. The disadvantages of the high-energy ball milling method are that the grains are uneven and impurities are easy to be introduced in the ball milling process.
Ultrafine copper powder was synthesized by mechanochemical method. The mixture of cupric chloride and sodium powder is mechanically comminuted, and the solid-state substitution reaction takes place. The mixture of cupric chloride and sodium chloride nanocrystals is formed. The sodium chloride in the mixture is cleaned and removed, and the ultrafine copper powder is obtained. If only copper chloride and sodium are used as the initial materials for mechanical comminution, the mixture will burn. If sodium chloride is added to the reaction mixture, combustion can be avoided, and the copper powder particles generated are relatively fine, and the particle size is between 20-50 nm.
1.2 gas phase evaporation method
This method is the most direct and effective way to prepare ultrafine metal powder. L'air liquid company in France adopts induction heating method to prepare ultrafine copper powder with improved gas-phase steam method. The yield is 0.5 Kg / h induction heating method is to evaporate the metal materials in the ceramic crucible by self heating under the induction of high frequency or medium frequency current. This heating method has strong induced stirring effect, fast heating speed and high temperature.
1.3 plasma method
With high temperature and fast reaction speed, nano powder with uniform and small particles can be obtained. It is easy to achieve mass production, and almost any nano material can be prepared. Plasma methods are divided into DC, NV and hybrid plasma methods. DC method is simple, easy to operate and fast in production. Almost any pure metal ultrafine powder can be prepared, but at high temperature, the electrode is easy to melt or evaporate and pollute the product; RF method has no electrode pollution, fast reaction speed and large reaction area, so it is widely used in the production of ultrafine powder. The disadvantages of this method are low energy utilization and poor stability. The hybrid plasma method combines DC method and RF method, which has not only large plasma space, high production efficiency and purity, but also good stability.
1.4, 7-ray irradiation hydrothermal crystallization combined method
Chen Zuyao et al. Prepared metal ultrafine particles by CO source strong r-ray irradiation, and obtained nano copper powder with average particle size of about 50 NLTL by r-ray irradiation hydrothermal crystallization method.
1.5 ultrasonic electrolysis
Zhu Xuebin et al. Prepared a solution with a lower concentration of 0.20-0.25m by analyzing pure copper sulfate, and added 1.8-2.0m sulfuric acid to prepare an electrolyte. The electrolysis device is introduced into the ultrasonic device at room temperature (the ultrasonic frequency is 20-60 kHz), and an appropriate amount of organic solvent is added in the electrolysis process to prevent oxidation, such as ethanol, toluene, oleic acid, etc. (all analytical pure). After electrolysis, the solution was centrifuged at high speed, filtered in vacuum, washed with alcohol and dried in vacuum to obtain powder products.
Li Sen prepared metal nano copper powder by ultrasonic electrodeposition, with an average particle size of 30 nm and good dispersibility; the composition, particle size, morphology and structure were analyzed by XRD and TEM, and the main factors affecting the preparation of nano copper powder were analyzed and optimized. The results show that the current density plays a controlling role in the formation of nano powder, and the surfactant and ultrasonic field are more important for powder dispersion.
1.6 supercritical fluid drying (SCFD)
By the combination of homogeneous solution chemical reduction method and supercritical fluid drying method, the cubic crystal nano copper powder with high purity, high dispersion and high oxidation resistance was prepared. Compared with the common drying method, the supercritical fluid drying method realizes one-step drying and surface modification of the powder.
2. Preparation of ultrafine copper powder by chemical reduction
2.1 formaldehyde method
Liao Rong et al. Directly reduced copper sulfate with formaldehyde, the copper powder obtained was coarse and poor uniformity. The ultra-fine copper powder with the particle size of 20-400 nm was prepared by pre reducing copper sulfate with glucose and reducing with formaldehyde under alkaline condition.
Wen chuangeng et al. Used formaldehyde as reducing agent, and prepared copper nanoparticle by liquid phase precipitation method. Characterized by TEM and XRD, the particle morphology is spherical, the average particle size is about 30 nm, the particle size distribution is narrow, the particle distribution is uniform, there is no hard agglomeration, it is cubic crystal system copper powder. The surface of the copper powder is passivated. It improves the ability of antioxidation. It can be stored in air.
2.2 hydrazine hydrate method
Gaoyang et al. Reacted the copper sulfate solution with dispersant and hydrazine hydrate solution to prepare copper powder with particle size of about 10nm and uniform particle size distribution
Zhao Bin et al. Used hydrazine hydrate as reducing agent to prepare ultrafine copper powder with different particle sizes (50-500 / LM). The preparation process of copper powder and the stability of copper powder with different particle sizes in air were studied. The homogeneity of copper powder obtained by direct reduction of hydrazine hydrate was improved by glucose reduction. The author thinks that gelatin, as a dispersant, can prevent particles from agglomerating and control the particle size of copper powder.
Sanoi et al. Reduced copper salt with hydrazine hydrate to obtain copper powder and added polymer to protect

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