ZrO<subscript>2</subscript> 9.5Y<subscript>2</subscript>O<subscript>3</subscript> 5.6Yb<subscript>2</subscript>O<subscript>3</subscript> 5.2Gd<subscript>2</subscript>O<subscript>3</subscript>; a promising TBC material with high resistance to hot corrosion.

Hot corrosion in Na 2 SO 4 -V 2 O 5 environments has been regarded as a major challenge in the destruction of thermal barrier coatings (TBCs). The present study introduces a new TBC (ZrO 2 9.5Y 2 O 3 5.6Yb 2 O 3 5.2Gd 2 O 3 (ZGYbY)) with enhanced resistance to hot corrosion compared to the yttria-stabilized zirconia (YSZ). ZGYbY and YSZ were applied on CoNiCrAlY, as a bond coat to nickel-based superalloy (IN738LC) using the atmospheric plasma spray (APS) technique. Hot corrosion behavior of TBCs was investigated in a cyclic approach (4 hours for each cycle) using Na 2 SO 4 -55 wt.% V 2 O 5 salts at 950°C. The findings showed the higher hot corrosion resistance of ZGYbY TBC compared to YSZ coating system. Regarding the lower basicity of Yb 2 O 3 and Gd 2 O 3 (compared to Y 2 O 3 ), the driving force for the reaction of Yb 2 O 3 /Gd 2 O 3 + Na 2 SO 4 -55 wt.% V 2 O 5 will be lower than that of Y 2 O 3 + Na 2 SO 4 -55 wt.% V 2 O 5 . Moreover, the stabilizers in the zirconia coating could be dissolved by sodium sulfate and vanadium oxide at high temperatures giving rise to the dis-integrity of the TBCs. [ABSTRACT FROM AUTHOR]

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