Novel Synthesis And Application Of Nano-sized Copper Powders

Nano-sized copper powders are widely used in electrical and electronic, chemical engineering, mechanical engineering, and biological medicine, etc, because of their unique physical and chemical properties. The purity, particle size, and its distribution, dispersion, microstructure have important influences on the properties of the nano-sized copper powders. With the development of modern high technology, there is a great demand of preparing nano-sized copper powders with high purity, spherical shape, good dispersibility and narrow particle size distribution.Gel-casting method has the advantages of low costs and simple conditions. It has been successfully employed to prepare many kinds of ceramic powders. In this dissertation, the gel-eating process was employed to prepare copper powders. To adjust the properties of the copper powders, graphite was added into the gels. Effects of graphite additions on the purity, particle size and distribution of the copper powders synthesized were studied, and process parameters of gel-casting method were optimized.Nano-sized copper powders have received extensively attention in conductive adhesives and lubricating oil additive and many other applications in recent years, because of their good electrical conductivity, low shear force and relatively low cost. In this dissertation, conductive adhesives contained nano-sized copper powders and lubricating oil with nano-sized copper powders as additive were also prepared, using the as-prepared nano-sized copper powders as conduction composition and additive, respectively. The effects of the nano-sized copper powders contents on the properties of conductive adhesives contained nano-sized copper powders and lubricating oil with nano-sized copper powders as additive were investigated.The main achievements of these works are listed as followings:1. The copper powders prepared by the gel-casting process are of high purity and well dispersed, with a near sperial particle shape and mean particle size of about 60nm. The addition graphite into the gels has an obvious influence on the purity, grain size, dispersion of the powders prepared. Based on the experiment analysis, the process parameters of the gel-casting method were optimized as following:calcination temperature of dry gel is 300℃, the reduction temperature of precursor powders is 500℃.2. By using the as-prepared nano-sized copper powders as conductive fillers and bisphenol A epoxy resins(E51) as matrix, conductive adhesives contained copper powders with good bonding strength and fine conductivity were obtained. Silane coupling agents(KH550) can obviously improve the oxidation of the nano-sized copper powders. The addition amount of nano-sized copper powders has a great effect on the volume resistivity and bonding strength of the conductive adhesives. The sample can be achieved with a volume resistivity of 1.7×10-3 Ω·cm and a bonding strength of 11.4MPa. The proper filling amount of nano-sized copper powders is about 60wt.%.3. Lubricating oil with nano-sized copper powders as additives with good anti-wear and anti-friction performance were successfully prepared. The nano-sized copper powders can be dispersed stably in the oil by being pretreated by PVP. The content of nano-sized copper powders also has a great influence on the properties of the lubricating oil, and the appropriate addition amount of nano-sized copper powders is about 0.6wt.% in practical application.