Effect of electrolyte acidity on copper powder properties and growth mechanism
Ultralight copper powder with dendritic structure exhibits excellent electrical conductivity,viewed as an indispensable key base material for the preparation of high-end electro-carbon materials.However,the dendritic structure formation process is difficult to control,preventing from the wide application of dendritic copper powders.In this study,micron-scale ultralight dendritic copper powders were produced by electrochemical deposition with CuSO4+H2SO4 electrolyte system at(40±2)℃.The effects of the dendrite growth process and sulfuric acid concentration on the properties of ultralight copper powders were investigated.The results showed that the concentration of sulfuric acid in the electrolyte was negatively correlated with the degree of dendrite development,average particle size and loose packing density,and positively correlated with the energy consumption of electrolysis.Meanwhile,the precipitation of hydrogen exerted an important influence on the formation of dendrite structure and the thickness of diffusion layer on the cathode surface;the loose packing density of copper powder decreased with the increase of sulfuric acid concentration in the electrolyte.The current efficiency was 80.72％and the energy consumption was 1 238.6(kW·h)/t at a sulfuric acid concentration of 140 g/L,and the loose-packed density of copper powder was small,specifically a value of 0.620 4 g/cm3.The dendrite growth of electrodeposited dendritic copper powder mainly goes through three stages:nucleation growth and expansion-particle aggregation-dendrite growth.
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