Abstract
Lifetime is a basic support for the thermal insulation function of thermal barrier coatings (TBCs). Therefore, extending the life span is essential to develop next-generation TBCs. For this objective, the columnar structure formed by vertical cracks appears to make sense. However, the underlying mechanism is still unclear. This work scrutinizes the influence of periodic vertical cracks on cracking behavior in order to tailor high strain tolerant TBCs. A finite element model was evolved to explore the crack behavior influenced by thermal mismatch strain between substrate and coating. The virtual crack closure technique (VCCT) was used to describe the propagation of crack under load. It is found clearly that the space between two vertical cracks (short for SVC) along the in-plane direction has a noteworthy influence on the strain tolerance of TBCs. Results indicate that the strain energy release rate (SERR) and stresses at the pre-crack tip increase continuously with the increase of the SVC, suggesting that the driving force for cracks is increasing. The crack is not propagated when the SVC is very small, whereas the crack grows continuously with the increase of the SVC. The growth of a crack can be prevented by reducing the SVC. A critical value for the SVC was found. When the SVC is less than the critical value, the SERR can be dramatically reduced. Thus, the SVC of periodic cracks can be tailored to obtain TBCs with high strain tolerance.
Highlights
The working temperature of advanced land-based gas turbines and aircraft engines continue to increase upon their thrust/weight ratio and performance
The coatings including vertical cracks had Coatings 2021, 11, 720 high crack resistance, especially for the thick coatings [54]. This result suggests that coatings with vertical cracks increase strain tolerance, which has a significant influence on the preparation and design of advanced protective coatings in future applications
To achieve some significant data, the distribution of stress in the ceramic TC layer was primarily investigated at the pre-crack tip due to thermal mismatch strain between coatings and substrate, which caused the degradation of coating
Summary
The working temperature of advanced land-based gas turbines and aircraft engines continue to increase upon their thrust/weight ratio and performance. The coatings including vertical cracks had Coatings 2021, 11, 720 high crack resistance, especially for the thick coatings [54] This result suggests that coatings with vertical cracks increase strain tolerance, which has a significant influence on the preparation and design of advanced protective coatings in future applications. Many previous investigations have disregarded the interaction of vertical cracks and propagation of cracks, while a few studies investigate the influence of crack space on the coating delamination and the durability of the TBCs [51,52,53,55]. This work develops a finite element model to explore the crack behavior induced by thermal mismatch strain between substrate and coating.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
