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Metastable alumina formation during oxidation of FeCrAl and its suppression by surface treatments
Author(s) -
N'Dah E.,
Galerie A.,
Wouters Y.,
Goossens D.,
Naumenko D.,
Kochubey V.,
Quadakkers W.J.
Publication year - 2005
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200503914
Subject(s) - isothermal process , materials science , slurry , coating , foil method , thermal treatment , annealing (glass) , thermal oxidation , chemical engineering , phase transition , atmospheric temperature range , metastability , analytical chemistry (journal) , metallurgy , chemistry , composite material , layer (electronics) , thermodynamics , organic chemistry , physics , engineering
The influence of various surface treatments of industrial FeCrAl grades was investigated in order to reduce the formation of transition aluminas during thermal oxidation in the 800–950°C temperature range. High temperature gas phase annealing in H 2 ‐H 2 O mixtures promoted the initial formation of an alpha thin film and no transition alumina formed during subsequent oxidation at lower temperatures, showing very low weight gains compared to non‐treated grades. Such a treatment was shown to be efficient for isothermal oxidation in oxygen of laboratory foil specimens but also for cyclic air exposure of fiber mats in near‐real operating conditions. Surface modification by application of a slurry TiO 2 coating before oxidation was also shown to greatly reduce the amount of transition alumina, observed by X‐Ray Diffraction and Laser Induced Optical Spectroscopy. For both treatments, the optimal conditions were determined and the influence on oxidation rate was assessed.