Potentiodynamic Polarization Analysis Research Articles

Synthesis and characterization of selenium-polyvinyl alcohol nanoparticles as eco-friendly corrosion inhibitor for carbon steel in 1.0 M H2SO4

Selenium nanoparticles capped with polyvinyl alcohol (Se-PVA NPs) have been synthesized by chemical reduction using ascorbic acid as a reducing agent. The synthesized nanoparticles were characterized using XRD, DLS, zeta potential, FT-IR, and TEM analysis and found to be stable. The solution of Se-PVA NPs was used as a carbon steel corrosion inhibitor in 1.0 M H2SO4. The effect of the presence of Se-PVA NPs in the corrosion medium was studied by potentiodynamic polarization and gravimetric analyses In the presence of Se-PVA NPs with a concentration of 600 ppm at 303 K, corrosion inhibition efficiency values of 92.86 % and 92.3 % were recorded by potentiodynamic polarization and gravimetric analysis methods, respectively. Over the Se-PVA NPs concentration range 100–600 ppm, it was found that increasing the concentration increases the inhibition efficiency, while the temperature has an adverse effect, inhibition efficiency values of 80.0 % was recorded at 323 K for the 600 ppm Se-PVA NPs solution. The potentiodynamic polarization measurements suggested that Se-PVA NPs work as a mixed-type inhibitor. The corrosion inhibition process was confirmed by testing the used specimens’ metal surface using SEM and AFM techniques, which showed that the acidic medium’s negative impact (distortion and roughness) on the carbon steel surface was reduced significantly in the presence of Se-PVA NPs. The inhibitor’s adsorption on the metal surface was studied. It obeys the Langmuir isotherm with a mixed-type adsorption process. The related kinetic and thermodynamic parameters were investigated.

An investigation on the mechanical and corrosion protection properties of poly(arylene ether nitrile) reinforced epoxy coating

To follow the current industrial demand, epoxy coatings which feature extraordinary comprehensive properties have been considered as a versatile and promising thermosetting resin for application in various middle and high-end sectors of multitudinous industries. Regrettably, epoxy coatings possess the inherent shortcoming of poor durability to external force and deformation, severely restricting further introjection in various fields. Herein, this study employs poly(arylene ether nitrile) with bisphenol A structure (PENBA) as superior intensifying agent to ameliorate the toughness and corrosion resistance of brittle epoxy coatings. As a linear thermoplastic polymer with satisfying mechanical performances, PENBA serves as epoxy's energy-dissipating medium and forms a semi-interpenetrating polymer network (SIPN) with epoxy matrix, efficiently impeding epoxy's fracture and crack propagation. As a result, the tensile strength, elongation at break, impact strength, and flexural strength of PENBA-modified epoxy possess considerable increments of 214 %, 360 %, 148 %, and 295 % in sequence by contrast with the pristine epoxy. Meanwhile, according to the potentiodynamic polarization analysis, the PENBA with outstanding chemical resistance also significantly promoted the epoxy's corrosion resistance, endowing the epoxy coating with the most positive Ecorr and icorr of −0.453 V and 9.439 × 10−10 A/cm2 when PENBA reached 15 % (mass percent) at the end of entire soaking process.

New insights into the mechanism causing the loss of anti-corrosion property of superhydrophobic titanium surfaces

In this paper, we provide new insights into the mechanism causing the loss of anti-corrosion property of superhydrophobic titanium (SHP Ti) during potentiodynamic polarization (PDP) measurements. The water contact angle and sliding angle values of the SHP Ti, produced by a facile two-step process: anodizing and coating, were >160° and 6±2°, respectively. The anodization of Ti resulted in randomly distributed micro-clusters of TiO2-xCly covering the Ti surface homogeneously while the low surface energy organic coatings were inhomogeneous in coverage and specifically distributed over the micro-clusters alone of the anodized titanium surface. The electrochemical impedance (EIS) analysis of the SHP CP-Ti samples has shown more than an order of magnitude improvement in their barrier /polarization resistance (Rp) values at ∼ 100 MΩ.cm2 suggesting the effectiveness of the SHP coatings as a barrier against corrosion in neutral chloride environments. However, the Rp values (∼ 10 M Ω.cm2) of the SHP coatings obtained from the PDP analysis were an order of magnitude lower than the Rp values derived from the EIS. SHP CP-Ti samples showed dual passive range behaviour with an initial narrow passive region due to the porous anodized TiO2-xCly layer while the later stage passivity due to the barrier TiO2 layer, where the outer anodized porous TiO2-xCly layer was less effective against corrosion in neutral chloride media. Detailed analysis showed that in PDP, the sample lost its SHP because of the permeation of electrolyte into the hierarchical surface, due to its sensitivity to polarization, owing to the lower thickness of the organic layers. The mechanism involved in the loss of SHP and the limitation of the PDP technique for the corrosion analysis of SHP / organic coatings on metal surfaces is highlighted.

Novel high-performance and cost-effective green inhibitor based on fundamental theoretical evaluations combined with electrochemical/surface examinations of Arachis hypogaea shell extract for pipeline steel corrosion in 1 M H2SO4 solution

Traditional corrosion inhibitors have been frequently used for metal protection against strong acids. However, most of them are hazardous compounds with high costs. Therefore, due to the strict environmentally friendly regulations, green and low-cost compounds from renewable sources have gained high consideration in recent applications. In the present study, the Arachis hypogaea shell extract, commonly called groundnut, a cost-effective was selected to inhibit API X 65 pipeline steel corrosion in 1 mol·L−1 H2SO4 solution. The Arachis hypogaea shell composition was examined by FTIR analysis. The Arachis hypogaea shell on pipeline steel in H2SO4 solutions was studied via gravimetric, potentiodynamic polarization, and surface analysis (SEM and EDX). Electron donor atoms present in the Arachis hypogaea shell extract molecules is responsible for its adsorption on the surface of the metal. Experimental study shows that with increasing Arachis hypogaea shell concentrations, the inhibition tendency increased and reached 98.84% at 4 g L−1 after 24 h. Arachis hypogaea shell extract behaved as mixed-type inhibitor, and the surface coverage fits the Langmuir isotherm, signifying that the steel surface was covered by a monolayer of inhibitor molecules without intermolecular interactions. SEM analysis shows that Arachis hypogaea molecule adsorption on the metal surface reduced considerably its dissolution rate resulting in a smooth and clean surface with few damaged areas. The use of water for extraction of Arachis hypogaea shell exhibiting inhibition efficiency, non-toxic, and cost-effective than other green inhibitors, proposes the Arachis hypogaea shell as an excellent green inhibitor for API X 65 steel corrosion in 1 mol·L−1 H2SO4 solution.

Sonication assisted superior anti-corrosion properties of cathodically deposited novel nickel-graphene oxide-zinc oxide coating

This study details the sonication-assisted synthesis and characterization of a cathodically deposited novel nickel-graphene oxide -zinc oxide (Ni-GO-ZnO) composite coating achieved through electrodeposition and its comparison with anodically deposited GO. This coating was comprehensively characterized using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM) coupled with Energy-dispersive X-ray spectroscopy (EDAX). Subsequently, its corrosion resistance for MS1010 mild steel in 3.5 wt % (NaCl) was evaluated via weight loss, contact angle, electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization, and surface analysis techniques. These observations suggest that graphene oxide-zinc oxide (GO-ZnO) adsorbs nickel onto the MS surface effectively and reduces defects, which helps in blocking active corrosion sites. Tafel plots and EIS revealed that the Ni-GO-ZnO coating exhibited the lowest current density (39.95 µAcm²) and the highest charge transfer resistance (1211 Ωcm²). This was further validated by long-term immersion testing, where the Ni-GO-ZnO coating exhibited significantly less weight loss (1.33 mils/Y) compared to the deposited GO coating (2.2 mils/Y). The mechanism of formation of deposited GO and Ni-GO-ZnO coating on the metallic surface is proposed. The enhanced corrosion resistance of the Ni-GO-ZnO coating is attributed to its ability to 1) form a more compact metallic layer and 2) Minimize the active surface area vulnerable to corrosion attack. 3) Diminishes the presence of holes and cracks for corrosive ion ingress.4) Functionally impedes the ingress of chloride ions, primarily liable for steel degradation. The synergistic effect of the GO-ZnO constituents within the nickel matrix significantly enhances the long-term durability and integrity of the protective layer, a phenomenon hitherto unexplored. The empirical outcomes advocate for the advanced application of GO-ZnO-nickel coatings in safeguarding infrastructural materials against corrosive degradation.

Electrochemical corrosion behaviour of UNS S32205 duplex stainless steel dependent on sigma phase precipitation

Abstract In this study, the microstructure and electrochemical corrosion behavior of the UNS S32205 alloy were investigated. Firstly, the phase diagram of the studied samples was determined by Thermo-Calc 2022 software, and the solution treatment temperature was designated. The studied samples were cooled by various cooling rates following the solution treatment at 1050 °C for 30 min. The samples were characterized by optical microscope, scanning electron microscope, and XRD analysis. Also, electrochemical corrosion behavior was investigated by potentiodynamic polarization, cyclic potentiodynamic polarization and electrochemical impedance spectroscopy analyses. Microstructural examinations revealed that decreasing cooling rate causes the precipitation of the sigma phase, and the ratio of the sigma phase was increased up to 29 % by the decreasing cooling rate. Furthermore, it was determined that precipitation of the sigma phase reduces the E pit values, and the sample with the highest amount of sigma exhibits the lowest corrosion resistance. On the other hand, presence of the sigma changed the electrochemical impedance spectroscopy behavior of the UNS S32205 and double-layered model fit the results.

Development and electrochemical investigations of enhanced corrosion-resistant Polyvinylcarbazole-TiO2 hybrid nanocomposite coatings on 316L SS for marine applications

The present study focuses on evaluating the corrosion resistance of 316L stainless steel substrates with Polyvinylcarbazole (PVK)/TiO2 hybrid nanocomposite coatings (HNC). Using the chronoamperometry approach, the HNC were electrochemically synthesized on 316L stainless steel substrates, incorporating various weight (%) 1 %, 2 %, 3 % of TiO2 nanoparticles into the PVK matrix. The findings of the surface morphology investigation verified that the 316L SS had a dense and smooth PVK/TiO2 coating. A low surface roughness and high contact value of the PVK/TiO2 coatings are also responsible for the decrease in corrosion rate of the 316L SS. The corrosion protection efficiency of the PVK/TiO2 HNC were investigated through open circuit potential (OCP) measurement, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) analysis in 3.5 wt% NaCl solution. The corrosion rate obtained from the polarization studies of the HNC coatings as follows PVKT-2 < PVKT-3 < PVKT-1 < PVK < 316L SS. Results revealed that an optimal loading of 2 wt% TiO2 nanoparticles significantly enhanced the corrosion resistance of the coating. The enhanced electrochemical impedance response for PVK/TiO2 coatings was verified by EIS experiments. The study demonstrates that the incorporation of TiO2 nanoparticles into the PVK matrix effectively creates a barrier layer at the coating-metal interface, inhibiting the entry of aggressive ions. Microhardness studies revealed the increase in hardness value of the PVK and PVK/TiO2 coatings indicated the protective nature of the coating and provided high mechanical strength to 316L SS. The tape adhesion tests carried out on the coated specimens also indicated a good adhesion of the PVK/TiO2 on the 316L SS surface.

Photoelectrocatalytic and photocorrosion behavior of MoS2- and rGO-containing TiO2 bilayer photocatalyst immobilized by plasma electrolytic oxidation

TiO2-based bilayer photocatalysts including MoS2 light-absorbing and rGO conductive layers were immobilized on titanium supports using the plasma electrolytic oxidation process. Their properties were studied to find out the photoelectrocatalytic activity and photocorrosion stability. Investigating the immobilization process revealed that the formation of the bilayer structure increased the photocatalyst's surface porosity, thickness, and roughness. The preparation of the MoS2/TiO2 and rGO/TiO2 layers synergistically enhanced the light-harvesting capability of the photocatalyst in the visible region and slowed down the recombination of the photoinduced charge carriers. The bilayer photocatalyst improved the photoelectrodegradation kinetics of methylene blue pollutant by 1.6 times under 100 W xenon irradiation and 5 V applied bias. Evaluating the photocorrosion stability in sulfate medium by potentiodynamic polarization and electrochemical impedance spectroscopic analysis confirmed that the polarization resistance of the bilayer photocatalyst improved by 4.5 and 3.8 times compared to the pure TiO2 photocatalyst under dark and xenon light, respectively. Moreover, the Mott-Schottky experiment denoted that the corrosive ion adsorption was reduced in the bilayer photocatalyst.

Elucidating the mechanisms of novel thiazole-based corrosion inhibitors in carbon steel/HCl interface: An integrated approach combining experimental and computational studies

Corrosion inhibitors serve as a paramount strategy in the domain of metal protection. This study investigates the efficacy of two thiazole derivatives, namely methyl (E)-5-(4-chlorophenyl)-2-((2-(1-hydroxynaphthalen-2-yl)vinyl)amino)thiazole-4-carboxylate (ThN), and methyl (E)-5-(4-chlorophenyl)-2-((2-hydroxystyryl)amino)thiazole-4-carboxylate (ThP) in mitigating corrosion of carbon steel in a 1 mol/L hydrochloric acid medium. Electrochemical Impedance Spectroscopy (EIS), Potentiodynamic Polarization (PDP), Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), and X-ray Diffraction analysis (XRD) were used to experimentally assess the corrosion inhibition performance of compounds under study. Experimental results revealed a concentration-dependent increase in the corrosion inhibition efficiencies of the thiazole derivatives, with ThP achieving 90 % and ThN attaining 93 %. The adsorption of both compounds adhered to the Langmuir adsorption model, indicating a physicochemical inhibition mechanism. PDP analyses revealed a mixed-type inhibitory behavior. Furthermore, SEM-EDX assessments validated the ability of the thiazole derivatives to enhance corrosion resistance. XRD studies revealed a marked decrease in corrosion-associated peaks upon the introduction of thiazole derivatives. The potential of zero charge (PZC) for the carbon steel was ascertained via EIS, clarifying the adsorption mechanism. Employing Conductor like Screening Model for Realistic Solvents (COSMO-RS), the solvation properties of the compounds were evaluated, while Quantum Chemical Calculations (QCCs) and Molecular Dynamics (MD) simulations contributed insights into reactivity descriptors and adsorption configurations on the Fe(110) surface. This study highlighted the impact of the aryl group on the adsorption and corrosion inhibition characteristics of investigated compounds, offering valuable guidance for future design and development.

Potentiodynamic polarization analysis with various corrosion inhibitors on A508/IN-182/IN-52M/308L/316L welds

In this study, dissimilar metal welding of A508/IN-182/IN-52M/308L/316L was employed in the fabrication of pipe nozzles for pressure vessels in pressurized water reactors (PWR). This process involved the fusion of low-alloy A508 and stainless steel 316L using gas tungsten arc welding (GTAW) welding, with the use of nickel-based alloy Inconel 182 as a filler material. Additionally, Inconel 52M served as an overlay layer, and material 308 acted as a buffer layer to facilitate bonding between 316L and the overlay welding layer. The primary objective of this study was to investigate the electrochemical aspects of galvanic corrosion and analyze the surface properties of dissimilar welds in a simulated PWR environment, specifically in a simulated hot water (SHW), over a three-month period. Potentiodynamic polarization tests were conducted on the testing solution, which contained a mixture of inhibitors, including sodium molybdate (Na2MoO4) and sodium nitrite (NaNO2). The surface morphology was thoroughly examined using optical microscopy and scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), while phase analysis was performed using x-ray diffraction (XRD) testing. The results indicated that the most efficient inhibitor combination treatment for dissimilar metal welds achieved an 89.98 % reduction in corrosion on A508 metal. This was accomplished by utilizing a mixed concentration of 6000 ppm sodium molybdates combined with 4000 ppm sodium nitrites. As a result, the corrosion rate of A508 decreased significantly from 0.475 mpy to 0.047 mpy, bringing it in line with the corrosion potential of other alloys and establishing a passive zone. In summary, the corrosion rate of A508/IN-182/IN-52M/308L/316L in PWR simulations decreased as the concentration of corrosion inhibitor, specifically sodium molybdate and sodium nitrite, increased. When the inhibitor dosage concentration was optimized, a protective thin molybdenum-containing film formed on the surface, effectively guarding against random pitting caused by galvanic corrosion.

Faradaic efficiency and anodic electrochemical behavior of Fe electrocoagulation: The role of co-existing ions and ultrasonic assistance

Anodic passivation is a key factor affecting the Faradaic efficiency of Fe electrocoagulation. In practice the electrolyte nature of water matrix played a critical role in governing the Faradaic efficiency. In this study the effect of co-existing ions and ultrasonic field on the Faradaic efficiency and the electrochemical behavior of iron anodes was investigated. The results showed that in Cl− and SO42− solution Fe anode exhibited a typical characteristic of dissolution with a high Faradaic efficiency (>90 %), but severe passivation appeared in NO3− solution with a low Faradaic efficiency (4 %). However, adding Cl− can impair the passivation effect of NO3−. As the Cl−: NO3− ratio increased to 1:10, the Faradaic efficiency significantly increased to 90.65 %. Potentiodynamic polarization and electrochemical impedance spectroscopy analysis showed that the thickness of the passive film decreased and the corrosion rate increased, and thus promoting the anodic dissolution. In addition, ultrasonic field was introduced to assist electrocoagulation. In 50 mM NaNO3 + 2.5 mM NaCl solution, the Faradaic efficiency was only 12 % without ultrasonic assistance, but it increased to 60.9 % when the ultrasonic power was 180 W. Therefore, ultrasonic assistance was beneficial to reduce the anodic passivation and increase the Faradaic efficiency.

Thorn apple (Datura stramonium) extract acts as a sustainable corrosion inhibitor for zinc alloy in hydrochloric acid solutions

The inhibition effectiveness of diverse concentrations of Datura Fruit Extract (DFE) on the corrosion of zinc in 0.05–0.1 M HCl solutions was examined by weight loss (WL), Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization (PDP), and surface analysis techniques. The mass loss method's results demonstrated that raising the DFE concentration improved the efficiency of the inhibition. The maximum inhibition efficiency was 99.40% at 2.0 g/L of DFE. In the temperature ranging from 303 to 333 K, the effect of temperature on the corrosion behavior while adding DFE was also investigated. A DFE extract had been adsorbed on the surface of the metal by Langmuir adsorption isotherm models. It was established that the DFE's activation parameters and negative Gibb's free energy show that rates of adsorption have been spontaneous. According to polarization analysis, DFE regulates both the cathodic and the anodic response. Images obtained using a SEM (Scanning Electron Microscope) reveal that the DFE reduces surface damage. The adsorption inhibition mechanism is supported by the AFM analysis findings. FT-IR (Fourier transform infrared) spectroscopy has been utilized to ascertain the functional group of the DFE. All of the applicable approaches' experimental findings are in good agreement.

Development of Novel Coating on Metallic Bipolar Plates for Proton Exchange Membrane Water Electrolyzer Application

Considering the demand for a more environmentally friendly system, renewable and sustainable energy sources, such as wind and solar power are regarded as a promising substitute for fossil fuels in the generation of electricity. Since these energy sources exhibit intermittency and unpredictability, there is a need to develop a highly efficient and rapidly responsive energy conversion system for the purpose of storing this energy as a chemical fuel. Due to their ability to manage the variability of intermittent energy sources, proton exchange membrane electrolyzer cells (PEMECs) are garnering considerable interest. However, their broad commercial adoption is hindered by their relatively modest performance and elevated costs. PEM electrolysis is a promising technology for generating substantial quantities of hydrogen from surplus electricity generated by renewable sources. Nonetheless, the expense of the electrolyzer stack arises primarily from the metallic bipolar plates, because it possesses heavy weight and expensive precious metal coatings. Significant efforts have been performed on the development of titanium-based bipolar plates, but it has high base material and fabrication cost. In recent years, there has been a substantial focus on stainless steel bipolar plates for PEM electrolyzer application. Stainless steel can serve as an alternative, but it requires a coating to enhance its anti-corrosion properties. Electroplated chromium coatings exhibit favorable mechanical characteristics and find extensive application in precision mechanical components such as molds and surgical instruments. Their outstanding wear resistance, high hardness, impressive corrosion resistance, and glossy finish make them appropriate for many other applications, including both decorative and functional coatings. As a result, chromium electroplating has emerged as one of the most extensively employed techniques within the electroplating sector. The dense pack chromium layer is prepared on a 316L stainless steel substrate to enhance the anti-corrosion property and electronic conductivity.Herein, the role of gold striking underlayer, and thick chromium coating is studied for preparing the anti-corrosive stainless steel bipolar plates. First, a gold striking film as an underlayer on the stainless-steel substrate is electroplated to passivate the chromium-based oxides. Further, a thick and dense chromium layer is deposited on the gold underlayer by electroplating. The electroplating bath is operated using platinized titanium felt as an anode and 316L stainless steel as a working electrode without the separation of anodic and cathodic compartments. The electroplating solution is consisting of Cr (VI) oxide and H2SO4 (pH = 2). The nanocrystalline chromium coating with a thickness of approximately 2 µm is bright and uniform. Furthermore, gold as a protective layer of thickness approximately 1 µm is coated by electroplating on the chromium surface. The Cr and Au/Cr coatings are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS) analysis. Subsequently, the protective layer-coated substrates were analyzed in a simulated PEM electrolyzer environment, and these coatings facilitated promising protective properties on the stainless-steel substrate. The corrosion testing was carried out in 0.5 M H2SO4 + 2 ppm HF solution at 70 0C purged with oxygen. The stable passive film and high corrosion resistance were obtained by gold striking underlayer and chromizing the 316L stainless steel substrate. As a result, the potentiodynamic polarization analysis showed the corrosion current density of 0.84 µA/cm2 for the Au/Cr-Au underlayer sample in a simulated operating environment. In contrast, the absence of the gold striking underlayer between Cr and stainless steel causes the pitting corrosion. The Au/Cr coating is tested in an acidic corrosion media for a long duration of 24 hours and it showed lower degradation as compared to without gold striking underlayer and without Cr film. The findings presented in this study illustrate the feasibility of employing stainless steel as the foundational material for the bipolar plate of a PEM electrolyzer.

Two novel phosphoramide derivatives moiety as corrosion inhibitor for mild steel: Experimental and theoretical study

Two novel phosphoramide containing thiazole derivatives with the name of bis(5‐amino‐1,3,4‐thiadiazol‐2‐yl) phenylphosphonotrithioate (C1) and O, O‐diethyl (5‐((diethoxyphosphorothioyl) thio)‐1,3,4‐thiadiazol‐2yl) phosphoramidothioate (C2) as corrosion inhibition were synthesized and identified by 1H NMR, 13C NMR, 31P NMR, IR, and mass spectroscopies. The electrochemical behavior of mild steel (MS) in hydrochloric acid 1‐M (HCl) solution was perused in the absence and presence of C1 and C2. To determine corrosion inhibition of phosphoramide compounds, scanning electron microscopy (SEM), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were used. The EIS results show that the charge transfer resistance increases with the addition of inhibitors to the hydrochloric acid solution. The most inhibitor efficiency was 89%, which demonstrated the appropriate anti‐corrosion property of C1. EIS results show better charge transfer resistance on the surface of MS at increased inhibitor concentrations. The PDP analysis showed that C1 and C2 are mixed‐type inhibitors. The PDP examination appeared that C1 and C2 are mixed‐type inhibitors. To way better get the comes about of corrosion inhibition and structure of target compounds, the highest occupied molecular orbital (HOMO) and least unoccupied molecular orbital (LUMO) energies, hardness, dipole moment, and electrophilicity index of synthesized compounds were explored computationally using the density functional theory (DFT) strategy. The hypothetical comes about in great understanding with the exploratory information.

Experimental and theoretical investigation of spiro heterocyclic compound as potential inhibitor for mild steel in acid media

The corrosion inhibition performance of spiropyrazoline was explored for mild steel corrosion in 1M HCl and 0.5M H2SO4 using weight loss, potentiodynamic polarization and electrochemical impedance studies. Inhibition efficiency of the inhibitor increased with increase in concentration within the range of 1–9 ppm. Spiropyrazoline inhibitor showed better inhibition performance of 92.6 %, 97.7 % in 1 M HCl and 0.5 M H2SO4, respectively at 9 ppm concentration by forming protective film on the metallic surface. Electrochemical impedance spectroscopy analysis (EIS) revealed an increase in polarization resistance due to the adsorbed inhibitor molecules. Potentiodynamic polarization analysis reveals that spiropyrazoline behaved as a mixed type inhibitor. The adsorption of the inhibitor on the metal surface found to obeying Langmuir and Temkin adsorption isotherm at room temperature. Surface morphology of the protective layer was examined by FTIR, scanning electron microscopy and atomic force microscopy. The inhibition mechanism of the inhibitor molecule was proposed in the light of the quantum chemical calculations using DFT.

Steel Anti-Corrosion Behavior for Pure and Mg-doped CuO Nanoparticles in Different Media: Raman, Potentiodynamic Polarization and Electrochemical Impedance Analysis

Steel Anti-Corrosion Behavior for Pure and Mg-doped CuO Nanoparticles in Different Media: Raman, Potentiodynamic Polarization and Electrochemical Impedance Analysis

Inhibition efficiency and mechanism of nitrilo-tris(methylenephosphonato)zinc on mild steel corrosion in neutral fluoride-containing aqueous media

Abstract Corrosion-electrochemical behaviour of steel E 235 in borate buffer solution (pH = 7.4) containing F− ions with and with no added ZnNTP as an inhibitor, where NTP = N(CH2PO3)3, was studied by the potentiodynamic polarization and depth-profiling XPS analysis of specimens polarized at different potentials applied. Depending on the potential applied, F− ion was shown to influence differently on the formation, composition and structure of passive film. At E &lt; 0.1–0.2 V/SSCE, F− ion promotes the passivation via forming sparingly soluble FeF2, and the resulting film is comprised of mainly iron(II) oxides and hydroxides, as well as sparingly soluble FeF2 and FeZnNTP. At E &gt; 0.1–0.2 V/SSCE, F− ion works for the destruction of the passive film by forming soluble compounds with Fe3+ ions, which leads to its thinning. ZnNTP inhibitor forms FeZnNTP heterometallic complex with iron ions, which is the most stable constituent of the passive film. When F− ion concentration does not exceed 1.4 mmol/L, ZnNTP inhibitor is optimal to be added in amount of 0.5–1.0 g/L, whereas concentrations of 5.6 mmol/L F− ion and higher require 5 g/L ZnNTP or even more to be added.

Effect of Microstructure Modifications on Stress Corrosion Endurance of 15-5 PH Stainless Steel Formed by Wire Laser Additive Manufacturing (WLAM)

Additive manufacturing (AM) technology using the direct energy deposition (DED) process and wires as feedstock material is commonly used to produce large components at an affordable cost. The wire laser AM (WLAM) process is one type of DED technology that uses welding wire as the raw material and a laser beam as the energy source. The goal of this study was to understand and evaluate the effect of microstructure modifications on the stress corrosion endurance of 15-5 PH stainless steels produced through WLAM, compared to their counterpart wrought alloy AISI 15-5 PH. All the tested alloys were heat treated using a standard age hardening treatment (H-1150M) prior to their examination. The microstructure analysis was performed using optical and electron microscopy (SEM and TEM) and X-ray diffraction analysis. The environmental behavior was characterized through electrochemical examination using potentiodynamic polarization and impedance spectroscopy analysis, while stress corrosion behavior was evaluated by means of slow strain rate testing (SSRT). The corrosion experiments were conducted in a simulated corrosive environment in the form of a 3.5% NaCl solution. The results showed that the microstructure modifications in the WLAM alloy (mainly in terms of austenite content, passivation capability and inherent printing defects) have a significant detrimental effect on stress corrosion resistance.

Corrosion, surface, and tribological behavior of electrophoretically deposited polyether ether ketone coatings on 316L stainless steel for orthopedic applications

Electrophoretic deposition (EPD) of polyether ether ketone (PEEK) coatings on metallic implants has recently attracted a great deal of interest; however, further investigation into their corrosion, surface, and tribological properties is required for their clinical application. Using Potentiodynamic polarization and Mott-Schottky analysis of PEEK coatings, we analyzed the electrochemical corrosion behavior of electrophoretically deposited PEEK coatings on 316L stainless steel (SS) substrates. In addition, the tribological behavior of the coatings was determined through pin-on-disc and scratch testing. Initially, the EPD parameters were optimized using a Taguchi Design of Experiment (DoE) approach. The coatings exhibited irregular shaped grains along with ∼66 μm of thickness. Fourier transform infrared spectroscopy confirmed the presence of functional groups ascribed with PEEK. The coatings were moderately hydrophobic and had an average roughness of ∼2 μm. The corrosion studies demonstrated promising features of current density and corrosion potential, indicating that corrosion resistance significantly improves with PEEK coating. Electrochemical impedance spectroscopy also confirmed the corrosion resistance of PEEK coating. The coatings exhibited a slightly lower wear resistance than SS samples, but still possessed adequate wear and scratch resistance for biomedical applications. The current study confirmed that the PEEK coatings on metallic implants is effective for orthopedic applications where corrosion and tribology are major concerns.

Enhancing the corrosion inhibition performance of Tinospora cordifolia extract using different fractions of methanol solvent on carbon steel corrosion in a seawater-simulated solution

The present study investigates the inhibition potential of Tinospora cordifolia extract in combination with different methanol solvents on the corrosion of carbon steel in artificial seawater environments. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) methods were utilized to evaluate this inhibitor. The measurement data show a positive correlation among inhibition efficiency (%IE), inhibitor concentration, temperature, and time. However, above 320 K, the efficiency has a slight decline, as well as when the exposure duration extends beyond 30 minutes. The highest observed inhibition efficiency was 85.94%, achieved by incorporating 300 mgL−1 of T. cordifolia extract (at 310 K). The inhibition by T. cordifolia extract was suggested to occur through adsorption on the metal surface and complies with the Langmuir adsorption isotherm. The potentiodynamic polarization analysis findings demonstrated that the extract of T. cordifolia mainly acted as a mixed inhibitor. The EIS study suggests that the T. cordifolia extract became effective by increasing the charge transfer resistance (Rct) by adsorbing on the steel surface. The FE-SEM study verified that T. cordifolia extract enhances the surface smoothness of the metal specimen. The adsorption mode of corrosion prevention is validated by the change in the chemical composition of the elemental surface examined by EDX studies. T. cordifolia extract mainly contains numerous aromatic phenolic compounds. FT-IR analysis confirmed the presence of several compounds with N and OH bonds in T. cordifolia extract. It has been established that T. cordifolia extract could be used for carbon steel in a marine environment.