Three years outdoor exposure of low carbon steel in Mauritius

Abstract

Purpose -This paper aims to investigate the corrosion behaviour of carbon steel in the Mauritian atmosphere over a three-year period. Atmospheric corrosion is a serious problem in Mauritius. Design/methodology/approach -Carbon steel samples were exposed outdoors at various sites. Mass loss analysis was performed to determine the corrosion behaviour of the metal over the exposure period. Scanning electron microscopy and Raman tests were performed to investigate the formation of the corrosion products on the carbon steel surface. Findings -It was found that the corrosion loss at two of the sites considered did not vary clearly according to the bilogarithmic law. Time of wetness was found to be a main factor affecting atmospheric corrosion in Mauritius. The corrosivity of the atmosphere was found to lie between categories C3 and C4, according to ISO 9223. Originality/value -The results can be of essential help to the construction industry, especially as steel buildings are becoming very common in Mauritius. Moreover, as Mauritius is a tropical island, the results obtained can be useful in other tropical islands.

Marine atmospheric corrosion of carbon steel in the tropical microclimate of Port Louis

“…A previous study carried out in an S 1 P 1 location in PL, lead to a C4 corrosivity classification. [ 50 ] Despite being situated on the seashore, Cl – deposition rate recorded at this site was much lower than the other sites investigated in the current study. However, the SO 2 level was relatively high, which could be the cause for the more corrosive atmosphere.…”

“…Furthermore, the formation of less adherent corrosion products such as lepidocrocite in high humidity conditions leads to enhanced diffusion of oxygen and water through the rust layer, which is in accordance with data obtained at other locations from previous studies in Mauritius. [ 50 ] However, there is no indication of any highly significant increase in corrosion kinetics during the most humid months for all sites.…”

“…Nevertheless, the build‐up of corrosion products with time would lead to the onset of cracks in the rust layer causing the corrosion rate to rise again. [ 50 ] This may lead to flaking of the outer rust layer, which is generally an agglomeration of crystalline phases, such as lepidocrocite and goethite. The residual rust layer is mainly amorphous FeOOH, which is compact and may contain magnetite and akaganeite.…”

Pitting corrosion of aluminium in the tropical climate of Mauritius

“…Since it is a small island, airborne salinity levels are expected to be high, especially near the coastline. However, having a calm sea shore with coral reefs situated as far as 500 m from the coastline, airborne salinity levels over the island have been found to be in the categories S 0 and S 1 , according to ISO 9223 [2]. Mauritius also has a clean atmosphere.…”

“…Mauritius also has a clean atmosphere. Sulphur dioxide levels have been observed to fall in the categories P 0 and P 1 , according to ISO 9223 [2]. It should be noted that chloride categories S 0 and S 1 refer to airborne salinity deposition rate of less than 3 mg m −2 day −1 and between 4 and 60 mg m −2 day −1 , respectively.…”