Improved thermal shock resistance of GYYZO-YSZ double ceramic layer TBCs induced by induction plasma spheroidization

In thermal barrier coatings (TBCs) applications, conventional Y2O3 stabilized ZrO2 (7-8YSZ) rapidly deteriorates when exposed to temperatures above 1200 C. Alternatively, Gd2O3-Yb2O3-Y2O3 co-stabilized ZrO2 (GYYZO) emerges as a promising TBC candidate for superior thermal insulation capability and phase stability up to 1300 C. In this study, we have fabricated and evaluated 7-8YSZ TBCs, GYYZO-YSZ double ceramic layer (DCL) with calcined GYYZO powder and GYYZO-YSZ DCL with calcined and induction plasma spheroidized GYYZO powder in terms of thermal shock resistance. Under thermal shocks up to 1300 C, YSZ quickly fails after 648 +/- 60 cycles for insufficient high temperature capability. Benefiting from the DCL system, the lifespan of calcined GYYZO-YSZ DCL is successfully prolonged to 1582 +/- 40 cycles, however the weak ceramic interface induces premature failure. By spheroidization, the lifetime of spheroidized GYYZO DCL is further increased to 2050 +/- 70 cycles, as a result of the combined effect of coating densification, interface enhancement and introduction of vertical cracks.