Journal
CERAMICS INTERNATIONAL
Volume 47, Issue 12, Pages 16547-16554Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2021.02.225
Keywords
Environmental barrier coating; Water vapor volatilization; Oxidation; Surface cracking; Numerical model
Categories
Funding
- National Science and Technology Major Project [2017-VI-0020-0093]
- Beijing Municipal Natural Science Foundation [1194026]
- Beijing Institute of Technology Research Fund Program for Young Scholars
Ask authors/readers for more resources
A numerical model has been developed to study the surface crack propagation in brittle ceramic coatings under combustion conditions in advanced gas turbines, specifically focusing on the failure of rare-earth silicate environmental barrier coating systems. The study reveals that rapid crack propagation during extended thermal cycling is the dominant mechanism leading to catastrophic failure of the coating.
A numerical model is developed for surface crack propagation in brittle ceramic coatings, aiming at the intrinsic failure of rare-earth silicate environmental barrier coating systems (EBCs) under combustion conditions in advanced gas turbines. The main features of progressive degradation of EBCs in such conditions are captured, including selective silica vaporization in the top coat due to exposure to water vapor, diffusion path-dependent bond coat oxidation, as well as crack propagation during cyclic thermal loading. In light of these features, userdefined subroutines are implemented in finite element analysis, where surface crack growth is simulated by node separation. Numerical results are validated by existing experimental data, in terms of monosilicate layer thickening, thermal oxide growth, and fracture behaviors. The experimentally observed quasi-linear oxidation in the early stage is also elucidated. Furthermore, it is suggested that surface crack undergoes rapid propagation in the late stage of extended thermal cycling in water vapor and leads to catastrophic failure, driven by both thermal mismatch and oxide growth stresses. The latter is identified as the dominant mechanism of penetration. Based on detailed analyses of failure mechanisms, the optimization strategy of EBCs composition is proposed, balancing the trade-off between mechanical compliance and erosion resistance.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available