EFFECTS OF ELECTROLYSIS AND BATH CONDITIONS ON THE SURFACE-ROUGHNESS, MORPHOLOGY AND CRYSTAL ORIENTATION OF ZINC ELECTRODEPOSIT

A study was conducted on the effects of electrolysis and bath conditions on the surface roughness, morphology and crystal orientation of zinc electrodeposits from sulfate and chloride baths. Surface roughness of the electrodeposit from a sulfate bath was increased by suppressing mass transfer of zinc through variations of electrolysis and bath conditions. Under conditions which promoted mass transfer in the sulfate bath, stacked platelet crystals were formed with the (0001) basal plane of zinc hexagonal lattice parallel or slightly oblique to the substrate. Under conditions which suppress mass transfer, formation of stacked platelet crystals with 1120 direction perpendicular to the substrate was observed. From the chloride bath, coarse zinc crystals were formed in the low current density range due to low overvoltage. Roughening of the surface in the high current density range occurred in the higher current density range from chloride baths. The preferred orientation of the zinc electrodeposit from both baths coincided with N.A. Pangarov's theory.