Emulsion - Preparation Of Electrolytic Processes Desorption Ultrafine Copper Powder

An increasing attention has been found in synthesizing the ultrafine especially nanoscale copper powders. Due to their outstanding physical and chemical property, the copper powder can be widely used in lubricating oil, electrically conductive paste, medicine, biological filter and other purposes. Besides, the morphology of copper powder can effect their application in some degree. As one of the most conventional method, electrodeposition plays important part in the preparation of the copper powder. However, the powders have to been trapped from cathodes by manually work during the electrodepositon process and once being separated from electrolytes they can be oxidized easily. So, it's very important to find a way which can achieve the auto-evolution and antioxidation treatment with the particle size and energy consumption under the control.Combing the ultrasonic emulsification technology with electrodeposition method, the novel emulsification-electrodeposition process was established. The results show that copper powder with good the auto-evolution ability and antioxidation property can be synthesized in the H₂O/B/oleic acid and H₂O/B/oleic acid electrolytes. While the powders prepared in H₂O/B/oleic acid electrolyte present ultrafine fishbone-like shape, the powders prepared in H₂O/B/oleic acid electrolyte present nanoscale granular morphology. Further study reveals that all of these ability and phonemes can be attribute to the formation of microemulsion with the function of and emulsifiers and unltrasonic wave.According to the results conducted by one-factor analysis of variance, in H₂O/B/oleic acid electrolyte, all of the three indexes are greatly affected by the factors; In H₂O/C/oleic acid electrolyte, only the pH value and current destiny have significant affection on particle size while the factors have similar influence on current efficiency as that in H₂O/B/oleic acid electrolyte. It is considered in H₂O/B/oleic acid electrolyte that the powder prepared at Cu²⁺ concentration of 0.07 mol/L and pH value of 3.5 and current destiny of 0.08 A/cm² obsesses the best properties with particle size of about 1.68μm and current efficiency of about 79.8%, while the powder prepared at Cu²⁺ concentration of 0.11 mol/L and pH value of 3.5 and current destiny of 0.08 A/cm obsesses the best properties with particle size of about 33 nm and current efficiency of about 76.8% in H₂O/C/oleic acid electrolyte.On the above basis, the effect mechanisms of process factors on powders properties were deeply investigated. The reseach finds that the size of the metallic powders is determined by the speed ratio between nucleation and growth of nuclei, of which the former is derectly affected by the over-potential and the latter is contrained by the degree of controlling under the reaction's electrochemical procdure. At different Cu²⁺ concentration and pH value, the current efficiency is determined by the speed ratio between copper powder evolution and hydrogen production which both close related to the stadant activation energy. The mathematic functions were proposed for the effects of concentration and pH value on current efficiency, and the results indicate that the current efficiency changes with Cu²⁺ concenttation according to a power function while it changes with pH value according to a negative exponent function.