The influence of temperature gradient on thermal cyclic lifetime of plasma-sprayed thermal barrier coatings

摘要

Gradient thermal cycling test was performed on atmospheric plasma sprayed (APS) thermal barrier coatings (TBC) to examine the influence of temperature gradient along cross section of ceramic top coat on the thermal cyclic lifetime. The TBC system consists of Inconel 738 substrate, cold-sprayed NiCoCrAlTaY bond coat (BC) and plasma-sprayed yttria-stabilized zirconia (YSZ) top coat. The YSZ surface temperatures were 1150℃, 1200℃ and 1250℃, corresponding to temperature differences of 150, 200, 250℃ across 250 μm thick YSZ coating, respectively. Every thermal cycling test included 120 s heating and 120 s cooling. Results indicated that the lifetime of APS TBC decreased with the increase of temperature gradient. The temperature gradient has little effect on failure mode of the TBC.