Kinetics of the Chloride-Induced Oxidation of Iron at 300 C.
Abstract
Iron was oxidized in the absence of oxygen at 300C in solutions containing chloride and/or iron(II) ions. The oxidation reaction was conveniently studied by the hydrogen-effusion method, which determines the rate at which hydrogen is evolved. The generally accepted concept that chloride ions accelerate the oxidation of iron has not received experimental verification, because, in addition to chloride ions, the system must contain iron(II) ions. An empirical equation has been derived that describes the extent of iron oxidation W with time t as a function of the iron(II) chloride molar concentrations. Magnetite, or Fe3O4, is deposited as a tightly adhered crystalline film at the metal/solution interface and apparently also quenches the reaction rate by serving as a physical barrier. The differential with respect to time of a term of the equation describes a rate mechanism that is proceeding under the diffusive control of ions migrating across the Nernst boundary layers of anodic and cathodic regions of an oxide-free metal/solution interface. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 08, 1971
- Accession Number
- AD0719887
Entities
People
- M. A. Scheiman
Organizations
- United States Naval Research Laboratory