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The purpose of this paper is to study the inhibitive effect of p‐toluene sulfonic acid (p‐TSA) doped polyaniline on corrosion of copper in 0.1 M hydrochloric acid (HCl) solution.

The electrochemical deposition of polyaniline doped with p‐TSA on pure copper metal was studied potentiodynamically. The electrochemical study of the working electrode was performed at open‐circuit potential, then using potentiodynamic polarization and also with electrochemical impedance spectroscopy in 0.1 M HCl solution. The p‐TSA doped polymer deposit was characterized using Fourier transform infrared spectroscopy, with the UV‐vis and thermogravimetric analysis/differential scanning calorimetry techniques. The morphology of the deposited polymer was studied by scanning electron microscopy.

The results revealed that the p‐TSA self‐doped polymer had better corrosion inhibition efficiency than did the un‐doped polyaniline. It exhibited approximately 88.9 percent inhibition efficiency at 2x10⁻³ M concentration of p‐TSA, according to charge transfer resistance (R_ct) values evaluated from Nyquist plots.

The high dissolution tendency of metal surfaces generally occurs before the electropolymerization potential of the monomer is achieved. It was difficult to electrodeposit the conducting organic polymer on the surface of metal.

Some organic conducting polymers are toxic and hazardous from the environmental viewpoint. The electrochemical deposition of p‐TSA doped polyaniline is impractical for larger structures.

The paper demonstrates that p‐TSA doped polyaniline is environmentally benign and can be used for the protection of copper metal as a cathodic inhibitor.

To develop electrode materials for supercapacitor with superior electrochemical performance and simple preparation process, the purpose of this study is to prepare flexible CC/NiS/a-NiS electrodes with self-supporting structure by loading hydrothermally synthesized a-NiS particles along with nano-NiS on carbon cloth by electroplating method.

The effects of current densities, temperatures and pH values on the loading amount and uniformity of the active substances during the plating process were investigated on the basis of optimization of surface morphology, crystalline structure and electrochemical evaluation as the cyclic voltammetry curves, constant current charge–discharge curves and AC impedance.

The a-NiS particles on CC/NiS/a-NiS were mostly covered by the plated nano-NiS, which behaved as a bulge and provided a larger specific surface area. The CC/NiS/a-NiS electrode prepared with the optimized parameter exhibited a specific capacitance of 115.13 F/g at a current density of 1 A/g and a Coulomb efficiency of 84% at 5 A/g, which is superior to that of CC/NiS electrode prepared by electroplating at a current density of 10 mA/cm², a temperature of 55°C and a pH of 4, demonstrating its fast charge response of the electrode and potential application in wearable electronics.

This study provides an integrated solution for the development of specifically structured NiS-based electrode for supercapacitor with simple process, low cost and high electrochemical charge/discharge performance, and the simple and easy-to-use method is also applicable to other electrochemically active composites.

The purpose of this paper is to study the corrosion behaviors of X70 steel under direct current (DC) interference at 0-1,200 A/m² in simulated soil solution.

The Tafel polarization curves of X70 steel under DC interference were tested using electrochemical method, the corrosion rate was calculated using weight-loss method and the change in steel surface was analyzed by optical microscopy.

The results showed that E-I polarization curves under 200-1,200 A/m² interference were linear; with an increase in the DC density, the corrosion potential of X70 steel shifted positively, solution pH after the weight-loss tests increased and corrosion rate increased linearly. A mathematical relationship between polarization resistance Rp and current density was established. Corrosion morphology indicated that pitting corrosion and crevice corrosion occurred on the X70 steel under DC interference in simulated soil solution.

All tests were conducted at a relative higher DC density (200-1,200 A/m²). The linear fitting method is proposed to fit data of Tafel polarization curves under DC interference. This study provides guidelines for safe operation of X70 steel pipelines.

Oil-water two-phase flow is the most prevalent medium in oil field gathering pipelines, and the corrosion of pipelines is often highly localized. Therefore, the purpose of this paper is to investigate the corrosion behavior of 20# pipeline steel in the oil-water stratified liquids, vary the water content of the upper emulsion and study the difference of the corrosion process.

Combine the wire beam electrodes (WBE) technique and the corrosion weight loss method to investigate the corrosion behavior of 20# steel in produced water simulation fluid and oil-water stratified liquids, and a corrosion mechanism model was established for analysis and explanation.

The results of mass loss experiments showed that the average corrosion rate increased with the increase in the water content of the upper emulsion. The corrosion current distribution maps indicated that the most serious corrosion occurred in the produced water simulation liquid, and the corrosion process showed the law of waterline corrosion. In addition, it was also found that the corrosion of the WBE in the stratified liquids had obvious non-uniformities. The electrode wires at the oil-water interface suffered from severe corrosion, caused by the dissolution of crude oil acids in water and the uneven distribution of oxygen in the corrosive medium.

The WBE technique provides a deep insight into the corrosion phenomena at the oil-water interface, which is helpful for characterization of the non-uniformity of corrosion parameters and evaluating the risks of multiphase corrosive media.

The purpose of this paper is to prepare a new modified activated carbon fibers (ACFs) of high specific capacitance used for electrode material of supercapacitor.

In this study, the specific capacitance of ACF was significantly increased by using the phenolic resin microspheres and melamine as modifiers to prepare modified PAN-based activated carbon fibers (MACFs) via electrospinning, pre-oxidation and carbonization. The symmetrical supercapacitor (using MACF as electrode) and hybrid supercapacitor (using MACF and activated carbon as electrodes) were tested in term of electrochemical properties by cyclic voltammetry, AC impedance and cycle stability test.

It was found that the specific capacitance value of the modified fibers were increased to 167 Fg^-1 by adding modifiers (i.e. 20 wt.% microspheres and 15 wt.% melamine) compared to that of unmodified fibers (86.17 Fg^-1). Specific capacitance of modified electrode material had little degradation over 10,000 cycles. This result can be attributed to that the modifiers embedded into the fibers changed the original morphology and enhanced the specific surface area of the fibers.

The modified ACFs in our study had high specific surface area and significantly high specific capacitance, which can be applied as efficient and environmental absorbent, and advanced electrode material of supercapacitor.

This paper aims to investigate the electrolytic deposition of corrosion-resistant chromium coatings from a trivalent chromium plating bath based on deep eutectic solvent, a new generation of room temperature ionic liquids.

The electrolyte contained chromium (III) chloride, choline chloride and the additive of extra water. The surface morphology was estimated by means of SEM technique. The microstructure of as-deposited and annealed coatings was studied using X-ray diffraction method. The kinetics of the chromium electrodeposition and the corrosion electrochemical behavior of the coatings were investigated by cyclic voltammetry technique.

Chromium coatings with an amorphous type of microstructure are electroplated from this bath. Some carbon and oxygen are included in deposits obtained. The step-wise mechanism of the electrochemical reduction of Cr(III) ions to Cr(0) is detected. The current efficiency in this system sufficiently exceeds that typical of usual aqueous electrolytes. The coatings fabricated using plating bath based on deep eutectic solvent showed enhanced corrosion resistance in an acidic medium: there is no current peak of active dissolution in polarization curve and the corrosion potential shifts to more positive values as compared with “usual” chromium.

The electrodeposition of chromium coatings from an environmentally acceptable trivalent chromium electrolyte, a deep eutectic solvent containing chloride choline and extra water additive has been investigated for the first time.

The purpose of this study is to prepare various CeO₂-based carbon material (CNT, CB, GO) nanocomposites through a wet chemical process for the development of a sensor probe to detect various environmental toxins by using an electrochemical approach under room temperature conditions. A comparative study on sensitive and selective phenolic sensor (4-methoxyphenol; 4-MP) has been fabricated by modifying a glassy carbon electrode (GCE) with various nanocomposites (NCs) such as CeO₂, CeO₂–CNT (carbon nanotubes), CeO₂–CB (carbon black) and CeO₂–GO (graphene oxide) NCs.

The CeO₂–CNT NCs were prepared by the wet chemical method at low temperature. NCs were characterized by various methods such as transmission electron microscopy (TEM), Fourier-transform infra-red (FTIR), ultra-violet/visible (UV-Vis) spectroscopy and XRD (X-ray diffraction). CeO₂–CNT NCs were immobilized as a film on the flat surface of the GCE by using binders (5% Nafion). The electrochemical measurements of the 4-MP detection with the CeO₂–CNT NCs/Nafion/GCE sensor were studied by the current-voltage method.

In the optimal conditions, the sensitivity, detection limit and limit of quantification of 4-MP sensor probe were found to be 47.56 µAcm-2 µM⁻¹, 12.0 ± 0.2 nM and 40.0 ± 0.5 nM (S/N of 3), respectively.

This electrochemical sensor showed an acceptable analytical performance in the detection of 4-MP with higher sensitivity, lower detection limit, large dynamic concentration range, good reproducibility and fast response time.

This electrochemical approach can be applied practically for the determination of selective 4-MP in real environmental and extracted samples.

CeO₂–CNT NCs/Nafion/GCE sensor probe was used for the safety of environmental and health-care fields at larger scales.

This electrochemical approach is a significant achievement on the development of sensor probe. The results are indicated as being technically detailed with an up-to-date account of recent chemical sensor research studies.

The purpose of this study was to investigate the corrosion of rusted carbon steel in dilute NaCl solution, with the purpose of exploring the effect of the rust layer on metal corrosion and establishing a corrosion model for rusted iron.

The corrosion behavior of rusted carbon steel in dilute NaCl solution was studied by means of weight-loss determinations, scanning electron microscopy, Raman spectrometry and electrochemical techniques.

The results indicated that carbon steel had a similar corrosion behavior in all three NaCl solutions. The iron rust, which consisted of a thin γ-FeOOH layer and a thick Fe₃O₄ layer, can facilitate the corrosion process of carbon steel via reduction of γ-FeOOH and the large area cathode of Fe₃O₄. Hence, the corrosion rate of carbon steel was accelerated significantly and finally was determined by the limiting diffusion rate of oxygen.

A corrosion model of rusted carbon steel was established, suggesting that iron rust formed in all slightly acidic waters with low alkalinity probably promotes the corrosion of carbon steel. Anti-corrosion measures for iron in this type of solution, such as desalination water, should be aimed to reduce the promotional effect of the rust layer on metal corrosion.

The purpose of this paper was to study the corrosion control of B10 copper-nickel alloy using the LiOH-N₂H₄ compound inhibitors and to evaluate the feasibility of replacing the original inhibitors (NaNO₂-Na₂MoO₄) with the new ones (LiOH-N₂H₄) for the chilled water system in a nuclear unit.

The corrosion resistance performance of B10 copper-nickel alloy was evaluated during the whole replacement process of inhibiters using electrochemical tests and surface analysis techniques.

The results indicated that the corrosion of B10 copper-nickel alloy could be prevented effectively using LiOH to increase the pH value of solution higher than 10.0 and using N₂H₄ to consume dissolved oxygen. During the replacement process of inhibitors from NaNO₂-Na₂MoO₄ to LiOH-N₂H₄, the corrosion resistance performance of B10 copper-nickel alloy had not decreased greatly. The new LiOH-N₂H₄ inhibitor, which could enhance the compactness of rust, was able to reduce the corrosion rate of rusted B10 metal.

It is feasible and operable to replace the NaNO₂-Na₂MoO₄ inhibitors with the LiOH-N₂H₄ inhibitors for the corrosion prevention of B10 copper-nickel alloy. The research results can provide guidelines for the inhibitor selection of chilled water system in a nuclear unit.

The purpose of this paper is to provide theoretical guidance and an experimental basis for a smart anti-corrosion coating of halloysite nanocontainers loaded with benzotriazole (BTA) inhibitors on copper in a marine corrosion environment.

In the present study, the smart anti-corrosion coatings of halloysite nanocontainers loaded inhibitors on copper were synthesized by adding BTA inside the halloysite nanocontainers. Then, the halloysite carrier’s surface topography and composition in the halloysite were observed using scanning electron microscopy. After the successful synthesis of the coating, the inhibitor’s physical and chemical properties, as well as the mass change in halloysite, were evaluated in terms of temperature fluctuation and time using thermal gravity analysis (TGA). Finally, electrochemical impedance spectroscopy was used to check the pH selectivity for the self-releasing of BTA out of the nanocontainers.

The results indicate that the efficiency of the nanotubes was enhanced by calcination at high temperatures. The thermal gravity analysis by TGA shows that halloysite nanoparticles store inhibitors BTA and there are approximately 37.39 Wt.% BTA loaded in each nanocontainer. The release of the preloaded BTA from the halloysite nanocontainers is pH 7 in a 3.5% NaCl solution.

The development of a new environmentally safe coating for corrosion protection of metallic surfaces has attracted great interest in material science over the past few years. At present, halloysite nanotubes (HNTs) have become a research hotspot internationally and are widely used in nanocomposites, catalysis, nanofiltration, drug sustained-release and other fields. However, the application of HNT is limited by its modification methods. As the carrier of metal nanocorrosion inhibitor in the Marine corrosive environment, the modification research of HNT still needs to be further studied and improved so as to expand the practical application of HNT in the Marine corrosive environment. In this paper, the modification of HNTs was investigated and observed. Four different modification schemes were used to observe and compare the structural properties of the nanotubes under different conditions so as to provide a theoretical basis for the further loading of HNTs as corrosion inhibitors.