Abstract
Preoxidized chromium specimens have been high vacuum annealed at 1200° and 1300°C to produce densified Cr 2O3 scales. These specimens have been reoxidized at the same temperatures at 10−6 atm O2. The initial reoxidation is linear with time and is concluded to reflect a volume diffusion controlled transport through the densified scale. The corresponding parabolic rate constant (w2 = kpt)is given by kp=1.4 · 10−2 exp(−235,000/RT)(gram of O) 2/cm4 sec. It is tentatively concluded that outward chromium diffusion predominates in an inner layer of the Cr2O3 scales and inward oxygen diffusion in an outer layer. Under the experimental conditions it has not been possible to maintain growth of the Cr2O3 scales controlled by volume diffusion. The “new” oxide layer consists of fine crystallites; the oxide grows at grain boundaries within the scales. This causes sideways growth of the scale, breakdown of the originally densified layer, and an increased rate of reaction.
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P. Kofstad and K. P. Lillerud,Oxid. Met. accepted for publication.
K. P. Lillerud and P. Kofstad,Oxid. Met. accepted for publication.
K. P. Lillerud and P. Kofstad,J. Electrochem. Soc. 127, 2397 (1980).
P. Kofstad and K. P. Lillerud,J. Electrochem. Soc. 127, 2410 (1980);128, 1388 (1981).
E. A. Gulbransen and S. A. Jansson,Oxidation of Metals and Alloys (ASM, Metals Park, Ohio, 1971), p. 63.
A. J. Rosenberg,J. Electrochem. Soc. 107, 795 (1960).
C. A. Phalnikar, E. B. Evans, and W. M. Baldwin,J. Electrochem. Soc. 103, 429 (1956).
L. Cadiou and J. Paidassi,Mem. Sci. Rev. Metall. 66, 217 (1969).
W. C. Hagel,Trans. Am. Soc. Met. 56, 583 (1963).
D. Caplan and M. Cohen,J. Electrochem. Soc. 112, 5 (1964).
D. Caplan and G. I. Sproule,9, 459 (1975).
K. P. Lillerud and P. Kofstad, Proceedings of the International Conference on High Temperature Corrosion, NACE, San Diego, California (March 1981).
K. P. Lillerud and P. Kofstad, 8th International Congress on Metallic Corrosion, Mainz (D) (September 1981).
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Lillerud, K.P., Kofstad, P. Reoxidation of chromium with densified Cr2O3 Scales. Oxid Met 17, 127–139 (1982). https://doi.org/10.1007/BF00606196
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DOI: https://doi.org/10.1007/BF00606196