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Stress‐Induced Failure Study on a High‐Temperature Air‐Stable Solar‐Selective Absorber Based on W–SiO 2 Ceramic Composite
Author(s) -
Yang Jiale,
Shen Honglie,
Yang Zhiyan,
Zuo Yuxin,
Zong Yang,
Huo Xiaomin,
Li Yufang
Publication year - 2020
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.202000336
Subject(s) - materials science , annealing (glass) , composite material , ceramic , composite number , stress (linguistics) , coating , cracking , linguistics , philosophy
A stress‐induced failure study on a high‐temperature air‐stable ceramic composite solar selective absorber (SSA) based on a W–SiO 2 system is reported. The as‐prepared SSA exhibits excellent spectral and structural stability after annealing in air at 500 °C for 36 h, proving its thermal stability against air corrosion. However, once the temperature is elevated to 600 °C, optical performance degradation and coating cracking happens. The X‐ray diffraction (XRD) patterns reveal that an O‐induced phase transition process from α‐W to β‐W occurs at the interface between the W IR reflector and W–SiO 2 layer during deposition. The phase transition induces immense internal stress, which becomes the incentive of crack generation. Further increasing the annealing temperature, drastic structural changes of oxidized W become the driving force for crack propagation and hole expansion, leading to a failure analogous to a volcanic eruption. To improve the temperature limit of coating, a Ni–SiO 2 stress buffer layer is introduced and successfully reduces the internal stress through Ni atom substitution for W atoms. Therefore, the optimized SSA keeps stable at 600 °C and the cracking temperature increases to 650 °C. These results suggest that the W–SiO 2 ‐based SSA is a good candidate for air‐stable high‐temperature solar thermal conversion.