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Processing, characterization, and properties of some novel thermal barrier coatings

Jadhav, Amol D.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1183851697

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Materials Science and Engineering.
The efficacy of ceramic thermal barrier coatings (TBCs) used to protect and to insulate metal components in engines increases with the thickness of the TBCs. However, the durabilities of thick TBCs deposited using conventional ceramic-coating deposition methods have not been adequate. Here the feasibility of depositing highly durable thick TBCs (1.5 to 4 mm thickness) of ZrO2-7 wt.% Y2O3 (7YSZ) on bond-coated superalloy substrates using the solution-precursor plasma spray (SPPS) method has been demonstrated. Thermal cyclic durabilities of the thick SPPS TBCs have been shown to be much superior compared to TBCs deposited using the conventional air-plasma-spray (APS) process. To evaluate the performance of thick APS and SPPS TBCs, mechanical properties of free-standing coatings and coating/substrate interfaces have been determined experimentally. Additional evaluation of TBC performance has been obtained from studies of damage and development of thermally grown oxide (TGO) at the interface as a result of thermal cycling. The later results are used to suggest mechanisms of chemical failure of TGO in thick plasma-sprayed TBCs. Based on the experimental results and numerical analysis of the TBC residual stresses, the dramatic improvement in the thermal cycling life in the SPPS TBCs is attributed to superior mechanical properties of SPPS coatings. The presence of the strain tolerant vertical cracks in SPPS TBCs reduces the driving force for TBC spallation under mode-II loading. Additionally, high in-plane fracture toughness in the SPPS TBCs under mode-I loading delays the TBC spallation significantly. Finally, thermal conductivity of the SPPS TBCs has been reduced by microstructural tailoring. Analytical and object-oriented finite element (OOF) models have been used to analyze the experimental thermal conductivity data, and to predict thermal conductivities of engineered TBCs.
Nitin Padture (Advisor)
Sheikh Akbar (Other)
John Morral (Other)
202 p.
Engineering, Materials Science
Thick thermal barrier coatings; Solution-precursor plasma spray; Mechanical properties; Thermal conductivity; Failure analysis

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Citations

  • Jadhav, A. D. (2007). Processing, characterization, and properties of some novel thermal barrier coatings [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1183851697

    APA Style (7th edition)

  • Jadhav, Amol. Processing, characterization, and properties of some novel thermal barrier coatings. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1183851697.

    MLA Style (8th edition)

  • Jadhav, Amol. "Processing, characterization, and properties of some novel thermal barrier coatings." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1183851697

    Chicago Manual of Style (17th edition)

osu1183851697
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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.