ON THE EMERGENCE AND SPACING OF ZINC STRIATIONS .1. DETERMINATION OF PREFERRED STRIATION FREQUENCY

Profiles normal to the flow direction were analyzed with Fourier trans forms and autocorrelation to determine the preferred wavelength of str iated zinc electrodeposits formed in flowing acid electrolytes. Striat ion frequency increases with current density to a minimum separation b etween striae of approximately 150 mum. At higher current densities, i ndependent of substrate, striae meld and form a smoother nodular depos it. At a given current density, emerging striae possess a higher frequ ency when deposition occurs on substrates with high growth-center dens ity. Independent control of growth-center spacing by the use of microp atterned electrodes equipped with artificial micron-size hemispherical protrusions triggers the emergence of thin striae earlier and extends the current density range over which they occur. A causal relationshi p between the density of growth centers and striation emergence is dem onstrated.