Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd_(2)Zr_(2)O_(7) thermal barrier coatings: Theoretical and experimental studies  

作　　者：Lei GUO Bowen LI Yuxian CHENG Lu WANG 

机构地区：[1]School of Materials Science and Engineering,Tianjin University,Tianjin 300072,China [2]Tianjin Key Laboratory of Advanced Joining Technology,Key Lab of Advanced Ceramics and Machining Technology of Ministry of Education,Tianjin 300072,China [3]AECC Shenyang Liming Aero-Engine Co.,Ltd.,Shenyang 110043,China

出　　处：《Journal of Advanced Ceramics》2022年第3期454-469,共16页先进陶瓷（英文）

基　　金：This research is sponsored by the National Natural Science Foundation of China (Grant No. 51971156);National Science and Technology Major Project (Grant No. 2017-VII-0007).

摘　　要：Sc was doped into Gd_(2)Zr_(2)O_(7) for expanding the potential for thermal barrier coating (TBC) applications. The solid solution mechanism of Sc in the Gd_(2)Zr_(2)O_(7) lattice, and the mechanical and thermophysical properties of the doped Gd_(2)Zr_(2)O_(7) were systematically studied by the first-principles method, based on which the Sc doping content was optimized. Additionally, Sc-doped Gd_(2)Zr_(2)O_(7) TBCs with the optimized composition were prepared by air plasma spraying using YSZ as a bottom ceramic coating (Gd-Sc/YSZ TBCs), and their sintering behavior and thermal cycling performance were examined. Results revealed that at low Sc doping levels, Sc has a large tendency to occupy the lattice interstitial sites, and when the doping content is above 11.11 at%, Sc substituting for Gd in the lattice becomes dominant. Among the doped Gd_(2)Zr_(2)O_(7), the composition with 16.67 at% Sc content has the lowest Pugh’s indicator (G/B) and the highest Poisson ratio (σ) indicative of the highest toughness, and the decreasing trends of Debye temperature and thermal conductivity slow down at this composition. By considering the mechanical and thermophysical properties comprehensively, the Sc doping content was optimized to be 16.67 at%. The fabricated Gd-Sc coatings remain phase and structural stability after sintering at 1400 ℃ for 100 h. Gd-Sc/YSZ TBCs exhibit excellent thermal shock resistance, which is related to the good thermal match between Gd-Sc and YSZ coatings, and the buffering effect of the YSZ coating during thermal cycling. These results revealed that Sc-doped Gd_(2)Zr_(2)O_(7) has a high potential for TBC applications, especially for the composition with 16.67 at% Sc content.

关 键 词：thermal barrier coating(TBC) first-principles calculation solid solution mechanism high-temperature stability thermal cycling 

分 类 号：TG174.4[金属学及工艺—金属表面处理] V261.933[金属学及工艺—金属学]