Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Design of Thermal Barrier Coating Systems
University West, Department of Engineering Science. (PTW, Thermal Spray)ORCID iD: 0000-0003-0209-1332
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Thermal barrier coatings (TBC’s) are used to provide both thermal insulation and oxidation protection to high temperature components within gas turbines. The development of turbines for power generation and aviation has led to designs where the operation conditions exceed the upper limits of most conventional engineering materials. As a result there has been a drive to improve thermal barrier coatings to allow the turbine to operate at higher temperatures for longer.

The focus of this thesis has been to design thermal barrier coatings with lower conductivity and longer lifetime than those coatings used in industry today. The work has been divided between the development of new generation air plasma spray (APS) TBC coatings for industrial gas turbines and the development of suspension plasma spray (SPS) TBC systems.

The route taken to achieve these goals with APS TBC’s has been twofold. Firstly an alternative stabiliser has been chosen for the zirconium oxide system in the form of dysprosia. Secondly, control of the powder morphology and spray parameters has been used to generate coating microstructures with favourable levels of porosity.

In terms of development of SPS TBC systems, these coatings are relatively new with many of the critical coating parameters not yet known. The focus of the work has therefore been to characterise their lifetime and thermal properties when produced in a complete TBC system.

Results demonstrate that dysprosia as an alternative stabiliser gives a reduction in thermal conductivity. While small at room temperature and in the as produced state; the influence becomes more pronounced at high temperatures and with longer thermal exposure time. The trade-off for this lowered thermal conductivity may be in the loss of high temperature stability. Overall, the greatest sustained influence on thermal conductivity has been from creating coatings with high levelsof porosity.

In relation to lifetime, double the thermo-cyclic fatigue (TCF) life relative to the industrial standard was achieved using a coating with engineered porosity. Introducing a polymer to the spray powder helps to generate large globular pores within the coating together with a large number of delaminations. Such a structure was shown to be highly resistant to TCF testing.

SPS TBC’s were shown to have much greater performance relative to their APS counterparts in thermal shock life, TCF life and thermal conductivity. Columnar SPS coatings are a prospective alternative for strain tolerant coatings in gas turbine engines.

Place, publisher, year, edition, pages
Trollhättan: University West , 2014. , 109 p.
Series
PhD Thesis: University West, 3
Keyword [en]
Industrial Gas Turbine; Aero Turbine; Thermal Barrier Coating; Atmospheric Plasma Spraying; Suspension Plasma Spraying; Thermal Conductivity; Thermo-cyclic fatigue; Thermal Shock
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
URN: urn:nbn:se:hv:diva-5931ISBN: 978-91-977943-9-8 (print)ISBN: 978-91-977943-8-1 (print)OAI: oai:DiVA.org:hv-5931DiVA: diva2:697741
Public defence
2014-02-28, F127, University West, Gustava Melins Gata 2, Trollhättan, 09:53 (English)
Opponent
Supervisors
Available from: 2014-02-19 Created: 2014-02-19 Last updated: 2015-06-24Bibliographically approved
List of papers
1. Next generation thermal barrier coatings for the gas turbine industry
Open this publication in new window or tab >>Next generation thermal barrier coatings for the gas turbine industry
Show others...
2011 (English)In: Journal of Thermal Spray Technology, Vol. 20, no 1-2, 108-115 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study is to develop the next generation of production ready air plasma sprayed thermal barrier coating with a low conductivity and long lifetime. A number of coating architectures were produced using commercially available plasma spray guns. Modifications were made to powder chemistry, including high purity powders, dysprosia stabilized zirconia powders, and powders containing porosity formers. Agglomerated & sintered and homogenized oven spheroidized powder morphologies were used to attain beneficial microstructures. Dual layer coatings were produced using the two powders. Laser flash technique was used to evaluate the thermal conductivity of the coating systems from room temperature to 1200 °C. Tests were performed on as-sprayed samples and samples were heat treated for 100 h at 1150 °C. Thermal conductivity results were correlated to the coating microstructure using image analysis of porosity and cracks. The results show the influence of beneficial porosity on reducing the thermal conductivity of the produced coatings. © 2010 ASM International.

Keyword
APS coatings, coatings for gas turbine components, porosity of coatings, TBC topcoats
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-2993 (URN)10.1007/s11666-010-9593-x (DOI)10599630 (ISSN) (ISBN)
Available from: 2011-01-13 Created: 2011-01-12 Last updated: 2016-02-11Bibliographically approved
2. Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems
Open this publication in new window or tab >>Evaluation of the Lifetime and Thermal Conductivity of Dysprosia-Stabilized Thermal Barrier Coating Systems
Show others...
2013 (English)In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 22, no 6, 864-872 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study was the further development of dysprosia stabilised zirconia coatings for gas turbine applications. The target for these coatings was a longer lifetime and higher insulating performance compared to today's industrial stan dard thermal barrier coating. Two morphologies of ceramic top coat were studied; one using a dual layer systems and the second using a polymer to generate porosity. Evaluations were carried out using laser flash technique to measure thermal properties. Lifetime testing was conducted using thermal shock testing and thermo-cyclic fatigue testing. Microstructure was assessed with SEM and Image analysis used to characterise porosity content. The results show that coatings with an engineered microstructure give performance twice that of the present reference coating.

Place, publisher, year, edition, pages
Materials Park, OH: , 2013
Keyword
Thermal spray, coating, WIL, Work-integrated learning, AIL
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Work Integrated Learning
Identifiers
urn:nbn:se:hv:diva-4911 (URN)10.1007/s11666-013-9932-9 (DOI)000321869400002 ()2-s2.0-84880511926 (Scopus ID)
Available from: 2012-12-20 Created: 2012-12-20 Last updated: 2016-02-11Bibliographically approved
3. Evolution of thermal conductivity of dysprosia stabilised thermal barrier coating systems during heat treatment
Open this publication in new window or tab >>Evolution of thermal conductivity of dysprosia stabilised thermal barrier coating systems during heat treatment
2012 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, ISSN 0257-8972, Vol. 209, 38-43 p.Article in journal (Refereed) Published
Abstract [en]

Dysprosia stabilised zirconia coatings offer a potential reduction in thermal heat transfer for thermal barrier coating systems with the added benefit of being producible with existing equipment and spray knowledge. However, there is little information on the long term performance of such systems relative to the standard coatings. While a low thermal conductivity is important for a gas turbine; sintering resistance is important to maintain properties over the lifetime of a component.

In this study, four dysprosia stabilised zirconia coatings are compared with a standard yttria stabilised coating in present industrial use.

Samples were exposed to isothermal furnace conditions at 1150 °C from 5 to 200 hours to observe the sintering resistance of the coating systems. Tests carried out include microstructural analysis with SEM, thermal conductivity measurements using laser flash analysis and porosity changes monitored using image analysis.

Keyword
Thermal barrier coating; Atmospheric plasma spraying; Thermal conductivity; Sintering
National Category
Materials Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-4692 (URN)10.1016/j.surfcoat.2012.08.018 (DOI)000310656200006 ()2-s2.0-84866883350 (Scopus ID)
Available from: 2012-09-27 Created: 2012-09-27 Last updated: 2015-06-24Bibliographically approved
4. Impact of Impurity Content on the Sintering Resistance and Phase Stability of Dysprosia- and Yttria-Stabilized Zirconia Thermal Barrier Coatings
Open this publication in new window or tab >>Impact of Impurity Content on the Sintering Resistance and Phase Stability of Dysprosia- and Yttria-Stabilized Zirconia Thermal Barrier Coatings
Show others...
2014 (English)In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 23, no 1-2, 160-169 p.Article in journal (Refereed) Published
Abstract [en]

Dysprosia-stabilized zirconia (DySZ) is a promising candidate to replace yttria-stabilized zirconia (YSZ) as a thermal barrier coating due to its lower inherent thermal conductivity. It is also suggested in studies that DySZ may show greater stability to high temperature phase changes compared to YSZ, possibly allowing for coatings with extended lifetimes. Separately, the impurity content of YSZ powders has been proven to influence high-temperature sintering behavior. By lowering the impurity oxides within the spray powder, a coating more resistant to sintering can be produced. This study presents both high purity and standard purity dysprosia and YSZ coatings and their performance after a long heat treatment. Coatings were produced using powder with the same morphology and grain size; only the dopant and impurity content were varied. Samples have been heat treated for exposure times up to 400 h at a temperature of 1150 °C. Samples were measured for thermal conductivity to plot the evolution of coating thermal properties with respect to exposure time. Thermal conductivity has been compared to microstructure analysis and porosity measurement to track structural changes. Phase analysis utilizing x-ray diffraction was used to determine differences in phase degradation of the coatings after heat treatment. © 2013 ASM International.

Place, publisher, year, edition, pages
Springer, 2014
Keyword
atmospheric plasma spray (APS), thermal and phase stability of coatings, thermal barrier coatings (TBCs), thermal conductivity, zirconia, WIL, Work-integrated Learning, AIL
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Work Integrated Learning
Identifiers
urn:nbn:se:hv:diva-5695 (URN)10.1007/s11666-013-0014-9 (DOI)000329106200021 ()2-s2.0-84891833854 (Scopus ID)
Conference
2013 International Thermal Spray Conference, held May 13-15, 2013, in Busan, South Korea
Available from: 2013-11-11 Created: 2013-11-07 Last updated: 2016-02-11Bibliographically approved

Open Access in DiVA

spikblad(100 kB)49 downloads
File information
File name SPIKBLAD01.pdfFile size 100 kBChecksum SHA-512
02e30099d125e9480d0aff99f68a1469816a2184f1dee40f0f13f1a6ef233e9871d5ece9eff933b4dc409ee8bb305a50c49b9c41106d6ac6637341b1d5535a1b
Type spikbladMimetype application/pdf
fulltext(3051 kB)1395 downloads
File information
File name FULLTEXT02.pdfFile size 3051 kBChecksum SHA-512
f1a2ee7362ab74e94696ca2c4614210b516669396b8960bd2b6cdd95416e716559fa980002a13ccf5ca861adec8e00a3e9fb1338f5215ac39b57ccda9fa940f0
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Curry, Nicholas
By organisation
Department of Engineering Science
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar
Total: 1395 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 644 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf