Showing papers on "Carbon steel published in 2020"

Evaluation of corrosion inhibition performance of phosphorus polymer for carbon steel in [1 M] HCl: Computational studies (DFT, MC and MD simulations)

Abstract: Pentaglycidyl ether pentabisphenol A of phosphorus (PGEPBAP) phosphorus polymer was investigated as corrosion inhibition for carbon steel in aggressive solution using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), weight loss (WL), scanning electron microscope (SEM), density functional theory (DFT), electrostatic potential (ESP), radial distribution function (RDF), molecular dynamics (MD) and Monte Carlo (MC) simulations. The higher inhibition efficiencies for PDP, EIS and WL studies at 10−3 M concentration of PGEPBA phosphorus polymer are 94.18 %, 91.79 % and 91.3 %, respectively. ΔEcorr (23.7 mV) value of PGEPBAP phosphorus polymer is lower than 85 mV has been assigned to mixed type inhibitor. PGEPBAP formed protective film on carbon steel surface by adsorption according to Langmuir adsorption isotherm. SEM morphology suggested that PGEPBAP could effectively block acid attack by chemisorption on metal surface. To evaluate the polymer inhibitor and potential mechanism were especially realized DFT, ESP, RDF, MD and MC simulations.

Inhibitive and adsorption behavior of thiadiazole derivatives on carbon steel corrosion in CO2-saturated oilfield produced water: Effect of substituent group on efficiency

Abstract: Three thiadiazole derivatives with different substituent groups, 2-(benzylthio)-5-methyl-1,3,4-thiadiazole(BMT), 2-(benzylthio)-5-(butylthio)-1,3,4-thiadiazole(BBT), and 5-(benzylthio)-1,3,4-thiadiazole-2-thiol(BTT), were synthesized and studied as the corrosion inhibitors for N80 carbon steel in CO2-saturated oilfield produced water. It is found that the synthesized thiadiazole derivatives could effectively inhibit the corrosion of N80 carbon steel by chemisorption. The corrosion inhibition performance of the organic compounds is in the order: BTT > BBT > BMT. The theoretical calculations indicate that the tautomeric transformation from thiol-BTT to thione-BTT may be responsible for the high inhibition performance of BTT.

Synergistic effect of potassium iodide and sodium dodecyl sulfonate on the corrosion inhibition of carbon steel in HCl medium : A combined experimental and theoretical investigation

Abstract: Carbon steel is an important industrial material, but it usually suffers from serious corrosion in the service environment. Using corrosion inhibitors is an effective approach to mitigate corrosion. The synergistic inhibition behavior of sodium dodecyl sulfonate (SDS) and potassium iodide (KI) on carbon steel corrosion in hydrochloric acid medium was investigated by electrochemical test, surface morphology analysis, and molecular simulation approaches. Results show that the corrosion inhibition performance is significantly enhanced after the two substances are compounded, and the inhibition efficiency can reach approximately 96% at small doses. The Tafel polarization curves suggest that the mixtures can be classified as anodic corrosion inhibitors. Impedance tests indicate that the inhibitor molecules are adsorbed on the steel surface, resulting in an increase of charge transfer resistance but a decrease of electric double layer capacitance. The adsorption process follows the Langmuir adsorption isotherm. Molecular simulation calculations further reveal the active sites of SDS and the stabilizing effect that I− plays in the inhibition process. The present research offers an economic, environmentally friendly and efficient measure of corrosion control, and provides theoretical guidance for the efficient use of carbon steels and the development of novel corrosion inhibitors.

Commercial and recycled carbon/steel fibers for fiber-reinforced cement mortars with high electrical conductivity

Abstract: The paper aims to provide a comprehensive study on the compositional optimization of high-conductive multifunctional fiber-reinforced cement mortars (FRCMs). Therefore, the effects of three different fiber types: virgin carbon fibers (VCFs), recycled carbon fibers (RCFs), and brass-plated steel fibers (BSFs), added at a broad range of concentrations, as 0.05%, 0.1%, 0.2%, 0.4%, 0.8%, 1.2%, and 1.6% by volume, on the mechanical, electrical and durability properties of FRCMs have been compared. The results showed that RCFs increase the flexural and tensile splitting strength up to 100%, whereas BSFs improve the compressive strength by 38%. Moreover, the fibers decrease both the capillary water absorption and the drying shrinkage by 39%. Electrical conductivity tests show that RCFs decrease the electrical resistivity of mortars up to one order of magnitude, in addition to a percolation threshold between 0.1 and 0.2 vol%.

Corrosion of Carbon Steel in Marine Environments: Role of the Corrosion Product Layer

Abstract: This article presents a synthesis of recent studies focused on the corrosion product layers forming on carbon steel in natural seawater and the link between the composition of these layers and the corrosion mechanisms. Additional new experimental results are also presented to enlighten some important points. First, the composition and stratification of the layers produced by uniform corrosion are described. A focus is made on the mechanism of formation of the sulfate green rust because this compound is the first solid phase to precipitate from the dissolved species produced by the corrosion of the steel surface. Secondly, localized corrosion processes are discussed. In any case, they involve galvanic couplings between anodic and cathodic zones of the metal surface and are often associated with heterogeneous corrosion product layers. The variations of the composition of these layers with the anodic/cathodic character of the underlying metal surface, and in particular the changes in magnetite content, are thoroughly described and analyzed to enlighten the self-sustaining ability of the process. Finally, corrosion product layers formed on permanently immersed steel surfaces were exposed to air. Their drying and oxidation induced the formation of akaganeite, a common product of marine atmospheric corrosion that was, however, not detected on the steel surface after the permanent immersion period.

Corrosion inhibition of carbon steel in hydrochloric acid solution using newly synthesized urea-based cationic fluorosurfactants: experimental and computational investigations

Abstract: The facile synthesis approach, surface-active properties, and anti-corrosive efficiency of innovative urea-based cationic fluorinated surfactants (FUS) of variable alkyl chain length were investigated. The effect of as-prepared FUS inhibitors on carbon steel corrosion in 15% HCl solution at 20–50 °C was examined using weight loss and various electrochemical methods (open circuit potential (OCP) vs. time, potentiodynamic polarization (PDA) and electrochemical impedance spectroscopy (EIS) methods). The corrosion protection capacities at an optimum concentration (0.5 mM) are 93.2% (FUS-8), 96.3% (FUS-10) and 97.6% (FUS-12) by PDA, comparable to the findings achieved by EIS. PDA measurements indicated that the studied FUS act as inhibitors of mixed-type and chemical adsorption on a carbon steel interface following the Langmuir isotherm model. The thermodynamic and kinetic indices of the corrosion and adsorption processes were estimated and interpreted. Surface examinations by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy and energy dispersive X-ray analysis (FESEM/EDX) revealed the formation of a protecting layer at the carbon steel/HCl interface. Quantum chemical indices (DFT based) delivered more understanding of the inhibition mechanism. Molecular dynamics (MD) simulations were accomplished to explore the configurational adsorption performance of the studied fluorosurfactants on the iron(110) interface. It is supposed that these findings are of some significance for the reasonable design of effective inhibitors for acidic corrosion.

Prediction of re-oxidation behaviour of ultra-low carbon steel by different slag series.

Abstract: A kinetic model was developed using FactSage Macro Processing to simulate the re-oxidation of ultra-low carbon steel via different oxidising slags. The calculated results show good agreement with experimental laboratory thermal simulation data. Therefore, the model can be used to predict the change behaviour of slag-metal-inclusion in the re-oxidation reaction of liquid steel. It can provide prediction and guidance for an accurate secondary oxidation control process. During the slag re-oxidation process, when the oxygen in the steel is supersaturated and the slag is low in oxidation, it can easily form stick-like and dendritic shape inclusions of Al2O3 in steel. As the (FeO) content increases in slag, the oxygen transfer from slag to steel is evident, and the inclusion size increases, showing clusters and spherical shapes. In addition, supersaturated oxygen in steel easily forms unstable Al2O3-TiOx inclusions with [Ti]. As the components of liquid steel tend to be uniform, the Al2O3-TiOx inclusions will decompose and disappear, forming stable Al2O3 and TiO2 inclusions. The number of inclusions can be reduced by increasing the basicity and the ratio of CaO to Al2O3 in the initial slag.