Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7887819 | Ceramics International | 2018 | 11 Pages |
Abstract
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 >â¯1200â¯Â°C. In this study, ZrO2 co-stabilized by 15â¯mol% CeO2 and 5â¯mol% TiO2 (CTZ) and CTZ/YSZ (zirconia stabilized by 7.4â¯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 1300â¯Â°C. The CTZ coating had a lower thermal conductivity than that of YSZ coating, decreasing from 0.89â¯Wâ¯mâ1 Kâ1 to 0.76â¯Wâ¯mâ1 Kâ1 with increasing temperature from room temperature to 1000â¯Â°C. The thermal expansion coefficients were in the range of 8.98â¯Ãâ¯10â6 Kâ1 - 9.88 Ã10â6 Kâ1. Samples were also thermally cycled at 1000â¯Â°C and 1100â¯Â°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 1000â¯Â°C can be effectively enhanced by using a YSZ buffer layer, while the thermal cycling life of CTZ/YSZ double-ceramic-layer TBCs at 1100â¯Â°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.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Jinshuang Wang, Junbin Sun, Jieyan Yuan, Qiangshan Jing, Shujuan Dong, Bing Liu, Hao Zhang, Longhui Deng, Jianing Jiang, Xin Zhou, Xueqiang Cao,