Microstructure and properties of duplex coatings on magnesium alloy

The duplex Ti cold spray + MAO coatings were deposited on the Mg alloy substrates using combined cold spray and micro arc oxidation (MAO). The microstructure, mechanical property and corrosion resistance of the duplex coatings were investigated compared with the MAO coated Mg alloy substrate. Results indicate that the Ti cold spray coating with 130 mu m showed an obvious boundary between the Mg substrate, and the TiO2 phase was formed by MAO on the top coating. The duplex coating showed a little coarse and porous structure, which resulted in low mechanical property and wear resistance compared with the MAO treated Mg substrate. However, it showed an excellent corrosion resistance due to the difference of chemical stability for the coatings. Furthermore, this duplex coating might be very useful for improving the photocatalytic ability of titania due to its markedly increasing specific area.