Yttria-stabilized zirconia (YSZ) coatings, extensively used for high-temperature protection, often harbor process-induced residual stresses and interfacial weaknesses when prepared by atmospheric plasma spraying, which can compromise their initial reliability. While conventional thermal annealing can relieve stress, it often induces undesirable grain coarsening and sintering. In this study, we investigated ultrasonic aging as a novel post-treatment technique. Our results show that ultrasonic aging effectively refines the coating microstructure and significantly reduces residual stress, by up to 81% depending on the processing conditions. This process consistently enhanced the bonding strength between the YSZ ceramic coating and the alloy bond coat, providing a more robust interface to resist subsequent degradation during service. However, a detrimental effect on the cohesive strength was observed with excessively long treatment durations, highlighting an optimal parameter window. The underlying mechanism by which ultrasonic aging modifies residual stress and enhances bonding strength is systematically analyzed. These findings demonstrate that ultrasonic aging is a promising low-temperature, high-efficiency post-treatment method to enhance the performance of YSZ coatings.
KANG et al. (Wed,) studied this question.