Abstract
In this study, (Gd0.9Yb0.1)2Zr2O7 (GYbZ)/yttria-stabilized zirconia (YSZ) double-ceramic-layer (DCL) thermal barrier coatings (TBCs) were prepared by plasma spray-physical vapor deposition (PS-PVD). The microstructure, mechanical performance, and thermal shock behavior of coatings prepared with spraying distances of 600, 800, and 1000 mm were investigated. The GYbZ coating prepared with a spraying distance of 600 mm showed a closely packed columnar structure. However, the GYbZ coatings prepared with spraying distances of 800 and 1000 mm showed a quasi-columnar structure. The GYbZ coating prepared with a spraying distance of 800 mm had the thickest columnar crystals with obvious inter-columnar gaps. In addition, this coating exhibited excellent mechanical performance and the best thermal shock resistance. The primary failure patterns appearing during thermal shocking on the surface of TBCs can be classified into the following five types: caves, exfoliation, delamination cracks, spalled areas, and radiate cracks. Furthermore, the failure behavior of these coatings in water-quenching tests is clarified.
Highlights
Thermal barrier coatings (TBCs) are increasingly employed to protect the underlying metal substrate in various products [1,2], such as gas turbines and aero-engines
Agglomerated powders with an incompact structure can promote the evaporation of powders, and the spherical structures can improve the fluidity of GYbZ agglomerated powders to meet the uniform 4 of 15 and stable powder-feeding requirements of the plasma spray-physical vapor deposition (PS-PVD) technique
We elucidated the influence of spraying distances on the performance and structure of GYbZ coatings prepared by the PS-PVD technique, and their failure behavior is summarized
Summary
Thermal barrier coatings (TBCs) are increasingly employed to protect the underlying metal substrate in various products [1,2], such as gas turbines and aero-engines. Among the various promising ultra-high-temperature TBC materials, gadolinium zirconate (Gd2Zr2O7; GZO) has received increasing attention due to its superior stability and insulation properties at elevated temperatures [5,6] It has some shortcomings, such as poor fracture toughness and a mismatched thermal expansion coefficient with substrates, resulting in several problems, including insufficient bonding strength and a short thermal cycling life of the GZO coatings [7]. Their thermophysical properties can be improved by substituting the Gd or Zr sites in GZO materials with other rare-earth cations [8]. The thermal cycle tests showed that the average service life of the TBCs exceeded 3700 cycles
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