Effects of polyamines on the deposition behavior and morphology of zinc electroplated at high-current densities in alkaline cyanide-free baths

The effect of polyamine additives and quaternized pyridine carboxylic acid (an inner compound) on the zinc deposition behavior in alkaline zinc cyanide-free baths is systematically studied in this work. The morphology and crystalline structure of various Zn deposits are examined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. All deposits prepared for the textural analyses are prepared under a direct-current electroplating mode at a current density of 100 mA cm− 2 (i.e., the high-current-density (HCD) zinc deposits for industry usage). Dependence of the electroplating behavior of Zn on the charge density of polyamines is discussed in order to gain an understanding on how to develop an alkaline zinc cyanide-free bath for the HCD Zn plating process.