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Aging effect on microstructure and property of strontium zirconate coating co‐doped with double rare‐earth oxides
Author(s) -
Ma Wen,
Meng Xiangfeng,
Wen Jing,
Li Enbo,
Bai Yu,
Chen Weidong,
Dong Hongying
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16047
Subject(s) - zirconate , coating , materials science , strontium , microstructure , phase (matter) , thermal barrier coating , thermal stability , composite material , thermal conductivity , conductivity , analytical chemistry (journal) , chemical engineering , chemistry , ceramic , organic chemistry , chromatography , engineering , titanate
Strontium zirconate coating co‐doped with ytterbia and gadolinia (Sr(Zr 0.9 Yb 0.05 Gd 0.05 )O 2.95 , SZYG) and strontium zirconate coating (SrZrO 3 , SZ) were prepared by atmospheric plasma spraying. The SZYG coating shows improved phase stability from room temperature to 1400°C, while its thermal conductivity (~0.8 W m −1 K −1 ) is at least ~40% lower than that of the SZ coating. Both SZYG and SZ coatings were heat‐treated at 1400°C up to 360 hours in air. The X‐ray diffraction results reveal that both the as‐sprayed SZYG and SZ coatings are composed of main phase SrZrO 3 and secondary phase t ‐ZrO 2 . These two phases do not undergo phase transition upon heat treatment up to 360 hours in the SZYG coating, whereas t ‐ZrO 2 transforms into m ‐ZrO 2 almost completely after 20 hours heat treatment in the SZ coating, suggesting a strong promoting role in stabilizing t ‐ZrO 2 by the additions of Yb 2 O 3 and Gd 2 O 3 in the SZYG coating. The content of t ‐ZrO 2 is ~4.3 wt.% in the as‐sprayed SZYG coating and increases to ~19.5 wt.% after 360 hours heat treatment, analyzed using Jade software. The thermal expansion coefficients (TECs) of the SZYG coatings have no abrupt decrease after heat treatment for more than 5 hours, whereas an abrupt decrease in the TECs of the SZ coating is observed after 100 hours heat treatment. The superior performance of the SZYG coating is attributed to the very stable secondary phase t ‐ZrO 2 stabilized by the co‐doping of ytterbia and gadolinia.