Enhanced oxidation resistance and structural stability of CoNiCrAlY - Yttria stabilized zirconia - LaMgAl11O19 dual ceramic coating by AlY planting layer and subsequent vacuum annealing treatment

Abstract

AlY plating layer and vacuum annealing were designed to enhance the oxidation resistance and structural stability of CoCrNiAlY–yttria stabilized zirconia (YSZ)–LaMgAl11O19 (LaMA) dual ceramic coating. Vacuum annealing induced a prominent recrystallization of LaMA resulting in numerous micro-cracks. During the oxidation test, these micro-cracks acted as the infiltration channels of O2, accelerating the formation of brittle (Ni, Co)Cr2O4 and high stress initiation, and eventually led to serious fracture. However, AlY plating layer experienced a competitive oxidation during the vacuum annealing and thus led to the formation of α-Al2O3. During the oxidation test, these α-Al2O3 offered a strong barrier ability to block the infiltration of O2, leading to an enhanced oxidation resistance and good structural stability.