Effect of environmental factors on electrochemical corrosion of galvanized steel wires for bridge cables

Purpose This paper aims to investigate the electrochemical corrosion rate of galvanized steel wires for bridge cables. Design/methodology/approach The electrochemical corrosion test and response surface analysis of galvanized steel wires were carried out, and the variety of polarization curves of galvanized steel wires under different corrosion parameters was discussed. The expression of corrosion rate of galvanized steel wires under the action of single and multi-factor coupling was established. Findings The polarization curves of galvanized steel wires under different Cl- concentrations, pH value and temperature were basically similar, but all show different degrees of deviation and some anodic polarization curves had inflection points. For example, when the Cl- concentration reached 3.5%, the corrosion rate of galvanized steel wire was four times that of pure water. Originality/value The influence relationship of single and multi-factor coupling on the corrosion rate of galvanized steel wires was as follows: RCl > RT * Cl > RT > RpH > RpH * T > RpH * Cl.

Selection of rational electrochemical methods for controlling the efficiency of machining of corrosion-resistant steel

The article discusses methods of controlling the processes of mechanical processing based on electrochemical effects. The corresponding anodic polarization curves of 1X18H9T steel obtained in electrolyte solutions without and with stirring are presented. The article discusses methods of machining processes control based on electrochemical effects. Lubricating and cooling technological media (LCTM) used in machining are in most cases electrolytes, therefore, electrochemical processes and phenomena actively occur during contact dynamic machining. It is possible to control the processes of machining by acting on the system elements of the tool - LCTM- part, in particular by activating the LCTM and reducing the strength characteristics of the processed steel in the cutting zone. A reserve for increasing the efficiency of mechanical processing can be the composition selection of the applied LCTM, combined with the simultaneous electrochemical polarization of the treated surface of friction pair parts. It was found that when cutting, the efficiency of machining and the chip shapes are changed, which is explained by the influence of the current density on the strength of the processed steel. In the conditions of machining, complex dynamic processes occur due to the rotation of the work piece and/or tool, so it is necessary to take into account the hydrodynamic phenomena and processes that arise in this case. Electrode potentials are considered to be the most important characteristic of the metal cutting process. The potential of the system can regulate such processes and indicators as wear and surface micro hardness. Anodic polarization curves of the steel 1X18H9T obtained in various electrolyte solutions without stirring and with stirring on a rotating disk electrode are given. The study allowed determining the factors affecting the processes occurring in the cutting zone and to identify rational current densities due to simulating the conditions of real technological processes of the combined steel processing. The increase in the processing intensity of the steel 1X18H9T with the cutting zone polarization is associated with the action of factors activating the selective anodic dissolution of the processed alloy.

Reliability Evaluation of Cu-Al WB in High Temperature and High Current Applications

High reliability harsh environment applications necessitate a better understanding of the acceleration factors under operating stresses. Automotive electronics has transitioned to the use of copper wire for first level interconnects. A number of copper wire formulations have emerged including palladium coated copper and gold-flash palladium coated copper. The corrosion reliability of copper wire bonds in high temperature conditions is not yet fully understood. The EMC used to encapsulate chips and interconnects can vary widely in formulation, including pH, porosity, diffusion rate, composition of contaminants and contaminant concentration. To realistically represent the expected wirebond reliability, there is need for a predictive model that can account for environmental conditions, operating conditions, and exposure to EMCs. In this paper, different EMCs were studied in a high-temperature-current environment with temperature range of 60°C–100°C under current of 0.2A–1A. The diffusion kinetics based on the Nernst-Planck Equation for migration of the chlorine ions has been coupled with the Butler-Volmer equation for corrosion kinetics to create a Multiphysics model. Polarization curves have been measured for copper, aluminum and intermetallics under a number of pH values, and chlorine-ion concentrations. Tafel parameters have been extracted through measurements of the polarization curves.

Experimental and Theoretical Studies of α-Linolenic Acid as Green Corrosion Inhibitor for Carbon Steel in 0.5 M Sulfuric Acid

A component of Salvia hispanica, α-linolenic acid, has been evaluated as a green corrosion inhibitor for 1018 carbon steel in 0.5 M sulfuric acid using weight loss tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Theoretical calculations using Density Functional Theory (DFT) were used also. The results have shown that this compound is a good corrosion inhibitor, with an efficiency which increased with an increase in its concentration up to 600 ppm, but it decreased with a further increase in the concentration. α-linolenic acid formed protective corrosion products layer because it was chemically adsorbed onto the steel surface according to a Langmuir type of adsorption isotherms. Polarization curves have shown that α-linolenic acid is a good, mixed type of inhibitor with a predominant effect on the cathodic hydrogen evolution reactions. EIS measurements indicated a charge transfer-controlled corrosion process. DFT calculations indicated that α-linolenic acid was more efficient in an acidic environment than in a neutral one because has a high tendency to donate electrons and can be easily protonated. In addition to this, it had the highest EHUMO value, the best chemical reactivity, the greatest tendency to transfer electrons and a greater facility of modifying its electronic configuration in the presence of carbon steel specimens according to its chemical hardness value.

Promising Antioxidant and Anticorrosion Activities of Mild Steel in 1.0 M Hydrochloric Acid Solution by Withania frutescens L. Essential Oil

The present study was conducted to evaluate the anticorrosive and antioxidant activities of essential oil from Withania frutescens L. In the present study, the extraction of Withania frutescens L. essential oil (Wf-EO) was conducted using hydrodistillation before being characterized by gas chromatographic analysis (GC/MS) and flame ionization detector (GC/FID). Four bioassays were used for antioxidant testing including 2,2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant capacity (TAC), ferric reducing antioxidant power (FRAP), and β-carotene bleaching. The inhibiting effect of Wf-EO on the corrosion behavior of mild steel in 1.0 M HCl was conducted by using polarization curves and electrochemical impedance spectroscopy techniques. The yield of Wf-EO was 0.46% including 175 compounds identified by GC-MS. The oil was mostly constituted of camphor (37.86%), followed by thujone (26.47%), carvacrol (6.84%), eucalyptol (3.18%), and linalool (2.20%). The anti–free radical activity of Wf-EO was 34.41 ± 0.91 μg/ml (DPPH), 9.67 ± 0.15 mg/ml (FRAP), 3.78 ± 0.41 mg AAE/g (TAC), and 89.94 ± 1.44% (β-carotene). The Wf-EO showed potent antioxidant activity in all bioassays used for testing. The anticorrosion activity, polarization curves as well as EIS diagrams indicated that the Wf-EO exhibited anticorrosive properties and reacted as a suitable corrosion inhibitor in an acidic medium.

Effect of Magnetic Field on the Corrosion of API-5L-X65 Steel Using Electrochemical Methods in a Flow Loop

Limited studies have been conducted on the effect of a magnetic field on the corrosion behavior of steels. Investigating the effect on pipeline material in the oil and gas industries will be beneficial regarding corrosion prediction and control. In this work, the effect of a magnetic field on the corrosion process of API 5L X65 carbon steel was investigated in a well-developed flow loop using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS). Using permanent magnets and a well-designed corrosion electrode set-up, the corrosion mechanism of API 5L X65 steel was studied at different magnetic orientations and different flow conditions in a NaCl solution. The surface morphology of the corroded samples was studied using a scanning electron microscope, and the micro-morphologies of the corrosion deposits and the surface elemental composition were analyzed. The results show that the presence of a magnetic field increases the corrosion rate of API 5L X65 carbon steel, and that flow velocities and magnetic orientation have a significant influence on the anodic corrosion current. The results of the polarization curves indicate a negative shift in the Tafel curve, leading to an increase in the corrosion rate with the introduction of a magnetic field in the flow system. The results of the EIS show that the charge transfer rate is decreased when a magnetic field is applied. This work provides important direction in terms of the understanding of the combined effect of magnetism and flow on the corrosion in pipelines used in the oil and gas industries.