Effect of Heat Treatment on the Thermal Conductivity of Plasma-Sprayed Thermal Barrier Coatings

Dutton, R.; Wheeler, R.; Ravichandran, K.; An, Kyong Jun

doi:10.1361/105996300770349935

Cited by 105 publications

(46 citation statements)

References 3 publications

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“…As-sprayed, R. Dutton et al [14] 1573 K, 50h, R. Dutton et al [14] Fig. 5 Thermal diffusivities (a) and thermal conductivities (b) of 8YSZ coatings.…”

Section: (B)mentioning

confidence: 99%

“…Some irreversible microstructure change took place during high temperature exposure. 8,14) In particular, reduction of the crack-like micro-porosity has been observed due to the densification processes, typically caused by sintering. These could be considered as the main mechanisms responsible for the increase of thermal conductivity.…”

Section: Effects Of Heat Treatment On Microstructures and Physical Prmentioning

confidence: 99%

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Effects of Heat Treatment on Microstructures and Physical Properties of Segmented Thermal Barrier Coatings

2005

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Highly segmented thermal barrier coatings (TBCs) were produced by ''hot'' plasma spraying. The effects of heat treatment on the microstructures, mechanical and thermophysical properties were studied. The segmented coatings are denser than traditionally plasma-sprayed TBCs due to its good insplat bonding at high substrate temperature. The segmentation cracks and associating branching cracks hardly propagated or closed during sintering process, indicative of a good stability of crack network. Due to its low porosity, the segmented coatings compromised the property of thermal insulation of TBCs. For the coatings after 24 h heat treatment at 1523 K, the thermal conductivity was improved by around 35%. The segmentation cracks had a strong impact on decreasing the Young's modulus. Heat treatment could not effectively promote the increase of the Young's modulus, especially for the case of highly segmented coatings.

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“…As-sprayed, R. Dutton et al [14] 1573 K, 50h, R. Dutton et al [14] Fig. 5 Thermal diffusivities (a) and thermal conductivities (b) of 8YSZ coatings.…”

Section: (B)mentioning

confidence: 99%

Section: Effects Of Heat Treatment On Microstructures and Physical Prmentioning

confidence: 99%

Effects of Heat Treatment on Microstructures and Physical Properties of Segmented Thermal Barrier Coatings

2005

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“…As a result, the thermal conductivity of as-deposited electron-beam physical vapor deposited (EB-PVD) coatings is reported to be about 1.8 -2.0 W/m.K and that of as-deposited air plasma sprayed (APS) coating is approximately 0.8 -1.0 W/m.K [2]. During high-temperature service however, the thermal conductivity of the coatings increases so that the thermal protection provided by the coatings is reduced [5,6] with the result that the metal surface temperature will increase. The observed increase in thermal conductivity is typically attributed to a combination of densification of the coating by removing porosity and micro-cracks that microstructural analysis reveals occurs during high-temperature exposure [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…During high-temperature service however, the thermal conductivity of the coatings increases so that the thermal protection provided by the coatings is reduced [5,6] with the result that the metal surface temperature will increase. The observed increase in thermal conductivity is typically attributed to a combination of densification of the coating by removing porosity and micro-cracks that microstructural analysis reveals occurs during high-temperature exposure [6][7][8]. However, analysis of our own measurements on the effect of thermal cycling on thermal conductivity of an EB-PVD 7YSZ [9] using effective medium theory [10] and expressed in the finite element results presented by Lu et al [8] suggests that the densification and porosity evolution are not sufficient to describe the observed conductivity increases.…”

Section: Introductionmentioning

confidence: 99%

Effect of high-temperature aging on the thermal conductivity of nanocrystalline tetragonal yttria-stabilized zirconia

et al. 2012

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The thermal conductivity of yttria-stabilized zirconia (YSZ) thermal barrier coatings increases with high temperature aging. This common observation has been attributed to the densification of the coatings as porosity sinters out and pores and cracks spheroidize to minimize their surface energy. We show that the thermal conductivity of fully-dense 3 mol% Y 2 O 3 stabilized zirconia (3YSZ) also increases with high temperature aging, indicating that densification and pore shape changes alone are not responsible for all the observed increase in thermal conductivity of coatings. Instead, there are increases due to a combination of phase separation and grain growth. The increase in thermal conductivity can be described by a LarsonMiller parameter. It is also found that the increase in thermal conductivity with aging is greatest when measured at room temperature and decreases with increasing measurement temperature. At 1000 o C, the thermal conductivity is almost temperature independent and the changes in thermal conductivity with aging are less than 15%, even after aging for 50 hours at 1400 o C.

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“…These compounds can create unsatisfactory wear performance for WC-based HVOF coatings [9,10]. On the other hand, Dutton et al and Samur et al have discussed that the heat treatment can change many physical properties of metallic compounds of sprayed coatings, and in general it can potentially increase resistance to general corrosion and sliding wear of sprayed coatings by grain growth mechanisms [11,12]. Bolelli et al have shown that performing heat treatment at 600°C for one hour can improve the sliding wear resistance of sprayed metallic coatings [13].…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Treatment on Wear Performance of Nanostructured WC-Ni/Cr HVOF Sprayed Coatings

2017

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The extraction and processing of bitumen from oil sands exposes machinery parts to constant abrasive wear which can cause severe surface degradation and component failure, resulting in production shut-downs. To reduce the effect of wear on performance of production machinery, wear resistant coatings must be used to extend component life. Recently, thick microstructured cermet coatings based on WC dispersions have been used to protect surfaces. In this study a nanostructured 83WC-17Ni/Cr coating was deposited on to C-Mn steel surfaces using High Velocity Oxy-Fuel (HVOF) spraying. The effect of heat treatment in air and nitrogen atmosphere on changes in the microstructure, hardness and wear resistance was investigated. The results showed that both the hardness and wear resistance increased with increasing heat treatment temperature in both air and nitrogen atmosphere. However, the use of heat treatments in air led to the formation of brittle metal oxides which resulted in micro-cracking within the coatings. This caused the coatings to fail by brittle fracture during wear testing. In comparison heat treatment in nitrogen produced better wear resistance because metal oxide formation was avoided.

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Effect of Heat Treatment on the Thermal Conductivity of Plasma-Sprayed Thermal Barrier Coatings

Cited by 105 publications

References 3 publications

Effects of Heat Treatment on Microstructures and Physical Properties of Segmented Thermal Barrier Coatings

Effects of Heat Treatment on Microstructures and Physical Properties of Segmented Thermal Barrier Coatings

Effect of high-temperature aging on the thermal conductivity of nanocrystalline tetragonal yttria-stabilized zirconia

Effect of Heat Treatment on Wear Performance of Nanostructured WC-Ni/Cr HVOF Sprayed Coatings

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