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

SURFACE & COATINGS TECHNOLOGY

卷:258

Article

Nordhorn, Christian¹  Muecke, Robert¹  Unocic, Kinga A.²  Lance, Michael J.²  Pint, Bruce A.²  Vassen, Robert¹ 

[1] Forschungszentrum Julich, IEK 1, D-52428 Julich, Germany

[2] Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA

关键词: Photo-stimulated luminescence-spectroscopy;    Thermally grown oxide;    MCrAlY bond coats;    Finite-element analysis;    Mechanical stress;   

DOI  :  10.1016/j.surfcoat.2014.08.028

来源: Elsevier

【 摘 要 】

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. The theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features. (C) 2014 Elsevier B.V. All rights reserved.

【 授权许可】

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