Study On Preparation And Properties Of Copper Oxide

If a silver layer is deposited on the surface of fine copper powder by plating chemically method, a composite powder with coated structure that the outer surface is silver layer and the core is fine copper powder, namely silver coated copper powder, will be prepared. It has the advantages of silver and copper for preparation of silver coated copper powder obtained by using this system, such as good electrical conductivity, oxidation resistance and stability, also the cost is lower. To a certain extent, using this silver coated copper powder can replace of silver powder in the industrial production, silver coated copper powder can be widely used in many fields of basic and high-tech industrial, such as electronics, printing, energy and communications. But at present, the preparation technology is not mature enough and perfect. Need further understanding the relationship between the process parameters and the silver coated copper powder. So it is worthy to carrying out research of the silver coated copper powder for its theoretical significance and practical value.In this respect, the experiments were conducted to prepare silver coated copper powder using the self-made spherical copper powder, and the effect of factors, such as pre-treatment process, bath composition and process conditions, of the properties of the silver coated copper powder were studied. Using a variety of detection methods, like XRD, SEM and EDS, the structure and properties, such as surface morphology, elemental composition, the apparent color, particle size, specific surface area, bulk density, electrical conductivity, oxidation resistance and so on, of the silver coated copper powder were characterized. The properties of the silver coated copper powder obtained from different conditions and pure copper and silver powder were compared, and the silver deposition mechanism of silver coated copper powder were preliminary discussed, and then an optimized process scheme to prepare the silver coated copper powder were obtained. The research indicates that:1. Pretreatment process, composition of silvering solution (reducing species, silver content, the amount of glucose) and process conditions of preparation (alkaline environment pH, bath temperature, chemical plating reaction time, dispersion process) and other factors are all have different degrees of effects on the chemical silver plating process and performance of the silver coated copper powder.2. Put forward the preparation scheme of silver coated copper powder in the grasp of the relevant conditions based on the law of silver coated copper powder:Copper powder is pre-treated by caustic washing first, and the mass ratio of Ag:Cu is 1.5:1; using glucose as reducing agent and the amount of glucose is in a molar ratio of Ag:C6H12O6 is 2:1; The pH of bath is adjusted to 10 and the temperature and time of chemical plating reaction are 50℃ and 30min, respectively; The obtained silver coated copper powders are treated by mechanical stirring and ultrasonic dispersion process.3. The silver coated copper powders synthesized by optimized preparation process possess good properties, such as good apparent color, coating uniformity, electrical conductivity, oxidation resistance and compactness, the silver content between 45% and 50%, without introduction of impurities or other oxide formation; Particles are spheroida and its size D50 is 8.290μm, and the specific surface area is 0.749m2/g, and the bulk density is 1.6～1.7g/cm3.4. The growth process of silver deposited on the surface of copper powder is not the layer growth mode that each silver particles are deposited uniformly densely cover the surface of copper powder and grow in the form of silver layer that coated layer by layer, but rather the growth mode that silver coated on the surface of copper powder forms in a small "island" structure first and then the "island" gradually grows and extend outward, and these "island" links up to others and form a bulk structure finally. A coated silver layer formed in this way may have a small amount of micro pores and inadequate complete and smooth surface.