A Study on the Initial Atmospheric Corrosion Behaviors of Carbon Steel Exposed to Urban and Marine Atmospheres in Cambodia

摘要

The atmospheric corrosion behaviors of carbon steel have been studied by one-year exposure test in urban, Phnom Penh, and marine, Sihanoukville, atmospheres in Cambodia. The morphology, crystalline phase, and the cross-sections of corrosion product were characterized. The annual corrosion rates in Phnom Penh, and Sihanoukville was approximately 9 μm y~(-1) and 27 μm y~(-1), respectively. According to the category of corrosivity classification ISO 9223, Phnom Penh is classified as a low corrosive atmosphere (C2 category), while Sihanoukville is classified as the medium corrosive atmosphere (C3 category). The severe corrosion attack in Sihanoukville resulted from the airborne salinity, which contained higher concentrations of Cl~- in this marine atmosphere along with the longer time of wetness, while the Phnom Penh atmosphere contained less chemical species with a short time of wetness. The formation of rust layer in the Phnom Penh was more adherent and compact than that in Sihanoukville thus the corrosion resistance of metal in the Phnom Penh was higher than that in the Sihanoukville atmosphere.