Revealing the oxidation growth mechanism and crack evolution law of Si-HfO2/Yb2Si2O7/Yb2SiO5/high-entropy hafnate thermal/environmental barrier coatings during thermal cycling
Year: 2024
Type: article
Abstract: The Si-HfO 2 /Yb 2 Si 2 O 7 /Yb 2 SiO 5 /(Dy 0.2 Ho 0.2 Er 0.2 Tm 0.2 Lu 0.2 ) 2 Hf 2 O 7 thermal/environmental barrier coating (T/EBC) protects ceramic matrix composites (CMCs) from turbine multi-corrosive media erosion. Challenges persist in the thermal cycling performance of multi-layered T/EBC, notably in understanding the oxidation of the Si-HfO 2 bond coat, compatibility of its mixed thermally grown oxide (m-TGO) with adjacent layers, and the evolution of cracks caused by thermal cycling. Utilizing plasma spraying physical vapor deposition (PS-PVD), this T/EBC on CMC substrates withstands up to 200 hours at 1450 ℃ to 1550 ℃. The m-TGO oxidation follows a parabolic growth curve , with oxygen diffusion activation energies of 160.31 kJ/mol from 1450 ℃ to 1500 ℃, and 125.16 kJ/mol from 1500 ℃ to 1550 ℃. Thermo-mechanical calculations indicate that elastic strain energy accumulation causes interlaminar cracks between m-TGO and adjacent layers. Controlling mud crack density is key to preventing the stress attraction at the tips of bifurcated cracks, thereby avoiding the formation of interlaminar cracks.
Authors: Ruixiang Liu, Wenping Liang, Qiang Miao, Hui Zhao, Xiaofeng Zhang, Shijie Sun, Feilong Jia, Kai Zang, Rongxue Yan, Xiaoqi Tan, Qijia Liu, Min Wu
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,900
OpenAlex ID: W4403271439