| In this work, a novel electrolytic equipment with a rotary cathode was designedand manufactured. The cathode plate can rotate automatically and the rotary speed canbe adjusted. The brush powder process can be performed automatically from thecathode plate during the rotation process. The effect of the different electrolysiscondition on nickel powder particle size was studied in this electrolytic equipment.Firstly, the effect of nickel ion concentration, pH value, current density, temperature,taking powder time, electrode spacing, cathode materials and additives eight factorson nickel powder particle size were studied in this paper, and also the analysis wasdone to the each factors influencing the nickel powder particle size. Orthogonal testswith three factors (nickel ion concentration, pH value, and current density) and threelevels were applied for the study, and the effects of this three main parameters onnickel powder particle size were investigated. The optimum conditions for theelectrolysis are: at normal temperature, with copper cathode, solution pH value of3~4,concentration of NH4Cl of10g/L, concentration of Ni2+of2.5g/L, current density of35A/dm2, electrode spacing of3cm, taking powder time of2min,under this electrolyticconditions we could get powder Dv50is2.5μm.Secondly, the influence of dispersant on nickel powder particle size was studiedunder the optimum electrolytic conditions. The effects of PVP (polyvinylpyrrolidone),six partial sodium phosphate and sodium silicate three influence of dispersant on thesize of nickel powder were studied. The results: three dispersants in certainconcentration range are reduced nickel powder particle size. When the PVP contentwas added too large, which could produced the pungent odor. The particle size ofnickel powder is smallest when the amount of addition of PVP is0.05%.when thePVP addition is0.05%, the Dv50is from2.47μm down to0.89μm, the Dv50compared with non-add PVP is reduced1.76μm. when the amount of addition of sixpartial sodium phosphate is0.01%, the Dv50is1.42μm, the Dv50compared withnon-add six partial sodium phosphate is reduced1.05μm. when the amount ofaddition of sodium silicate is0.005%, the Dv50is1.19μm, the Dv50compared withnon-add sodium silicate is reduced1.28μm.PVP decreases the size of nickel powderremarkably in three kinds of dispersant.Finally, the influence of rotary speed on nickel powder particle size was studied.The nickel powder was prepared in the cathode of rotating equipment, theconditions of preparation solution are: Ni2+concentration of2.5g/L, current density of35A/dm2,pH value of3~4, NH4Cl concentration of10g/L, PVP addition of0.05%,under this solution the influence of cathode plate speed on the size of nickel powderwas studied at room temperature. The results: when the cathode plate don’t rotate, thenickel powder has a tree shape, and its size is relatively thick, about2.5μm; when thespeed is3-10r/min, the electrolytic copper powder has spherical shape approximately,and its particle size is very fine, between20~50nm, and the nickel powder is verypure, only a little is oxidized; when the rotary speed is more than10r/min, the nickelpowder is dense nickel on the cathode plate.The electrolytic device has the advantages of compact structure and the finepowder can be produced continuously, which can be helpful to realize automationproduction and will greatly improve work efficiency and reduce labor intensity. Theequipment is applied to copper, cobalt and other fine powder’s production. |
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