Characterization of the Corrosion Products Formed on Carbon Steel in Qinghai Salt Lake Atmosphere Available to Purchase

The corrosion products formed on carbon steel exposed to the Qinghai Salt Lake atmosphere for 12 months was studied using scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), x-ray diffraction (XRD), infrared transmission spectroscopy (IRS), and electrochemical techniques. The rust was mainly composed of akaganeite (β-FeOOH), iron hydroxy-chloride (Fe₈[O,OH]₁₆Cl_1.3), and a little lepidocrocite (γ-FeOOH). Amorphous δ-FeOOH was only on the downward surface, and the upward surface was corroded more severely than the downward surface. Cl, Mg, and Si foreign elements were rich in the rust. The rust on carbon steel decreased anodic dissolution and increased cathodic current. A low free corrosion potential of the rusted electrode and a very small value of rust resistance (R_R) demonstrated that the rust was nonprotective in the Qinghai Salt Lake atmosphere.