Influence of bath temperature on zinc plating and passivation process

Zinc films were prepared by a typical chloride zinc system electrodeposition on iron substrate. Effects of different temperatures on deposition rate, structures and surface morphology of zinc films were investigated in the paper. Trivalent chromium passivation technology was also studied in the paper to improve corrosion resistance of zinc films. Higher temperature could dramatically improve bath conductivity, which contributed directly to the rise in mass transfer and deposition rate. The deposited films were crystalline and showed characteristic peaks of zinc. However, zinc films with bad crystallinity would be obtained at higher temperatures due to thermal decomposition of additives. With the increase in temperature, zinc films with rough surface could be observed. Zinc passivation layer with optimal corrosion resistance could be obtained at passivation time of 30 s, temperature of 303 K and pH 3.