On the oxidation of iron in CO sub 2 +CO gas mixtures: I. Scale morphology and reaction kinetics

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

DOI:https://doi.org/10.1007/BF00664422· OSTI ID:6016831

Bredesen, R; Kofstad, P ^[1]

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1. Department of Chemistry, Oslo (Norway)

High-purity iron has been oxidized in CO{sub 2} and CO{sub 2}+CO gas mixtures and different total gas pressures (0.1-1 atm.) at 1,000-1,200C. Reaction rates and kinetics have been studied by thermogravimetry and reacted specimens have been characterized by electron microscopy and x-ray diffraction. The time dependence of the growth of wuestite may generally be described by an S-shaped curve. The scale texture of initially formed wuestite is related to that of the underlying {gamma}-iron; however, as the scale grows, the texture gradually changes to a final one in which the (001) plane of wuestite is parallel to the iron substrate. The oxidation rate increases with this change in texture. It is concluded that the oxidation during these initial stages is essentially controlled by a surface reaction, and that the increasing reaction rate reflects an increased number of reaction sites at the surface during the change in texture. As the scale grows in thickness, the reaction rates go through a maximum, and are followed by a decreasing, parabolic-like behavior, reflecting that iron diffusion through the scales becomes increasingly important.

• OSTI ID: 6016831
• 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
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
DATA
DIFFRACTION
ELECTRON MICROSCOPY
ELEMENTS
EXPERIMENTAL DATA
GRAVIMETRIC ANALYSIS
INFORMATION
IRON
KINETICS
MEASURING METHODS
METALS
MICROSCOPY
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
SCALING
SCATTERING
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
TRANSITION ELEMENTS
VERY HIGH TEMPERATURE
X-RAY DIFFRACTION