Morphology and thermal conductivity of La2(Ce0.3Zr0.7)2O7-3wt.%Y2O3 coatings

• Published in: Surface & coatings technology Vol. 291; pp. 216 - 221
• Main Authors: Xiaofeng, Zhang, Xiwen, Song, Xiangzhong, Cui, Min, Xie, Shengli, An
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2016
• Subjects: Coatings; Deposition; Electron-beam physical vapor deposition; Heat transfer; La2(Ce0.3Zr0.7)2O7; Morphology; Porosity; Pyramids; Texture; Thermal barrier coatings; Thermal conductivity; Tips; Thermal barrier coatings; Thermal conductivity; La2(Ce0.3Zr0.7)2O7; Texture; Morphology
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2016.02.039

The La2(Ce0.3Zr0.7)2O7-3wt%Y2O3 coating was deposited by electron beam physical vapor deposition (EB-PVD). In order to reveal the structure evolution of the coating with the deposition parameter, the selected rotation rates of the substrate were 0rpm, 5, 15 and 25rpm, while the substrate temperature was fixed at 870°C based on the structure zone model of 0.3<Tsub/Tmp<0.5. The microstructure of the column tips ranged from a ‘triangular pyramid’ (branch tips at 5rpm and column tips at 0rpm) to a ‘roof top’, then to a ‘pyramid’ with increasing the rotation rate. Under stationary deposition, the columnar crystals grew along the direction. The tips of the ‘roof top’ or the pyramids were covered by four {111} planes. During rotation deposition, the columnar crystal grew along the direction. If one assumes that the pore fraction has little effect on the thermal conductivity, the ‘C’ shaped Type I pores reduced the thermal conductivity, the straight Type I pores increased the thermal conductivity, the lamellar Type II pores significantly reduced the thermal conductivity. The minimum thermal conductivity was 0.761W/(mK) at the rotation rate of 15rpm. This gives an approach to optimize the structure of the La2(Ce0.3Zr0.7)2O7-3wt%Y2O3 coatings. •Microstructures of columnar crystals regularly change at different rotation rates.•The growth direction of columnar crystals differs under stationary or rotation deposition.•The shape of pores play major role on thermal conductivities of the coatings.•The pore fractions of the coatings, deposited under different rotation rates, are showed.