Electroplating is an electrochemical process, but also a redox process. The basic process of plating is immersed in the metal salt solution as a cathode, the metal plate as the anode, connected to the DC power supply, deposited on the required parts Plating.
For example: Nickel plating, the cathode to be plated parts, the anode is pure nickel plate, respectively, in the anode and cathode were the following reactions:
Cathode (plating): Ni2 ++ 2e → Ni (main reaction)
2H + + 2e → H2 ↑ (side reaction)
Anode (nickel plate): Ni-2e → Ni2 + (main reaction)
4OH - 4e → 2H2O + O2 (side reaction)
Not all of the metal ions can be deposited from the aqueous solution, and if the cathode reaction reduces hydrogen to hydrogen, the metal ions hardly precipitate on the cathode. According to the experiment, the possibility of electrodeposition of metal ions from an aqueous solution , From the periodic table to get a certain rule.