Preparation of 8YSZ and Double-Ceramic-Layer La₂Zr₂O₇/8YSZ Thermal Barrier Coatings on GH4169 Superalloy Substrates and their Static High Temperature Oxidation Behaviour

Abstract

Thermal barrier coatings (TBCs) are very important ceramic coating materials due to their excellent performance at high temperature. Double-ceramic-layer (DCL) La2Zr2O7 (LZ)/8YSZ TBCs, nanostructured single-ceramic-layer (SCL) 8YSZ and conventional SCL 8YSZ TBCs with the same thickness were fabricated by atmospheric plasma spraying in the present work. The static high temperature oxidation behaviour of the three as-sprayed coatings at 1000 and 1200 was investigated systematically. The results indicated that the LZ/8YSZ has higher oxidation resistance than that of SCL 8YSZ. The addition of LZ ceramic layer can increase the insulation temperature, impede the oxygen transferring to the bond coat and decrease the formation rate of the thermally grown oxide (TGO). The formation of the oxidized isolated islands in the bond-coat has decreased the effective thickness of the TGO at the bond coat/ceramic layer interface due to the depletion of the metallic elements in the bond-coat.