Preparation and Characterization of 8YSZ Thermal Barrier Coatings on Rare Earth-Magnesium Alloy

Thermal barrier coatings (TBCs) of zirconia stabilized by 8 wt.% yttria (8YSZ) on top of rare earth-magnesium alloy were fabricated by atmospheric plasma spraying. Three coatings were prepared by controlling the substrate temperature with different cooling media including cold water, compressed air, and natural cooling during deposition. The phase compositions, mechanical properties, and thermal shock resistance of these coatings were investigated. These coatings are very helpful to the improvement of corrosion and wear resistances and thermal protection of magnesium alloy. During plasma spraying, the substrate temperature affects the microstructure of substrate and the bonding strength between the coating and the substrate. The coating whose substrate was cooled by compressed air during plasma spraying has a good thermal shock resistance. The coating failure is mainly induced by the substrate oxidation and thermal expansion mismatch between the coating and the substrate.