Thermal radiation and conduction in functionally graded thermal barrier coatings. Part I: Experimental study on radiative properties

Ge, Weichun; Zhao, Chang; Wang, Boxiang

doi:10.1016/j.ijheatmasstransfer.2019.01.018

Cited by 30 publications

(7 citation statements)

References 37 publications

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“…It resulted in a significant decrease of residual stresses and in improvement of adhesion between subsequent layers leading to the long-term performance of TBC [249]. The concept could be realized by mixing the zirconia and MCrAlY alloy powders and then spraying the mixtures [293,294]. The authors found out that some interlamellar discontinuities were formed in the final structure because of different properties of the mixed feedstock.…”

Section: Thermal Barrier Coatingsmentioning

confidence: 99%

Review of Functionally Graded Thermal Sprayed Coatings

et al. 2020

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The paper briefly describes major thermal spray techniques used to spray functionally graded coatings such as atmospheric plasma spraying, high velocity oxy-fuel spraying, suspension and solution precursor plasma spraying, and finally low and high pressure cold gas spray method. The examples of combined spray processes as well as some examples of post spray treatment including laser and high temperature treatments or mechanical one, are described. Then, the solid and liquid feedstocks used to spray and their properties are shortly discussed. The reviewed properties of functional coatings include: (i) mechanical (adhesion, toughness, hardness); (ii) physical (porosity, thermal conductivity and diffusivity, thermal expansion, photo-catalytic activity), and; (iii) bioactivity and simulated body fluid (SBF) corrosion. These properties are useful in present applications of functionally graded coatings as thermal barriers, the bioactive coatings in prostheses, photo-catalytic coatings in water treatment, coatings used in printing industry (anilox and corona rolls). Finally, some of the future possible fields of functional thermal sprayed coatings applications are discussed, e.g., to coat polymer substrates or to use the cheap technology of low pressure cold gas spray method instead of expensive technology of vacuum plasma spraying to obtain bond coatings.

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Section: Thermal Barrier Coatingsmentioning

confidence: 99%

Review of Functionally Graded Thermal Sprayed Coatings

et al. 2020

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“…The radiative properties of the TBCs were not quantified. Ge et al 37 showed that pure YSZ systems show transmittance in the 1–8 µm wavelength range but for systems with a small percent nickel included in the TBC the transmittance drops to nearly zero. The TBCs investigated in this study all include a 5% NiCrAl alloy in the top TBC layer; therefore, the optical properties of the TBCs are not expected to be significantly different from the base metal piston.…”

Section: Tbcmentioning

confidence: 99%

The impact of piston thermal barrier coating roughness on high-load diesel operation

Gingrich

Tess

Korivi

et al. 2019

International Journal of Engine Research

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Thermal barrier coatings of various thickness and surface roughness were applied to the piston crown of a single-cylinder research engine and tested over a range of high-output diesel operating conditions, some near 30 bar gross indicated mean effective pressure. Three yttria-stabilized zirconia coated pistons were compared to a baseline metal piston. At each operating condition, a start-of-injection sweep was conducted to generate efficiency trends and find the optimal combustion phasing. Three variations of pistons coated with a graded-layer thermal barrier coating were tested: (1) 0.185 mm coating thickness with a surface roughness of approximately Ra = 11.8 µm, (2) 0.325 mm thickness with Ra = 11.8 µm, and (3) 0.325 mm thickness with Ra = 6.0 µm. Both coated pistons with Ra = 11.8 µm did not show any statistically significant improvement to engine performance when compared to the metal baseline piston, but did produce higher filter smoke numbers. The coated piston with Ra = 6.0 µm and 0.325 mm showed an increase of gross indicated thermal efficiency of up to 3.5% (relative) compared to the metal baseline piston for operating conditions comparable to standard engine operation and a reduction of filter smoke number back to the metal baseline. The increase in efficiency was found to correlate with additional late-cycle apparent heat release and a reduction in in-cylinder heat transfer. The very high-output conditions showed statistically insignificant changes in performance or heat transfer, which may have been related to the long injection duration used for these cases targeting outside of the piston bowl.

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“…Ge et al. [ 18 ] fabricated and studied the radiative transport properties of YSZ/NiCoCrAlY duplex TBCs and multilayered functionally graded TBCs with varying multilayer structures, porosities, and thicknesses. They found a negligible transmittance for the majority of YSZ/NiCoCrAlY functionally graded TBCs studied, with the top YSZ layer having a strong influence on the overall reflectance.…”

Section: Introductionmentioning

confidence: 99%

Machine Learning Designed and Experimentally Confirmed Enhanced Reflectance in Aperiodic Multilayer Structures

Roy Chowdhury,

Khot,

Song

et al. 2023

Advanced Optical Materials

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Machine learning (ML) methods have gained widespread attention in optimizing nanostructures for target transport properties and discovering unexpected physics. Here, an ML method is developed to discover and experimentally confirm binary CeO2‐MgO aperiodic multilayers (AMLs) for thermal barrier coatings with significantly enhanced reflectance. The effect of varying AML design parameters like total thickness, average period, and randomness in layer thicknesses, on the spectral and total reflectance is demonstrated. Introducing aperiodicity in layer thicknesses is shown to lead to a broadband increase in spectral reflectance due to photon localization. Since the number of possible AML structures increases exponentially with total thickness, a Genetic Algorithm optimizer is developed to efficiently discover AMLs with enhanced reflectance, for total thicknesses of 5–50 µm. Surprisingly, all the optimized structures show an odd number of layers with a CeO2 layer at both ends, deviating from the traditional way of designing binary superlattices with paired layers. The optimized AML and a reference periodic superlattice of 5 µm thickness are fabricated by Pulsed Laser Deposition and characterized by optical reflectance measurements. The fabricated AML, despite considerable fabrication uncertainty, still enhances the reflectance to 48% from 40% of the reference superlattice, validating the effectiveness of our ML‐based optimization process.

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Thermal radiation and conduction in functionally graded thermal barrier coatings. Part I: Experimental study on radiative properties

Cited by 30 publications

References 37 publications

Review of Functionally Graded Thermal Sprayed Coatings

Review of Functionally Graded Thermal Sprayed Coatings

The impact of piston thermal barrier coating roughness on high-load diesel operation

Machine Learning Designed and Experimentally Confirmed Enhanced Reflectance in Aperiodic Multilayer Structures

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