Dip-Galvanizing Prelreatment Process for Silver Electroplating of Aluminum and Aluminum Alloy Parts

The diffiiculties for silver electroplating of aluminum and aluminum alloy parts were discussed. The dip-galvanizing pretreatment process suitable to the electroplating of silver on Al and Al alloys wan established, while the formulation and conditions for two-step dip-galvanizing of the Al and Al alloys beforesilver electroplating were optimized.In addition,the bonding strength of the electroplated Ag coating to the substrate and its corrosion resistance were investigated. As the results, it was imperative lo carry out two-step dip-galvanizing of the substrate in a dip-galvanizing solution composed of 400-500 g/l. NaOH. 50-80 g/l. ZnO, and a proper amount of additives, each step for a dipping duration of 30-60s. The resulting electroplated Ag coating had good corrosion resistance and good adhesion to the substrate as well.