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Effect of Heat Treatment on Pore Architecture and Associated Property Charges in Plasma Sprayed TBCs

Effect of Heat Treatment on Pore Architecture and Associated Property Charges in Plasma Sprayed TBCs
Effect of Heat Treatment on Pore Architecture and Associated Property Charges in Plasma Sprayed TBCs
Plasma sprayed TBCs exhibit many interlamellar pores, voids and microcracks. These microstructural features are primarily responsible for the low global stiffnesses and the low thermal conductivities commonly exhibited by such coatings. The pore architecture thus has an important influence on such thermophysical properties. In the present work, the effect of heat treatment (at temperatures up to 1400C, for times of up to 100 hours) and coating purity on the pore architecture in detached YSZ top coats has been characterised by Mercury Intrusion Porosimetry (MIP) and BJH Analysis. While the overall porosity level (measured by densitometry) remained relatively unaffected (at around 10-12%) after the heat treatments concerned, there were substantial changes in the pore size distribution and the (inter-connected) specific surface area, although these changes occurred less rapidly with coatings produced using high purity powders. Fine pores (<~50 nm) rapidly disappeared, while the specific surface area dropped dramatically, particularly at high treatment temperatures (>~1300C). These changes are thought to be associated with improved inter-splat bonding and increased contact area, leading to disappearance of much of the very fine inter-splat porosity. These microstructural changes are reflected in sharply increased stiffness and thermal conductivity. Measured thermal conductivity data are compared with predictions from a recently-developed analytical model [1], using the deduced inter-splat contact area results as input parameters. Good agreement is obtained, suggesting that the model captures the main geometrical effects and the porosity architecture measurements reflect the most significant microstructural changes. REF.1. Golosnoy, IO, Tsipas, SA and Clyne, TW, An Analytical Model For Simulation Of Heat Flow In Plasma Sprayed Thermal Barrier Coating, J. Thermal Spray Techn., 14 (2005) 205-214.
Plasma spray coatings, Porous material, Sintering, Thermal Conductivity, Young’s modulus
411-416
Paul, S.
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Cipitria, A.
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Golosnoy, I.O.
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Clyne, T.W.
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Xie, L.
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Dorfman, M.R.
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Marple, B.R.
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Hyland, M.M.
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Lau, Y.-C.
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Li, C.-J.
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Lima, R.S.
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Montavon, G.
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Paul, S.
83953eee-4704-4a37-a39a-3f885b22af28
Cipitria, A.
53f2ee50-b925-41f3-a195-ecb46fce2c01
Golosnoy, I.O.
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Clyne, T.W.
00678bf7-17de-46e8-9b35-bf1ca73bce9b
Xie, L.
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Dorfman, M.R.
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Marple, B.R.
557588b3-3884-49aa-8174-05ef48ddec0a
Hyland, M.M.
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Lau, Y.-C.
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Li, C.-J.
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Lima, R.S.
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Montavon, G.
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Paul, S., Cipitria, A., Golosnoy, I.O., Clyne, T.W., Xie, L. and Dorfman, M.R. (2007) Effect of Heat Treatment on Pore Architecture and Associated Property Charges in Plasma Sprayed TBCs. Marple, B.R., Hyland, M.M., Lau, Y.-C., Li, C.-J., Lima, R.S. and Montavon, G. (eds.) 2007 International Thermal Spray Conference, Beijing, China. 13 - 15 May 2007. pp. 411-416 .

Record type: Conference or Workshop Item (Paper)

Abstract

Plasma sprayed TBCs exhibit many interlamellar pores, voids and microcracks. These microstructural features are primarily responsible for the low global stiffnesses and the low thermal conductivities commonly exhibited by such coatings. The pore architecture thus has an important influence on such thermophysical properties. In the present work, the effect of heat treatment (at temperatures up to 1400C, for times of up to 100 hours) and coating purity on the pore architecture in detached YSZ top coats has been characterised by Mercury Intrusion Porosimetry (MIP) and BJH Analysis. While the overall porosity level (measured by densitometry) remained relatively unaffected (at around 10-12%) after the heat treatments concerned, there were substantial changes in the pore size distribution and the (inter-connected) specific surface area, although these changes occurred less rapidly with coatings produced using high purity powders. Fine pores (<~50 nm) rapidly disappeared, while the specific surface area dropped dramatically, particularly at high treatment temperatures (>~1300C). These changes are thought to be associated with improved inter-splat bonding and increased contact area, leading to disappearance of much of the very fine inter-splat porosity. These microstructural changes are reflected in sharply increased stiffness and thermal conductivity. Measured thermal conductivity data are compared with predictions from a recently-developed analytical model [1], using the deduced inter-splat contact area results as input parameters. Good agreement is obtained, suggesting that the model captures the main geometrical effects and the porosity architecture measurements reflect the most significant microstructural changes. REF.1. Golosnoy, IO, Tsipas, SA and Clyne, TW, An Analytical Model For Simulation Of Heat Flow In Plasma Sprayed Thermal Barrier Coating, J. Thermal Spray Techn., 14 (2005) 205-214.

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More information

Published date: 14 May 2007
Additional Information: Event Dates: May 14-16, 2007
Venue - Dates: 2007 International Thermal Spray Conference, Beijing, China, 2007-05-13 - 2007-05-15
Keywords: Plasma spray coatings, Porous material, Sintering, Thermal Conductivity, Young’s modulus
Organisations: EEE

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Local EPrints ID: 264634
URI: http://eprints.soton.ac.uk/id/eprint/264634
PURE UUID: 2fd3dac3-f1e8-4546-9be2-5df4bf2e082f

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Date deposited: 03 Oct 2007
Last modified: 06 Oct 2020 23:18

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