Simulating Pitting Corrosion in AM 316L Microstructures Through Phase Field Methods and Computational Modeling

This work investigates how the crystallographic features of additive manufactured (AM) microstructures impact the pitting corrosion process through computational simulations of phase field models. Crystallographic influence is explored by introducing orientation dependencies into the corrosion potentials and elastic constants of the model through microstructural data provided from AM 316L samples. Comparisons of evolved pit morphologies and stress responses are made to a standard homogeneous, semi-circular model to better highlight how the complexity of AM microstructures affects pit evolution and stress concentrations. The results illustrate that AM-informed modeling cases produce larger, deeper pits with numerous locations of elevated stress concentrations along the pit front.

Corrosion Inhibition of Carbon Steel in 2.0M HCl Solution Using Novel Extract (Pulicaria undulate)

Plant Pulicaria undulate (PU) extract is examined as a corrosion inhibitor for carbon steel (CS) dipped in 2.0M HCl. The study was conducted utilizing ac impedance spectroscopy (EIS), Mass loss (ML), polarization (PDP) tests, and surface checks were utilized to illustrate the importance of this PU extract to prevent the corrosion process for CS. The influence of temperature and concentration of PU on the efficacy of inhibition were tested. The corrosion mechanism occurs when the PU extract molecules block the active center in the electrode surface. Langmuir isotherm is the isotherm that is applied in the process of adsorption. The effect of temperature at various temperatures on the corrosion efficacy was investigated in case of the presence and absence of the extract. Finally, thermodynamic parameters for the activation and adsorption processes were determined. Results of all methods used were in good agreement.

Evaluation of corrosion in steel reinforced concrete with brick waste

The massive demolition of old buildings in recent years has generated tons of waste, especially brick waste. Thus, a concern of recent research is the use of this waste for the production of environmentally friendly concrete. At the same time, corrosion of the reinforcement steel rebar in classical concrete is a current problem. In this context, in the present paper a study was carried out on the corrosion of metal reinforcement in cement mortars with added brick waste. The corrosion process was analyzed on four compositions of mortars without and with 15%, 25% and 35% brick waste replacing the sand. The brick waste has majority content in SiO2, Al2O3, FeO3 and CaO. The grain size distribution of brick waste was close to that of the sand (dmax = 2 mm). The preparation method of the samples was similar to ordinary mortars. The corrosion action on the rebar in concrete, at different brick waste concentrations, was investigated by electrochemical measurements (polarization curves and electrochemical impedance spectroscopy (EIS)) at 1 month and 26 months. The results obtained at 26 months revealed that the addition of the brick waste in mortar improved the anticorrosion properties in the case of all samples compared with the etalon mortar. The best results were obtained in the case of the sample with 15% brick waste (the efficiency was ≈ 90%). The corrosion intermediary layer formed on the rebar surface was evidenced by SEM-EDX.

Scientific insights of electrochemical replacement approach to describe the origin of Pre-Columbian Peruvian gilded copper-based objects

Pre-Columbian Peruvian goldsmiths developed gilded copper-based objects by ancient techniques that require identification to propose conservation strategies. Lechtman H, conducted experiments to suggest that the electrochemical replacement was the gilding technique used by the Moche and Vicus cultural groups. Despite her remarkable achievement, the quantitative data provided by her is still open to discussion. This work focused on obtaining experimental data to recreate her protocol by introducing less gold precursor. Polished copper pieces were plated with an adherent gold film of up to 7.5 µm after immersing them into an electrolytic solution for 3 min and 6 min at 80 °C. Our results demonstrated that the electrochemical replacement technique gives rise to anodic regions in the plated objects. Further studies around the corrosion process that undergoes these heritage objects in burial and environmental conditions are suggested to determine their deterioration rate. Moreover, electroless and galvanic techniques should be explored in order to improve current approaches.

Evaluation of the corrosion behavior of AZ31 magnesium alloy with different protein concentrations

Purpose The purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L). Design/methodology/approach Electrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film. Findings Experimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance. Originality/value When the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.

Effect of Bacillus megaterium Biofilm and its Metabolites at Various Concentration Biodiesel on the Corrosion of Carbon Steel Storage Tank

Microorganisms in biodiesel storage tanks may generate bio-corrosion due to their hygroscopic and susceptible fuel degradation. The organisms, including Bacillus megaterium present in the hydrocarbons, resulted from the EPS and metabolites processes that subsequently control the corrosion process of the tank. This present study examined the effect of biodiesel concentration on microbial activity through TPC analyzing growth for B. megaterium. Furthermore, this study investigated EPS formation and acid metabolites production by B. megaterium based on SEM observations and acidimetric titration. Meanwhile, this study investigated the microorganism-induced corrosion impact based on gravimetric analysis. The results explained a higher biodiesel concentration in diesel oil promoted an increase in the growth of B. megaterium and the corrosion rate. Conversely, the acid metabolites produced from bacteria under the biofilm did not significantly increase the corrosion rate. Corrosion products resulting from the B. megaterium activity on the surface of the steel included Iron (II, III) oxide (Fe2O3 and Fe3O4). The formation of oxide and pitting may control the strength of the surface tank in the course of biofuel storage, which may lead to the failure of the material.

Corrosion behavior of X80 pipeline steel local defect pits under static liquid film

In this work, the corrosion electrochemical information under different thicknesses of liquid film was tested. The local corrosion development process of X80 steel under different thicknesses of liquid film was studied by combining the detection and analysis of scale and the matrix corrosion morphology. The corrosion was studied by EIS. The composition and microstructures of corrosion scale at different locations were detected by EDS and SEM, and the metal matrix was detected by 3D topography technology to analyze the local corrosion. The results show that a liquid film with a thickness greater than or equal to 1 mm has no effect on the mechanism of the corrosion process, but has a control effect on the corrosion rate and the time of each stage in corrosion. The corrosion process can be divided into two stages: in the early stage, the concentration of ions inside and outside ADP is the same, so the corrosion is uniform; in the later stage, due to the influence of CO2 dissolution and mass transfer distance, the cathodic reaction is mainly outside ADP and the anodic reaction is mainly inside ADP. In addition, corrosion acidification occurs in ADP, which enhances the corrosion process in ADP.