Effect Of Chloride Concentration Research Articles

Effect of Chloride Concentration on the Environment-Assisted Cracking Behavior of an Al-Mg Alloy in Atmospheric Environments

The effect of chloride concentration on the environment-assisted cracking (EAC) behavior of AA5083-H131 in atmospheric environments was investigated using high-fidelity fracture mechanics-based testing and concurrent electrochemical potential measurements. EAC susceptibility was found to increase across all environments as chloride concentration increased, denoted by a decrease in the threshold stress intensity and faster stage II crack growth rates. However, EAC susceptibility for a given chloride concentration decreased across all chloride concentrations as cathodic limitation due to solution geometry effects increased. These results are analyzed in the context of the proposed anodic dissolution-enabled hydrogen embrittlement mechanism for EAC in Al-Mg alloys. Specifically, the increase in EAC susceptibility noted at higher chloride concentrations is postulated to arise from an increased overpotential for hydrogen production at the crack tip. Conversely, the decrease in EAC susceptibility observed as the solution geometry becomes more restrictive is attributed to cathodic limitation at the bulk surface decreasing dissolution at the crack tip, resulting in a concomitant less aggressive crack chemistry, and thus lower levels of hydrogen production and uptake at the crack tip. A close correlation between the open-circuit potential on the bulk specimen surface and the crack growth kinetics was also observed across all environments and chloride concentrations, with higher chloride concentrations and cathodic limitations resulting in larger changes in electrochemical potential. This correlates well with known electrochemical potential-dependent EAC observations for these alloys.

Corrosion of steel rebars across UHPC joint interface under chloride attack

Corrosion of steel rebars across ultra-high-performance concrete (UHPC) joint interface under chloride attack is experimental investigated in the present study. The cases of concrete joint interface with normal concrete (NC) and high-performance concrete (HPC) are also investigated as the contrast. Twelve specimens are prepared and subjected to corrosion test. The corrosion potential and corrosion current density are measured to monitor the corrosion evolution of steel rebars. The effects of chloride concentration and cracking on the corrosion of steel rebar across the concrete joint interface are clarified. And the corrosion characteristic of steel rebars with a high corrosion loss are further investigated through the accelerated corrosion method. Results show that steel rebars across joint interface trend easily to be corroded for all the three cases with NC, HPC and UHPC. Corrosion of steel rebar across UHPC joint interface is just a little slower or slighter than the other cases across NC and HPC joint interface. The corrosion of steel rebars is highly centralized and localized at the joint interface for the case with UHPC, but relatively uniform without significant difference around the joint interface for the other cases with NC and HPC. Corrosion of steel rebars across concrete joint interface is sensitive to chloride concentration and interface cracking, especially for the case with UHPC.

Influence of the casting process on corrosion behaviour of 2024-T6 aluminium alloy in different conditions of pH and NaCl concentration

ABSTRACT Corrosion behaviour of 2024-T6 castings produced by sand mould and metallic mould has been studied in media with different sodium chloride concentrations and pH values, using electrochemical techniques and scanning electron microscope. Corrosion rates and anodic and cathodic reaction kinetics are detailed to provide a fundamental understanding of the electrochemical behaviour of 2024-T6 at different conditions. The study shows a different corrosion mechanism depending on the pH. At pH 12, the more negative values of E corr confirmed that the alkalinisation of aluminium incites the dissolution of the Al substrate. The effect of chloride concentration is reflected in shifts of E corr towards more negative values. The research on the effect of the used mould demonstrates that the impact of the casting process in the cooling rate affects the pitting corrosion resistance.

The Effects of Sulfate on the Parameters for Maximum Pit Size Calculations on Stainless Steel 316L

Dry storage canisters that contain radioactive waste containers in the United States are typically made of stainless steel such as 316L. The longevity of such canisters put into service around forty years ago is a primary concern to the United States Department of Energy. Due to their location, many of these canisters undergo fluctuations in relative humidity and temperature, as well as an accumulation of deliquescent salts on their surface. The nature of the anions present in these salts establishes whether or not proper conditions for pit propagation exist. In order to predict these canisters’ maximum pit size, computational models that employ input parameters on the pit kinetics can be utilized. Such kinetic parameters are the critical pit stability product (i·x)crit and the repassivation potential (Erp), as they are key to the anodic current demand in a pit and the cathodic current supply outside a pit, respectively. Previous models that focused on the effect of chloride concentrations on the maximum observed pit size have shown to be overly conservative. Therefore, to increase the accuracy of the model, a more complex solution that contains inhibiting ions, such as sulfates, should be considered. In this study, artificial 1-D pit electrochemical experiments were carried out in a 50.8μm diameter SS316L wire exposed to solutions containing different concentrations of magnesium chloride (MgCl2) and magnesium sulfate (MgSO4). Maximum pit size calculations were performed utilizing the kinetic parameters obtained from these experiments. A theoretical model that seeks to describe the formation and growth of a complex salt film precipitate at the bottom of the pit is presented as well.

Effect of chloride concentration on the cytotoxicity, bioavailability, and bioreactivity of copper and silver in the rainbow trout gut cell line, RTgutGC.

Chloride (Cl-) influences the bioavailability and toxicity of metals in fish, but the mechanisms by which it influences these processes is poorly understood. Here, we investigated the effect of chloride on the cytotoxicity, bioavailability (i.e., accumulation) and bioreactivity (i.e., induction of mRNA levels of metal responsive genes) of copper (Cu) and silver (Ag) in the rainbow trout gut cell line (RTgutGC). Cells were exposed to metals in media with varying Cl- concentrations (0, 1, 5 and 146 mM). Metal speciation in exposure medium was analyzed using Visual MINTEQ software. Cytotoxicity of AgNO3 and CuSO4 was measured based on two endpoints: metabolic activity and membrane integrity. Cells were exposed to 500 nM of AgNO3 and CuSO4 for 24 h in respective media to determine metal bioavailability and bioreactivity. Ag speciation changes from free ionic (Ag+) to neutral (AgCl), to negatively charged chloride complexes (AgCl2-, AgCl3-) with increasing Cl- concentration in exposure media whereas Cu speciation remains in two forms (Cu2+ and CuHPO4) across all media. Chloride does not affect Ag bioavailability but decreases metal toxicity and bioreactivity. Cells exposed to Ag expressed significantly higher metallothionein mRNA levels in low Cl- media (0, 1, and 5 mM) than in high Cl- medium (146 mM). This suggests that chloride complexation reduces silver bioreactivity and toxicity. Conversely, Cu bioavailability and toxicity were higher in the high chloride medium (146 mM) than in the low Cl- (0, 1, and 5 mM) media, supporting the hypothesis that Cu uptake may occur via a chloride dependent mechanism. CLINICAL TRIALS REGISTRATION: This study did not require clinical trial registration.

Effect of Chloride on the Pitting Corrosion of Carbon Steel in Alkaline Solutions

The effect of chloride concentration on the passivity breakdown of carbon steel in deaerated pH = 13.5 alkaline solution was investigated. The results show that chloride plays an important role for the pitting corrosion of carbon steel. When NaCl the carbon steel is passive but for NaCl < 2 the carbon steel transfers from passive to passivity breakdown. When NaCl passive film breakdown occurs and the passivity breakdown potential (E b ) of carbon steel is linearly-dependent on the logarithm of the chloride activity in the alkaline solution. As predicted by the PDM, the near-normal distribution of is well indicated by the near straight line in the cumulative distribution probability. The analysis in this study gives us a method to calculate the of carbon steel in alkaline solution and its distribution for any given chloride concentration.

Crevice corrosion of steel rebar in chloride-contaminated concrete

In this paper, crevice corrosion was proposed as one of the important mechanisms responsible for the damage of steel rebar in concrete, which was experimentally verified in simulated concrete pore solution (SCPS) and concrete blocks. The effects of chloride concentration and temperature on the crevice corrosion were comparatively investigated by means of potentiodynamic polarization, immersion, electrochemical impedance spectroscopy (EIS) and galvanic current measurements. The crevice corrosion products in chloride-contaminated SCPS were examined by X-ray photoelectron spectroscopy (XPS). The results indicated that chloride contamination and temperature elevation could significantly accelerate the crevice corrosion.

Effect of Chloride Concentration in a Simulated Concrete Pore Solution on Metastable Pitting of 304 Stainless Steel

Effect of Chloride Concentration in a Simulated Concrete Pore Solution on Metastable Pitting of 304 Stainless Steel

Local corrosion characteristics of a graphene-oxide-modified inner coating

Pencil hardness testing, electrochemical impedance spectroscopy, scanning electron microscopy, and scanning Kelvin probe microscopy were used to study the local corrosion characteristics of a graphene-oxide-modified inner coating. The effect of chloride concentration on the corrosion of the damaged inner coating was studied. The effects of chloride ions on damaged internal coatings and graphene-oxide-modified internal coatings were investigated. It was proposed to add graphene oxide into the epoxy coating to effectively inhibit the metal corrosion at the breakage. Because of the existence of graphene oxide(GO), the modified coating had a better physical property and had the effective infiltration of H2O and Cl− into the coating. The results showed that graphene oxide coatings can give X80 steel better corrosion resistance in sodium chloride solution.

Effect of Chloride Concentration on Stress Corrosion Behavior and Mechanism of SA516Gr70N Steel in Alkaline NaCl/Na2S Solution

The effects of chloride on the electrochemical process and susceptibility to stress corrosion cracking (SCC) of SA516Gr70N steel in alkaline NaCl/Na2S solution were investigated by using electrochemical techniques (impedance spectroscopy and polarization curve measurement) and slow strain rate tensile (SSRT) tests. SA516Gr70N steel exhibited SCC susceptibility to a certain extent in alkaline NaCl/Na2S solution. The susceptibility to SCC decreased with increasing chloride concentrations in solutions with pH values of 9 and 11, while susceptibility was not apparent in higher pH solutions. Electrochemical analysis showed that the corrosion potential became more negative, and the anodic corrosion rate decreased with increasing chloride concentration due to the competitive adsorption of HS− and Cl−. The mechanism of SCC is mainly controlled by anodic dissolution with the addition of chloride.

Effects of Chloride Concentration on the Water Disinfection Performance of Silver Containing Nanocellulose-based Composites

The availability of microbially-safe drinking water is a challenge in many developing regions. Due to the well-known antibacterial effect of silver ions, materials used for their controlled release have been widely studied for point-of-use water disinfection. However, even if it is in principle known that chloride anions can suppress the antibacterial efficiency of silver, the majority of previous studies, surprisingly, have not focused on chloride concentrations relevant for freshwaters and thus for practical applications. Here, we prepared low-cost nanocellulose-aluminium oxyhydroxide nanocomposites functionalized with silver nanoparticles. Field samples obtained from Chennai, India were used as a guideline for choosing relevant chloride concentrations for the antibacterial studies, i.e., 10, 90, and 290 ppm. The antibacterial performance of the material against Escherichia coli and Bacillus subtilis was demonstrated and the influence of chloride concentration on the antibacterial effect was studied with E. coli. A 1 h contact time led to bacterial reductions of 5.6 log10, 2.9 log10, and 2.2 log10, respectively. This indicates that an increase of chloride concentration leads to a substantial reduction of antibacterial efficiency, even within chloride concentrations found in freshwaters. This work enables further insights for designing freshwater purification systems that utilize silver-releasing materials.

Effect of Chloride Concentration on Copper Deposition in Through Silicon Vias

Bottom-up Cu deposition in metallized through silicon vias (TSV) depends on a co-adsorbed polyether–Cl− suppressor layer that selectively breaks down within recessed surface features. This work explores Cu deposition when formation of the suppressor blocking layer is limited by the flux of Cl−. This constraint leads to a transition from passive surfaces to active deposition partway down the via sidewall due to coupling between suppressor formation and breakdown as well as surface topography. The impact of Cl− concentration and hydrodynamics on the formation of the suppressor surface phase and its potential-dependent breakdown is examined. The onset of suppression breakdown is related to the local Cl− coverage as determined by the adsorption isotherm or transport limited flux. A two-additive co-adsorption model is presented that correlates the voltammetric potential of suppression breakdown with the depth of the passive-active transition during TSV filling under conditions of transport limited flux and incorporation of Cl−. The utility of potential waveforms to optimize the feature filling process is demonstrated. At higher Cl− concentrations (≥80 μmol/L), sidewall breakdown during Cu deposition occurs near the bottom of the via followed by a shift to bottom-up growth like that seen at higher Cl− concentrations.

Effects of chloride concentration on CO2 corrosion of novel 3Cr2Al steel in simulated oil and gas well environments

The corrosion behavior of novel 3Cr2Al steel in simulated oil and gas well environments was investigated using scanning electron microscopy, electron diffraction spectroscopy, potentiodynamic polarization, and potentiostatic polarization. The results revealed that the corrosion rate of 3Cr2Al steel increased as the Cl− concentration increased. The thickness of the corrosion product film decreased as the Cl− concentration increased. The increase in Cl− concentration caused a decrease in pH value, subsequently causing an increase in the solubility of Cr(OH)3 and Al(OH)3 and hindering the deposition of corrosion product, eventually yielding a thinner corrosion film.

Corrosion inhibition of carbon steel by dipotassium hydrogen phosphate in alkaline solutions with low chloride contamination

This work deals with the corrosion inhibition of carbon steel by dipotassium hydrogen phosphate (DKP) in both mildly and highly alkaline solutions (pH 8 and 12) contaminated with low levels of chloride (1–5 mmol L−1). To this end, the electrochemical methods of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) together with different surface analysis methods including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy were employed. In mildly alkaline solution, the [DKP]/[Cl-] ratio should be greater than the critical value (3.7) to form a stable passive film on the metal surface; additionally, the best inhibition against uniform corrosion was achieved at [DKP]/[Cl-] = 5.5, while the passive film resistance to pitting resistance continuously improved as the [DKP]/[Cl-] ratio increased. The effect of chloride concentration on the characteristic of passive film was described by a logarithmic relationship. In highly alkaline solution, addition of 11 mmol L−1 DKP has a significant effect on uniform corrosion. The surface analysis methods demonstrated the formation of a duplex layer on the metal surface composed of an inner layer of iron oxides and an outer layer of iron phosphate complexes mainly as FeHPO4 and Fe3(PO4)2.

Systematic Insight into Chloride Concentration, Applied Potential and Time Effect on the Passive Film of Cu-Zn-Ni Ternary Alloy in Alkaline Solution

The effects of chloride concentration, applied potential and time on the passive film of Cu-Zn-Ni ternary alloy in alkaline solution were systematically investigated using potentiodynamic and potentiostatic polarizations, electrochemical impedance spectroscopy, Mott–Schottky analysis, laser confocal microscopy, atomic force microscopy and x-ray photoelectron spectroscopy. Results showed that the pitting potential decreased as a linear function of log( $$ a_{{{\text{Cl}}^{ - } }} $$ ), and the size of pits extended faster in the horizontal direction than in the vertical direction. The passive oxide film formed on Cu-Zn-Ni alloy mainly exhibited p-type semiconductor behavior, which was consistent with cuprous and nickel oxide, the main components in the film. The density of cation vacancy (approximately 1020-1021 cm−3) increased with potentiostatic time but reduced by the increasing potentials. The kinetics of passive film growth followed a parabolic law D = m * tn, where m is a constant considered as the initial growth rate and n is the time exponent. Subsequent to the formation of a compact and coherent passive film at higher potential, it was hard for an ion to migrate or for an aggressive ion to penetrate, which indicated better corrosion resistance for passive film formed under higher potential.

Thermodynamic modeling of the essential physicochemical interactions between the pore solution and the cement hydrates in chloride-contaminated cement-based materials

The chloride transport properties of cement-based materials are determined via the physicochemical interactions between the pore solution and the cement hydrates. Herein, a thermodynamic model based on surface complexation reactions and dissolution/precipitation reactions was established to investigate the essential physicochemical interactions. The effects of chloride concentration, temperature, and saturation degree (the ratio of water volume to pore volume) on the physicochemical interactions were studied in detail using the resulting thermodynamic model. The published experimental results indicate that the resulting thermodynamic model accurately reflects the adsorption capacity of cement hydrates for chloride ions. Thus, this thermodynamic model can be coupled to the transport equations to achieve the durable designs for new reinforced concrete structures (RCSs) or to predict the service life of existing RCSs. It can also optimize corrosion control strategies for RCSs based on the thermodynamics and kinetics of the material.

Pitting corrosion behaviour of 2101 duplex stainless steel in chloride solutions

ABSTRACTThe corrosion behaviour of 2101 duplex stainless steel (DSS) in NaCl solution was studied and compared with that of 2205 DSS. The effects of chloride concentration and solution temperature on pitting corrosion behaviour were focused. The relative sensitivity to pitting corrosion of the constituent phases in both 2101 and 2205 DSSs was also explored. Pitting corrosion susceptibility was evaluated by conducting cyclic polarisation curve measurement. The corrosion morphology was examined by a scanning electron microscope equipped with energy dispersive spectrometer. The experimental results showed that the pitting corrosion resistance of 2101 DSS was inferior to that of 2205 DSS by exhibiting a lower threshold chloride concentration and a lower critical pitting temperature. For both 2101 and 2205 DSSs, the ferrite phase was more susceptible than austenite phase to pitting corrosion.This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17).

Effect of chloride concentration on passive film properties on copper

ABSTRACTThe semiconducting properties of passive films formed on copper, in anaerobic alkaline sodium chloride solution, were studied using Mott–Schottky analysis and electrochemical impedance spectroscopy, based on the point defect model. Results showed that the corrosion resistance increased with increasing potential, which was attributed to a well crystallised, refined grain structure, and a thicker passive film at higher potential. P-type semiconducting characteristics were obtained with or without chloride. The density of copper vacancies was approximately 1020 cm−3, and increased with the increasing chloride concentration, which was attributed to faster film-formation in a higher chloride environment. The diffusion coefficient of the defects, a key dynamic parameter for passive film breakdown, was in the range of 10−16–10−15 cm2 s−1, and increased with increasing chloride concentration, thus leading to a greater probability of pitting.

Experimental and modelling studies of neodymium solvent extraction from chloride media with methyl-tri(octyl/decyl)ammonium oleate ionic liquid diluted in kerosene

A study of the solvent extraction process of Nd(III) from chloride solutions has been carried out using an ionic liquid (AliOle) prepared from Aliquat 336 (Methyl-tri(octyl/decyl)ammonium chloride) and Oleic Acid. The IL was chosen among other homemade ionic liquids and commercial extractants due to its high Nd(III) extraction ability and good phase separation. Increasing AliOle concentration improves the extraction of Nd(III) as expected. The pH of the aqueous phase strongly influences the extraction process. The appropriate equilibrium pH region has been established in the range 5–6.5. The effect of chloride concentration in the aqueous phase has been investigated. High concentrations of Cl− anion contribute to increasing the extraction yield by promoting neodymium(III) speciation in the aqueous phase.Two extraction models are proposed from experimental data. Chloride concentration in the aqueous phase determines the Nd(III) extraction mechanism. The models consider extraction of Nd3+ species when chloride concentration in the solution is low and NdCl2+ species when chloride concentration is high. Competitive extraction between HCl and the metal ions is also included in the models. They are able to reproduce feasibly the experimental Nd(III) extraction extension.

Effects of chloride transients on stress corrosion crack in pressure vessel low alloy steels in high temperature water

This paper evaluated the effects of chloride transients that may occur in boiling water reactor on stress corrosion cracking of pressure vessel low alloy steels. Crack growth rate and the delayed cracking response were enhanced by chloride transient in normal water chemistry while no chloride effect was observed in hydrogen water chemistry. The effects of chloride concentration, stress intensity factor, corrosion potential, and steel heat on the crack growth were discussed. The results from this work provide direct inputs to crack growth disposition models for low alloy steels, water chemistry guidelines and the plant operation practice during chloride transient.