Hot Corrosion of NiCrAIY/(ZrO_2-CeO_2-Y_2O_3) Composite Coatings in NaCI-Na_2SO_4 Molten Salt

摘要

The metal/ceramic composite coatings that consisted of (Ni-22Cr-10Al-1Y) and (ZrO_2-25CeO_2-2.5Y_2O_3) were prepared by the air plasma spray (APS) method. The as-sprayed coatings consisted of metal-rich and ceramic-rich regions, between which the α-Al2O3 oxide stringers existed owing to the oxidation of Al in (Ni-22Cr-10Al-1Y) during APS. The composite coatings were hot corroded at 800 and 900 °C for up to 50 h in 75％NaCl-25％Na_2SO_4 molten salt. The corrosion products that formed on the coating surface during hot corrosion were mostly dissolved off into the molten salt. The scales that remained on the coating surface consisted primarily of Cr_2O_3, and a lesser amount of NiO and Al_2O_3. The corrosion resistance decreased, as not only the test temperature and time but also the amount of metal in the coating increased.