Toughening Mechanism of Thermal Barrier Coatings

Chen, Yuhui; Zhang, Ruolin; Zhang, Guoshuai; Jiang, Pengyang; Song, Jun; Chu, Xiaowan

doi:10.1007/s10765-021-02820-1

Cited by 11 publications

(4 citation statements)

References 80 publications

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“…The main crack (i.e., the crack at the right side) propagated until it reached the TC/BC interface, then diverted at the splat boundary and propagated horizontally along the interface. Altering the direction of crack propagation is beneficial as it contributes to an increase in the fracture toughness of coatings and enhances their durability [44,45]. The propagation of horizontal cracks along the interface between the top coat and the bond coat can be considered an indication of inadequate adhesion between TC and BC layers, resulting in top coat spallation [26].…”

Section: In-situ Bending Sample #1mentioning

confidence: 99%

“…On the other hand, altering the path of crack propagation is a favorable mechanism for enhancing the toughness of brittle materials (e.g., ceramics). Crack deflection dissipates or absorbs the fracture energy needed for crack propagation and improves the fracture toughness of the coatings [44,45]. Various factors can affect crack propagation, such as changes in material properties, interfaces, stress gradients, and the presence of inclusions or defects.…”

Section: In-situ Bending Sample #1mentioning

confidence: 99%

“…The same crack changed its propagation path and deviated at the splat boundaries (crack propagated along the splat interface) within the bond coat layer as shown in Figure 11d (dashed red arrow 3). Since the toughness of materials is measured by their ability to restrict or prevent crack propagation, the microstructural features such as splat boundaries that cause crack deflection are important mechanisms that impart increased toughness to prolong the life of the thermal barrier coating [44,45]. On the other hand, the main crack (on the left side) propagated vertically through the top coat layer, the TC/BC interface, and the bond coat layer without any observation of crack branching or deviation phenomena.…”

Section: In-situ Bending Sample #3mentioning

confidence: 99%

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Unraveling the Cracking Mechanisms of Air Plasma-Sprayed Thermal Barrier Coatings: An In-Situ SEM Investigation

Amer,

Curry,

Arshad

et al. 2023

Coatings

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In this research work, real-time three-point bending coupled with the scanning electron microscopy (SEM) technique were used to study the crack formation and growth of air plasma spraying (APS) thermal barrier coatings (TBCs). The acquired micrographs were then used to study the strain fields in the vicinity of the cracking region using digital image correlation (DIC) analysis. Fractography analysis for the fractured regions of the APS coatings was also discussed. Based on real-time observation, it was found that roughness of the coatings’ free surface (e.g., valleys) can promote the initiation of cracks since it acts as stress concentration points. Pores and splats features of the coating microstructure contribute to crack branching and crack path deflection, respectively. The former phenomenon (i.e., crack branching) negatively affects the lifetime of the TBC system as it results in an increased fracture area, while the latter can improve the fracture toughness of the coatings and its durability through improving the coating’s ability to dissipate the energy required for crack propagation.

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Section: In-situ Bending Sample #1mentioning

confidence: 99%

Section: In-situ Bending Sample #1mentioning

confidence: 99%

Section: In-situ Bending Sample #3mentioning

confidence: 99%

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Unraveling the Cracking Mechanisms of Air Plasma-Sprayed Thermal Barrier Coatings: An In-Situ SEM Investigation

Amer,

Curry,

Arshad

et al. 2023

Coatings

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“…As the flying speed increases, the extreme aeroheating brings the problem of the “heat barrier”, which is the major barrier for the next generations of high-speed aircraft [ 1 , 2 ]. An in-depth understanding of how aerothermal heat is generated and how to accurately predict the amount of heat produced is of paramount importance for designing reliable thermal protection systems (TPS) [ 3 , 4 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Sensitivity Analysis of the Catalysis Recombination Mechanism on Nanoscale Silica Surfaces

Cui

Sun

et al. 2022

Nanomaterials

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A deep understanding of surface catalysis recombination characteristics is significant for accurately predicting the aeroheating between hypersonic non-equilibrium flow and thermal protection materials, while a de-coupling sensitivity analysis of various influential factors is still lacking. A gas–solid interface (GSI) model with a hyperthermal flux boundary was established to investigate the surface catalysis recombination mechanisms on nanoscale silica surfaces. Using the reactive molecular dynamics (RMD) simulation method, the effects of solid surface temperature, gas incident angle, and translational energy on the silica surface catalysis recombination were qualified under hyperthermal atomic oxygen (AO), atomic nitrogen (AN), and various AN/AO gas mixtures’ influence. It can be found that, though the Eley–Rideal (E–R) recombination mechanism plays a dominant role over the Langmuir–Hinshelwood (L–H) mechanism for all the sensitivity analyses, a non-linear increasing pattern of AO recombination coefficient γO2 with the increase in incident angle θin and translational energy Ek is observed. Compared with the surface catalysis under hyperthermal AO impact, the AN surface adsorption fraction shows an inverse trend with the increase in surface temperature, which suggests the potential inadequacy of the traditional proportional relationship assumptions between the surface adsorption concentration and the surface catalysis recombination coefficient for other species’ impact instead of AOs. For the incoming bi-component AO/AN gas mixtures, the corresponding surface catalysis coefficient is not the simple superposition of the effects of individual gases but is affected by both the intramolecular bond energies (e.g., O2, N2) and intermolecular energies (e.g., Si/N, Si/O).

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