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Design of Low Thermal Conductivity Thermal Barrier Coatings by Finite Element Modelling
Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). (PTW)ORCID-id: 0000-0002-4201-668X
Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). (PTW)ORCID-id: 0000-0001-7787-5444
2011 (engelsk)Inngår i: Surface Modification Technologies XXIV: SMT24, Dresden, September 7-9, 2010 / [ed] T. S. Sudarshan, Eckhard Beyer, and Lutz-Michael Berger, 2011, s. 353-365Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Fundamental understanding of relationships between coating microstructure and thermal conductivity is important to be able to understand the influence of coating defects, such as delaminations and pores, on heat insulation in thermal barrier coatings (TBC). Object Oriented Finite element analysis (OOF) has recently been shown as an effective tool for evaluating thermo-mechanical material behaviour as this method is capable of incorporating the inherent material microstructure as an input to the model. The objective of this work was to evaluate a procedure where this technique is combined with Tbctool, a plasma-sprayed TBC like morphology generator, thus enabling development of low thermal conductivity coatings by simulation. Input parameters for Tbctool were computed from SEM images of sprayed microstructures using the image analysis software, Aphelion. Microstructures for as-sprayed as well as heat treated samples were evaluated. The thermal conductivities of the artificially generated microstructures were determined using OOF. Verification of the modelling procedure was performed by comparing predicted values by OOF with corresponding measured values using the laser flash technique. The results, although tentative in nature, indicate that the proposed simulation approach can be a powerful tool in the development of new low conductivity coatings.

sted, utgiver, år, opplag, sider
2011. s. 353-365
HSV kategori
Forskningsprogram
TEKNIK, Produktions- och materialteknik
Identifikatorer
URN: urn:nbn:se:hv:diva-3818OAI: oai:DiVA.org:hv-3818DiVA, id: diva2:451925
Konferanse
SMT24, Dresden, September 7-9, 2010
Tilgjengelig fra: 2011-10-27 Laget: 2011-10-27 Sist oppdatert: 2019-01-04bibliografisk kontrollert
Inngår i avhandling
1. Design of Microstructures in Thermal Barrier Coatings: A Modelling Approach
Åpne denne publikasjonen i ny fane eller vindu >>Design of Microstructures in Thermal Barrier Coatings: A Modelling Approach
2013 (engelsk)Licentiatavhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Plasma sprayed Thermal Barrier Coating systems (TBCs) are commonly used for thermal protection of components in modern gas turbine application such as power generation, marine and aero engines. The material that is most commonly used in these applications is Yttria Stabilized Zirconia (YSZ) because of this ceramic’s favourable properties, such as low thermal conductivity, phase stability to high temperature, and good erosion resistance. The coating microstructures in YSZ coatings are highly heterogeneous, consisting of defects such as pores and cracks of different sizes which determine the coating’s final thermal and mechanical properties, and the service lives of the coatings. Determination of quantitative microstructure–property correlations is of great interest as experimental procedures are time consuming and expensive.

This objective of this thesis work was to investigate the relationships between coating microstructure and thermal-mechanical properties of TBCs, and to utilise these relationships to design an optimised microstructure to be used for next generation TBCs. Simulation technique was used to achieve this goal. Important microstructural parameters influencing the performance of TBCs were identified and coatings with the identified microstructural parameters were designed, modelled and experimentally verified. TBCs comprising of large globular pores with connected cracks inherited within the coating microstructure were shown to have significantly enhanced performance. Low thermal conductivity, low Young‘s modulus and high lifetime were exhibited by these coatings. The modelling approach described in this work can be used as a powerful tool to design new coatings as well as to achieve optimised microstructures.

sted, utgiver, år, opplag, sider
Göteborg: Chalmers University of Technology, 2013. s. 40
Serie
Technical report / Department of Materials and Manufacturing Technology, Chalmers University of Technology, ISSN 1652-8891 ; 81
Emneord
thermal barrier coatings, microstructure, thermal conductivity, Young‘s modulus, lifetime, finite element modelling, design
HSV kategori
Forskningsprogram
TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-5065 (URN)
Presentation
2013-03-01, F127, University West, Trollhättan, 10:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2013-03-11 Laget: 2013-01-18 Sist oppdatert: 2019-11-26bibliografisk kontrollert
2. Design of Thermal Barrier Coatings: A modelling approach
Åpne denne publikasjonen i ny fane eller vindu >>Design of Thermal Barrier Coatings: A modelling approach
2014 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Atmospheric plasma sprayed (APS) thermal barrier coatings (TBCs) are commonly used for thermal protection of components in modern gas turbine application such as power generation, marine and aero engines. TBC is a duplex material system consisting of an insulating ceramic topcoat layer and an intermetallic bondcoat layer. TBC microstructures are highly heterogeneous, consisting of defects such as pores and cracks of different sizes which determine the coating's final thermal and mechanical properties, and the service lives of the coatings. Failure in APS TBCs is mainly associated with the thermo-mechanical stresses developing due to the thermally grown oxide (TGO) layer growth at the topcoat-bondcoat interface and thermal expansion mismatch during thermal cycling. The interface roughness has been shown to play a major role in the development of these induced stresses and lifetime of TBCs.The objective of this thesis work was two-fold for one purpose: to design an optimised TBC to be used for next generation gas turbines. The first objective was to investigate the relationships between coating microstructure and thermal-mechanical properties of topcoats, and to utilise these relationships to design an optimised morphology of the topcoat microstructure. The second objective was to investigate the relationships between topcoat-bondcoat interface roughness, TGO growth and lifetime of TBCs, and to utilise these relationships to design an optimal interface. Simulation technique was used to achieve these objectives. Important microstructural parameters influencing the performance of topcoats were identified and coatings with the feasible identified microstructural parameters were designed, modelled and experimentally verified. It was shown that large globular pores with connected cracks inherited within the topcoat microstructure significantly enhanced TBC performance. Real topcoat-bondcoat interface topographies were used to calculate the induced stresses and a diffusion based TGO growth model was developed to assess the lifetime. The modelling results were compared with existing theories published in previous works and experiments. It was shown that the modelling approach developed in this work could be used as a powerful tool to design new coatings and interfaces as well as to achieve high performance optimised morphologies.

sted, utgiver, år, opplag, sider
Trollhättan: University West, 2014. s. xvi, 85
Serie
PhD Thesis: University West ; 5
Emneord
Thermal barrier coatings, Microstructure, Thermal conductivity, Young’s modulus, Interface roughness, Thermally grown oxide, Lifetime, Finite element modelling, Design
HSV kategori
Forskningsprogram
TEKNIK, Produktions- och materialteknik
Identifikatorer
urn:nbn:se:hv:diva-7181 (URN)978-91-87531-06-4 (ISBN)
Disputas
2015-01-28, 09:00 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2014-12-16 Laget: 2014-12-16 Sist oppdatert: 2019-01-04bibliografisk kontrollert

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