Preparation and characterization of magnesium coating deposited by cold spraying

Magnesium (Mg) and its alloys have a great potential as structural materials due to their beneficial combination of high strength to weight ratio, high thermal conductivity and good machinability. However, few literatures about Mg coatings fabricated by cold spraying can be found. In this study, Mg coatings were fabricated by cold spraying, and the microstructure, phase structure, oxygen content and microhardness of the coating prepared under different main gas temperatures were investigated. The critical velocity of the particle was evaluated through numerical simulations. The particle deformation behavior and bonding mechanism were discussed. The result of the oxygen content test shows that the oxygen contents of the coatings did not increase comparing with that of the feedstock powder. The simulation results show that the critical velocity of Mg particles was in a range of 653 m/s to 677 m/s. The observation of the coating fracture morphology shows that the formation of the coating was due to the intensive plastic deformation and mechanical interlocking. The microhardness of the coating increased with the increase of the main gas temperature from 350oC to 450oC due to the decrease of the coating porosity.