Preparation and hot corrosion behavior of plasma sprayed nanostructured Gd2Zr2O7-LaPO4 thermal barrier coatings

Abstract Nanostructured 30 mol% LaPO 4 doped Gd 2 Zr 2 O 7 (Gd 2 Zr 2 O 7 -LaPO 4 ) thermal barrier coatings (TBCs) were prepared by air plasma spraying (APS). The chemical composition of the coating is close to that of the agglomerated particles used for thermal spray. Nanozones were obviously found in the coating microstructure. Hot corrosion tests were conducted in V 2 O 5 and Na 2 SO 4 +V 2 O 5 salts at 900 °C to study the corrosion resistance of the coatings. Results indicated that the coating exhibited excellent corrosion resistance in both salts, but it performed better in V 2 O 5 salt. After 4 h corrosion tests, a continuous, dense reaction layer formed on the coating surfaces, effectively arresting further penetration of the molten salt. By comparison, Na 2 SO 4 +V 2 O 5 salt corrosion caused thinner reaction layer than V 2 O 5 corrosion, and some NaVO 3 trace was found in the inner regions of the coating. Furthermore, the nanozones in the coating have positive function on reducing the molten salts infiltration.