An innovative model coupling TGO growth and crack propagation for the failure assessment of lamellar structured thermal barrier coatings

2020 ◽  
Vol 46 (2) ◽  
pp. 1532-1544 ◽  
Author(s):  
Zhi-Yuan Wei ◽  
Hong-Neng Cai ◽  
Guo-Hui Meng ◽  
Adnan Tahir ◽  
Wei-Wei Zhang
Keyword(s):  
Crack Propagation ◽  
Thermal Barrier Coatings ◽  
Model Coupling ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Failure Assessment ◽  
Innovative Model ◽  
Tgo Growth

scholarly journals Understanding the Failure Mechanism of Thermal Barrier Coatings Considering the Local Bulge at the Interface between YSZ Ceramic and Bond Layer

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 275
Author(s):  
Zhi-Yuan Wei ◽  
Hong-Neng Cai
Keyword(s):  
Crack Propagation ◽  
Thermal Barrier Coatings ◽  
Local Stress ◽  
Ceramic Layer ◽  
Thermal Barrier ◽  
Interface Morphology ◽  
Barrier Coatings ◽  
Coating Failure ◽  
Bond Layer ◽  
Tgo Growth

The TC/BC interface morphology in APS TBC is one of the important factors leading to crack propagation and coating failure. Long cracks are found near the bulge on the TC/BC interface. In this study, the TBC model with the bulge on the interface is developed to explore the influence of the bulge on the coating failure. Dynamic TGO growth and crack propagation are considered in the model. The effects of the bulge on the stress state and crack propagation in the ceramic layer are examined. Moreover, the effects of the distribution and number of bulges are also investigated. The results show that the bulge on the interface results in the redistribution of local stress. The early cracking of the ceramic layer occurs near the top of the bulge. One bulge near the peak or valley of the interface leads to a coating life reduction of about 75% compared with that without a bulge. The increase in the number of bulges further decreases the coating life, which is independent of the bulge location. The results in this work indicate that a smooth TC/BC interface obtained by some possible surface treatments may be an optional scenario for improving coating life.

A LIFE PREDICTION MODEL OF THERMAL BARRIER COATINGS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3161-3166 ◽  
Author(s):  
LIYONG NI ◽  
CHAO LIU ◽  
CHUNGEN ZHOU
Keyword(s):  
Crack Propagation ◽  
Prediction Model ◽  
Thermal Barrier Coatings ◽  
Life Prediction ◽  
Crack Propagation Rate ◽  
Thermal Barrier ◽  
Critical Crack ◽  
Critical Crack Length ◽  
Barrier Coatings ◽  
Life Prediction Model

The durability and reliability of thermal barrier coatings(TBCs) have become a major concern of hot-section components due to lack of a reliable life prediction model. In this paper, it is found that the failure location of TBCs is at the TBC/TGO interface by a sequence of crack propagation and coalescence process. The critical crack length of failure samples is 8.8mm. The crack propagation rate is 3-10µm/cycle at the beginning and increases largely to 40µm/cycle near coating failure. A life prediction model based a simple fracture mechanics approach is proposed.

scholarly journals A Simulation Study on the Crack Propagation Behavior of Nanostructured Thermal Barrier Coatings with Tailored Microstructure

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 722
Author(s):  
Lei Zhang ◽  
Yu Wang ◽  
Wei Fan ◽  
Yuan Gao ◽  
Yiwen Sun ◽  
...  
Keyword(s):  
Tensile Stress ◽  
Crack Propagation ◽  
Thermal Barrier Coatings ◽  
Element Model ◽  
Nano Particles ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Propagation Behavior ◽  
Stress Zone ◽  
Crack Propagation Behavior

The initiation and propagation of cracks are crucial to the reliability and stability of thermal barrier coatings (TBCs). It is important and necessary to develop an effective method for the prediction of the crack propagation behavior of TBCs. In this study, an extended finite element model (XFEM) based on the real microstructure of nanostructured TBCs was built and employed to elucidate the correlation between the microstructure and crack propagation behavior. Results showed that the unmelted nano-particles (UNPs) that were distributed in the nanostructured coating had an obvious “capture effect” on the cracks, which means that many cracks easily accumulated in the tensile stress zone of the adjacent UNPs and a complex microcrack network formed at their periphery. Arbitrarily oriented cracks mainly propagated parallel to the x-axis at the final stage of thermal cycles and the tensile stress was the main driving force for the spallation failure of TBCs. Correspondingly, I and I–II mixed types of cracks are the major cracking patterns.

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