KINETICS OF OXIDATION OF IRON-CHROMIUM ALLOYS AND THE TRANSPORT PROPERTIES OF THE OXIDES IN CARBON DIOXIDE-CARBON MONOXIDE MIXTURES. End of Year Report

Technical Report · Thu Jan 31 04:00:00 EST 1963

OSTI ID:4740378

Levin, R L; Wagner, Jr, J B

The oxidation of iron--chromium alloys containing 0.20, CO/sub 2/--CO mixtures over the temperature range 800 to 1100 nif- C under conditions where wustite is the only stable iron oxide. The experimental results, obtained from a continuous recording of the gain in weight by a semi- micro automatic recording balance, show that all of the alloys oxidize in CO/sub 2/-CO mixtures with the same sequence of mechanisms. The first stage of the reaction is one of linear oxidation where the rate-controlling process is a phase- boundary reaction at the wustite/gas interface which is determined to be the adsorption of CO/sub 2/ below about 950 nif- C and the dissociation of CO/sub 2/ into CO and adsorbed oxygen atoms or ions above this temperature. The second stage of the reaction is one of parabolic oxidation kinetics where diffusion of the metal ions and electrons through the scale is the rate- determining step. The oxide thickness at which the kinetics transform from linear to parabolic is dependent upon chromium content in the wustite and upon temperature. The effect of soluble chromium in the wustite lattice is to cause an increase in the cation vacancy concentration which is manifested as an increase in the rate of parabolic oxidation of the Fe--Cr alloys over that of pure iron oxidized under the same conditions. The rate of oxidation of Fe--Cr alloys is shown also to be many times more rapid in CO/sub 2/--CO mixtures than in oxygen. (auth)

• Research Organization: Northwestern Univ., Evanston, Ill.
• NSA Number: NSA-17-018700
• OSTI ID: 4740378
• Report Number(s): TID-18420
• Country of Publication: United States
• Language: English

Related Subjects

ADSORPTION
ATOMS
CARBON DIOXIDE
CARBON MONOXIDE
CATIONS
CHROMIUM ALLOYS
DECOMPOSITION
DEFECTS
DIFFUSION
ELECTRONS
GRAIN BOUNDARIES
HIGH TEMPERATURE
IONS
IRON ALLOYS
IRON OXIDES
LATTICES
METALS, CERAMICS, AND OTHER MATERIALS
MIXING
OXIDATION
OXYGEN
REACTION KINETICS
SURFACES
THICKNESS
VACANCIES
VARIATIONS
VELOCITY
WEIGHT
WUESTITE