Time-/space-sensitive sintering kinetics of plasma sprayed multi-modal nanostructured coating

Sintering is considered to be one of the main reasons that accelerate performance degradation and shorten lifetime of thermal barrier coatings (TBCs). The anti-sintering design and underlying sintering kinetics are of great importance for optimizing the microstructure of TBCs. In this study, the competitive sintering of a novel multi-modal nanostructured coating is systematically studied by a burner-rig test. The results suggested that, due to the coexistence of unmelted nanozone, amorphous area and recrystallized region, the sintering behavior of nanostructured coating exhibited obvious time-/space-sensitive effects. Time-sensitive feature was initially associated with the coalescence growth of nano-particles and healing of micro-pores within the unmelted nanozone. Subsequently, the sintering was accompanied by the abnormal growth of grains in the unmelted nanozone and the formation of multi-contact neck in the recrystallized region. The diffusion-driven stiffening of recrystallized region promoted the stage-progressive enhancement of elastic modulus. The space-sensitive sintering kinetics caused the spontaneous formation and evolution of multi-scale cracks at the unmelted nanozone/recrystallized region interface.