Journal
SURFACE & COATINGS TECHNOLOGY
Volume 423, Issue -, Pages -Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.surfcoat.2021.127572
Keywords
Thermal barrier coatings; Probabilistic approach; Gas turbine blade; Lifetime prediction; Interfacial oxidation; Thermal mismatch
Funding
- National Natural Science Foundation of China [51671085]
- Outstanding Youth Science Foundation of Hunan Province [2020JJ3031]
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This paper introduces a method to analyze the lifetime variation of thermal barrier coatings (TBCs) under different working conditions, combining probabilistic methods and lifetime prediction models. The performance of TBCs is studied by setting failure criteria and calculating failure probabilities. Experimental results show that the predictive failure probabilities of TBCs under furnace isothermal cycling are 0.1% at 300 cycles, and the maximum failure probabilities of TBCs under a hot gas stream increase with time.
Thermal barrier coatings (TBCs) - as porous ceramic materials - have varying lifetimes because of their unstable mechanical properties and harsh working conditions. In this paper, a probabilistic approach to quantify the risk of interface spallation in TBCs by thermally grown oxide (TGO) growth and thermal mismatch, along with a lifetime prediction method based on the critical failure probability is proposed. First, a failure criterion for TBCs is set to determine a boundary between the failure and safe region. Second, parameters relating to failure, along with the stochastic characteristics of these parameters, are analysed thoroughly. Third, the failure probability is calculated. Finally, the lifetime of TBCs on turbine blades in a hot gas stream is predicted. Under furnace isothermal cycling, the predictive failure probabilities of TBCs are 0.1% (300 cycles), 1.5% (600 cycles), and 7.49% (1000 cycles). The experiment results for turbine blades are 1.03% (300 cycles), 1.73% (600 cycles), and 5.12% (1000 cycles). Under a hot gas stream, the maximum failure probabilities of TBCs after 200, 300, 500, and 1000 h are 40%, 45% 50%, and 70%, respectively. The lifetimes of TBCs are 273, 332, 406, and 523 h if the critical area ratio of the metal substrate exposed to the hot gas is 5%, 10%, 15%, and 20%, respectively.
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