Investigation of corrosion products formed on the surface of carbon steel exposed in Banda Aceh's atmosphere

Abstract

This research aims to study the corrosion rate and characteristics of corrosion products of carbon steel due to exposure in the environment of Banda Aceh, Indonesia. The ASTM G50 was used as the basis for the specifications of the specimens for corrosion rate calculation. The corrosion rate was calculated based on ASTM G1. The features of corrosion products studied are morphological features, types, and chemical compounds of the rust. These characteristics were identified using scanning electron microscopy (SEM) and x-ray diffractometer (XRD). The corrosion rate of carbon steel was obtained using the weight-loss method. The study was conducted for twelve months, i.e. January to December of 2018. After one year of exposure, it was found that the highest corrosion rate occurred in the March–April period which was 0.024 mpy and falls into outstanding category of relative corrosion resistance. Various morphological features of corrosion products found during the period of exposure, including worm nest, bird's nest, globular, cotton ball, laminar, lath, bar, needle-shaped, and whisker structures. These structures were lepidocrocite (γ-FeOOH) and goethite (α-FeOOH). During twelve months of exposure, corrosion products formed were dominantly lepidocrocite and goethite. It was found that the lepidocrocite might transform into goethite through prolonged exposure time.

Atmospheric corrosion of carbon steel: Results of one-year exposure in an andean tropical atmosphere in Colombia

“…Floral and plate crystals typical of lepidocrocite and cotton ball structures common to semi-crystalline goethite samples [ 6 , 22 ] were easily identified in all samples. None of the analyzed samples exhibited the magnetite pattern, which consists of flat, dark patches with round disks [ 34 ].

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Integrating the root cause analysis to machine learning interpretation for predicting future failure

“…In contrast, the flowery shape (needle shape) appears in location 2 ( Fig. 7 b) which indicates the presence of the hexagonal of feroxyhyte or δ-FeOOH [ 50 ].…”

Anti-corrosion, anti-bacterial and durable atmospheric weatherability of polydimethylsiloxane coating with intrinsic hydrophobicity

“…For intrinsically hydrophobic PDMS coating, on the contrary, the smooth surface micro-nano scale topography and extremely low surface energy reduces the liquid-solid interfacial contact area and attachment positions, which supplies an effective anti-bacterial performance [42,43]. According to the surface morphology of corrosion products under different magnifications (figure 11(a)), abundant micro-bump and nano-porous structures can be observed which were the most common forms of lepidocrocite [44,45]. The EDS spectra and XRD pattern in figure 11(a) present that the corrosion products were mainly composed of the first formed lepidocrocite (γ-FeOOH) and goethite (α-FeOOH), and small amount of magnetite (Fe 3 O 4 ).…”

“…Figures 11(a) and (b) show the SEM, EDS and XRD results of Q235 carbon steel with and without PDMS coating protection after exposure to atmospheric environment for 30 days. The bare Q235 carbon steel reacted with H 2 O, O 2 in the surrounding environment, forming various oxides on the surface with hierarchical micro-nano structures.According to the surface morphology of corrosion products under different magnifications (figure11(a)), abundant micro-bump and nano-porous structures can be observed which were the most common forms of lepidocrocite[44,45]. The EDS spectra and XRD pattern in figure11(a) present that the corrosion products were mainly composed of the first formed lepidocrocite (γ-FeOOH) and goethite (α-FeOOH), and small amount of magnetite (Fe 3 O 4 ).…”