Preparation And Structure-Property Of Superfine Copper Powder By Alcohol Solvothermal Method

Material of the micro nano it regular size unmatched performance and more extensive application.Superfine copper powder is widely used in electronics,chemical industry,light industry,energy and other fields because of its high activity,high specific surface area,excellent conductivity and ductility.The large-scale preparation of high performance copper powder has attracted more and more attention from various industries.In this paper,liquid organic alcohol was used as solvent and reducing agent to prepare superfine copper powder by solvothermal reduction method.The method has the advantages of liquid phase preparation and can be used for the controllable preparation of superfine copper powder.At the same time,organic alcohols as solvent can effectively reduce the agglomeration of particles and have a positive effect on the oxidation resistance of copper powder.This method has low production cost,low waste toxicity,good product performance,easy to achieve large-scale production,and high industrial value.The main research contents and results of this paper are as follows:（1）Preparation of superfine copper powder by solvent-thermal method with glycerol and its properties were studied.Superfine copper powder was prepared under alkaline conditions with glycerol as solvent and reducing agent without any stabilizer or dispersant.The effects of different reaction parameters on the experiment and the product were studied,the reaction mechanism and the formation mechanism of copper particles were explored,and the oxidation resistance of copper powder was tested and analyzed.Na OH was one of the most important experimental factors.On the one hand,it can improve the reducibility of alcohol molecules and speed up the reaction rate.On the other hand,it can promote the dissolution of intermediate Cu₂O and affect the concentration of copper ion and the morphology and particle size of copper powder.Copper source is an important factor affecting the morphology of copper powder,which is related to the modification of anionic ions on crystal surface.Using Cu（NO₃）₂as copper source,alkali-copper ratio of 3∶1and reaction temperature of 150℃,spherical copper powders with average particle size of 230 nm were prepared by glycerol method.The initial oxidation temperature is about 180℃,and no oxidation occurs in the air for at least 1 month,with good thermal stability and oxidation resistance.（2）Preparation of superfine copper powder by ethanol solvothermal method and its properties were studied.The ethanol method and glycerol method have similar reaction principle.However,the reducibility of ethanol is weak.In the early stage of the reaction,the copper precursor will dehydrate to form Cu O at high temperature,and then be reduced to Cu₂O and elemental copper.Using ethanol as solvent and reducing agent,Cu（CH₃COO）₂as copper source,alkali-copper ratio of 2∶1,reaction temperature of 210℃and reaction time of 4 h,spherical copper particles with average particle size of 180 nm were prepared.In the antioxidant test,the copper powder prepared by ethanol method can keep free from oxidation for at least 5 months in the atmospheric environment,and the initial oxidation temperature is about 150℃,showing excellent oxidation resistance and good thermal stability.High crystallinity is an important factor for high oxidation resistance of copper powder.（3）The preparation of superfine copper powder by ethanol prereduction-hydrogen reduction method and its micro-nano structure control were studied.Cupric powder can be obtained by the two-step reduction process of ethanol solvothermal prereduction and hydrogen reduction.Using ethanol as solvent and prereducing agent,Cu（NO₃）₂as copper source,alkali-copper ratio of 3∶1,reaction temperature of 200℃and reaction time of 3 h,cubic Cu₂O with size of about 500 nm was prepared.Using Cu₂O as a precursor,the Cu₂O was transformed into elemental copper by using5%hydrogen mixture at 200℃for 2 h,and the shape and particle size remained basically unchanged.The formation of Cu₂O cube appearance is mainly related to the concentration of Na OH in the pre-reduction process.