Abstract
For zinc electroplated from a bath consisting of zinc chloride and ammonium chloride, we investigated the influence of some commercial brighteners on crystal growth and surface morphology. The bath was developed for formation of chrome (III) hydroxide type chemical conversion coatings, which contribute high corrosion resistance to zinc films. With increasing concentration of brighteners and cathode current density, the overpotential increased and the zinc deposits changed from a gray to a brighter appearance. Over the critical concentration of brighteners, zinc deposits invariably showed the preferred orientation of 10·1 plane and 10·0 plane in accordance with Pangarov's view. Especially, the latter plane might be a twin crystal formed along the twin boundary of the 10·2 plane on 00·1 plane of electroplated zinc. Increased concentration of the brighteners did not change the preferred orientation greatly, but it did reduce the grain size of zinc deposits.
