A comparison between novel Gd ₂ Zr ₂ O ₇ and Gd ₂ Zr ₂ O ₇ /YSZ thermal barrier coatings fabricated by plasma spray‐physical vapor deposition

Abstract

Abstract Spherical Gd 2 Zr 2 O 7 hollow powders with a mean size of 8.8 μm were fabricated as feedstock for thermal barrier coatings (TBCs) by spray‐drying. The single‐ceramic‐layer (SCL) Gd 2 Zr 2 O 7 TBCs and double‐ceramic‐layer (DCL) Gd 2 Zr 2 O 7 /YSZ TBCs with quasi‐columnar structure were successfully fabricated by plasma spray‐physical vapor deposition (PS‐PVD). Tensile and water‐quenching tests were applied to evaluate TBCs performances. The results show that adhesion strength of SCL Gd 2 Zr 2 O 7 TBCs and DCL Gd 2 Zr 2 O 7 /YSZ TBCs is 36.5 MPa and 15.4 MPa, respectively. The delamination of SCL Gd 2 Zr 2 O 7 TBCs and DCL Gd 2 Zr 2 O 7 /YSZ TBCs in the tensile test takes place at the middle and bottom of Gd 2 Zr 2 O 7 layer, respectively, due to relatively lower fracture toughness of Gd 2 Zr 2 O 7 layer. After 40 cycles of water‐quenching test, DCL Gd 2 Zr 2 O 7 /YSZ TBC surface keeps relatively intact, while SCL Gd 2 Zr 2 O 7 TBC surface shows 20% visible destroyed regions, which demonstrates that DCL Gd 2 Zr 2 O 7 /YSZ TBCs have a better thermal shock resistance than SCL Gd 2 Zr 2 O 7 TBCs. The cracks in the SCL system propagate near thermally grown oxide (TGO) due to thermal mismatch and TGO growing stress, while cracks in the DCL system propagate in the Gd 2 Zr 2 O 7 layer due to its relatively lower fracture toughness.