Environmental barrier coatings(EBC)are crucial for the use of SiC-based ceramic matrix composites in high-temperature combustion environments,yet knowledge of oxygen diffusion in these coatings is limited.This study i...Environmental barrier coatings(EBC)are crucial for the use of SiC-based ceramic matrix composites in high-temperature combustion environments,yet knowledge of oxygen diffusion in these coatings is limited.This study investigates oxygen diffusion dynamics in theβ-RE_(2)Si_(2)O_(7)system to minimize oxygen penetration in rare earth disilicates.We analyze defect formation energy under varying oxygen conditions,identifying key diffusion mechanisms.In oxygen-rich environments,the most favorable neutral interstitial oxygen diffuses along the[110]direction.In oxygen-poor conditions,neutral oxygen vacancies rotate around Y and Si atoms,exhibiting a diffusivity of 6.59×10^(−22)m^(2)/s at 1500 K forβ-Yb_(2)Si_(2)O_(7).Under intermediate oxygen levels,charged interstitial oxygen diffuses via concerted interstitialcy along the[001]direction with a diffusivity of 6.21×10^(−17)m^(2)/s.Additionally,alloying rare earth Y with Er and Yb increases diffusion barriers,contributing to improved EBC performance in extreme environments.The insights gained provides valuable guidance for designing robust coatings tailored to withstand extreme operational environments.展开更多
基金support of the U.S.Department of Energy’s(DOE)Fossil Energy and Carbon Management Advanced Energy Materials Research Program.The research was executed through the National Energy Technology Laboratory’s(NETL)Research and Innovation Center’s Advanced Materials Development Field Work ProposalThis research used resources of the National Energy Research Scientific Computing Center(NERSC),a U.S.DOE Office of Science User Facility supported by the Office of Science under Contract No.DE-AC02-05CH11231 using NERSC awards ALCC-ERCAP0022624 and ALCC-ERCAP0029917.
文摘Environmental barrier coatings(EBC)are crucial for the use of SiC-based ceramic matrix composites in high-temperature combustion environments,yet knowledge of oxygen diffusion in these coatings is limited.This study investigates oxygen diffusion dynamics in theβ-RE_(2)Si_(2)O_(7)system to minimize oxygen penetration in rare earth disilicates.We analyze defect formation energy under varying oxygen conditions,identifying key diffusion mechanisms.In oxygen-rich environments,the most favorable neutral interstitial oxygen diffuses along the[110]direction.In oxygen-poor conditions,neutral oxygen vacancies rotate around Y and Si atoms,exhibiting a diffusivity of 6.59×10^(−22)m^(2)/s at 1500 K forβ-Yb_(2)Si_(2)O_(7).Under intermediate oxygen levels,charged interstitial oxygen diffuses via concerted interstitialcy along the[001]direction with a diffusivity of 6.21×10^(−17)m^(2)/s.Additionally,alloying rare earth Y with Er and Yb increases diffusion barriers,contributing to improved EBC performance in extreme environments.The insights gained provides valuable guidance for designing robust coatings tailored to withstand extreme operational environments.
