2020 Volume 61 Issue 10 Pages 1958-1966
To elucidate the effects of polyethylene glycol (PEG) and glue on the deposition of Zn from electrowinning solution and its resulting crystal structure, Zn electrodeposition was performed at a current density of 600 A·m−2 and a charge of 8.64 × 106 C·m−2 in an agitated sulfate solution containing 1.07 and 1.8 mol·dm−3 of ZnSO4 and H2SO4, respectively, at 45°C. With the additions of PEG and glue, the evolution of hydrogen was suppressed at the current density region less than the critical current density for Zn deposition, decreasing the critical current density of Zn. The degree of decrease in the critical current density of Zn was larger with glue than that with PEG. The current efficiency for Zn deposition was higher with PEG and glue than that without at the low current density region because the critical current density of Zn decreased with additives. Since the additives suppressed Zn deposition more than the hydrogen evolution at the high current density region, the current efficiency of Zn decreased by increasing the additive concentration. At the high current density region, little difference was observed in the current efficiency of Zn between PEG and glue. The effect of the molecular weight of PEG on the current efficiency of Zn was rarely observed at the molecular weight above 2000. With the addition of PEG, the deposits became fine platelets with preferred orientation of {1011} and layered pyramidally, while {1120} orientation was obtained, and the platelets grew perpendicularly to the substrate with the addition of glue. The surface roughness of deposited Zn decreased with additives, and it decreased further with PEG compared with that with glue.
This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 84 (2020) 58–65.
