Atmospheric corrosion of zinc in coastal atmospheres

Abstract

The atmospheric corrosion of zinc in pure marine coastal atmospheres has not been extensively studied. This paper presents the results obtained in six pure marine atmospheres located at different distances from the seashore in the same coastal area with annual chloride deposition rates of between 47 and 1142 mg · m−2 · day−1. Zinc specimens were exposed for 3, 6, 9, and 12 months in two annual exposure sequences starting 6 months apart. Tests were performed to determine the corrosion rate and its evolution with exposure time. Quantitative (Rietveld) grazing X‐ray diffraction and X‐ray photoelectron spectroscopy (C 1s) were applied to analyze the corrosion products formed. Scanning electron microscopy/energy dispersive X‐ray spectrometry were employed to study the morphology of the corrosion layers. The most relevant findings of this study are: (a) the presence of hydrozincite [Zn5(CO3)2(OH)6]; (b) the aqueous precipitation can be a major controlling factor of the atmospheric corrosion of zinc in atmospheres with low chloride deposition rates (30–50 mg · m−2 · day−1); and (c) the formation of zinc hydroxysulfates also takes place due to the presence of sulfate ions in the marine aerosol.

Physicochemical studies of galvanized steel corrosion in urban, industrial, and marine environments, and corrosion mapping of Karachi city: An important coastal city of the 21st‐century modern maritime silk route

“…SEM, scanning electron microscopy Numerous investigations have reported the characterization of the corrosion products on galvanized steel upon exposure to the atmosphere. [14,[39][40][41] The present study agreed well with the findings of other studies where morphologies usually found were platelets or hexagonal type or spherically aggregated simonkolleite, needle-like structure, or flatten the dark surface of hydrozincite. [14,[39][40][41] 3.5.2 | FTIR spectroscopy Figure 9 shows infrared spectra and Table 5 depicts the FTIR characteristic bands of the corrosion products formed on galvanized steel exposed at the urban, industrial, and marine test sites located in Karachi coastal city.…”

“…[14,[39][40][41] The present study agreed well with the findings of other studies where morphologies usually found were platelets or hexagonal type or spherically aggregated simonkolleite, needle-like structure, or flatten the dark surface of hydrozincite. [14,[39][40][41] 3.5.2 | FTIR spectroscopy Figure 9 shows infrared spectra and Table 5 depicts the FTIR characteristic bands of the corrosion products formed on galvanized steel exposed at the urban, industrial, and marine test sites located in Karachi coastal city. It was found that the corrosion products formed on galvanized steel exposed at all the test sites were F I G U R E 7 SEM images of the galvanized steel after 12 months of exposure at the industrial (T 6 and T 7 ) and marine test sites (T 8 -T 10 ) located in Karachi coastal city.…”

“…The presence of Na + ions in this compound indicates the exposure to a marine environment. [41] 4 | CONCLUSIONS This study project is the continuation of our previously reported work about corrosivity of Karachi city. [43] T A B L E 3 A comparison of the scanning electron microscopy (SEM) results indicating morphologies of corrosion products formed on galvanized steel after 12 months of exposure at the urban (T 1 -T 5 ), industrial (T 6 and T 7 ), and marine (T 8 -T 10 ) test sites of Karachi coastal city Test sites SEM images Morphologies of corrosion products formed on galvanized steel This study has accomplished the physicochemical characterization of the corrosion products formed on galvanized steel exposed at urban, industrial, and marine test sites located in Karachi coastal city.…”

Corrosion and Structural Properties of Erbium–Zinc Thin Films at Low‐to‐Medium Erbium Concentrations

“…This causes the deposition of a Zn layer on top of the steel alongside several Fe–Zn intermetallic layers which create a protective barrier from the environment . The Zn layer itself is corrodible by ambient air, creating several corrosion products depending on the environment of the workpiece limiting the coatings life time . These corrosion products, on the contrary, can also contribute to the corrosion protection in particular if they are forming insoluble products that have a large volume and may reduce access of water and oxygen to the plane surface or into scratches.…”

“…These corrosion products, on the contrary, can also contribute to the corrosion protection in particular if they are forming insoluble products that have a large volume and may reduce access of water and oxygen to the plane surface or into scratches. Such products can be zinc carbonate, hydrozincite, akaganeite, or simonkolleite …”