Nature of Atmospheric Rust on Iron

Abstract

In order to elucidate the mechanism of self‐protection of weathering steel, the action of atmospheric rust was studied through a discussion of physical, chemical, and electrochemical nature of rust, with special attention to the effect of copper addition. The aggregating state of rust layer is influenced by two factors: the time of exposure and beneficial elements added to steel. Copper addition inhibits the growth of primary colloidal particle. This action of copper has an effect on the properties of rust and serves to increase the protective ability of rust layer.

Some Clarifications Regarding Literature on Atmospheric Corrosion of Weathering Steels

“…The optically isotropic layer was mainly composed of amorphous spinel-type iron oxide and the optically active layer was γ-FeOOH. Raman et al [33] and Suzuki et al [34] described that the outer layer of WS contains several different crystalline oxyhydroxides, including lepidocrocite (γ-FeOOH), goethite (α-FeOOH), akaganeite Dillmann et al [35] studied in detail that the major phases of the rust layers are magnetite, goethite, and lepidocrocite. Lepidocrocite seems to be more present in the outer layer and goethite seems to be the major constituent of the inner layer.…”

Atmospheric corrosion of mild steel

“…Rust formed on steel freely exposed to rain shows a dense (less porous) and laminated structure, compared to the less protective powder-like grainy structure of rust formed on sheltered surfaces [87] where diffusion to the steel/rust interface is less impeded.…”

Corrosion Behavior of Silicon-Bearing Steel in a Wet/Dry Environment Containing Chloride Ions

“…While there have been many analyses of rust on the steels in mild environments, [3][4][5][6][7][8][9][10] there are many problems that remain unclear regarding the basic mechanisms of the rust formation 11) and the effect of alloy elements [12][13][14] in saline environments. Therefore, in order to obtain the corrosion guidance for weathering steels that can be used in coastal environment, the thermodynamic stability of various rusts (Fe-X system) was investigated using a binary-phase potential-pH diagram.…”