Electrochemical Behavior Of Alloy Research Articles

Effect of heavy ion irradiation on the electrochemical behavior of 321 stainless steel

Aiming to the environment for 321 stainless steel (SS) in primary circuit of pressurized water reactor (PWR), the effect of heavy ion irradiation to simulate neutron irradiation on the electrochemical behavior of alloy is unclear. The purpose of this work is to evaluate the corrosion resistance of 321 SS at different doses and the contribution of heavy ion irradiation in it. This work reveals that the corrosion resistance decreases in the order of 2 dpa > 0 dpa > 10 dpa > 60 dpa at room temperature, consistent with the sequence of δ-phase content near the surface. The effect of irradiation dose on the corrosion resistance of 321 SS is inversely proportional at higher dose and optimal performance of the SS irradiated to 2 dpa is attributed to the highest content of Cr-rich δ-phase. The pits occur in C enrichment zone, accompanied by increase of O content, while no pit occurs in Ti enrichment area. The results provide a reference for the irradiated SS with heavy ion to acquire optimal pitting resistence.

Comparative corrosion behavior of Au50-Ag25-Pd25 and Ni88.6-Cr11.4 alloys utilized in dental applications

The electrochemical behaviour of alloys (Au50-Ag25-Pd25 and Ni88.6-Cr11.4) was studied in Fusayama's artificial saliva at pH 6.5 and 37 °C by using open circuit potential, electro­chemical impedance spectroscopy, and potentiodynamic polarization measure­ments. Electrochemical impedance spectroscopy results were simulated with an equivalent electrical circuit. After immersion in artificial saliva, surface characterization of samples was done using scanning electron microscopy connected with energy-dispersive spectro­scopy. All obtained results revealed that Au50-Ag25-Pd25 alloy is much more resistive than Ni88.6-Cr11.4 and can be recommended for the effective treatment of patients with dental prosthetics that have metal frameworks. s.

Effect of Si and B on the Electrochemical Behavior of FeCoNiCr-Based High-Entropy Amorphous Alloys

The ability to produce high-entropy alloys with an amorphous structure, so-called high-entropy metallic glasses (HEMGs), offers the possibility to produce new compositions with good mechanical properties and resistance to corrosion. In this study, corrosion behavior was studied in two HEMGs, FeCoNiCrB and FeCoNiCr(BSi). In both cases, the total amount of metalloid atoms was kept constant at 20 at.%. The electrochemical behavior of these alloys was studied by means of linear polarization resistance (LPR) measurements and electrochemical impedance spectroscopy in a 3 wt.% NaCl solution. The effect of corrosion was characterized by using X-ray photoelectron spectroscopy (XPS) and the surface morphology was checked using a scanning electron microscope (SEM). The results show that samples with B but without Si exhibit better corrosion resistance due to its chemical homogeneity and lack of structural heterogeneity.

Characterisation, hardness and corrosion behaviour of electrodeposited ZnFe and ZnFe/BN composite coatings

ABSTRACT ZnFe and ZnFe/BN composite coatings were successfully electrodeposited on 304 stainless steel substrates by pulse electrodeposition technique. The effect of various concentrations of BN particles in the plating solution on the structural, hardness and corrosion properties of electrodeposited ZnFe alloy and ZnFe/BN composites were investigated. The deposition process and electrochemical behaviour of alloy and composite coatings were analysed by the Cyclic Voltammetry (CV) method. X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used for the structural, and morphological characterisation of the coatings. Vickers micro hardness indentation was used to determine the hardness of the deposits. The corrosion behaviour of ZnFe alloy and ZnFe/BN composites was investigated by open circuit potential (OCP), Tafel plots, and electrochemical impedance spectroscopy (EIS) methods. As the BN particle content in ZnFe/BN composite coatings rose, the microhardness, and corrosion resistance of coatings increased, which was due to the function of grain refinement and changing dispersion strengthening. Meanwhile, grain sizes were strongly affected from the presence of BN particles and their content. The ZnFe/BN composite coatings with the BN particle concentration of 20 g L−1 had the highest corrosion resistance, and microhardness.

Effect of Er-Rich Precipitates on Microstructure and Electrochemical Behavior of the Al–5Zn–0.03In Alloy

The effect of Er-rich precipitates on microstructure and electrochemical behavior of the Al–Zn–In anode alloy is investigated. The results showed that with the increase in Er content, the microstructure was refined, the amount of interdendritic precipitates gradually increased, and the morphology changed from discontinuous to continuous network gradually. With the addition of Er element, the self-corrosion potential of the Al–5Zn–0.03In–xEr alloy moved positively, the self-corrosion current density decreased, and the corrosion resistance increased. When the Er content was less than 1 wt.%, the addition of Er improved the dissolution state of the Al–5Zn–0.03In–xEr alloy, and increased the current efficiency of the Al–5Zn–0.03In–xEr alloy. When the Er content was more than 1 wt.%, the current efficiency was reduced. The major precipitate of the alloy was Al3Er. According to the element composition of Al3Er in the Al–Zn–In–Er alloy, the simulated-segregated-phase alloy was melted to explain the effect of Al3Er segregation on the electrochemical behavior of alloys, and the polarization curve and AC impedance spectrum of the simulated-segregated-phase alloy and the Al–Zn–In alloy were measured. The results showed that Al3Er was an anodic segregation phase in the Al–Zn–In–Er alloy, and the preferential dissolution of the segregation phase would occur in the alloy, but the Al3Er phase itself was passivated in the dissolution process, which inhibited the further activation of the dissolution reaction of the Al–Zn–In–Er alloy to a certain extent.

Digital Signal Analysis of Electrochemical Signals of Graphene Oxides for Display Devices

ABSTRACTBy using electrochemical tests, small signal variations were study by digital signal processing techniques. Electrochemical noise and electrochemical polarization curves were very useful to obtained electrochemical behavior of alloys, but the low signal levels of measurements obtained showed that some of the information was not likely to be measured and, therefore, not being able to identify. Graphene oxides (GO) samples were prepared by ball milling procedure adding Lithium. SIGVIEW software was used for Digital Signal studies. Comparing, the signals obtained by electrochemical techniques and the research by computational tools; it was possible to find out a behavior path of samples. Display devices made by graphene were observed to provide new information about the structure of samples and how nanotechnology area can be improved. The current investigation aimed at maintaining electrochemical stability, since different deformations, as twisting and bending are quite relevant in portable electronics devices.

Effect of Temperature on Electrochemical Behavior of Alloy 690 in Simulated PWR Secondary Circuit Water

Effect of Temperature on Electrochemical Behavior of Alloy 690 in Simulated PWR Secondary Circuit Water

Hyperfine structure and electrochemical behavior of Fe-Cr-Ni alloys

With the use of nuclear γ-resonance Mossbauer spectroscopy, the hyperfine structure of quenched (1100° C, 1 h, water) Fe-∼20% Cr-(9.6, 40.8, 70.7)% Ni alloys is studied. With the Normos program package, the isomer (chemical) shift Γ (mm/s) of the singlet and doublet signals, the half-width Γ (mm/s) of the singlet and doublet spectral components, the area part S (%) of the components in the general spectra, and the probability distribution function of hyperfine magnetic fields P(Heff) are calculated. The effect of nickel on the electron density distribution around 57Fe nuclei is discovered. Novel data on the presence of ferromagnetic phases, their nuclei and clusters in Fe-19.6% Cr-9.6% Ni are obtained. The data of Mossbauer spectroscopy are compared to the anodic polarization curves recorded in a 1 N H 2SO4 solution with the aim to clarify the relation between the electronic structure and electrochemical behavior of alloys

Effect of Aging on Electrochemical Behavior of T6-Treated WE54 Mg Alloy

Microstructural examinations of T6-treated WE54 magnesium alloy were conducted after different aging conditions, and the influence of aging on electrochemical behavior of this alloy was investigated. For three batches of samples, with increasing aging time, the amount of precipitate phases was greatly promoted, and they formed in a strengthening continuous way. Electrochemical study showed that the value of corrosion potential followed the tendency to decrease when the aging condition transformed from under-aged to peak-aged. However, after peak-aging, the corrosion potential was raised to higher values. Explanations for the observed phenomena were based on the relationship between microstructure, especially precipitate phases, and electrochemical behavior. At under-aged condition, matrix served as galvanic cathode and precipitates acted as galvanic anode. Because the amount of precipitate would rise with prolonging aging time, it is natural that corrosion potential decreased. For over-aged alloys, metastable precipitate phases might in situ change to equilibrium phases, rendering increase of corrosion potential possible.

The effect of oxidation of amorphous Fe70Cr15B15 alloy on its corrosion behavior in the acidic sulfate media

The effect of surface oxidation on the corrosion behavior of amorphous Fe70Cr15B15 alloys in the acidic sulfate media with constant ionic strength is studied. It is found that the main factor determining the electrochemical behavior of alloy is not only the elemental composition of the surface, but primarily, its chemical composition. Surface nanooxide films have the strongest effect. Films with spinel structure are most corrosion-resistant. Oxidation has an effect predominantly on the anodic process.

Electrochemical characterization of cobalt-based alloys using the mini-cell system

Objectives The aim of this work was to investigate the electrochemical behavior of cobalt-based alloys of different compositions using the mini-cell system (MCS) and to test the sensitivity of this technique in the detection of variations in the electrochemical behavior caused by the different compositions of cobalt-based alloys. Methods The electrochemical measurements were performed on two cobalt-based alloys, having a small content of gold (Bärlight and Gold Core); one cobalt–platinum–ruthenium alloy (Porta Smart) and one classical Co-based alloy (Wironit), in two different electrolytes, 1% NaCl and phosphate buffered solution (PBS). Results Based on I versus E curves, enhanced pitting corrosion capability was observed for the cobalt-based alloys, especially for those with lower chromium content and with the addition of a small amount of gold. The alloying of Co with Pt and Ru (Porta Smart), and the standard Co-based alloy do not show any critical instability; in contrast, a small addition of Au enhanced the pitting corrosion activity and reduced the corrosion stability. For higher alloy stability, a minimum 30% atomic ratio of chromium in the alloy composition is necessary. Furthermore, it was shown that MCS has sensitivity for the qualitative comparison of the alloys as well as in the electrochemical characterization of each alloy. Significance Electrochemical measurements are essential to assess the quality of an alloy. MCS might help in understanding the role the elements play in the electrochemical behavior of the alloys and at the same time contribute to the selection of the alloys in terms of their quality, even before more complex tests in vitro or in vivo are applied, and might reduce the costs for materials research.

Investigation of Thermodiffusion Carbonitride Coatings on Titanium Alloys

We study specific features of the processes of phase formation and gas saturation in VT1-0, VT14, OT-4, and VT20 titanium alloys held in a carbon-and-nitrogen-containing medium for 5 h at 1100°C. Depending on the type of alloy, the TiC x N y carbonitride phases of different compositions are formed on the metal surface under the indicated conditions. The analysis of the corrosion and electrochemical behavior of alloys shows that the best protective properties are exhibited by the carbonitrides formed on the surface of VT20 alloy (whose composition is close to equiatomic and the surface roughness is minimum).

Electrochemical behaviour of alloy CoW0·013C0·001 in acidic sulphate solutions

Elucidation of the electrochemical behaviour of the CoWxCy binder alloy is a basic step in understanding the corrosion performance of hard metals of the WC–Co type. The anodic oxidation mechanism of the alloy CoW0·013C0·001 has been studied in 0·1M H2SO4 by linear sweep and cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The morphology, composition, and structure of the reaction products were studied by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, respectively. In this paper, the main features of the pseudopassivating behaviour are described and a simple model for the reaction kinetics is suggested. The development of corrosion layers with different inhibiting effectiveness is reported and the relationship between the features of these layers and the evolution of the surface composition is highlighted. The formation of a hydrated mixed oxide (Co3W7O24·19H2O) is revealed, which provides evidence for the complexity of the reactions involved. A comparison of the corrosion product morphologies and surface structures suggests a correlation between the orientation of the surface grains and the type and stability of the inhibiting layer.

Investigation of the ZrVGe system alloys

The ZrVGe system alloys were investigated using different methods of physico-chemical analysis: microstructural, X-ray phase and electron probe X-ray analyses and measurements of Vickers hardness and micro-hardness. The electrochemical behaviour of alloys in solutions of mineral acids was studied. The isothermal cross-section of the phase diagram of the ZrVGe system at 1170 K was constructed. The formation of ten binary in termetallic compounds in the system at this temperature was corroborated and the range of existence of ternary solid solutions based on these compounds was found. New ternary compounds of tentative composition Zr 2V 3Ge 4 and ZrVGe were detected.