  This study investigates failure mechanisms in a typical thermal barrier
coating (TBC) system comprising an EB-PVD columnar top coat, an aluminide bond
coat, and a Ni-based single crystal superalloy substrate, simulating gas
turbine operating conditions using a burner rig. TBC degradation, initiated by
interfacial defects from the LASAT method, was studied during thermal gradient
cycling under fast and slow cooling. In-situ optical and infrared imaging,
along with ex-situ SEM cross-sectional analysis, monitored failure mechanisms.
The Laser Shock for Damage Monitoring (LASDAM) technique provided insights into
gradient and cooling rate impacts on columnar TBC damage. Results showed
significant effects of cooling rate on delamination and localized failure at
blister sites, with LASDAM revealing significant overheating at damage sites.
Analysis included full-field temperature and damage assessment, emphasizing
blister-driven delamination under severe thermal gradients. Discussion focused
on elastic stored energy effects, noting that fast cooling induced transient
conditions where reversed temperature gradients increased damage, limiting TBC
lifespan
