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  • 1.
    Brodin, Håkan
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Eriksson, Robert
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Johansson, Sten
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology. Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Fracture Mechanical Modelling of a Plasma Sprayed TBC System2009In: Advanced Ceramic Coatings and Interfaces IV / [ed] Dongming Zhu and Hua-Tay Lin, Westerville, OH, United States: American Ceramic Society Inc. , 2009, Vol. 30, no 3, p. 113-124Conference paper (Refereed)
    Abstract [en]

    A thermal barrier coating (TBC) system subjected to thermal cycling will develop a microcrack partem near the interface between the metallic bond coat and the ceramic top coat. These small cracks link up and form internal TBC delaminations during repeated heating / cooling. After a longer time period, the internal delamination cracks will form a larger spallation damage, where the TBC is detached from the underlying material. Since cracks are initiated in multiple sites of the thermal barrier coating, the damage is initially considered to be governed by local stress conditions. The purpose of the present work is to compare experimental data with predictions of a physically based fatigue life model. The present study has been performed on plasma-sprayed TBCs where the interface geometry has been varied. In the present work, calculation of fatigue life is done for a number of cases under thermal fatigue loading. Different interface geometries are compared in order to understand the influence of variations in the TC/BC interface roughness on oxidation behaviour and thermal fatigue life. Thermal fatigue tests indicate that an increased surface roughness is beneficial from a fatigue life point of view.

  • 2.
    Brodin, Håkan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Eriksson, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Östergren, Lars
    Volvo Aero Corporation, Trollhättan.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Sjöström, Sören
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Solid Mechanics.
    Finite Element Modelling and Damage Evaluation of Air Plasma Sprayed Thermal Barrier Coatings2012Conference paper (Refereed)
  • 3.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Siemens Industrial Turbomachinery AB, Berlin.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Högberg, Jan
    AB Sandvik Materials Technology R&D Center Sandviken.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Local Surface Phase Stability During Cyclic Oxidation Process2017In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 879, p. 855-860Article in journal (Refereed)
  • 4.
    Calmunger, Mattias
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Influence of Cyclic Oxidation in Moist Air on Surface Oxidation-Affected Zones2017Conference paper (Refereed)
  • 5.
    Calmunger, Mattias
    et al.
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Management and Engineering, Engineering Materials.
    Eriksson, Robert
    Siemens AG, Huttenstr. 12, 10553 Berlin, Germany.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering. Sandviken, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Surface Phase Transformation in Austenitic Stainless Steel Induced by Cyclic Oxidation in Humidified Air2015In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 100, p. 524-534Article in journal (Refereed)
    Abstract [en]

    The formation of α’ martensite at the surface of an AISI 304 stainless steel subjected to cyclic heating in humidified air is reported. The α’ martensite formed during the cooling part of the cyclic tests due to local depletion of Cr and Mn and transformed back to austenite when the temperature again rose to 650 °C. The size of the α’ martensite region increased with increasing number of cycles. Thermodynamical simulations were used as basis for discussing the formation of α’ martensite. The effect of the α’ martensite on corrosion is also discussed.

  • 6.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    High-temperature degradation of plasma sprayed thermal barrier coating systems2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Thermal barrier coating systems (TBCs) are used in gas turbines to prevent high-temperature degradation of metallic materials in the combustor and turbine. One of the main concerns regarding TBCs is poor reliability, and accurate life prediction models are necessary in order to fully utilise the beneficial effects of TBCs. This research project aims at developing deeper understanding of the degradation and failure mechanisms acting on TBCs during high temperature exposure, and to use this knowledge to improve life assessments of TBCs. The present work includes a study on the influence of coating interface morphology on the fatigue life of TBCs and a study on the influence of some different heat treatments on the adhesive properties of TBCs.

    The influence of coating interface morphology on fatigue life has been studied both experimentally and by modelling. Large interface roughness has been found experimentally to increase fatigue life of TBCs. The modelling work do, to some extent, capture this behaviour. It is evident, from the study, that interface morphology has a large impact on fatigue life of TBCs.

    Three thermal testing methods, that degrade TBCs, have been investigated: isothermal oxidation, furnace cycling and burner rig test. The degraded TBCs have been evaluated by adhesion tests and microscopy. The adhesion of TBCs has been found to depend on heat treatment type and length. Cyclic heat treatments, (furnace cycling and burner rig test), lower the adhesion of TBCs while isothermal oxidation increases adhesion. The fracture surfaces from the adhesion tests reveal that failure strongly depends on the pre-existing defects in the TBC.

    List of papers
    1. Fracture Mechanical Modelling of a Plasma Sprayed TBC System
    Open this publication in new window or tab >>Fracture Mechanical Modelling of a Plasma Sprayed TBC System
    2009 (English)In: Advanced Ceramic Coatings and Interfaces IV / [ed] Dongming Zhu and Hua-Tay Lin, Westerville, OH, United States: American Ceramic Society Inc. , 2009, Vol. 30, no 3, p. 113-124Conference paper, Published paper (Refereed)
    Abstract [en]

    A thermal barrier coating (TBC) system subjected to thermal cycling will develop a microcrack partem near the interface between the metallic bond coat and the ceramic top coat. These small cracks link up and form internal TBC delaminations during repeated heating / cooling. After a longer time period, the internal delamination cracks will form a larger spallation damage, where the TBC is detached from the underlying material. Since cracks are initiated in multiple sites of the thermal barrier coating, the damage is initially considered to be governed by local stress conditions. The purpose of the present work is to compare experimental data with predictions of a physically based fatigue life model. The present study has been performed on plasma-sprayed TBCs where the interface geometry has been varied. In the present work, calculation of fatigue life is done for a number of cases under thermal fatigue loading. Different interface geometries are compared in order to understand the influence of variations in the TC/BC interface roughness on oxidation behaviour and thermal fatigue life. Thermal fatigue tests indicate that an increased surface roughness is beneficial from a fatigue life point of view.

    Place, publisher, year, edition, pages
    Westerville, OH, United States: American Ceramic Society Inc., 2009
    Series
    Ceramic Engineering and Science Proceedings, ISSN 0196-6219 ; 3
    Keywords
    Fracture mechanical modelling, thermal barrier coating, plasma spraying, thermal cycling, metallic bond coat
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:liu:diva-57007 (URN)10.1002/9780470584293.ch12 (DOI)000281124900012 ()978-0-470-45753-5 (ISBN)
    Conference
    33rd International Conference on Advanced Ceramics and Composites, Daytona Beach, FL, USA, January 18-23, 2009
    Available from: 2010-06-14 Created: 2010-06-09 Last updated: 2016-05-17Bibliographically approved
    2. Influence of isothermal and cyclic heat treatments on the adhesion of plasma sprayed thermal barrier coatings
    Open this publication in new window or tab >>Influence of isothermal and cyclic heat treatments on the adhesion of plasma sprayed thermal barrier coatings
    Show others...
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 23-24, p. 5422-5429Article in journal (Refereed) Published
    Abstract [en]

    The adhesion of thermal barrier coatings (TBC) has been studied using the standard method described in ASTM C633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrate coupons of Ni-base alloy Hastelloy X. The bond coat (BC) is of a NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation at 1100 °C up to 290 h, 2) thermal cycling fatigue (TCF) at 1100 °C up to 300 cycles and 3) thermal shock at ~ 1140 °C BC/TC interface temperature up to 1150 cycles. The adhesion of the specimens is reported and accompanied by a microstructural study of the BC and the thermally grown oxides (TGO), as well as a discussion on the influence of BC/TC interfacial damage on adhesion properties of TBC. The adhesion was found to vary with heat treatment, as well as with heat treatment length.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Keywords
    Thermal barrier coating, TBC, adhesion, thermal cycling fatigue, thermal shock, burner rig test
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67882 (URN)10.1016/j.surfcoat.2011.06.007 (DOI)000294103700025 ()
    Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2017-12-11Bibliographically approved
    3. Fractographic and microstructural study of isothermally and cyclically heat treated thermal barrier coatings
    Open this publication in new window or tab >>Fractographic and microstructural study of isothermally and cyclically heat treated thermal barrier coatings
    Show others...
    2014 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 243, p. 82-90Article in journal (Refereed) Published
    Abstract [en]

    The fracture surfaces from adhesion tested thermal barrier coatings (TBC) have been studied by scanning electron microscopy. The adhesion test have been made using the standard method described in ASTM 633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrates of Hastelloy X. The bond coat (BC) is of NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation 2) thermal cycling fatigue (TCF) and 3) burner rig test (BRT). The fracture surfaces of the adhesion tested specimens where characterised. A difference in fracture mechanism were found for the different heat treatments. Isothermal oxidation gave fracture mainly in the top coat while the two cyclic heat treatments gave increasing amount of BC/TC interface fracture with number of cycles. Some differences could also be seen between the specimens subjected to burner rig test and furnace cycling.

    Keywords
    Thermal barrier coating, TBC, fractography, adhesion, thermal cycling, burner rig
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67883 (URN)10.1016/j.surfcoat.2012.02.040 (DOI)000335542100014 ()
    Note

    On the day of the defence date of the Thesis the status of this article was Manuscript.

    Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2017-12-11Bibliographically approved
    4. Fractographic Study of Adhesion Tested Thermal Barrier Coatings Subjected to Isothermal and Cyclic Heat Treatments
    Open this publication in new window or tab >>Fractographic Study of Adhesion Tested Thermal Barrier Coatings Subjected to Isothermal and Cyclic Heat Treatments
    Show others...
    2011 (English)In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 10, p. 195-200Article in journal (Refereed) Published
    Abstract [en]

    Thermal barrier coatings (TBC) are used in gas turbines to protect metallic components from high temperature. In the present study adhesion tests have been conducted on APS TBC coated specimens subjected to different heat treatments. Isothermal and cyclic heat treatments have been conducted at temperatures around 1100 °C and the adhesion have been tested using the method described in ASTM C633. The fracture surfaces resulting from the adhesion test have been investigated and the fracture behavior has been characterized. A difference in fracture mechanism between the three heat treatments has been found. The two cyclic heat treatments give fracture in the top coat/bond coat interface while isothermal heat treatment gives fracture in the top coat.

    Place, publisher, year, edition, pages
    Elsevier: , 2011
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-70541 (URN)10.1016/j.proeng.2011.04.035 (DOI)
    Available from: 2011-09-12 Created: 2011-09-12 Last updated: 2017-12-08
  • 7.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Thermal Barrier Coatings: Durability Assessment and Life Prediction2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Thermal barrier coating (TBC) systems are coating systems containing a metallic bond coat and a ceramic top coat. TBCs are used in gas turbines for thermal insulation and oxidation resistance. Life prediction of TBCs is important as high-temperature exposure degrades the coatings through mechanisms such as thermal fatigue and the formation and growth of thermally grown oxides (TGOs). This thesis presents research on durability assessment and life prediction of air plasma sprayed TBCs.

    The adhesion of thermal barrier coatings subjected to isothermal oxidation, thermal cycling fatigue and thermal shock was studied. The adhesion strength and fracture characteristics were found to vary with heat treatment type.

    The influence of interdiffusion between bond coat and substrate was studied on TBCs deposited on two different substrates. The thermal fatigue life was found to differ between the two TBC systems. While fractography and nanoindentation revealed no differences between the TBC systems, the oxidation kinetics was found to differ for non-alumina oxides.

    The influence of bond coat/top coat interface roughness on the thermal fatigue life was studied; higher interface roughness promoted longer thermal fatigue life. Different interface geometrieswere tried in finite element crack growth simulations, and procedures for creating accurate interface models were suggested.

    The influence of water vapour and salt deposits on the oxidation/corrosion of a NiCoCrAlY coating and a TBC were studied. Salt deposits gave thicker TGOs and promoted an Y-rich phase. The effect of salt deposits was also evident for TBC coated specimens.

    A microstructure-based life model was developed using the Thermo-Calc software. The model included coupled oxidation-diffusion, as well as diffusion blocking due to the formation of internal oxides and pores. The model predicted Al-depletion in acceptable agreement with experimental observations.

    List of papers
    1. Influence of isothermal and cyclic heat treatments on the adhesion of plasma sprayed thermal barrier coatings
    Open this publication in new window or tab >>Influence of isothermal and cyclic heat treatments on the adhesion of plasma sprayed thermal barrier coatings
    Show others...
    2011 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 23-24, p. 5422-5429Article in journal (Refereed) Published
    Abstract [en]

    The adhesion of thermal barrier coatings (TBC) has been studied using the standard method described in ASTM C633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrate coupons of Ni-base alloy Hastelloy X. The bond coat (BC) is of a NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation at 1100 °C up to 290 h, 2) thermal cycling fatigue (TCF) at 1100 °C up to 300 cycles and 3) thermal shock at ~ 1140 °C BC/TC interface temperature up to 1150 cycles. The adhesion of the specimens is reported and accompanied by a microstructural study of the BC and the thermally grown oxides (TGO), as well as a discussion on the influence of BC/TC interfacial damage on adhesion properties of TBC. The adhesion was found to vary with heat treatment, as well as with heat treatment length.

    Place, publisher, year, edition, pages
    Elsevier, 2011
    Keywords
    Thermal barrier coating, TBC, adhesion, thermal cycling fatigue, thermal shock, burner rig test
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67882 (URN)10.1016/j.surfcoat.2011.06.007 (DOI)000294103700025 ()
    Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2017-12-11Bibliographically approved
    2. Fractographic and microstructural study of isothermally and cyclically heat treated thermal barrier coatings
    Open this publication in new window or tab >>Fractographic and microstructural study of isothermally and cyclically heat treated thermal barrier coatings
    Show others...
    2014 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 243, p. 82-90Article in journal (Refereed) Published
    Abstract [en]

    The fracture surfaces from adhesion tested thermal barrier coatings (TBC) have been studied by scanning electron microscopy. The adhesion test have been made using the standard method described in ASTM 633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrates of Hastelloy X. The bond coat (BC) is of NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation 2) thermal cycling fatigue (TCF) and 3) burner rig test (BRT). The fracture surfaces of the adhesion tested specimens where characterised. A difference in fracture mechanism were found for the different heat treatments. Isothermal oxidation gave fracture mainly in the top coat while the two cyclic heat treatments gave increasing amount of BC/TC interface fracture with number of cycles. Some differences could also be seen between the specimens subjected to burner rig test and furnace cycling.

    Keywords
    Thermal barrier coating, TBC, fractography, adhesion, thermal cycling, burner rig
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-67883 (URN)10.1016/j.surfcoat.2012.02.040 (DOI)000335542100014 ()
    Note

    On the day of the defence date of the Thesis the status of this article was Manuscript.

    Available from: 2011-05-02 Created: 2011-05-02 Last updated: 2017-12-11Bibliographically approved
    3. Influence of substrate material on the life of atmospheric plasmas prayed thermal barrier coatings
    Open this publication in new window or tab >>Influence of substrate material on the life of atmospheric plasmas prayed thermal barrier coatings
    Show others...
    2013 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 232, no 15, p. 795-803Article in journal (Refereed) Published
    Abstract [en]

    Thermal barrier coatings (TBCs) are used in gas turbines to prolong the life of the underlying substrates and to increase the efficiency of the turbines by enabling higher combustion temperatures. TBCs may fail during service due to thermal fatigue or through the formation of non-protective thermally grown oxides (TGOs). This study compares two atmospheric plasma sprayed (APS) TBC systems comprising of two identical TBCs deposited on two different substrates (Haynes 230 and Hastelloy X). The thermal fatigue life was found to differ between the two TBC systems. The interdiffusion of substrate elements into the coating was more pronounced in the TBC system with shorter life, however, very few of the substrate elements (only Mn and to some extent Fe) formed oxides in the bond coat/top coat interface. Fractography revealed no differences in the fracture behaviour of the TBCs; the fracture occurred, in both cases, to about 60% in the top coat close to the interface and the remainder in the interface. Nanoindentation revealed only small differences in mechanical properties between the TBC systems and a finite element crack growth analysis showed that such small differences did not cause any significant change in the crack driving force. The oxidation kinetics was found to be similar for both TBC systems for the formation of Al2O3 but differed for the kinetics of non-Al2O3 TGOs where the TBC system with shortest life had a faster formation of non-Al2O3 TGOs caused by a faster Al depletion. The difference in non-Al2O3 TGO growth kinetics was considered to be the main reason for the difference in life.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Thermal barrier coating; TBC; Substrate influence; Interdiffusion; Fatigue life; Oxidation kinetics
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-96810 (URN)10.1016/j.surfcoat.2013.06.101 (DOI)000327691300103 ()
    Available from: 2013-08-27 Created: 2013-08-27 Last updated: 2017-12-06Bibliographically approved
    4. TBC bond coat-top coat interface roughness: influence on fatigue life and modelling aspects
    Open this publication in new window or tab >>TBC bond coat-top coat interface roughness: influence on fatigue life and modelling aspects
    Show others...
    2013 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 236, p. 230-238Article in journal (Refereed) Published
    Abstract [en]

    Thermal barrier coatings (TBCs), when used in gas turbines, may fail through thermal fatigue, causing the ceramic top coat to spall off the metallic bond coat. The life prediction of TBCs often involves finite element modelling of the stress field close to the bond coat/top coat interface and thus relies on accurate modelling of the interface. The present research studies the influence of bond coat/top coat interface roughness on the thermal fatigue life of plasma sprayed TBCs. By using different spraying parameters, specimens with varying interface roughness were obtained. During thermal cycling it was found that higher interface roughness promoted longer thermal fatigue life. The interfaces were characterised by roughness parameters, such as Ra, Rq and Rq, as well as by autocorrelation, material ratio curves, probability plots and slope distribution. The variation of spray parameters was found to affect amplitude parameters, such as Ra, but not spacing parameters, such as RSm. Three different interface geometries were tried for finite element crack growth simulation: cosine, ellipse and triangular shape. The cosine model was found to be an appropriate interface model and a procedure for obtaining the necessary parameters, amplitude and wavelength, was suggested. The positive effect of high roughness on life was suggested to be due to a shift from predominantly interface failure, for low roughness, to predominantly top coat failure, for high roughness.

    Keywords
    thermal barrier coating, TBC, thermal cycling fatigue, interface, roughness, Ra
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-96811 (URN)10.1016/j.surfcoat.2013.09.051 (DOI)000329884300032 ()
    Available from: 2013-08-27 Created: 2013-08-27 Last updated: 2017-12-06Bibliographically approved
    5. Cyclic Hot Corrosion of Thermal Barrier Coatings and Overlay Coatings
    Open this publication in new window or tab >>Cyclic Hot Corrosion of Thermal Barrier Coatings and Overlay Coatings
    Show others...
    2013 (English)In: Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT2013, The American Society of Mechanical Engineers (ASME) , 2013, Vol. 4, p. 1-8Conference paper, Published paper (Refereed)
    Abstract [en]

    The influence, and interdependence, of water vapor and Na2SO4–50 mol% NaCl on the oxidation of a NiCoCrAlY coating and a thermal barrier coating (TBC) were studied at 750 °C. Water vapor was found to have a negligible effect on oxide composition, but influenced the oxide morphology on the NiCoCrAlY coating. Na2SO4–50 mol% NaCl deposits on the coatings influencedoxide composition, most notably by the promotion of a Y rich phase. The effect of Na2SO4–50 mol% NaCl deposits was also evident for the TBC coated specimen, where the formed metal/ceramic interface oxide was affected by salt reaching the interface by penetration of the zirconia TBC.

    Place, publisher, year, edition, pages
    The American Society of Mechanical Engineers (ASME), 2013
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-95556 (URN)10.1115/GT2013-95526 (DOI)000361499900009 ()978-0-7918-5518-8 (ISBN)
    Conference
    ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT2013, San Antonio, Texas, USA, June 3-7, 2013
    Note

    Paper No. GT2013-95526

    Available from: 2013-07-08 Created: 2013-07-08 Last updated: 2016-05-13Bibliographically approved
    6. Modeling of the microstructural evolution and lifetime prediction of MCrAlX coatings on Nickel based superalloys in high temperature oxidation
    Open this publication in new window or tab >>Modeling of the microstructural evolution and lifetime prediction of MCrAlX coatings on Nickel based superalloys in high temperature oxidation
    Show others...
    2013 (English)In: Surface and Coatings Technology, Vol. 232, no 15, p. 204-215Article in journal (Refereed) Published
    Abstract [en]

    At high temperature, MCrAlX coatings are deposited onto the surface of superalloy to provide oxidation and corrosion protection by forming a thermalgrowing oxide scale. In this project, the oxidation behavior of an HVOF CoNiCrAlYSi coating on IN792 was studied in both isothermal oxidation (900, 1000 and 1100 °C) and thermal cycling (1100-100 °C). The microstructural evolution in the MCrAlX coatings after oxidation was investigated. It was found that Al-rich β phase is gradually consumed due to two effects: surface oxidation and coating-substrate interdiffusion. Some voids and oxides along the coating-substrate interface, or inside the coating, were considered to play a role in blocking the diffusion of alloying elements. Based on the microstructural observation, an oxidation-diffusion model was developed by using Matlab and DICTRA software to predict the lifetime of MCrAlX coatings. Several effects influencing the microstructural evolution were included: surface oxidation, coating-substrate interdiffusion and diffusion blocking. The results showed good agreement between the experimental composition profiles and modeling ones. Furthermore, by choosing suitable diffusion blocking factors, the accuracy of coating life prediction could be improved.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    MCrAlX coating; HVOF; Life prediction; Interdiffusion; Oxidation; Diffusion blocking
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-90013 (URN)10.1016/j.surfcoat.2013.05.008 (DOI)000327691300027 ()
    Available from: 2013-03-14 Created: 2013-03-14 Last updated: 2014-10-08Bibliographically approved
    7. Microstructure-based Life Prediction of Thermal Barrier Coatings
    Open this publication in new window or tab >>Microstructure-based Life Prediction of Thermal Barrier Coatings
    2014 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    The widespread use of thermal barrier coatings (TBC) in gas turbines stresses the importance of accurate life prediction models for TBCs. During service, the TBC may fail due to thermal fatigue or through the formation of thermally grown oxides (TGOs). The current paper presents a Thermo-Calc/Dictra-based approach to life prediction of isothermally oxidised atmospheric plasma sprayed (APS) TBCs. The β-phase depletion of the coating was predicted and compared to life prediction criteria based on TGO thickness and Al content in the coating. All tried life models underestimated the life of the coating where the β-depletion-based model was the most conservative.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Keywords
    Thermal barrier coating, TBC, life prediction, isothermal oxidation, interdiffusion
    National Category
    Engineering and Technology Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-95554 (URN)10.4028/www.scientific.net/KEM.592-593.413 (DOI)000336694400091 ()
    Conference
    THERMEC,2-6 December, 2013, Las Vegas, USA
    Available from: 2013-07-08 Created: 2013-07-08 Last updated: 2014-12-10Bibliographically approved
  • 8.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspong, Sweden.
    Cyclic Hot Corrosion of Thermal Barrier Coatings and Overlay Coatings2013In: Proceedings of ASME Turbo Expo 2013: Turbine Technical Conference and Exposition, GT2013, The American Society of Mechanical Engineers (ASME) , 2013, Vol. 4, p. 1-8Conference paper (Refereed)
    Abstract [en]

    The influence, and interdependence, of water vapor and Na2SO4–50 mol% NaCl on the oxidation of a NiCoCrAlY coating and a thermal barrier coating (TBC) were studied at 750 °C. Water vapor was found to have a negligible effect on oxide composition, but influenced the oxide morphology on the NiCoCrAlY coating. Na2SO4–50 mol% NaCl deposits on the coatings influencedoxide composition, most notably by the promotion of a Y rich phase. The effect of Na2SO4–50 mol% NaCl deposits was also evident for the TBC coated specimen, where the formed metal/ceramic interface oxide was affected by salt reaching the interface by penetration of the zirconia TBC.

  • 9.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    Volvo Aero Corporation, Trollhättan, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, SE-61283 Finspång, Sweden.
    Fractographic and microstructural study of isothermally and cyclically heat treated thermal barrier coatings2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 243, p. 82-90Article in journal (Refereed)
    Abstract [en]

    The fracture surfaces from adhesion tested thermal barrier coatings (TBC) have been studied by scanning electron microscopy. The adhesion test have been made using the standard method described in ASTM 633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrates of Hastelloy X. The bond coat (BC) is of NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation 2) thermal cycling fatigue (TCF) and 3) burner rig test (BRT). The fracture surfaces of the adhesion tested specimens where characterised. A difference in fracture mechanism were found for the different heat treatments. Isothermal oxidation gave fracture mainly in the top coat while the two cyclic heat treatments gave increasing amount of BC/TC interface fracture with number of cycles. Some differences could also be seen between the specimens subjected to burner rig test and furnace cycling.

  • 10.
    Eriksson, Robert
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Brodin, Håkan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    Volvo Aero Corporation, Trollhättan.
    Li, Xin-Hai
    Siemens, Industrial Turbomachinery AB, Finspång.
    Fractographic Study of Adhesion Tested Thermal Barrier Coatings Subjected to Isothermal and Cyclic Heat Treatments2011In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 10, p. 195-200Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBC) are used in gas turbines to protect metallic components from high temperature. In the present study adhesion tests have been conducted on APS TBC coated specimens subjected to different heat treatments. Isothermal and cyclic heat treatments have been conducted at temperatures around 1100 °C and the adhesion have been tested using the method described in ASTM C633. The fracture surfaces resulting from the adhesion test have been investigated and the fracture behavior has been characterized. A difference in fracture mechanism between the three heat treatments has been found. The two cyclic heat treatments give fracture in the top coat/bond coat interface while isothermal heat treatment gives fracture in the top coat.

  • 11.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    Volvo Aero Corporation, SE-46181 Trollhättan, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, SE-61283 Finspång, Sweden.
    Influence of isothermal and cyclic heat treatments on the adhesion of plasma sprayed thermal barrier coatings2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 23-24, p. 5422-5429Article in journal (Refereed)
    Abstract [en]

    The adhesion of thermal barrier coatings (TBC) has been studied using the standard method described in ASTM C633, which makes use of a tensile test machine to measure the adhesion. The studied specimens consist of air plasma sprayed (APS) TBC deposited on disc-shaped substrate coupons of Ni-base alloy Hastelloy X. The bond coat (BC) is of a NiCoCrAlY type and the top coat (TC) consists of yttria–stabilised–zirconia. Before the adhesion test, the specimens were subjected to three different heat treatments: 1) isothermal oxidation at 1100 °C up to 290 h, 2) thermal cycling fatigue (TCF) at 1100 °C up to 300 cycles and 3) thermal shock at ~ 1140 °C BC/TC interface temperature up to 1150 cycles. The adhesion of the specimens is reported and accompanied by a microstructural study of the BC and the thermally grown oxides (TGO), as well as a discussion on the influence of BC/TC interfacial damage on adhesion properties of TBC. The adhesion was found to vary with heat treatment, as well as with heat treatment length.

  • 12.
    Eriksson, Robert
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Brodin, Håkan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    Volvo Aero Corporation, Trollhättan.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    The Influence of Substate Material on the Thermal Cycling Fatigue Life of Thermal Barrier Coating Systems2012In: ECF19 Proceedings, 2012Conference paper (Refereed)
  • 13.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    GKN Aerospace Engine Systems, Trollhättan.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Thermal Cycling Fatigue of Thermal Barrier Coatings- Rig and Experiment Design2014Conference paper (Refereed)
    Abstract [en]

    Ceramic thermal barrier coatings are used for thermal insulation in gas turbines to protect metallic components from high-temperature degradation. The ceramic coating may, due to its different coefficient of thermal expansion, crack and spall off the metallic component, thus rendering the component unprotected against high-temperature. Thermal cycling rigs of various designs are used to evaluate the durability of thermal barrier coatings. The present paper reports the result from a round robin test including three thermal cycling rigs at different locations. To better understand the influence of rig design on the thermal cyclic lives of thermal barrier coatings, some test parameters, such as the material of the specimen table and the cooling rate, were varied in one of the rigs. Furthermore, two different specimen geometries, rectangular and disc-shaped, were tested. The specimen table material was found to greatly influence the cooling rate of the specimens, more so than variations in the cooling airflow. The rectangular specimens were found to be more sensitive to test setup than the disc-shaped specimens; under certain conditions, the rectangular specimens could be made to fracture from the long side, rather than the short side of the specimen edge, which shortened the thermal cyclic life of the coatings.

  • 14.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Chen, Zhe
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Jonnalagadda, Krisha Praveen
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Bending Fatigue of Thermal Barrier Coatings2017In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 139, no 12, p. 122101-1-122101-6Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) are ceramic coatings used in gas turbines to lower the base metal temperature. During operation, the TBC may fail through, for example, fatigue. In this study, a TBC system deposited on a Ni-base alloy was tested in tensile bending fatigue. The TBC system was tested as-sprayed and oxidized, and two load levels were used. After interrupting the tests, at 10,000–50,000 cycles, the TBC tested at the lower load had extensive delamination damage, whereas the TBC tested at the higher load was relatively undamaged. At the higher load, the TBC formed vertical cracks which relieved the stresses in the TBC and retarded delamination damage. A finite element (FE) analysis was used to establish a likely vertical crack configuration (spacing and depth), and it could be confirmed that the corresponding stress drop in the TBC should prohibit delamination damage at the higher load.

  • 15.
    Eriksson, Robert
    et al.
    Siemens Industrial Turbomachinery AB, Berlin, Germany.
    Gupta, Mohit
    University West, Trollhättan, Sweden.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jonnalagadda, Krisha Praveen
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Nylén, Per
    University West, Trollhättan, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Stresses and Cracking During Chromia-Spinel- NiO Cluster Formation in TBC Systems2015In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 6, p. 1002-1014Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBC) are used in gas turbines to reduce the temperatures in the underlying substrate. There are several mechanisms that may cause the TBC to fail; one of them is cracking in the coating interface due to extensive oxidation. In the present study, the role of so called chromia-spinel-NiO (CSN) clusters in TBC failure was studied. Such clusters have previously been found to be prone to cracking. Finite element modeling was performed on a CSN cluster to find out at which stage of its formation it cracks and what the driving mechanisms of cracking are. The geometry of a cluster was obtained from micrographs and modeled as close as possible. Nanoindentation was performed on the cluster to get the correct Young’s moduli. The volumetric expansion associated with the formation of NiO was also included. It was found that the cracking of the CSN clusters is likely to occur during its last stage of formation as the last Ni-rich core oxidizes. Furthermore, it was shown that the volumetric expansion associated with the oxidation only plays a minor role and that the main reason for cracking is the high coefficient of thermal expansion of NiO.

  • 16.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Östergren, Lars
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Influence of substrate material on the life of atmospheric plasmas prayed thermal barrier coatings2013In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 232, no 15, p. 795-803Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs) are used in gas turbines to prolong the life of the underlying substrates and to increase the efficiency of the turbines by enabling higher combustion temperatures. TBCs may fail during service due to thermal fatigue or through the formation of non-protective thermally grown oxides (TGOs). This study compares two atmospheric plasma sprayed (APS) TBC systems comprising of two identical TBCs deposited on two different substrates (Haynes 230 and Hastelloy X). The thermal fatigue life was found to differ between the two TBC systems. The interdiffusion of substrate elements into the coating was more pronounced in the TBC system with shorter life, however, very few of the substrate elements (only Mn and to some extent Fe) formed oxides in the bond coat/top coat interface. Fractography revealed no differences in the fracture behaviour of the TBCs; the fracture occurred, in both cases, to about 60% in the top coat close to the interface and the remainder in the interface. Nanoindentation revealed only small differences in mechanical properties between the TBC systems and a finite element crack growth analysis showed that such small differences did not cause any significant change in the crack driving force. The oxidation kinetics was found to be similar for both TBC systems for the formation of Al2O3 but differed for the kinetics of non-Al2O3 TGOs where the TBC system with shortest life had a faster formation of non-Al2O3 TGOs caused by a faster Al depletion. The difference in non-Al2O3 TGO growth kinetics was considered to be the main reason for the difference in life.

  • 17.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Siemens AG, Berlin, Germany.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Influence of Cu and Zn Residues from Wire Electro-Discharge machining on TBS Durability2014In: Proceedings of the 2014 Energy Materials Conference  (CD-ROM), Wiley-TMS , 2014, p. 387-392Conference paper (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBC) are deposited on superalloys in gas turbines to prolong component life. Electro-discharge machining (EDM) provides a convenient way of machining superalloys prior to coating deposition. Wire-EDM may leave residues from the wire material on the cut surface. A study was performed to investigate if brass residues from the EDM wire affected TBC oxidation behavior and spallation life. Isothermal oxidation at 1050 ℃ and thermal cycling at 1100 ℃ were performed on plasma sprayed TBCs on two different EDM cut substrates. No decrease in TBC life was detected due to the brass residues on the cut surfaces.

  • 18.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Sjöström, Sören
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Solid Mechanics.
    Brodin, Håkan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    GKN Aerospace Engine Systems, Trollhättan.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Influence of Interface Roughness on the Fatigue Life of Thermal Barrier Coatings2013Conference paper (Refereed)
  • 19.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Brodin, Håkan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Östergren, Lars
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    TBC bond coat-top coat interface roughness: influence on fatigue life and modelling aspects2013In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 236, p. 230-238Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs), when used in gas turbines, may fail through thermal fatigue, causing the ceramic top coat to spall off the metallic bond coat. The life prediction of TBCs often involves finite element modelling of the stress field close to the bond coat/top coat interface and thus relies on accurate modelling of the interface. The present research studies the influence of bond coat/top coat interface roughness on the thermal fatigue life of plasma sprayed TBCs. By using different spraying parameters, specimens with varying interface roughness were obtained. During thermal cycling it was found that higher interface roughness promoted longer thermal fatigue life. The interfaces were characterised by roughness parameters, such as Ra, Rq and Rq, as well as by autocorrelation, material ratio curves, probability plots and slope distribution. The variation of spray parameters was found to affect amplitude parameters, such as Ra, but not spacing parameters, such as RSm. Three different interface geometries were tried for finite element crack growth simulation: cosine, ellipse and triangular shape. The cosine model was found to be an appropriate interface model and a procedure for obtaining the necessary parameters, amplitude and wavelength, was suggested. The positive effect of high roughness on life was suggested to be due to a shift from predominantly interface failure, for low roughness, to predominantly top coat failure, for high roughness.

  • 20.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering.
    Yuan, Kang
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    INTERSPLAT OXIDATION OF ATMOSPHERIC PLASMA SPRAYED MCRALY COATINGS2014In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2014, VOL 6, AMER SOC MECHANICAL ENGINEERS , 2014, no V006T22A017Conference paper (Refereed)
    Abstract [en]

    MCrAlY coatings and thermal barrier coatings (TBC) are commonly used in gas turbines to prolong the life of structural parts. The atmospheric plasma spray (APS) process yields coatings with a typical splat-on-splat structure which oxidizes at intersplat boundaries during high-temperature exposure. A study was performed to establish the influence of intersplat oxidation on Al depletion. It was found that the P -depletion based life may be overestimated by a factor of 1.8-18 if intersplat oxidation is not considered. Two different mechanisms of intersplat oxidation were observed: At high temperature (1050 degrees C), a fraction of the intersplat boundaries remained in contact with the coating surface and oxidized with the same kinetics as the surface oxides. At lower temperature (900 degrees C), intersplat oxidation occurred by considerable slower growth rates than surface oxidation. The mechanisms behind intersplat oxide growth was further studied by O diffusion calculations.

  • 21.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Yuan, Kang
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Microstructure-based Life Prediction of Thermal Barrier Coatings2014Conference paper (Refereed)
    Abstract [en]

    The widespread use of thermal barrier coatings (TBC) in gas turbines stresses the importance of accurate life prediction models for TBCs. During service, the TBC may fail due to thermal fatigue or through the formation of thermally grown oxides (TGOs). The current paper presents a Thermo-Calc/Dictra-based approach to life prediction of isothermally oxidised atmospheric plasma sprayed (APS) TBCs. The β-phase depletion of the coating was predicted and compared to life prediction criteria based on TGO thickness and Al content in the coating. All tried life models underestimated the life of the coating where the β-depletion-based model was the most conservative.

  • 22.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Yuan, Kang
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Life Prediction of High-Temperature MCr AIY Coatings Based on Microstructural Observations2014In: THERMEC 2013, Trans Tech Publications Inc., 2014, Vol. 922, p. 143-148Conference paper (Refereed)
    Abstract [en]

    Thermal barrier coatings are commonly used in gas turbines for protection against high tem-perature and oxidation. Life prediction of oxidation protective coatingsmay be done bymicrostructure-based techniques such as -depletion based life criteria. In this study, a thermal barrier coating sys-tem, with an overlay NiCoCrAlY coating as bond coat, was oxidised up to 10000 h at 900 C. Themicrostructure was studied and related to Al depletion. It was found that a -depletion based lifecriterion could not be used for the studied coating composition and temperature as it would be tooconservative. A 0-depletion based model was instead suggested and supported by interdiffusion sim-ulation.

  • 23.
    Eriksson, Robert
    et al.
    Siemens AG, Energy Sector, Berlin, Germany.
    Yuan, Kang
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Corrosion of NiCoCrAIY Coatings and TBC Systems Subjected to Water Vapor and Sodium Sulfate2015In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 6, p. 953-964Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coating (TBC) systems are commonly used in gas turbines for protection against high-temperature degradation. Penetration of the ceramic top coat by corrosive species may cause corrosion damage on the underlying NiCoCrAlY bond coat and cause failure of the TBC system. In the current study, four oxidation/corrosion conditions were tried: (i) lab air, (ii) water vapor, (iii) sodium sulfate deposited on the specimens, and (iv) water vapor + sodium sulfate. The test was done at 750 °C in a cyclic test rig with 48 h cycles. The corrosion damage was studied on NiCoCrAlY-coated specimens, thin APS TBC specimens, and thick APS TBC specimens. Water vapor was found to have very minor influence on the oxidation, while sodium sulfate increased the TGO thickness both for NiCoCrAlY specimens and TBC-coated specimens; the influence of the TBC thickness was found to be very small. Sodium sulfate promoted thicker TGO; more Cr-rich TGO; the formation of Y oxides, and internally, Y sulfides; pore formation in the coating as well as in the substrate; and the formation of a Cr-depleted zone in the substrate.

  • 24.
    Eriksson, Robert
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Yuan, Kang
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    MCrAIY Coating Design Based on Oxidation-Diffusion Modelling. Part II: Lifing Aspects2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 253, p. 27-37Article in journal (Refereed)
    Abstract [en]

    Coatings from MCrAlY-type alloys are commonly used for oxidation and corrosion protection in gas turbines. As coated components are exposed to high temperature, the coating provides oxidation protection by the formation of an alumina scale, thus depleting the coating of Al which, eventually, will cause the coating to fail. The present study deals with MCrAlY alloy design from a lifing perspective. A previously developed coupled oxidation-diffusion model was used to study the influence of coating composition, substrate composition and oxidation temperature on the expected life of MCrAlY coatings. Eight model coatings, covering the wide range of MCrAlY compositions used industrially, and two model substrates, corresponding to a blade material and a combustor material, were evaluated by the oxidation-diffusion model. Three life criteria were tried: 1) beta-phase-depletion, 2) critical Al content at the coating surface, and 3) a critical TGO thickness. It was shown that the critical TGO thickness was the most conservative life criterion for high-Al coatings on high-Al substrates. For low-Cr and low-Co coatings, the beta-depletion criterion was usually the most conservative. For cases where beta-stability was high (such as at low temperatures and for coatings high in Cr, Co and Al) the critical-Al criterion was often the most conservative.

  • 25.
    Gupta, M
    et al.
    University West, Trollhättan, Sweden.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Sand, U
    EDR Medeso, Västerås, Sweden.
    Nylén, P
    University West, Trollhättan, Sweden.
    A Diffusion-based Oxide Layer Growth Model Using Real Interface Roughness in Thermal Barrier Coatings for Lifetime Assessment2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 271, p. 181-191Article in journal (Refereed)
    Abstract [en]

    The development of thermo-mechanical stresses during thermal cycling can lead to the formation of detrimental cracks in Atmospheric Plasma Sprayed (APS) Thermal Barrier Coatings systems (TBCs). These stresses are significantly increased by the formation of a Thermally Grown Oxide (TGO) layer that forms through the oxidation of mainly aluminium in the bondcoat layer of the TBC. As shown in previous work done by the authors, the topcoat–bondcoat interface roughness plays a major role in the development of the stress profile in the topcoat and significantly affects the lifetime of TBCs. This roughness profile varies as the TGO layer grows and changes the stress profile in the topcoat leading to crack propagation and thus failure.

    In this work, a two-dimensional TGO growth model is presented, based on oxygen and aluminium diffusion–reaction equations, using real interface profiles extracted from cross-section micrographs. The model was first validated by comparing the TGO profiles artificially created by the model to thermally cycled specimens with varying interface roughness. Thereafter, stress profiles in the TBC system, before and after the TGO layer growth, were estimated using a finite element modelling model described in previous work done by the authors. Three experimental specimens consisting of the same chemistry but with different topcoat–bondcoat interface roughness were studied by the models and the stress state was compared to the lifetimes measured experimentally. The combination of the two models described in this work was shown to be an effective approach to assess the stress behaviour and lifetime of TBCs in a comparative way.

  • 26.
    Jonnalagadda, Krisha Praveen
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Yuan, Kang
    Li, Xin-Hai
    Ji, Xiaojuan
    Yu, Yueguang
    Peng, Ru Lin
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    A Study of Damage Evolution in High Purity Nano TBCs During Thermal Cycling: A Fracture Mechanics Based modeling approach.2017In: ASME Turbine Expo, Elsevier, 2017, Vol. 37, p. 2889-2899, article id 8Conference paper (Refereed)
    Abstract [en]

    This work concerns the study of damage evolution in a newly developed high purity nano 8YSZ thermal barrier coating during thermal cyclic fatigue tests (TCF). TCF tests were conducted between 100 °C–1100 °C with a hold time of 1 h at 1100 °C, first till failure and later for interrupted tests. Cross section analysis along the diameter of the interrupted test samples revealed a mixed-type failure and that the most of the damage occurred towards the end of the coating’s life. To understand the most likely crack growth mechanism leading to failure, different crack growth paths have been modelled using finite element analysis. Crack growing from an existing defect in the top coat towards the top coat/TGO interface has been identified as the most likely mechanism. Estimated damage by the model could predict the rapid increase in the damage towards the end of the coating’s life.

  • 27.
    Jonnalagadda, Krisha Praveen
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Yuan, Kang
    Beijing General Reseach Institute of Mining and Metallurgy, Beijing, China.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Ji, Xiaojuan
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Yu, Yueguang
    Beijing General Research Institute of Mining and Metallurgy, Beijing, China.
    Peng, Ru Lin
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Comparison of Damage Evolution During Thermal Cycling in a High Purity Nano and Conventional Thermal Barrier Coating2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 332, p. 47-56Article in journal (Refereed)
    Abstract [en]

    Thermal barrier coatings (TBCs), consisting of a ceramic top coat and a metallic bond coat, offer resistance against high temperature degradation of turbine components. Cyclic oxidation of the bond coat, thermal stresses due to their thermal mismatches during cyclic operations, and sintering of the top coat are considered to be the common ways by which thermal barrier coatings fail. To reduce sintering, a nano structured high purity yttria stabilized zirconia (YSZ) was developed. The focus of this work is to compare the damage development of such high purity nano YSZ TBC during thermal cycling with a conventional YSZ TBC. Thermal cyclic fatigue (TCF) tests were conducted on both the TBC systems between 100 °C and 1100 °C with a 1 h hold time at 1100 °C. TCF test results showed that conventional YSZ TBC exhibited much higher life compared to the high purity nano YSZ TBC. The difference in the lifetime is explained by the use of microstructural investigations, crack length measurements along the cross-section and the difference in the elastic modulus. Furthermore, stress intensity factors were calculated in order to understand the difference(s) in the damage development between the two TBC systems.

  • 28.
    Li, Xin-Hai
    et al.
    Siemens Industrial Turbomachinery AB, Finspång.
    Heinze, Sebastian
    Siemens Industrial Turbomachinery AB, Finspång.
    Brodin, Håkan
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Eriksson, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Engineering Materials.
    Studies of Air Plasma Sprayed Thermal Barrier Coatings and Their Surface Roughness for Applications in Siemens Medium Size Gas Turbines2012Conference paper (Refereed)
  • 29.
    Peng, Ru
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Chai, Guocai
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Sandvik Materials Technology, Sandviken, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    SEM Study of Fatigue Crack Growth Behavior in Duplex Stainless Steels2014In: TMS 2014 Supplemental Proceedings, John Wiley & Sons, 2014, p. 631-638Conference paper (Refereed)
    Abstract [en]

    Mechanical properties of duplex stainless steels (DSSs) are strongly dependent on their microstructure and micromechanical behavior of the constitutive phases. The present work has investigated the growth behavior of fatigue crack in two DSSs, SAF 2507 and SAF 2906, having a different hardness ratio between the constitutive austenite and ferrite. By microstructural examination in SEM under in situ loading and also after ex situ loading, the slip activities, the development of localized cyclic plasticity and the propagation of the fatigue crack in an austenite-dominant region in the respective steel were closely followed. The growth of cracks and formation of secondary cracks were correlated to slip heterogeneities within the same grain under cyclic loading and localization of cyclic plastic strains. More profound localization of cyclic plastic strains were observed in the crack tip region in SAF 2507 than in SAF 2906, likely attributed to a softer austenite in SAF 2507.

  • 30.
    Saarimäki, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology. Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Influence of Overloads on Dwell Time Fatigue Crack Growth in Inconel 7182014In: Materials Science and Engineering: A, Vol. 612, p. 398-405Article in journal (Refereed)
    Abstract [en]

    Inconel 718 is one of the most commonly used superalloys for high temperature applications in gasturbines and aeroengines and is for example used for components such as turbine discs. Turbine discs can be subjected to temperatures up to ~700 °C towards the outer radius of the disc. During service, the discs might start to develop cracks due to fatigue and long dwell times. Additionally, temperature variations during use can lead to large thermal transients during start-up and shutdown which can lead to overload peaks in the normal dwell time cycle. In this study, tests at 550 °C with an overload prior to the start of each dwell time, have been performed. The aim of the investigation was to get a better understanding of the effects of overloads on the microstructure and crack mechanisms. The microstructure was studied using electron channelling contrast imaging (ECCI). The image analysis toolbox in Matlab was used on cross sections of the cracks to quantify: crack length, branch length, and the number of branches in each crack. It was found that the amount of crack branching increases with an increasing overload and that the branch length decreases with an increasing overload. When the higher overloads were applied, the dwell time effect was almost cancelled out. There is a strong tendency for an increased roughness of the crack path with an increasing crack growth rate.

  • 31.
    Yuan, Kang
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Wang, Yandong
    School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China.
    Interdiffusion and Microstructure Simulation in Ni and Co Based Overlay Coatings on a Ni-Based Superalloy at High Temperatures2013Conference paper (Refereed)
  • 32.
    Yuan, Kang
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Wang, Yandong
    University of Science and Technology, Beijing, China.
    MCrAIY Coating Design Based on Oxidation-Diffusion Modelling. Part I: Microstructural Evolution2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 254, p. 79-96Article in journal (Refereed)
    Abstract [en]

    To improve the efficiency of modern gas turbines, it is highly desired to develop durable MCrAlY alloys, to be used as protective coatings against oxidation and corrosion for superalloys which are the base materials for some hot components like turbine blades and vanes. In this paper, an oxidation-diffusion model was used to simulate the diffusion of alloying elements and the corresponding microstructural changes in different superalloy-coating systems at high temperature. Two important processes are considered in this model: oxidation of the coating and interdiffusion between the superalloy and the coating. The model showed an accurate predictability of the diffusion and microstructural evolution in real superalloy-coating diffusion couples studied at high-temperature exposure. The model was further applied to investigate the elemental effects of Ni, Co, Cr and Al on the microstructural evolution, considering the development of two important phases in superalloys and coatings, i.e. FCC-γ′ and BCC-β, at different temperatures. The results in this paper deepen the knowledge of the MCrAlY coating design for superalloy-coating systems in high-temperature applications.

  • 33.
    Yuan, Kang
    et al.
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Eriksson, Robert
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Peng, Ru
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Finspång.
    Johansson, Sten
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, The Institute of Technology.
    Wang, Yandong
    School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China.
    Modeling of the microstructural evolution and lifetime prediction of MCrAlX coatings on Nickel based superalloys in high temperature oxidation2013In: Surface and Coatings Technology, Vol. 232, no 15, p. 204-215Article in journal (Refereed)
    Abstract [en]

    At high temperature, MCrAlX coatings are deposited onto the surface of superalloy to provide oxidation and corrosion protection by forming a thermalgrowing oxide scale. In this project, the oxidation behavior of an HVOF CoNiCrAlYSi coating on IN792 was studied in both isothermal oxidation (900, 1000 and 1100 °C) and thermal cycling (1100-100 °C). The microstructural evolution in the MCrAlX coatings after oxidation was investigated. It was found that Al-rich β phase is gradually consumed due to two effects: surface oxidation and coating-substrate interdiffusion. Some voids and oxides along the coating-substrate interface, or inside the coating, were considered to play a role in blocking the diffusion of alloying elements. Based on the microstructural observation, an oxidation-diffusion model was developed by using Matlab and DICTRA software to predict the lifetime of MCrAlX coatings. Several effects influencing the microstructural evolution were included: surface oxidation, coating-substrate interdiffusion and diffusion blocking. The results showed good agreement between the experimental composition profiles and modeling ones. Furthermore, by choosing suitable diffusion blocking factors, the accuracy of coating life prediction could be improved.

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