Corrosion Protection Of Low Carbon Steel Research Articles

Camphor tree bark extract as green corrosion inhibitor of LCS in 0.5 M H2SO4 with and without salt effect

AbstractThis work tested the ethanol extract of camphor tree Cinnamomum camphora bark (CTBEE) as a green corrosion inhibitor of low carbon steel (LCS) in 0.5 M H2SO4 with and without the synergistic effect of 4000 ppm NaCl or 800 ppm of KI. The corrosion protection of LCS was significantly increased in the presence of CTBEE‐KI and CBWE‐NaCl blends compared with CTBEE alone, according to data performed by electrochemical impedance spectroscopy (EIS) and electrochemical polarization (EP) analyses. The formation of a film by the blends blocks the LCS surface area, preventing corrosive gradients from reaching its surface. Inhibition efficiency (IE%) of 81% and 89% were obtained in the presence of 800 ppm CTBEE‐4000 ppm NaCl and CTBEE‐800 ppm KI, respectively, compared with IE of 65% in the presence of 800 ppm CTBEE only. A maximum IE% of 89% and 97% were reached after 72 h of immersion in the presence of CTBEE‐NaCl and CTBEE‐KI, respectively. Potentiodynamic experiments indicate that the blends act as mixed‐type inhibitors. The inhibition efficiency of CTBEE, CTBEE‐KI, and CTBEE‐NaCl remained effectively high during the testing period of immersion time, which proved the excellent stability of CTBEE in the corrosive acidic media.

Experimental and DFT Atomistic Insights into the Mechanism of Corrosion Protection of Low-Carbon Steel in an Acidic Medium by Polymethoxyflavones from Citrus Peel Waste

Developing green anticorrosive films is gaining great attention in science and engineering. Citrus fruit peels are mainly discarded as waste, although they can be an excellent repository of phytochemicals, that can be exploited as mitigating agents for corrosion. Herein, we report the high anticorrosion activity of a citrus extract for low-carbon steel in 1 M HCl solution at different temperatures. The main extract constituents were identified by MS and NMR. Two polymethoxyflavones (PMFs), namely nobiletin and heptamethoxyflavone, were identified as major constituents of the extract and the crude PMFs-based extract was investigated for corrosion protection. Using potentiodynamic polarization, weight loss and electrochemical impedance spectroscopy (EIS) methods, this extract revealed improved inhibition efficiency of 94%. The inhibition mechanism was elucidated by considering electrochemical kinetics and adsorption thermodynamics. SEM and UV–vis supported the electrochemical results. PMFs-based extract acted as a mixed-type inhibitor with a Langmuir model of adsorption. Importantly, DFT simulations provided atomic-level insights into the inhibition mechanism and unraveled donor-acceptor interactions between the methoxy groups of PMFs and iron atoms, facilitating the formation of a stable inhibition adsorption layer, and thus supporting the experimental findings. In addition to the physical barrier effect of PMF inhibitor, π-back bonding effect between PMF and steel was suggested.

Interplay of Hydrophobic Thiol and Polar Epoxy Silicate Groups on Microstructural Development in Low-Alcohol, Crosslinked Sol–Gel Coatings for Corrosion Prevention

We have demonstrated that our patented, crosslinked, sol–gel, epoxy–thiol silicates made from the combination of (a) tetraethoxysilane (TEOS, T), 3-glycidoxypropyltrimethoxysilane (GPTMS, G), and the (b) sulfur-containing 3-mercaptopropyltrimethoxysilane (MPTMS, S) with TEOS in a 1:1 stoichiometric ratio form the 1:1 TGST (crosslinked epoxy and thiol silicates) coating, which can be successfully utilized for the corrosion protection of low-carbon steel. Alcohols that are a by-product of sol–gel reactions influence the network formation, crosslinking density, and formulation stability, are volatile organic contents, and are regulated in the coatings industry. To improve environmental sustainability, a series of low-alcohol (LA) formulations with TG:ST ratios of 3:1 to 1:3 was prepared to investigate the microstructural development and crosslinking reactions emerging from the interplay of the hydrophobic thiol and polar epoxy silicates induced by the low-alcohol environment. The impact on crosslinking density was characterized by Fourier Transform Infrared (FTIR), Raman, XPS, viscosity, and pot-life measurements. Low-alcohol TGST (LA(TGST)) formulations were compared, using the example of 1:1 TGST, to corresponding TGST formulations where alcohols were retained. The reduced impact of LA(TGST) formulations on global warming was quantified. The glossy and scratch-resistant LA(TGST) coatings showed 71% enhanced corrosion protection compared to the non-crosslinked hybrids.

Corrosion protection in saline environment of a carbon steel coated (aluminum & three-layer painting system) by eats

This paper presents a comparative study on corrosion protection of low-carbon steel coated with two different painting systems. The first set of samples was coated with an aluminum layer of primer deposited by Electric Arc Thermal Spray (EATS), after which two additional layers of paint were applied, thereby creating an aluminum-painting system; while the second set of samples was coated with the traditional three-layer painting system (zinc-rich layer of primer). Afterwards, all the samples were exposed to the salt spray chamber. The samples were monitored to record their reactions in the corrosive saline environment. Scanning Electron Microscopy (SEM), adhesion and electrochemical corrosion tests were performed to characterize the coatings and report changes in their properties (adhesion, topography and homogeneity), which are related to exposure time. The three-layer painting system barely complied with manufacturer claims on protection time under corrosive conditions; on the other hand, the aluminum-painting system yielded better results by prolonging protection time.

Conducting polyaniline/nano-zinc phosphate composite as a pigment for corrosion protection of low-carbon steel

Zinc phosphate (Zn3(PO4)2) nanocrystals were synthesized and used for making conducting polyaniline/nano-zinc phosphate composite by chemical oxidative method. The product was characterized by UV–visible absorption spectroscopy. The crystal structure, morphology and thermal stability of the product were studied by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermo gravimetric analysis, respectively. The epoxy-based paint containing conducting polyaniline/nano-zinc phosphate composite pigment was applied on low-carbon steel samples. Corrosion protection performance of the painted low-carbon steel samples in 3.5 mass % sodium chloride solution was evaluated using electrochemical technique. Transmission electron microscopic image revealed the formation of core shell structure of the composite. Composite was found to be more thermally stable than the conducting polyaniline. The corrosion rate of conducting polyaniline/nano-zinc phosphate-painted low-carbon steel was found to be 5.1 × 10−4 mm per year, about 34 times lower than that of unpainted low-carbon steel and 10 times lower than that of epoxy nano-zinc phosphate paint-coated steel. The study reveals the possibility of using conducting polyaniline/nano-zinc phosphate as a pigment for corrosion protection.

New architectured hybrid sol-gel coatings for wear and corrosion protection of low-carbon steel

The replacement of expensive stainless steel in various socio-economic sectors such as mechanical or alimentary is an issue that would be possible to solve by developing a protective coating on low-carbon steel. In these applications, complex pieces are in contact with different kinds of fluids, with or without particles when functioning. Consequently, the expected coating function is to effectively protect the equipment from corrosion, abrasion and erosion. In this work thin hybrid coatings obtained by the sol-gel process have been developed for corrosion and wear protection on low-carbon steel. This innovative system is constituted of alumino-silicate epoxy based sol-gel coatings acting as barrier layers which, when loaded with zirconia particles, improve the mechanical properties. Taking into account the specificity of the carbon steel, we developed two architectured coatings displaying corrosion and wear protection. They are built by superposition of a bi-layered hybrid primer coating and a mono-layered zirconia loaded hybrid coating. Using two different zirconia contents, 30 wt.% and 40 wt.%, thin coatings of 5 and 10 μm are achieved. What is of interest is that the combination of antiwear tests and EIS to evaluate the influence of abrasive wear on anticorrosion properties has, for the first time, been demonstrated on such thin hybrid sol-gel coatings. The loss of corrosion protection of the lower zirconia loaded coating was attributed to the formation of localized defects after removal of material. On the contrary, the higher zirconia loaded coating demonstrated an interesting corrosion and wear behavior with the formation of a compacted layer at the top of the outer layer providing a barrier effect against water and ion permeation. To further characterize the protective systems, the morphology and the microstructure of the coatings were investigated by scanning electron microscopy.