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Title:Bond coat surface rumpling in thermal barrier coatings
Author(s):Panat, Rahul P.; Zhang, Sulin; Hsia, K. Jimmy
Subject(s):Stress Driven Surface Diffusion
Thermally Activated Processes
Thin Films
Abstract:Long term durability of thermal barrier coatings is determined by the mechanisms responsible for the nucleation and growth of interfacial cracks between coating and substrate. One such mechanism is the progressive roughening or "rumpling" of the bond coat surface upon thermal cycling. A thermodynamic analysis is presented in this paper based on a stress-driven surface diffusion mechanism to explain the bond coat rumpling process. The surface chemical potential variation required for such a diffusion process is caused by the changes in the surface energy and the elastic strain energy in the system. It is found that the amplitude of surface fluctuations with a wavelength higher than a threshold value monotonically increases with thermal cycling, while the amplitude for fluctuations with lower wavelength than the threshold value monotonically decreases. A range of wavelengths is identified to have a high monotonic amplitude increase accounting for the surface rumpling of the bond coat upon thermal cycling. This range of wavelengths obtained from the model agrees reasonably well with experimental observations.
Issue Date:2002-01
Publisher:Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report:TAM R 993
Genre:Technical Report
Rights Information:Copyright 2002 Board of Trustees of the University of Illinois
Date Available in IDEALS:2021-11-04

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  • Technical Reports - Theoretical and Applied Mechanics (TAM)
    TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.

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