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 works about Mg coatings fabricated by cold spraying can be found in the literature. Thus, Mg coatings prepared at different main gas temperatures by cold spraying were investigated as well as their microstructure, phase structure, oxygen content and microhardness. 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 measurement shows that the oxygen contents of coatings did not increase compared with that of the feedstock powder. The simulation results show that the critical velocity of Mg particles was in the range from 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 350 °C to 450 °C due to the decrease of the coating porosity.