超细银包铜粉的工艺研究

发布时间：2018-03-11 15:26

  本文选题：超细粉末　切入点：银包铜　出处：《北京有色金属研究总院》2017年硕士论文　论文类型：学位论文

【摘要】：超细银包铜粉可以充分发挥银的高导电性和抗氧化性能,改善超细铜粉的物化性能,降低纯银粉的应用成本。因此,超细银包铜粉被越来越多的应用在导电涂料、导电胶等产品中。但是,超细银包铜粉在应用中仍然存在着导电性能不够,抗氧化性能差的缺点,而且国内产品与国外一些企业的产品相比存在着一些不足。所以,本课题的目的是通过对银包铜粉制备工艺的研究,提高粉末的性能,填补市场中高性能超细银包铜粉的不足,替代国外相关产品。本课题实施的意义在于,对超细铜粉进行银包覆以后,不但可以改善铜粉的抗氧化性、导电性,拓展超细电解铜粉的应用领域,同时可以替代银粉,在满足电磁屏蔽、导电填料、导电胶等领域的需求方面具有重要价值。本课题以超细电解铜粉为原料,通过分析对比直接置换、化学还原法的实验原理及实验结果,确定了以复合法制备超细银包铜粉末的工艺。通过优化实验研究了超细银包铜粉制备过程中分散剂、还原剂对粉末性能的影响,并确定了络合分散剂和还原剂种类及用量,还研究了体系pH值和银氨添加速率等实验参数对制备工艺的影响。通过扫描电子显微镜、能谱仪、X射线衍射仪、氧含量测试仪、激光粒度仪、热重分析仪等设备对超细银包铜粉末的结构和性能进行了分析,同时与原料铜粉和超细银包铜粉产品在性能上进行了对比研究。最后,对超细银包铜粉在导电胶中的应用进行了研究,并且比较了使用不同导电粉作为导电填料的导电胶的性能和结构。得出了以下结论:(1)本实验选择超细电解铜粉作为原料进行镀银。通过对比不同化学镀方法,本课题确定了一种置换预镀银和化学还原相结合的复合法制备超细银包铜粉。(2)通过对超细银包铜粉制备过程中使用的化学试剂的实验分析,本实验确定了粉末制备工艺中的主要试剂为:一定量的EDTA-2Na作为络合分散剂,酒石酸钾作为还原剂更合适;通过对工艺中各参数的调整,确定了制备超细银包铜粉过程中的参数:体系温度为30℃、pH为9～10、镀液浓度为0.4mol/L、镀液添加速率为8mL/min。(3)对粉末的结构分析表明,粉末颗粒分散均匀,表面光滑;制备的超细银包铜粉有完整的包覆结构,且包覆结构均匀致密;粉末的银包覆层能够达到一定厚度。实验表明,制备粉末比市场中某产品氧含量和电阻率更低;包覆后的粉末与原料铜粉相比抗氧化性能得到较大提高;热重分析结果中显示,制备的超细银包铜粉末的抗氧化性能优于原料铜粉和某产品银包铜粉。(4)将不同的导电粉制备成的导电胶,对导电胶的结构和性能进行分析可得,制备的超细银包铜粉末制备成导电胶后有较好的导电性能,已经达到了市场中某片状银包铜粉的性能;通过SEM图片可以看出,制备的粉末能够在导电胶中形成连接,起到导电的作用。
[Abstract]:Ultrafine silver coated copper powder can give full play to the high electrical conductivity and oxidation resistance of silver, improve the physical and chemical properties of ultrafine copper powder, and reduce the application cost of pure silver powder. However, in the application of ultrafine silver coated copper powder, there are still some shortcomings such as insufficient electrical conductivity and poor oxidation resistance, and there are some shortcomings in domestic products compared with those of some foreign enterprises. The purpose of this project is to improve the properties of silver coated copper powder by studying the preparation process of silver coated copper powder, to fill the shortage of high performance superfine silver coated copper powder in the market, and to replace foreign related products. After silver coating of ultrafine copper powder, not only can the oxidation resistance and electrical conductivity of copper powder be improved, but also the application field of ultrafine electrolytic copper powder can be expanded. At the same time, it can replace silver powder and meet the requirements of electromagnetic shielding and conductive filler. The demand of conductive adhesive and other fields is of great value. In this paper, ultrafine electrolytic copper powder is used as raw material, and the experimental principle and results of direct replacement and chemical reduction are compared and analyzed. The preparation process of ultrafine silver coated copper powder by composite method was determined. The influence of dispersant and reductant on the properties of ultrafine silver coated copper powder was studied by optimizing experiments, and the kinds and dosage of complexing dispersant and reducing agent were determined. The effects of pH value of the system and the rate of silver ammonia addition on the preparation process were also studied. By means of scanning electron microscope (SEM), energy spectrometer (EDS), X-ray diffractometer (XRD), oxygen content tester, laser particle size meter, etc. The structure and properties of ultrafine silver coated copper powder were analyzed by thermogravimetric analyzer and compared with raw copper powder and ultrafine silver coated copper powder. The application of ultrafine silver coated copper powder in conductive adhesive was studied. The properties and structure of conductive adhesive with different conductive powder as conductive filler were compared. The following conclusion was drawn: in this experiment, ultrafine electrolytic copper powder was chosen as raw material for silver plating. In this paper, a composite method of replacing preplating silver and chemical reduction was established to prepare ultrafine silver coated copper powder. The chemical reagents used in the preparation of ultrafine silver coated copper powder were analyzed experimentally. In this experiment, the main reagents in the powder preparation process are determined as follows: a certain amount of EDTA-2Na as complexing dispersant, potassium tartrate as reducing agent is more suitable, by adjusting the parameters of the process, The parameters in the preparation of ultrafine silver coated copper powder were determined: the system temperature was 30 鈩，

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