Study On The Effect Of Cathode Materials On Electrolysis Of Low Loose Density Copper Powder And Its Process Optimization

The high dendritic copper powder with an apparent density lower than 1.0 g/cm~3 is a key basic material for high-end manufacturing and its preparation has become a problem that needs to be solved in China’s electrolytic copper powder industry.The traditional electrolytic cell structure,manipulation method and electrolyte system will change the powder formation conditions on the cathode surface,affecting the copper powder dendrite growth environment and making it difficult to obtain copper powder with well-developed dendrite arms.In fact,the apparent density,particle morphology and particle size of copper powder on the cathode plate surface are not only related to the overpotential,but also to the cathode material used.However,there is little research on what new cathode materials are used in the preparation of electrolytic copper powder,especially on the influence of such materials on the nucleation growth,apparent density and morphology of copper powder.Based on this,the electrochemical characteristics of copper,titanium and 316L stainless steel plates and the growth process of copper powder on different cathode materials were investigated in this paper using experimental studies and modern characterization methods.Furtherly,the effects of electrolytic control parameters such as current density,copper ion concentration,acidity of electrolyte and electrolyte circulation speed on the apparent density,particle morphology and particle size of copper powder also were studied through single-factor optimization experiments.The following conclusions were obtained.(1)The polarization curves and AC impedance of copper plate,titanium plate and 316L stainless steel plate as cathode materials were studied,and the experimental results showed that:in the polarization range(-1.2 V～-1.6 V),the polarization values of copper plate,titanium plate and 316L stainless steel plate electrode processes were 2.9,1.7 and 1.1 which mean the order of polarization values of different cathode materials were:copper plate>titanium plate>316L stainless steel plate.AC impedance in the high frequency region of the impedance spectrum showed that the order of resistance values of different cathode materials was titanium plate>316L stainless steel plate>copper plate.(2)Under the experimental conditions of copper ion concentration of 5 g/L,sulfuric acid concentration of 150 g/L and current density of 1200 A/m2,the growth process of copper powder on different cathode materials was studied,and the result showed that when the electrolysis time was 2 seconds,copper powder were preferentially formed spherical particles at the defects of the electrode plate,and the precipitation of copper powder was consistent with the polarization value of the cathode material.The order of the precipitation of copper powder was copper plate>Titanium plate>316L stainless steel plate.When the electrolysis time was10 minutes,copper plate,titanium plate,316L stainless steel plate precipitated dendritic copper powder.(3)The effect of current density,copper ion concentration,electrolyte acidity,electrolyte circulation speed on the preparation of copper powder cathode material was studied.The results showed that when titanium plate,copper plate and 316L stainless steel plate were used as cathode materials,apparent density decreased with the increase of current density,with the increase of electrolyte copper ion concentration increases,with the increase of electrolyte acidity decreases,and with the increase of electrolyte circulation speed increases.The apparent density of copper powder on the 316L stainless steel plate was greater than on the copper and titanium plate.(4)Under the comprehensive experimental conditions of current density of 1500 A/m2,copper ion concentration of 6 g/L,sulfuric acid concentration of 120 g/L,electrolyte circulation rate of 0.3 L/min,electrolyte temperature of 50±2℃,and electrode plate spacing of 20 mm,the apparent density of copper powder prepared from titanium plate,copper plate,and 316L stainless steel plate was 0.4899 g/cm3,0.5113 g/cm3,and 0.7736 g/cm3 respectively.Its particle size D50 was 30.52μm,33.26μm and 38.03μm respectively and the current efficiency was 79.54%,75.04%and 62.21%respectively.The energy consumption was 1266 k Wh/t,1212 k Wh/t and 1412 k Wh/t respectively,and the copper powder’s morphology was dendritic.Considering all the factors,it was recommended to use titanium plate as the cathode material in the preparation of low apparent density copper powder by electrolysis.