Journal
CERAMICS INTERNATIONAL
Volume 44, Issue 8, Pages 9353-9363Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2018.02.149
Keywords
Thermal barrier coating; Phase stability; Thermo-physical properties; Thermal cycling
Categories
Funding
- National Natural Science Foundation of China [51501137, 51702244]
- Natural Science Foundation of Hubei Province [2017CFB285]
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ZrO2 co-stabilized by CeO2 and TiO2 with stable, nontransformable tetragonal phase has attracted much attention as a potential material for thermal barrier coatings (TBCs) applied at temperatures > 1200 degrees C. In this study, ZrO2 co-stabilized by 15 mol% CeO2 and 5 mol% TiO2 (CTZ) and CTZ/YSZ (zirconia stabilized by 7.4 wt% Y2O3) double-ceramic-layer TBCs were respectively deposited by atmospheric plasma spraying. The microstructures, phase stability and thermo-physical properties of the CTZ coating were examined using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric-differential scanning calorimeter (TG-DSC), laser pulses and dilatometry. Results showed that the CTZ coating with single tetragonal phase was more stable than the YSZ coating during isothermal heat-treatment at 1300 degrees C. The CTZ coating had a lower thermal conductivity than that of YSZ coating, decreasing from 0.89 W m(-1) K-1 to 0.76 W m(-1) K-1 with increasing temperature from room temperature to 1000 degrees C. The thermal expansion coefficients were in the range of 8.98 x 10(-6) K-1- 9.88 x 10(-6) K-1. Samples were also thermally cycled at 1000 degrees C and 1100 degrees C. Failure of the TBCs was mainly a result of the thermal expansion mismatch between CTZ coating and superallloy substrate, the severe coating sintering and the reduction-oxidation of cerium oxide. The thermal durability of the TBCs at 1000 degrees C can be effectively enhanced by using a YSZ buffer layer, while the thermal cycling life of CTZ/YSZ double-ceramic-layer TBCs at 1100 degrees C was still unsatisfying. The thermal shock resistance of the CTZ coating should be improved; otherwise the promising properties of CTZ could not be transferred to a well-functioning coating.
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