Abstract
Sintering of advanced thermal barrier coatings (TBCs) at high temperatures is key challenge as it can adversely affect service performance and thermal fatigue resistance of TBCs. In this study, sintering behavior of pyrochlore-type La2(Zr0.7Ce0.3)2O7 (LZ7C3) was investigated using experiments and molecular dynamics. Meanwhile, the corresponding dynamic process and behind mechanism were uncovered. Results showed that novel LZ7C3 exhibited significantly higher sintering resistance than host La2Zr2O7 (LZ) and typical 8 wt% yttria-stabilized zirconia (8YSZ) at temperature up to 1773 K, which indicated that pyrochlore-type LZ7C3 is a promising TBC candidate to replace conventional 8YSZ at high temperatures. Further study also revealed that initial stage played crucial role in sintering process, and the sintering mainly occurred at grain boundary (GB) region. Intrinsic sintering activation energy of LZ7C3 GB (695.248 J mol−1) is larger than that of LZ GB (384.171 J mol−1) and 8YSZ GB (173.303 J mol−1), which resulted in outstanding sintering resistance for LZ7C3. Furthermore, no obvious enrichment of second phase was observed at the GB of LZ7C3. This study thus concluded that hindering the atomic diffusion of GB, as well as introducing foreign atom with larger mass and bond energy may act as effective strategy to enhance the sintering resistance of TBCs materials.
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