Galvanic Effect Research Articles

Influence of Cr and Ni elements on the electrochemical and early corrosion behavior of FeMnAlC low-density steel

FeMnAlC low-density steel (LDS) is considered to be a promising material due to its good mechanical properties and light weight, its corrosion resistance, however, needs to be improved. In this paper, the effect of Cr and Ni on the electrochemical and early corrosion behavior of a Fe–25Mn–10Al–1.5C LDS in a 3.5% NaCl solution was studied through microstructure characterization, electrochemical tests and immersion tests. The results showed that Cr and Ni alloying reduced the austenite grain size and promoted the formation of the B2 phase. Adding 2% Cr or Ni to the Fe–25Mn–10Al–1.5C LDS clearly inhibited the electrochemical activity and initial micro galvanic effect between the second phases and the austenite. Moreover, the properties of the corrosion product film were optimized, and the local corrosion process beneath the product film was mitigated. Compared with 2% Cr addition, 2% Ni addition improved the corrosion resistance of the FeMnAlC LDS better from the aspects of electrochemistry, corrosion product film and corrosion mode.

Corrosion and wear of coatings fabricated by HVOF-spraying of nanostructured and conventional WC–10Co-4Cr powders on Al7075-T6

The present work compares WC-10Co-4Cr coatings fabricated by HVOF spraying of a conventional powder (1.33 ± 0.67 μm) and a nanostructured powder (0.17 ± 0.06 μm) on Al7075-T6, in terms of microstructure and phase composition, microhardness and fracture toughness, corrosion performance in 3.5 wt% NaCl (potentiodynamic polarization, chronoamperometry, galvanic effect measurements and salt spraying) and sliding wear performance under lubrication. Τhe nanocoating, despite its greater microporosity and decarburization, displayed higher microhardness, fracture toughness and surface roughness compared to its conventional counterpart. A superiority of the corrosion behaviour and sliding wear behaviour of the nanocoating as compared to its conventional analogue was observed in terms of a higher resistance to general/localized corrosion, lower passive film conductivity, lower wear rate, subtler wear scars and greater occurrence of islands of tribofilms. The reasons for such superiority are being clarified. A good galvanic compatibility between the nanocoating and its substrate was manifested. Both coatings exhibited high corrosion resistance during salt spraying for 45 days. The mechanisms of corrosion and wear degradation are being proposed.

Synergistic effect of crevice corrosion and galvanic coupling on 304SS fasteners degradation in chloride environments

The synergistic effect of crevice corrosion and galvanic coupling on the degradation of 304 stainless steel fasteners exposed to a chloride environment was investigated using electrochemical and surface analysis techniques. Results obtained revealed that the crevice region of the fastener showed lower corrosion resistance due to decreased surface passivation induced by the crevice geometry and low oxygen conditions, while the exposed region with a higher oxygen supply exhibited improved corrosion resistance. Coupling of the exposed and crevice regions of the fastener demonstrated accelerated corrosion attributable to galvanic effect. The driving force for the galvanic effect on the fastener was linked to three (3) key factors: (I) the potential difference established between the different regions on the fastener surface due to uneven oxygen distribution, (II) the difference in the solution environment, and (III) the difference in surface properties (active-passive surface). Morphological studies showed localised corrosion occurring mainly in the crevice.

Effect of selective atomic clustering, surface texture and grain boundary constitution on the corrosion behaviour of electrodeposited Sn-xBi coatings

Sn-xBi (x = 4, 7, 10, 14, and 17 wt%) coatings were electrodeposited onto mild steel to elucidate their corrosion behaviour. The B14 (Sn-14 wt% Bi) and B7 (Sn-7 wt% Bi) coating exhibited the highest (Polarization resistance (Rp) = 12,810.2 Ω·cm2) and least corrosion resistance (Rp = 2843.2 Ω·cm2), respectively. B14 coating exhibited the lower energy near (301) plane orientation against B7 coating which showed higher energy (321) and (111) plane orientation along the exposed surface. The galvanic coupling effect alleviated in B14 coating due to Sn nanoclusters into Bi grains as revealed by the atom probe tomography analysis.

(Bio)dissolution of arsenopyrite coupled with multiple proportions of pyrite: Emphasis on the mobilization and existential state of arsenic

The formation of arsenic-bearing acid mine drainage (AMD) via the oxidation of arsenopyrite refuse ore has attracted significant attention. Pyrite, as main a concomitant mineral, is a crucial factor that affects the (bio)dissolution of arsenopyrite, but there are still some points on the detailed action mechanism under normal environmental conditions that need further study. In this study, the effect mechanism of pyrite with a systematic pyrite content (0, 10, 25, 50, 75, 90, and 100 wt %) on arsenopyrite oxidation and arsenic release in the presence of Acidithiobacillus ferrooxidans was investigated. The X-ray diffraction (XRD), scanning election microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical analyses were also carried out. Results showed that the existence of pyrite and Acidithiobacillus ferrooxidans significantly accelerated the dissolution of arsenopyrite and the oxidation of As (Ⅲ) to As (Ⅴ), resulting from the galvanic effect, an increase in the Fe3+/Fe2+ ratio and the oxidation–reduction potential (Eh) value, and a decrease in pH level. As the detected main intermediate products, element sulphur was considered as the dominating obstructive factor during arsenopyrite oxidation, while the added pyrite could accelerate its oxidation. Moreover, a close relationship between different mineral proportions and the galvanic effect was also observed and discussed. Finally, suggestions on AMD governance and source control are proposed.

Effect of P Content on the Corrosion Behavior of Electrodeposited Fe-P Coatings

Eco-friendly Fe-P coatings containing different P contents up to 20 wt% were electrodeposited on pure copper substrate. Scanning electron microscopy (SEM), grazing incident X-ray diffraction (GIXRD), microhardness, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization tests were used to investigate the effect of P content on the microstructure and corrosion behavior of the coatings in 3.5 wt% NaCl solution. Results showed that the surface becomes smoother with increasing the P content and superficial microcracks form at 20 wt% P. Coatings containing 5 and 10 wt% P showed a nanocrystalline microstructure, while a fully amorphous microstructure obtained at higher P contents. The best corrosion resistance was seen for the coatings containing 10 and 15 wt% P, which was related to their microstructure and smooth surfaces. Defect-free Fe-P coatings can increase the corrosion resistance of the copper and have the ability to protect the substrate through galvanic effect in which the coating acts as the anode. The coating hardness revealed an inverse Hall-Petch relationship so that the hardness of the coating decreased with decreasing the crystallite size of the deposit.

Effect of sulfate reducing bacteria on the galvanic corrosion behavior of X52 carbon steel and 2205 stainless steel bimetallic couple

Effect of sulfate reducing bacteria (SRB) on the galvanic corrosion between 2205 SS (stainless steel) and X52 carbon steel in enriched artificial seawater (EASW) was comprehensively investigated, which was significant for understanding the microbiologically influenced corrosion of bimetallic composite pipelines. Electrochemical tests indicate that the galvanic effect in the SRB-containing medium was higher than that in the sterile medium. The coupling also promoted the corrosion of 2205 SS in biotic medium with a 13-fold increase in weight loss. The galvanic effect could increase the sessile cell density and accelerate the deterioration of the passive film of 2205 SS.

Enhancing energy extraction from water microdroplets through synergistic electrokinetic and galvanic effects

An efficient carbon black based water-evaporation generator for raising energy extraction from water droplets and its multiple self-powered applications in low-power electronic devices are reached via synergistic electrokinetic and galvanic effects.

Vestibular projections to the striatum: the mechanism of galvanic vestibular stimulation effects in Parkinson’s Disease?

Vestibular projections to the striatum: the mechanism of galvanic vestibular stimulation effects in Parkinson’s Disease?

Microstructures, mechanical properties, corrosion, and biocompatibility of extruded Mg-Zr-Sr-Ho alloys for biodegradable implant applications

In this study, the microstructures, mechanical properties, corrosion behaviors, and biocompatibility of extruded magnesium-zirconium-strontium-holmium (Mg–Zr–Sr–Ho) alloys were comprehensively investigated. The effect of different concentrations of Ho on the microstructural characteristics, tensile and compressive properties, corrosion resistance, and biocompatibility were investigated. The microstructures of the extruded Mg-1Zr-0.5Sr-xHo (x = 0.5, 1.5, and 4 wt.%) alloys consisted of α-Mg matrix, fine α‒Zr particles, and intermetallic phase particles of Mg17Sr2 and Ho2Mg mainly distributed at the grain boundaries. Extensive {101¯2} tensile twins were observed in the partially recrystallized samples of Mg-1Zr-0.5Sr-0.5Ho and Mg-1Zr-0.5Sr-1.5Ho. Further addition of Ho to 4 wt.% resulted in a complete recrystallization due to activation of the particle stimulated nucleation around the Mg17Sr2 particles. The evolution of a rare earth (RE) texture was observed with the Ho addition, which resulted in the weakened basal and prismatic textures. Furthermore, a drastic increase of 200% in tensile elongation and 89% in compressive strain was observed with Ho addition increased from 0.5 to 4 wt%, respectively. The tension–compression yield asymmetry was significantly decreased from 0.62 for Mg-1Zr-0.5Sr-0.5Ho to 0.98 for Mg-1Zr-0.5Sr-4Ho due to the weakening of textures. Corrosion analysis of the extruded Mg–Zr–Sr–Ho alloys revealed the presence of pitting corrosion. A minimum corrosion rate of 4.98 mm y−1 was observed in Mg-1Zr-0.5Sr-0.5Ho alloy. The enhanced corrosion resistance is observed due to the presence of Ho2O3 in the surface film which reduced galvanic effect. The formation of a stabilized surface film due to the Ho2O3 was confirmed through the electrical impedance spectroscopy and XPS analysis. An in vitro cytotoxicity assessment revealed good biocompatibility and cell adhesion in relation to SaOS2 cells.

Зависимость процесса коррозии биорезорбируемого сплава ZX10 от структурных факторов и локального уровня pH

Magnesium biodegradable alloys are a promising material for self-dissolving surgical implants. Magnesium is known to be sensitive to electrochemical corrosion due to the galvanic effect between the matrix and particles of secondary phases and inclusions. Another important factor is the pH level. The behavior of certain chemical reactions depends on the pH level, so one can assume that the pH level of a corrosive medium at the material surface is a factor determining what chemical reactions can occur there. Finally, there is evidence that variability of the crystallographic orientation of the grains may be a cause of anisotropy of corrosion properties. The purpose of this work is to reveal the influence of the electrode potential of the microstructural elements, the crystallographic orientation of the grains, and the pH level of the near-surface volume of the corrosion solution on the corrosion process. In the study, sections of 2×1.5 mm were marked on the ZX10 alloy samples, for which maps of the distribution of crystallographic orientations and chemical composition were drawn. To assess the influence of the electrode potential of the particles, the authors carried out a Kelvin probe mapping in the 90×90 µm area. Next, corrosion tests were carried out with video filming of the surface on the marked area. To determine the pH level influence, the solution circulation in the cell was varied. Upon completion of the tests, corrosion products and corrosion damage were examined in detail. According to the results, the pH level in the liquid near-surface micro-volumes has a greater influence than the electrode potential of the particles as it provokes the formation of corrosion products of a different composition, which leads to passivation of the surface areas around the particles. The authors identified two different types of filiform corrosion. For filiform corrosion, a correlation between the corrosion direction and the crystallographic orientation of the grains was established.

Enhanced degradation performance of Fe75B12.5Si12.5 amorphous alloys on azo dye.

The Fe75B12.5Si12.5 and Fe75B12.5C12.5 amorphous alloy ribbons were prepared by the melt spinning method. The decolorization performances of these ribbons were investigated in details. It is found that the Fe75B12.5C12.5 amorphous ribbons and Fe75B12.5Si12.5 annealed ribbons only adsorbed the azo dye molecules, with no chemical degradation process. However, the Fe75B12.5Si12.5 amorphous ribbons can reduce -N = N- to -NH2 because of their high reactivity and the local galvanic effect that occurred during the reaction to accelerate electron transfer. The reaction rate constant kobs is 0.0872min-1, 0.0474min-1, and 0.0064min-1 for Fe75B12.5Si12.5 amorphous ribbons, Fe75B12.5C12.5 amorphous ribbons, and Fe75B12.5Si12.5 annealed ribbons in the same condition, respectively. Fe75B12.5Si12.5 amorphous ribbons can effectively degrade Acid Orange II (AO II) azo dyes and achieve decolorization by breaking azo bonds in the dye in a short time, indicating the prominent capacity of Fe75B12.5Si12.5 ribbons on the degradation of AO II. Furthermore, the influence of chemical factors such as ribbons thickness, reaction temperature, initial pH, and AO II concentration of the solution on the reaction rate constant kobs of Fe75B12.5Si12.5 amorphous ribbons had also been studied. The kobs can reach 0.177min-1 under optimal conditions. In addition, all the degradation processes in this work were fitted well with the pseudo-first-order kinetic model. The results are guidance for the practical applications, and they have important implications in developing Fe-based amorphous alloys for functional application materials in the field of wastewater treatment.

Corrosion Study of Additively Manufactured Hip Implant Acetabular Shells: The Influence of Porous Structure and Post-treatment

Additively manufactured (AM) implants are rapidly increasing in the medical field, but corrosion resistance remains an essential concern on the newly developed AM implants. In the current study, three kinds of AM shells were evaluated in a three-electrode system under cyclic polarization and electrochemical impedance spectroscopy with bovine calf serum (BCS). The commercial acetabular shell with BIOFOAM® from MicroPort Inc. was the control group. We hypothesized that the AM shells would demonstrate comparative corrosion properties to the control group. After the corrosion testing, all groups were examined with scanning electron microscopy (SEM) with elemental analysis of energy-dispersive spectroscopy (EDS). Based on results of corrosion experiments, AM shells presented less corrosion current in cyclic polarization, which is supported by electrochemical impedance spectroscopy (EIS). After fitted with the equivalent circuit with EIS data, AM shells exhibited higher resistance of polarization and lower capacitance, indicating higher corrosion resistance. With examination of SEM with EDS, a patchy layer of titanium with higher carbon and oxygen concentration was apparent on the surface of the control group, which might cause the galvanic effect inducing higher corrosion currents. In conclusion, AM shells demonstrated a better corrosion resistance than the control group, but there were several limitations in the current study. Future research is required to fully assess the corrosion properties of implants.

Microstructured Electroceutical Fiber‐Device for Inhibition of Bacterial Proliferation in Wounds

AbstractAntibiotic‐resistant infections caused by bacterial pathogens pose a serious threat to public health, hampering wound healing and causing significant morbidities worldwide. A biomedical fiber‐device that functions as a drugless antiseptic is introduced as a solution to this problem. Through stitching, piercing, or topical application to the wound, this fiber slows down the proliferation of pathogenic bacteria, thereby reducing the risks associated with inflammation and inhibiting infections. The fiber's bacterial proliferation inhibition function is based on the galvanic effect, which disturbs bacterial quorum sensing. Detailed herein are the fiber design optimization, scalable fabrication approach, electrical function characterization, and antiseptic function verification in cultures of typical wound pathogens. Such a fiber—mechanically and environmentally resilient, insensitive to harsh storage conditions with nominally infinite shelf‐life, resulting from machining rather than pharmacochemical fabrication— provides a cost‐effective and widely available alternative to current antibiotic treatments of physical injury.

Synthesis of crystalline BaZrO3 thin films over preferred-oriented ZrN by a hydrothermal-galvanic couple method for photoelectrochemical evaluations

Crystalline barium zirconate (BaZrO 3 ; BZO) films which could be applied to photoelectrochemical cells and fuel cells were synthesized by a hydrothermal-galvanic couple (HT–GC) method using preferred-oriented ZrN thin-film electrodes. The HT–GC synthesis was carried out at 90°C in alkaline solutions. Substantial galvanic currents were detected without applying any external power sources throughout the synthesis. X-ray diffraction patterns reveal that BZO films with different crystallinities were achieved by such a facile synthesis. Moreover, the BZO films that grew on close-packed (200)-preferred oriented ZrN underlayer exhibited higher crystallinity and growth rates than on the (111)-preferred oriented ZrN. The obtained BZO films exhibited fast on-off photoelectrochemical responses while the BZO films with higher crystallinity over the (200)-ZrN possessed better photoelectrochemical responses. • Crystalline BaZrO3 films could be synthesized on ZrN by a hydrothermal-galvanic couple method • Crystallinity and photoelectrochemical performance of the films were tailored through ZrN • Galvanic effects were enhanced by using (200)-oriented ZrN rather than (111) oriented ZrN • Higher crystallinity of the films could be achieved by a more close-packed (200)-ZrN • Better and fast on-off photoelectrochemical responses of the films were obtained by (200)-ZrN

Electrochemical properties and dissolved behavior of laser solid formed Ti6Al4V alloy in NaCl solution with different current densities

The hybrid manufacturing process of additive manufacturing (AM) and electrochemical machining (ECM) is a new approach to advanced manufacturing technology. The feasibility of using ECM to machine an as-deposited Ti6Al4V alloy fabricated by the laser solid forming (LSF) method of AM was investigated in 15 wt.% NaCl solution. As the machining current density increased, the material removal rate increased linearly, and the current efficiency dropped from 140% to 93%. The current efficiency over 100% at low current densities was attributed to the electrochemical reactions of atoms in lower valence states. The microdissolved grooves, resulting from selective preferential dissolution of the α phase, were shallowed when machined at a higher current density (>3 A cm −2 ) and are attributed to the weakening of the galvanic effect at higher machining voltages. Additionally, the dissolved surface topography exhibited the worst waviness at the delimited current density of 10 A cm −2 , and the surface waviness decreased rapidly as the current density increased in the positive delimited range. Considering the machining efficiency and the surface quality of ECM, the as-deposited Ti6Al4V machined at a current density of 40 A cm −2 will be the preferred ECM current parameter.

Unexpected enhanced catalytic performance via highly dense interfaces in ultra-fine amorphous-nanocrystalline biphasic structure

Metallic glasses (MGs) as effective catalysts have been extensively studied due to essentially disordered atomic configurations and widely adjustable micro-morphologies. The catalysis performance could be greatly promoted by introducing additional crystalline phases in the amorphous matrix due to the synergistic advantages of the crystalline and amorphous phases. However, the conventional casting and annealing approaches induced amorphous-crystalline (a/c) composites restrict the synergistic and galvanic cells effects because the generated crystalline phases are easily coarsened with meager a/c interfaces. Here, the artificial ultra-fine a/c Fe76Si8B13Nb3 catalyst with spinodal decomposition morphology and extremely high dense a/c interfaces of 2 × 1016 m−2 are achieved from MG film precursor with nanoscale phase separation by controllable surface diffusion during deposition and suppressive crystalline coarsening procedures. The designed ultra-fine a/c catalyst exhibits admirable cycling degradation property and extraordinary dye degradation efficiency of 300 times than that of the commercial Fe powder. Especially, the outstanding catalytic performances of a/c composite are achieved without the additional involvement of hydrogen peroxide assistance, which provides an environmental-friendly neutral catalytic condition and avoids the corrosive damage during commercial sewage-treatment. This work provides a distinct perspective to design and regulate catalytic performances by amorphous precursor with pre-existent ultra-fine structures.

Influence of W content on microstructure and corrosion behavior of laser cladded Inconel 718 coating

The microstructure and corrosion behavior of Inconel 718-xW (x = 0, 6, 12, and 18 wt%) coating was investigated. The results reveal that W addition can inhibit the formation of interdendritic, refine the grain size, promote the formation of Laves phase, and even form the Fe2W phase inside the Inconel 718-18W coating. The Inconel 718-6W coating demonstrates excellent corrosion resistance in 3.5 wt% NaCl solution with low corrosion current density, and high potential, and its polarization resistance is 11.99 times higher than that of the Inconel 718 coating. W element is able to promote production of more oxides and hydroxides on the surface of the coating by other elements, significantly enhancing the denseness and stability of the passive film. While excessive addition of W leads to a reduction in the corrosion resistance of the coatings, due to the increase in negative galvanic effect caused by the large number of Laves and Fe2W phases generated within the coatings. In addition, the geometrically necessary dislocations inside the coatings increase with the rise of W content, which can destroy the integrity of the passive film, adversely affecting the corrosion resistance.

Localized Depth of Galvanic Corrosion at Dissimilar Metal Welding A508/Inconel 182/316L

Recently, efforts have been made to develop the use of dissimilar metal welding in industrial components. Pressurized water reactors (PWR) in nuclear power plants frequently use dissimilar metal welding (DMW) in their primary water systems (NPP). The selection of the combination of stainless steel and low alloy steel is adjusted to the working conditions of work in high-temperature environments. Nickel-based Inconel 82/182 alloy is used as a weld filler in the GTAW method of joining to produce A508/Inconel-182/316L dissimilar welds with variations in the immersion time of the material at high temperatures. The depth of galvanic corrosion related to morphology using an optical microscope and SEM, changes in potential and current density using a potentiodynamic polarization test, and depth of galvanic corrosion using surface profiler (α -step) were thoroughly investigated. The results showed that low alloy steel A508 generally suffered from corrosion attacks. Still, the most severe corrosion attack was in the weld joint interface area of low alloy steel A508/Inconel 182 due to the influence of galvanic corrosion. These symptoms will not be seen if observed on the outside of the surface only, but severe symptoms occur on the inside of the weld joint A508/Inconel 182. Finally, there has been a change in the shape of the gap and concave (depth of galvanic corrosion effect) of the welded joint interface between Inconel 182 and low alloy steel A508 because the effects of galvanic corrosion with changes in potential, current density, and immersion time of dissimilar welded materials.

Corrosion behavior of wire arc additive manufactured and wrought 309 stainless steel in acidic solution

In this study, 309 stainless steel (309SS) was fabricated by wire arc additive manufacturing (WAAM) process and characterized using optical microscopy and X-ray diffractometry. Corrosion behavior of WAAM 309SS in 1 mol/L H2SO4 solution at room temperature was investigated in comparison to that of wrought 309SS using electrochemical impedance spectroscopy, pontentiodynamic polarization, and immersion test. Mott-Schottky analysis, double loop electrochemical potentiokinetic reactivation (DLEPR) test and galvanic corrosion test using zero resistance ammeter (ZRA) technique were also conducted. The results showed that WAAM 309SS exhibited lower corrosion resistance than AISI 309SS due to microstructural differences engendered by the additive manufacturing process. Galvanic corrosion test showed that galvanic effect between the two stainless steels was minimal despite the microstructural differences while DLEPR test revealed the absence of chromium-depleted zones in both WAAM 309SS and AISI 309SS.