Anti-corrosion Mechanism of Zn-Mg Alloy Coating on Steel Prepared by Vacuum Evaporation

Vacuum evaporation and short-term thermal treatment were used to prepare Mg layer on galvanized steel. Using electrochemical analysis, the corrosion process was studied and the anti-corrosion mechanism was also discussed. The results show that a dense layer forms on the top of zinc layer at the first stage of corrosion. The dense layer consists of magnesium hydroxide, zinc hydroxide and magnesium oxide, and is compact, insoluble and consequently well corrosion resistant. After the dense layer decomposes, the zinc layer as an anode protects steel.