Porosity and Corrosion Properties of Electrolyte Plasma Coatings on Magnesium Alloys

It is shown that oxide-ceramic coatings on magnesium alloys are, in general, characterized by high corrosion resistance depending on the porosity of the coating. The surface topology of oxide-ceramic coatings on IMV2 and VMD10 alloys is studied to reveal discontinuities by using special procedures of immersion and electrochemical deposition. Craters detected as a specific feature of the topology of the coatings and not always through and, in this case, they do not affect the corrosion resistance of the alloys. Isolated pores are formed, most often around the craters, in the process of oxidation under the action of high thermal stresses. On the basis of the comparative analysis of various materials and corrosive media, it is possible to make a conclusion that the corrosion resistance of magnesium alloys with oxide-ceramic coatings in acid media is mainly determined by the chemical composition of the alloy. At the same time, in neutral media, it is determined by the porosity of the coatings.