Codeposited Zn–Mg coating with improved mechanical and anticorrosion properties

A Zn–Mg coating was prepared by magnetron co-sputtering method on carbon steel with Zn layer pre-deposited using an alkaline non-cyanide zinc bath. The morphologies, chemical compositions, mechanical properties and anticorrosion properties of specimens were investigated. The microhardness of the Zn–Mg coating increased from 244 HV25 of the electroplated Zn coating to 323 HV25. The electrochemical test in NaCl solution showed that the Zn–Mg coating had a passive region around the potential of 300 mV. Salt water immersion test in 3.5 wt.% NaCl solution also showed corrosion property improvement. The red rust generation time of Zn–Mg coating was doubled compared with the Zn coating. The possible mechanism of the improvement of corrosion resistance of Zn–Mg coating is proposed.