Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

Journal Article · Wed Aug 20 00:00:00 EDT 2014 · Surface and Coatings Technology

DOI:https://doi.org/10.1016/j.surfcoat.2014.08.028· OSTI ID:1286703

Nordhorn, Christian ^[1]; Mücke, Robert ^[1]; Unocic, Kinga A. ^[2]; Lance, Michael J. ^[2]; Pint, Bruce A. ^[2]; Vaßen, Robert ^[1]

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1. Forschungszentrum Julich GmbH (Germany)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division

In this paper, furnace cycling experiments were performed on free-standing high-velocity oxygen-fuel bond coat samples to investigate the effect of material composition, surface texture, and cycling conditions on the average stresses in the formed oxide scales after cooling. The oxide scale thicknesses were determined by SEM image analyses and information about the stresses were acquired by photo-stimulated luminescence-spectroscopy. Additionally, the scale thickness dependent stress fields were calculated in finite-element analyses including approximation functions for the surface roughness derived on the basis of profilometry data. The evolution of the average residual stress as a function of oxide scale thickness was subject to stochastic fluctuations predominantly caused by local scale spallations. In comparison to the supplemental modeling results, thermal stresses due to mismatch of thermal expansion coefficients are identified as the main contribution to the residual stresses. Finally, the theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Fossil Energy (FE)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1286703
• Journal Information: Surface and Coatings Technology, Vol. 258; ISSN 0257-8972
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
bond coatings
high temperature oxidation
alumina scale
residual stress
modeling