Corrosion behavior of PS-PVD spray Yb2Si2O7 environmental barrier coatings during continuous water vapor exposure

Yb2SiO5 and Yb2Si2O7 have been considered to be promising EBCs materials for silicon‐based ceramics. Besides the various requirements EBCs must satisfy, it must be resistant to severe corrosion by high‐temperature water vapor as well as CMAS. In this work, the Yb2SiO5, Yb2Si2O7 coatings and Yb2SiO5/Yb2Si2O7/Si, Yb2SiO5/Si EBCs were subjected to steam with alumina at 1400°C for 200 h. Results showed that Yb3Al5O12 reaction layer and Yb2SiO5 corrosion layer were formed on the Yb2SiO5 coating, while porous Yb2SiO5 corrosion layer with Yb3Al5O12 phase was formed on the Yb2Si2O7 coating. By designing Yb2Si2O7 as intermediate layer, the corrosion resistance of Yb2SiO5/Yb2Si2O7/Si EBCs was significantly improved. In addition to phase transition of β‐cristobalite to α‐phase, crystallization of amorphous SiO2 also caused volume change, inducing longitudinal cracks through the TGO layer, which may lead to the failure of EBCs.This article is protected by copyright. All rights reserved

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Corrosion behavior and mechanism of ytterbium silicates environmental barrier coatings subjected to thermal cycling in water vapor

Zhong,

Liang,

Hong

et al. 2023

“…The structural and overall properties of the rhombohedral ( R ‐3 c ) In 2 O 3 are lacking. We know that the structural stability, electronic and optical properties of a solid are markedly effected by these defects (point defect, dislocation, and interface) and alloying 22–27 . In particular, the point defect (such as vacancies) would change the balanced electrons of an oxide near the Fermi level ( E F ), and then influence the electronic and optical properties.…”

Section: Introductionmentioning

confidence: 99%

“…We know that the structural stability, electronic and optical properties of a solid are markedly effected by these defects (point defect, dislocation, and interface) and alloying. [22][23][24][25][26][27] In particular, the point defect (such as vacancies) would change the balanced electrons of an oxide near the Fermi level (E F ), and then influence the electronic and optical properties. Unfortunately, the role of vacancies on the structural stability, electronic and optical properties of the rhombohedral In 2 O 3 is unclear.…”

Section: Introductionmentioning

confidence: 99%

Influence of vacancies on the optical and electronic properties of the rhombohedral In₂O₃ oxide

Pan,

Wen

2023

To study the vacancy mechanism of In2O3, we apply the first‐principles method to study the influence of vacancy on the structural stability, electronic and optical properties of the rhombohedral In2O3. Two vacancies: In‐vacancy (V‐In) and O‐vacancy (V‐O) are considered here. The calculated results show that the rhombohedral In2O3 with In‐vacancy and O‐vacancy are thermodynamic and dynamical stabilities based on the vacancy formation energy and phonon dispersion. In particular, In‐vacancy has better thermodynamic stability in comparison to the O‐vacancy. Importantly, the rhombohedral In2O3 exhibits ultraviolet properties. However, two vacancies lead to the peak migration from the ultraviolet region to the visible light region. Furthermore, it is found that the calculated band gap of In2O3 with In‐vacancy is 1.07 eV, which is wider than the parent In2O3 (0.841 eV). Naturally, the wide band gap of In‐vacancy is that the removed In atom aggravates the difficulty of the electronic interaction between the conduction band and the valence band near the Fermi level. On the contrary, O‐vacancy shows metallic behavior because O‐vacancy (V‐O) enhances the electronic interaction near the Fermi level.

“…In high-temperature applications, the BC of EBCs and TBCs oxidize to form SiO 2 and Al 2 O 3 , respectively, which is called thermal growth oxides (TGO). 36,[38][39][40][41] The growth and thickening of the TGO lead to the spallation and failure of EBCs and TBCs due to the enormous thermal stress between ceramic coatings and BC. The stress is caused by the differences of their thermal expansion coefficients (TECs) and mechanical properties.…”

Section: Introductionmentioning

confidence: 99%

Ferroelastic rare‐earth tantalates for multifunctional thermal/environmental barrier coatings: A perspective

Chen,

Wang,

Zhang

et al. 2023

This perspective outlines the research directions of ferroelastic rare‐earth (RE) tantalates (RETaO4), which have been studied as multifunctional thermal/environmental barrier coatings (T/EBCs) with working temperatures above 1600°C. Ferroelastic RETaO4 ceramics exhibit several distinct features, including the reversible second‐order ferroelastic phase transition, high toughness, low thermal conductivity, low oxygen ion conductivity, and adjustable thermal expansion coefficients. This perspective provides a concise summary of the research progress on tantalate coatings synthesized via air plasma spraying and electron beam physical vapor deposition. The service performance of tantalate coatings is typically evaluated through thermal fatigue and shock measurements. Uncovering the failure mechanisms and understanding influencing factors are key aspects for future studies. In this regard, establishing the synthesis‐structure‐property relationship of RETaO4 coatings is essential. This brief perspective can serve as a guide for future work on RETaO4 coatings and further advancements in their applications across various fields, including aviation engines and gas turbines.This article is protected by copyright. All rights reserved