Observation of oscillating reaction rates during the isothermal oxidation of ferritic steels

Journal Article · Sat Dec 01 04:00:00 EST 1990 · Oxidation of Metals; (USA)

DOI:https://doi.org/10.1007/BF00664425· OSTI ID:6174308

Hurdus, M H; Tomlinson, L; Titchmarsh, J M ^[1]

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1. AEA Technology, Oxfordshire (England)

Oscillating reaction rates have been observed in the steam oxidation of 2 1/4Cr-1MoNb and 9Cr-1Mo ferritic steels at 500-550C. Changes in reaction rate are associated with the formation of a laminated, inner-oxide layer, made up of bands of fine and coarse-grain spinel oxide. The lowest reaction rates occur during growth of the fine-grain oxide. Coarse-grain oxide generally contains the same levels of Cr, Mo, and Si as the steel (after allowing for loss of Fe to the outer layer), while the fine-grain material contains three times these levels. Ni builds up in the metal and is present in the oxide as metallic particles (mostly associated with fine-grain oxide). A mechanism is proposed in which the highest reaction rates are controlled by diffusion of Fe ions through the oxide layer (as in normal parabolic oxidation) and the lowest rates by diffusion of Fe through the Ni-rich layer in the metal.

• OSTI ID: 6174308
• Journal Information: Oxidation of Metals; (USA), Journal Name: Oxidation of Metals; (USA) Vol. 34:5-6; ISSN 0030-770X; ISSN OXMEA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
DATA
EXPERIMENTAL DATA
FERRITIC STEELS
GRAIN SIZE
HIGH TEMPERATURE
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
KINETICS
MEASURING METHODS
MICROSTRUCTURE
NUMERICAL DATA
OXIDATION
REACTION KINETICS
SCALING
SIZE
STEELS