Corrosive Solution Research Articles

Influence of corrosion fatigue on the fatigue strength of an AlSi10MgMn high‐pressure die‐casting alloy with regard to the surface condition

AbstractThis study investigates the influence of corrosion fatigue on the fatigue strength of an AlSi10MgMn high‐pressure die‐casting alloy with regard to the surface condition. Two different surface conditions are compared. First, an unmachined surface condition with a rough surface () and second a machined and polished surface condition with a smooth, polished surface () are tested. The specimens are loaded with a cyclic bending moment at a constant stress ratio of R = 0 till failure. A 5 wt% NaCl solution enables the corrosion fatigue tests. Corrosion fatigue leads to a significant reduction of the endurable stresses along the whole load spectrum independent from the surface condition. The applied corrosive solution prevents the formation of a pronounced long‐life fatigue strength limit within the tested load cycle range. Hence, the reduction of the endurable stresses increases with the increasing number of load cycles, reaching approximately 37% at load cycles. No significant influence of the surface condition, independent of the environment (air, 5 wt% NaCl), on the fatigue behaviour is found.

Effect of different corrosive media on the corrosion resistance and mechanical properties of armor steel

Abstract Armor steel samples were exposed to corrosion for 24, 72, 168, and 720 h in two different corrosive media. The corrosion rate was determined using mass loss, measurement of the concentration of components in the corrosive medium solution, and Tafel extrapolation methods. Before and after corrosion experiments, the tensile properties, surface characteristics, and phase structures of the samples were examined. The surface analyses were performed using the SEM technique combined with EDX analyses, and the phase analyses were performed by X-ray diffraction. The corrosion rate determined by the mass loss method was 0.02 ± 0.01 mm year−1 for the 3.5 wt% NaCl medium and 2.66 ± 0.16 mm year−1 for the 1 M HCl medium. The corrosion rate values determined by the Tafel extrapolation method were 0.02 ± 0.01 mm year−1 in the 3.5 wt% NaCl medium and 1.21 ± 0.01 mm year−1 in the 1 M HCl medium. There was a decrease in the tensile, yield strengths, and elongation to fracture values of the corroded samples compared to the non-corroded samples. While intergranular ductile fracture occurred in samples exposed to 3.5 wt% NaCl medium, there were features reminiscent of the brittle fracture in samples exposed to the 1 M HCl/168 h medium.

Electrochemistry evaluation and quantum corroboration with surface analysis of potential anticorrosive of two new pyridazine derivatives for mild steel in 1 M HCl solution

Two new structurally related pyridazine derivatives, Ortho (PO) and Para (PP), were synthesized by greener chemical pathway, and were spectroscopically specified by 1H NMR and 13C NMR. Their application in corrosion inhibition of mild steel (MS) in 1.0 M HCl was explored by experimental electrochemical tests of Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS), with a surface and corrosive solution analyses by means of Scanning Electron Microscopy (SEM), Energy Dispersive X˗ray (EDX) analysis, and UV˗vis spectroscopy, as well as by Density functional theory (DFT) calculations for corroboration and development of an interpretation of the experimentally obtained anticorrosive activity by referring to the particular effects of molecular structure. Electrochemical experiments tests provided that the two compounds act by physisorption and chemisorption adsorption modes, with a maximum efficiency of 94.4% and 95.4% for PO and PP, respectively at 10˗3 mol L˗1, and obey of Langmuir’s theory of monolayer adsorption. SEM/EDX and UV˗vis analysis confirmed this state of adsorption by an inhibitor film. DFT quantum chemical descriptors and molecular dynamics simulations showed a reasonable correlation with experimentally corrosion inhibition performance.

Synergistic inhibition effect of imidazoline and thiourea on pitting corrosion of Q235 carbon steel

Pitting corrosion is a significant issue which significantly shorten the service life of carbon steel. In this study, imidazoline and thiourea are combined to assess the synergistic in the localized corrosion of Q235 carbon steel by a combined system. In detail, five different proportions of corrosion inhibitors are used in the simulated corrosion solution (5 wt. % NaCl + 0.5 wt. % CH3COOH + 1.0 wt. % Na2S) in the closed area to investigate the corrosion inhibition performance of Q235 steel at 80 °C. The corrosion behavior of the steel in the simulated solution was investigated using potentiodynamic polarization test and electrochemical impedance spectroscopy test. Due to the combination of imidazoline (IM) and thiourea (TU) corrosion inhibitors, the corrosion inhibitors in the simulated solution of the occlusion zone reduce the migration of corrosive anions to the occlusion zone and slowed the acidification of the solution resulting in lower concentrations of Cl- and S2- to varying degrees and reaching a higher pH of the solution. As a result, the compounded corrosion inhibitors exhibit improved corrosion inhibition rate (80 mg/L IM+20 mg/L TU (86.91 %), 50 mg/L IM+ 50 mg/L TU (95.67 %), 20 mg/L IM+ 80 mg/L TU (86.16 %)) to Q235 steel, which is superior to that using imidazoline (63.42 %) or thiourea (92.77 %) alone. This enhanced performances fully prove the synergistic effect of imidazoline with thiourea.

Simple and eco-friendly fabrication of highly tolerant chitosan/alginate@sepiolite hybrid films on nylon textile for oil/water separation in harsh conditions

Because of the need of achieving efficient separation to oil/water mixture, the construction of separation coating with good mechanical strength and chemical resistance are highly desired. Although many polysaccharide-based coating for oil/water separation have been prepared, the poor durability and the environmentally unfriendly preparation process greatly restrict their applications. Herein, sepiolite (SP) was introduced into chitosan/alginate (CS/AG) matrix to produce nacre-like composite films with superb robustness and stability via a simple and green layer-by-layer (LbL) self-assembly technique. After the composite films are fabricated on nylon textile (NT), the hydrophilicity and underwater superoleophobicity of the NT surface are significantly improved. The composite coating also reveals excellent oleophobic stability after being subjected to corrosive liquids immersion, high-temperature treatment, strong abrasion, and organic solvents immersion. Furthermore, the modified NT is able to separate oil/pure water, oil/cold corrosive water, and oil/hot corrosive water mixtures with high filtration efficiency (>98.3 %). Especially, the separation to oil/hot corrosive solution mixtures can be repeated at least 40 times without obvious decrease of separation efficiencies. This investigation offers a new and eco-friendly strategy to prepare SP coating-based membrane materials with good superhydrophilicity, mechanical property, and recyclability for oily wastewater purification.

Irradiation enhanced corrosion resistance of CrN/TiSiN multilayers synthesized by cathodic arc ion plating

The effect induced by irradiation is often considered as ‘negative impact’. Irradiation damage normally leads to defects in materials, including vacancies, clusters and interstitials, therefore resulting in the attenuation of stability such as corrosion resistance. Here, multilayered CrN/TiSiN coatings have been fabricated by cathodic arc ion plating and the corrosion properties of prepared coatings have been investigated before and after irradiation. Microstructure of irradiated samples revealed amorphization on the surface layer induced by irradiation. The corrosion behavior was studied by electrochemical tests, and multilayered CrN/TiSiN coatings revealed enhancement in corrosion resistance as the corrosion potential increased and corrosion current decreased in all irradiated samples. It turned out that the multilayered CrN/TiSiN coatings deposited with a bias voltage of 150 V and Ti80Si20 targets revealed the best corrosion resistance after irradiation. Given that, surface morphology analysis of corroded surface was conducted to provide further evidence. This irradiation enhanced corrosion resistance of multilayered CrN/TiSiN coatings could be explained by the rapid formation of passive films upon the irradiation induced amorphous layer during corrosive process, which function as barriers between the substrate and the corrosive solution. Our results reveal profound insights into corresponding corrosion mechanism of nitride coatings based on the microstructure investigation of corroded coatings and contribute to the understanding of corrosion behaviors of irradiated nitride coatings.

Fabricated of the SCC Reference Specimen for Increasing of In-Service Inspection Accuracy in Nuclear Power Plant

To achieve the safety assurance of the nuclear power plants, in-service inspection have were enforced periodic for nondestructive test in weldment. Among them, the ultrasonic evaluation is widely used for the measurement of the defects. Generally, non-destructive inspectors have calibrated a UT machine using the reference specimen in the artificial cracks such as EDM, mechanical notch. As the reflected ultrasonic signal of real crack was detected amplitude value 50% lower than artificial cracks. Therefore, domestic ultrasonic inspectors have a little experience in measuring actual cracks generated in the nuclear power plant field, such as SCC(Stress corrosion cracks, below SCC) and thermal fatigue cracking. Accordingly, in order to improve the inspection accuracy of non-destructive inspectors during operation inspection of nuclear power plant structures, it is necessary to have a lot of experience in inspecting actual cracks.In this study, non-penetration SCC for using in educational specimen of the NDT inspector were fabricated by using the simulated nuclear environment system in base metal of STS 304 pipe. The size of the used pipe were 8 inch(80 sch., thickness 12.7mm). The end of the pipe was used a flange to simulating a fixed environment of the nuclear power plant structure. To accelerate the fabrication of SCC, a corrosive environment was composed by used a blending corrosion solution of the NaOH 1M and Na2S9-H2O 0.1M inside the pipe. The potential of hydrogen of the caustic solution was 14. The fabricated SCC was confirmed for crack size and shape by used UT and RT.

High catalytic activity derived from TiNbAlC MAX towards improving the hydrogen storage properties of MgH2

MXenes are great catalysts for MgH2 hydrogen storage material. Nevertheless, the synthesis of MXenes needs a large quantity of corrosive HF solution to remove the Al layers from the MAX materials, which is harmful to the environment. In this work, TiNbAlC MAX was employed without HF-treatment to tailor the hydrogen storage of MgH2. The MgH2 + 10 wt% TiNbAlC composite was prepared by ball milling. The addition of 10 wt% TiNbAlC greatly reduces the onset temperature of MgH2 desorption from 332 °C to 197 °C. The composite can desorb 6.2 wt% of H2 in 10 min at a constant temperature of 300 °C. Moreover, the dehydrided MgH2 + 10 wt% TiNbAlC composite can start to absorb hydrogen at room temperature under a H2 pressure of 6 MPa. The hydrogen desorption activation energy of the composite was calculated by Kissinger’s method to be 101 kJ mol−1. Microstructures studies demonstrated that TiNbAlC will partially react with MgH2/H2 to form TiH1.971, which can act as a “hydrogen pump” to facilitate the hydrogen sorption of MgH2. This work suggests that MAX materials are good catalysts for hydrogen storage of MgH2 and provides new insight into the role of MAX phase in tailoring the hydrogen storage of Mg-based hydrogen storage materials.

Corrosion Research and Fractal Characteristics of As-Cast and Semisolid AZ91D Magnesium Alloys

As-cast and semisolid AZ91D magnesium alloy samples were corroded in distilled water, 0.9% NaCl solution, and 3.5% NaCl solution for various times, respectively. With the increase of corrosion time and the concentration of corrosion solution, the corrosion degree of the alloys gradually deepened. The corrosion resistance of semisolid alloy with nearly spherical grain refinement was significantly reduced, resulting in more corrosion pits and a higher corrosion rate. According to the fractal analysis, the corrosion process of semisolid alloy was more uniform under the same conditions. The fractal theory accurately described the corrosion process, further providing a better grasp of the corrosion behavior of AZ91D magnesium alloy.

Ion corrosion behavior of tunnel lining concrete in complex underground salt environment

In this study, the ion corrosion behavior of tunnel lining concrete in complex underground salt corrosion environment was investigated using a self-designed corrosion simulation test device in a complex underground environment. The results indicated the following: the corrosion of flowing water leads to the dissolution of lining concrete, and the load promotes the development of cracks in the tensile area of lining concrete and inhibits the development of defects in the compression area, resulting in the transmission speed of chloride and sulfate ions in lining concrete under different corrosion conditions given as follows: concrete in tensile zone under flowing corrosive solution and load > flowing corrosion solution acting alone > static corrosion solution > concrete in compression zone under flowing corrosive solution and load. When the flowing corrosion solution alone and flowing corrosion solution and load act on the concrete in the tensile zone, the pore volume fraction of gel decreases and the macropore volume fraction increases. Under the combined action of static corrosion solution and flowing groundwater and load, the pore volume fraction of gel in the pressurized area increases and the harmless pore volume fraction decreases.

Exploring the corrosion inhibition mechanism of Serine (Ser) and Cysteine (Cys) in alkaline concrete pore solution simulating carbonated environment

The corrosion inhibition mechanism of two amino acids, Serine (Ser) and Cysteine (Cys) for steel in alkaline concrete pore solution simulating carbonated environment was explored by the means of electrochemical techniques, namely, open circuit potential, potentiodynamic polarization scan and electrochemical impedance spectroscopy. High inhibition efficiencies (>90 %) were recorded by both the inhibitors. Moreover, used amino acids prevented the corrosion of steel by acting as anodic-type inhibitors. The inhibitive solution analysis was performed through UV–vis technique which confirmed the formation of inhibitor-Fe(III) complexes signifying clear interaction between steel and corrosion inhibitors. Surface of steel was analysed after submergence in corrosive solutions, with and without the inhibitors, by the means of optical microscopy, SEM-EDS, FTIR and XPS. The results highlighted the formation of a compact, barrier layer comprising of metal-inhibitor complex. The type of adsorption occurred and the isotherm followed during the adsorption were explored by performing gravimetric analysis at six different concentrations of Ser and Cys. The outcomes revealed that both the amino acids adsorbed on the steel surface by physiochemisorption process following the Langmuir isotherm. Subsequently, with the help of the aforementioned techniques, an inhibition mechanism for Ser and Cys in carbonated concrete environment was conjectured. Ser bound with Fe ions through the carboxylate functional group only, while Cys formed chelate with Fe ions through thiolate as well as carboxylate functional groups. A more thermodynamically stable protective layer was formed in the case of Cys attributed to the strong interaction between Fe ions and thiolate functional group.

Hollow fiber polytetrafluoroethylene membrane heat exchanger with anti-corrosion properties

Thin hollow polytetrafluoroethylene (PTFE) fibers (thickness: 200 μm; outer diameter: 1.3 mm; inner diameter: 0.9 mm) were produced by a specially designed die via stretching and sintering, and assembled into a shell-and-tube membrane heat exchanger. The effects of the flow velocities on the heat transfer performance and thermal resistance were studied in a water-water system. The maximum overall heat transfer coefficient (OHTC) was up to 391 W/(m2‧K) (flow velocities: 0.24 m/s for hot water; 0.11 m/s for cold water). The OHTC became larger (increased from 229 to 391 W/(m2‧K)) at a higher cold water flow velocity (increased from 0.02 to 0.11 m/s) on the shell side when maintaining the hot water flows on the tube side. The OHTC increased from 119 to 391 W/(m2‧K) first and then decreased to 298 W/(m2‧K) with the increase of the hot water flow velocities (from 0.08 to 0.40 m/s) on the tube side, while maintaining the cold water flow velocity on the shell side. The thermal resistance results showed that the increased flow velocity (0.11 m/s) on the shell side significantly reduced the thermal resistance to 2.56 × 10−3 K m2/W on the shell side. Furthermore, the flow turbulence on the tube side is favorable for the heat transfer, and the optimum flow velocity on the tube side was 0.24 m/s. The hollow PTFE fibers were extremely stable and durable in corrosive solutions, with less than 1% changes in bursting strength, tensile strength at break, and elongation at break. This work opens new opportunities for the fabrication and application of hollow fiber PTFE membrane heat exchangers to reuse waste heat in high temperature corrosive environments.

Corrosion Behaviour of NiCr/TiO2 coated 316L stainless steel before and after thermal shock exposure

ABSTRACT Understanding the impact of high-temperature thermal cycle on coating composition and its corrosion characteristics is essential for coating development. The present study investigated NiCr/TiO2-coated 316L austenitic stainless steel (316L SS) under thermal shock exposure and their corrosion behaviour in 3.5% NaCl solution. The electrochemical parameters were evaluated using potentiodynamic polarisation and electrochemical impedance spectroscopy techniques to understand the corrosion characteristics. Various techniques, viz. field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy, were employed to examine the morphology, elemental composition, crystalline and oxidation characteristics of all the samples. The NiCr/TiO2-coated 316L SS demonstrated thermal resistance up to 9-h oxidation period and five thermal cycles. Afterwards, with gradual weight loss, TiO2 spallation appeared on the coated samples. The as-deposited sample revealed an increased pitting potential of 118.76% and improved corrosion resistance over ten times in magnitude than the bare sample. This improvement in the coated sample is attributed to high charge transfer resistance and chemically stable coating layer between the metal matrix and corrosive solution. In contrast, the delaminated sample revealed over four times greater resistance than the bare sample, which is credited to the limited surface area for possible redox reactions and passive NiCr bond coat layer over the metal matrix.

Environmentally conscience corrosion inhibitors for mild steel in corrosive hydrochloric acid solution by Uncaria Cordata extract: experimental and theoretical studies

The Uncaria Cordata as corrosion inhibitors for mild steel (MS) in a 1.0 M hydrochloric acid (HCl) solution. The EIS, polarization, and LPR measurements were used as experimental measurements to confirm the anti-corrosion performances of the Uncaria Cordata at room temperature. The corrosion inhibitors, even at a low dosage range, achieved inhibition efficiencies to a maximum of 97.0% for 400 ppm of Uncaria Cordata. Surface morphology via AFM and SEM/EDX was carried out to validate the presence of protected film and an optimum concentration of each extract above the metal’s surface in the corrosive acidic solution. The ΔG o ads value − 19.70 kJ/mol proved a spontaneous merge of physical and chemical adsorption by the extract compounds at the interface of MS and the HCl solution. DFT was governed to accommodate the elevated inhibition efficiency upshot obtained by the electrochemical tests and recommend a synergy mechanism for most of the adsorbed active compounds in Uncaria Cordata inhibitors with the MS surface. Monte Carlo simulation indicates three active compounds, namely 1, 2, and 8, found to have parallel adsorption on MS. This encourages the highest surface coverage and shields the MS surface from the intrusion of corrosive agents.

New Strategy for the Design of Anti-Corrosion Coatings in Bipolar Plates Based on Hybrid Organic–Inorganic Layers

As a star material in conducting polymers, a polypyrrole coating was assembled onto the surface of 316 stainless steel by an electrochemical method. In the next step, the composite layer consisting of carbon nitride nanosheets (CNNS) and polymethyl methacrylate (PMMA) was sprayed. The corrosion manner of composite coatings in a simulated proton-exchange membrane fuel cell (PEMFC) environment was evaluated. The results show that the final coating generated at a voltage of 1.0 has demonstrated the optimized corrosion resistance. The polypyrrole layer improves the corrosion resistance of the stainless steel substrate, and the CNNS/PMMA coating further strengthens the physical barrier effect of the coating in corrosive solutions.

Green nanomaterials and nanocomposites for corrosion inhibition applications

Abstract Corrosion of metals is considered a global dilemma that is attracting an increasing number of researchers in the scientific community. One of the fundamental solutions against corrosion is using corrosion inhibitors. Corrosion inhibitors are the substances added to the medium or the metal to inhibit corrosion through different mechanisms, most commonly by the formation of a protective layer on the metal surface. Organic corrosion inhibitors constitute most of the known and used corrosion inhibitors, however, due to the toxicity and cost of synthesis, green replacements are needed. Green nanomaterials corrosion inhibitors provide a green and sustainable solution for corrosion. The low toxicity, availability, and cost-effectiveness of green nanoparticles made them a growing research field. This review article highlights the synthesis, use, and application of green nanomaterials in corrosion inhibition. Moreover, the article provides insight into the different types of green nanomaterials inhibitors and their common characterization techniques.

Elastic wave properties in ultra-high strength steel (HV670) exposed to various corrosive solutions

Elastic wave properties in ultra-high strength steel (HV670) exposed to various corrosive solutions

A novel dual-functional layer exhibiting exceptional protection and photocatalytic activity by organic functionalization of plasma electrolyzed layer

The formation of inorganic-organic hybrids (IOH) on the metallic substrates would play a decisive role in improving their structural and functional features. In this work, the growth of organic coating (OC) consisting of coumarin-3-carboxylic acid (3-CCA) and albumin (ALB) on the inorganic layer (IC), produced by plasma electrolysis of AZ31 Mg alloy, led to enabling organically synergistic reactions on the porous inorganic surface, forming a flake-like structure sealing the structural defects of IC. Synergistic actions between OC and IC endow the flake-like structures with chemical protection and photocatalytic performance. Upon contact with a corrosive solution, the IOH layer possesses stable morphologies that delay the corrosive degradation of the whole structure. The electrochemical stability of the sample produced by immersion IC in the organic solution for 10 h (IOH2 sample) was superior to the other samples as it had the lowest corrosion current density (1.69×10−10 A.cm−2) and the highest top layer resistance (1.2 × 107 Ω.cm2). Moreover, the IOH layer can photodegrade the organic pollutants in model wastewater, where the highest photocatalytic efficiency of 99.47% was found in the IOH2 sample. Furthermore, computational calculations were performed to assess the relative activity of different parts of the ALB and 3-CCA structures, which provide helpful information into the formation mechanism of the IOH materials.

Corrosion Inhibition of Mild Steel In (1 M Hcl) Solution Using Plant Extract and The Synergistic Effect of Iodide Ions

The corrosion inhibitive impacts of a mixture (4:1) of Citrus Limon leaf (CLL) extract and potassium iodide additives when the mild steel was exposed to the corrosive solution (1M HCl) were evaluated using the weight-loss method at temperatures of )303, 313, 323, and 333( K. It was noted that the mixture acts as an inhibitor of mild steel corrosion at concentrations of )1.25, 2.5, 3.75, 5, and 6.25( ml/L. It was observed also that the inhibition efficiency (%I) of the mixture increased with an increase in temperature in the presence of the synergistic effect of the iodide ion. It was found that at the highest mixture concentrations and temperatures, the inhibition competence increased to 95.20%. Inhibitor adsorption characteristics were reached by the Langmuir isotherm and were compatible. The adsorption thermodynamic parameters that were calculated supported the mixed-adsorption of the mixture on a mild steel surface. A surface analysis technique (SEM) used to confirm the occurrence of an adsorption process on the surface.

Deterioration of alkali-activated and Portland cement-based mortars under sulfur oxidizing bacteria corrosion

This study investigated the deterioration behavior of the metakaolin based alkali-activated mortar (MK-M), flay-ash-based alkali-activated mortar (FA-M) and granulated blast furnace slag powder-based alkali-activated mortar (SG-M) under simulated microbial induced acid corrosion (MIAC). For comparison, the MIAC induced corrosion of the Ordinary Portland cement-based mortar (OPC) was also studied. The pH variation of the corrosive solution (sulfur oxidizing bacteria liquid medium), visually observation, and mass loss were monitored to estimate the deterioration. X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA) were used to analyze the composition and morphology of different samples. The results revealed that the three alkali-activated cement-based mortars displayed a higher alkalinity compared to the Portland cement-based mortar. MK-M and SG-M exhibited better resistance to MIAC with a smooth surface and without the formation of typical corrosives owing to the stable structure of N-A-(S)–H and the lower content of calcium ion. However, SG-M suffered severe corrosion, which was similar to OPC-M, with the formation of abundant gypsum and ettringite and visually changed morphology for its high content of calcium ion and degenerated structure.