Neutron Pair Distribution Function Analysis to the Local Structure of High-Entropy RE<sub>2</sub>SiO<sub>5</sub> Environmental Barrier Coating

doi:10.11900/0412.1961.2024.00115

IMR OpenIR

	Neutron Pair Distribution Function Analysis to the Local Structure of High-Entropy RE₂SiO₅ Environmental Barrier Coating
	Wang Haoyu 1; Lu Xirui 1; Chen Qi 1,2; Xiong Ying 3; Luo Zhixin 1; Zhang Jie 1; Wang Jingyang 1
通讯作者	Zhang Jie(jiezhang@imr.ac.cn)
	2024-08-11
发表期刊	ACTA METALLURGICA SINICA
ISSN	0412-1961
卷号	60 期号:8 页码:1130-1140
摘要	Environmental barrier coatings (EBCs) enable SiCf/SiC ceramic matrix composites (CMC) to operate under high-temperature combustion conditions. They reduce the oxidation rate of SiC f/SiC, the volatilization of the composites due to reaction with water vapor, and the surface temperature of the composites. Rare-earth monosilicates (RE2SiO5), owing to their excellent high-temperature durability, low thermal conductivity, and good phase stability, are used as the top layer of EBCs. However, they exhibit a high coefficient of thermal expansion (CTE), leading to thermal mismatch and inducing tensile residual stress (with a magnitude of several hundred MPa) in the coating, resulting in the formation of vertical cracks, which act as extremely-high-diffusivity paths for oxidation species transportation and silica volatilization. Therefore, regulating the CTE of RE2SiO5 EBCs and minimizing the CTE mismatch among constituent RE2SiO5 layers with SiC f/SiC CMCs are critical for multilayered EBCs. Through atmospheric plasma spraying, a typical Yb2SiO5/Yb 2Si2O7/Si coating system and a tri-layer structured multicomponent (Y1/4Ho1/4Er1/4Yb1/4)(2)SiO5/Yb2Si2O7/Si coating system with better matched CTEs were manufactured. Both the coatings remained adhered to the substrate during deposition and after annealing, and no mud cracks that would compromise the coating gas-tightness quality and delamination cracks were observed at any of the coating interfaces. In thermal cycling tests, (Y1/4Ho1/4Er1/4Yb1/4)(2)SiO5/Yb2Si2O7/Si coatings showed a lifetime that is three times longer than that of conventional Yb2SiO5/Yb2Si2O7/Si coatings. The failure mechanisms in thermal cycling were investigated via the finite element simulation of stress. It was found that the stress in the substrate was low, and the residual thermal stress was mainly concentrated on the top, inter, and bond layers and increased with an increase in temperature. Compared with that of the (Y1/4Ho1/4Er1/4Yb1/4)(2)SiO5 top coat, the Yb2SiO5 top coat showed obviously higher residual tensile stress, which contributed to a higher tendency for mud-crack formation and higher energy release rate, substantially reducing the coating.. s thermal cycling lifetime. Through neutron powder diffraction and pair distribution function (PDF) analysis, the average and local structures of RE2SiO5 were studied. Overall, the average and local structures did not differ significantly, both of which can be described using the C2/c structure. Nevertheless, the PDF results demonstrated some differences in the disorder degree of Si-O and RE-O coordination environments. In particular, Rietveld refinement results of the PDF showed lower local distortion degree of [ORE4] tetrahedrons when compared with that of the average structure. It is effective to reduce the distortion degree of [ORE4] tetrahedrons by introducing Y3+, Ho3+, and Er3+ into the Yb3+ sites of Yb2SiO5, and smaller distortion degrees lead to lower CTE values. Coordinative local disturbances introduced by strategic high-entropy design have been proposed as the key method for CTE regulation.
关键词	neutron diffraction pair distribution function rare-earth silicate environmental barrier coating burner rig test
DOI	10.11900/0412.1961.2024.00115
收录类别	SCI
语种	英语
WOS研究方向	Metallurgy & Metallurgical Engineering
WOS类目	Metallurgy & Metallurgical Engineering
WOS记录号	WOS:001281277300012
出版者	SCIENCE PRESS
引用统计
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/189632
专题	中国科学院金属研究所
通讯作者	Zhang Jie
作者单位	1.Chinese Acad Sci, Shenyang Natl Lab Mat Sci, Inst Met Res, Shenyang 110016, Peoples R China 2.Univ Sci & Technol China, Sch Mat Sci & Engn, Hefei 230000, Peoples R China 3.AECC Shenyang Liming AEROENGINE Sci & Technol Co, Shenyang 110043, Peoples R China
推荐引用方式 GB/T 7714	Wang Haoyu,Lu Xirui,Chen Qi,et al. Neutron Pair Distribution Function Analysis to the Local Structure of High-Entropy RE₂SiO₅ Environmental Barrier Coating[J]. ACTA METALLURGICA SINICA,2024,60(8):1130-1140.
APA	Wang Haoyu.,Lu Xirui.,Chen Qi.,Xiong Ying.,Luo Zhixin.,...&Wang Jingyang.(2024).Neutron Pair Distribution Function Analysis to the Local Structure of High-Entropy RE₂SiO₅ Environmental Barrier Coating.ACTA METALLURGICA SINICA,60(8),1130-1140.
MLA	Wang Haoyu,et al."Neutron Pair Distribution Function Analysis to the Local Structure of High-Entropy RE₂SiO₅ Environmental Barrier Coating".ACTA METALLURGICA SINICA 60.8(2024):1130-1140.