Effect of CMAS infiltration on the optical properties of thermal barrier coatings: Study of the mechanisms supported by FDTD simulations and ALD

Blanchard, F.; Kadi, M.J.; Bousser, Étienne; Baloukas, Bill; Azzi, M.; Klemberg-Sapieha, J.E.; Martinů, L.

doi:10.1016/j.actamat.2023.118830

Cited by 5 publications

(2 citation statements)

References 31 publications

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“…Within the FDTD module, the porosity of the TBCs could be defined by setting the refractive index and extinction coefficient [40]. Additionally, we varied the thickness of the coating (150-300 μm with a step size of 30 μm) and surface roughness (including both the ceramic layer surface roughness and the interface roughness between the ceramic layer and substrate, ranging from 0.5-5 μm with a step size of 0.5 μm).…”

Section: Fdtd Simulationmentioning

confidence: 99%

Data-Driven Method for Porosity Measurement of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

et al. 2023

Coatings

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Accurate measurement of porosity is crucial for comprehensive performance evaluation of thermal barrier coatings (TBCs) on aero-engine blades. In this study, a novel data-driven predictive method based on terahertz time-domain spectroscopy (THz-TDS) was proposed. By processing and extracting features from terahertz signals, multivariate parameters were composed to characterize the porosity. Principal component analysis, which enabled effective representation of the complex signal information, was introduced to downscale the dimensionality of the time-domain data. Additionally, the average power spectral density of the frequency spectrum and the extreme points of the first-order derivative of the phase spectrum were extracted. These extracted parameters collectively form a comprehensive set of multivariate parameters that accurately characterize porosity. Subsequently, the multivariate parameters were used as inputs to construct an extreme learning machine (ELM) model optimized by the sparrow search algorithm (SSA) for predicting porosity. Based on the experimental results, it was evident that the predictive accuracy of SSA-ELM was significantly higher than the basic ELM. Furthermore, the robustness of the model was evaluated through K-fold cross-validation and the final model regression coefficient was 0.92, which indicates excellent predictive performance of the data-driven model. By introducing the use of THz-TDS and employing advanced signal processing techniques, the data-driven model provided a novel and effective solution for the rapid and accurate detection of porosity in TBCs. The findings of this study offer valuable references for researchers and practitioners in the field of TBCs inspection, opening up new avenues for improving the overall assessment and performance evaluation of these coatings.

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Section: Fdtd Simulationmentioning

confidence: 99%

Data-Driven Method for Porosity Measurement of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

et al. 2023

Coatings

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“…Figure 2 shows the finite element simulation model constructed by the Lumerical 2020 R2 software, with perfectly matched layer (PML) boundary conditions (BCs) at the top and bottom and simulation regions defined by periodic BCs on both sides. The FDTD solver directly solves Maxwell's equations, and the geometry of the coating is fully represented in 2D, which can represent Fresnel reflections and the interaction of multiple reflections in a wider wavelength range and more complete angular details [28].…”

Section: Finite Element Model Establishmentmentioning

confidence: 99%

Effect of High-Temperature Thermal Shock on Solar Absorption Rate of Alumina Coating

Liu,

Wang,

Yang

et al. 2023

Coatings

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With the development of the aerospace industry, the close exploration of the Sun has become a human demand. However, close-range exploration means that the detection satellite needs to accept the test of high temperatures above 1400 °C, so a thermal protective coating is a necessary part of the detection satellite to isolate heat and reflected light. Al2O3 coating has the characteristics of high emissivity and low absorptivity, and it is the best choice for thermal protection coating. However, the coating is subjected to thermal cycles, including heating and cooling, as the satellite rotates around the Sun, which could result in a change in the structure and properties of the coating. Therefore, thermal shock experiments were carried out, and the influence of microstructure on the absorption rate of the Al2O3 coating was investigated. In this study, an Al2O3 coating was prepared by atmospheric plasma spraying (APS). The coating was subjected to a thermal shock (TS) test at 1400 °C using a self-made flame shock device, and coating samples under different thermal shock degrees were obtained. A scanning electron microscope (SEM) was used to characterize the coating pores, and the effects of the coating pore size, aspect ratio (A/R) and cracks in the coating on the optical properties of the coating under different thermal shock degrees were analyzed. In order to clarify the influence of coating microstructure changes on the optical properties of the coating under different thermal shock degrees, not only relevant experiments were carried out, but also the solar reflectivity of Al2O3 coatings with different pore structures was analyzed by the finite element method using finite-difference time-domain (FDTD). The results show that increasing the porosity and aspect ratio of the pores can improve the partial solar absorption of the coating. It was also found that the transverse crack propagation improves the solar reflectance of the coating.

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Interaction laws of RE2O3 and CMAS and rare earth selection criterions for RE-containing thermal barrier coatings against CMAS attack

Guo,

Zhang,

Gao

et al. 2024

Corrosion Science

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Effect of CMAS infiltration on the optical properties of thermal barrier coatings: Study of the mechanisms supported by FDTD simulations and ALD

Cited by 5 publications

References 31 publications

Data-Driven Method for Porosity Measurement of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Data-Driven Method for Porosity Measurement of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Effect of High-Temperature Thermal Shock on Solar Absorption Rate of Alumina Coating

Interaction laws of RE2O3 and CMAS and rare earth selection criterions for RE-containing thermal barrier coatings against CMAS attack

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