Improving the throwing power of acidic zinc sulfate electroplating baths

What is it about?

The addition of PA and/or DBS into the baths greatly improves their throwing power. However, DBS has the more pronounced improving effect on the throwing power. Such improvement is attributed to the inhibitory influence of these organic compounds on the reduction of Zn2+ ions. The inhibition of zinc reduction is assumed to occur via adsorption of PA or DBS molecules on the cathode surface. The adsorption is found to follow a Langimur adsorption isotherm. On the other hand, the photomicrograph of the as-plated zinc examined by using SEM shows that in the presence of PA, DBS or a combination of them, ®negrained, uniform and homogeneous electrodeposits can be obtained due to the effect of these adsorbed species. Visual observation showed that grey-zinc deposits were obtained from additives-free baths. The addition of PA to the electrolyte improves the compactness and smoothness of the deposits. However, the addition of DBS enhances the brightness of the deposits. A combination between the two additives produces compact, smooth and very bright deposits. Although the inhibition of zinc reduction is assumed to occur via adsorption of PA and/or DBS on the cathode surface.

Featured Image

Why is it important?

Our findings show that addition of PA and/or DBS into the baths greatly improves their throwing power. However, DBS has the more pronounced improving effect on the throwing power.