Cyclic Voltammetric Studies on Selected Tin-Silver Binary Alloys in Sodium Hydroxide Solution (original) (raw)
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Corrosion characterization of new tin–silver binary alloys in nitric acid solutions
Corrosion Science, 2008
Electrochemical techniques were used to characterize the corrosion behavior of four new binary alloys xSn-Ag (x = 26, 50, 70 and 96.5 wt%) alloys and their individual metal components in nitric acid solutions. The experimental data were collected by using open-circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Over the concentration range studied (0.075-4.5 M), each of the two corrosion parameters (E corr and i corr ) shows a regular dependency on both the alloy composition and the solution concentration. In general, for all studied samples, especially pure Ag and those with lower Sn contents (26 and 50 wt%), increasing the acid concentration increases i corr , meanwhile causes a shift of the corresponding E corr towards more positive values. This is probably due to the increase in the effect of cathodic depolarizer as the nitric acid concentration is increased. EIS results at the free corrosion potential confirmed well this behavior, where at concentrations 61.5 M the thickness of the surface film increases while its resistance decreases with increasing tin wt%, indicating formation of less protective thicker film. However, at higher concentrations all samples exhibit identical behavior.
Electrochemical Behaviour of a Silver Electrode in NaOH Solutions
Monatshefte fuer Chemie/Chemical Monthly, 1998
Studies of the electrochemistry of metals and alloys are very important ®elds of scienti®c and industrial work. The present investigation includes detailed studies on the corrosion and electrochemical behaviour of Ag in aqueous NaOH solutions under various conditions using cyclic voltammetry, chronoamperometry, and potentiostatic techniques. It was found that the anodic polarization curve of Ag in NaOH solutions is characterized by the occurrence of ®ve anodic peaks (A1±A5). A1 is due to the electroformation of soluble [Ag(OH) 2 ] À complex species, A2 to the electroformation of Ag 2 O, A3 to nucleation and three dimensional growth of the Ag 2 O layer, A4 to the formation of AgO, and A5 presumably to the formation of Ag 2 O 3 . X-ray diffraction patterns con®rmed the existence of passive Ag 2 O and AgO layers on the electrode surface potentiodynamically polarized up to oxygen evolution.
Evaluating Corrosion and Passivation by Electrochemical Techniques
International journal of mechanical engineering and robotics research, 2016
In this study, the electrochemical techniques used to analyze corrosion behavior and passive films are introduced in detail. These electrochemical techniques include Linear Sweep Voltammetry (LSV), Cyclic Polarization (CP), Cyclic Voltammetry (CV), Tafel Extrapolation (TE), and Electrochemical Impedance Spectroscopy (EIS). The advantages and disadvantages of these techniques are also introduced in this study. As an example to examine the efficiency and performance of these techniques, electrochemical measurements were carried out in a three-electrode system whereby a commercial copper nickel alloy, C70600 was used as the working electrode. These measurements were performed in natural seawater and in artificial saline solutions with different sulphate content. The results obtained from these electrochemical investigations were compared with the results from conventional immersion tests reported in previous studies. The results conclude that these techniques provide a very convenient and efficient way to evaluate the corrosion and passivation processes in both the laboratory and field within a very short time.
Perchlorate Pitting Corrosion of a Passivated Silver Electrode
Monatshefte fuer Chemie/Chemical Monthly, 1999
The passivation and pitting breakdown of a silver electrode in sodium hydroxide solutions containing sodium perchlorate was studied using potentiodynamic and potentiostatic techniques. In perchlorate-free alkali solution, the voltammogram exhibits three anodic peaks prior to oxygen evolution. The ®rst two peaks correspond to the oxidation of Ag and formation of a passive ®lm of Ag 2 O on the electrode surface, the third to the conversion of Ag 2 O to AgO. In the presence of ClO À 4 , the voltammogram depends considerably on perchlorate concentration. ClO À 4 increases the height of the three anodic peaks, and at potentials above a limiting value breakdown of the anodic passivity and initiation of pitting corrosion occurs. The pitting potential decreases linearly with ClO À 4 concentration but increases with scan rate. The potentiostatic current/time transients show that pitting corrosion can be described in terms of an instantaneous three dimensional growth under diffusion control.
Electrochemical behaviour of polycrystalline silver in 0�5M NaOH containing sulphide ions
Corros Eng Sci Technol, 2005
The electrochemical behaviour of silver in 0?5M NaOH solution containing different concentrations (0?0005-0?007M) of sodium sulphide was studied using cyclic voltammetry, potentiodynamic, and current transient techniques. The anodic sweep of the voltammogram in NaOH was characterised by the appearance of three anodic peaks A 3 , A 4 and A 5 that are related to the formation of AgO 2 , Ag 2 O and Ag 2 O 2 on the electrode surface. The presence of Na 2 S in NaOH solution resulted in the appearance of two additional anodic peaks A 1 and A 2. These two peaks are related to the formation of Ag 2 S and S, respectively. The addition of Na 2 S also increases the heights of the anodic peaks A 3 , A 4 and A 5. The increase in the current density of the anodic peaks A 3 and A 4 is mainly due to surface enlargement resulting from pitting and the precipitation of sulphur on the electrode surface. Also, the large increase in the current density of the anodic peak A 5 is due to the formation of the soluble SO 22 4 compound. The morphology of the electrode surface was examined by scanning electron microscopy. Characterisation of the corrosion products formed anodically on the electrode surface was undertaken using X-ray diffraction analysis. Potentiostatic current-time transients showed that the formation of Ag 2 S, S and Ag 2 O layers involves a nucleation and growth mechanism under diffusion control.
Journal of the Electrochemical Society, 2014
Electrochemical impedance spectroscopy was used to study the degradation behavior of thin multilayer stacks; Si 3 N 4 /Ag/Si 3 N 4. Measurements were carried out in 0.5 M Na 2 SO 4 adjusted at pH 10. The impedance data collected at the open circuit potential were analyzed with a physical model where all elements are clearly defined. The results suggest a constant phase element behavior at the electrolyte dielectric interface assigned to an in-depth distribution of local resistivity through the dielectric layer induced by the electrolyte penetration. To explain the electrochemical behavior of the thin silver layer, a localized corrosion in a delaminated zone between the upper dielectric and the silver layers was adopted. The localized corrosion was found to be related to the granular structure of the silver layer in which pores are formed between the grains of silver. This model is equivalent to a recently developed double porosity or pore-in-pore model.
CORROSION, 2023
Electrochemical impedance spectroscopy (EIS) was utilized to delve into the corrosion inhibition of eutectic Cu-Ag alloy and its components (Cu and Ag) in aqueous, aerated 0.1 Electrochemical impedance spectroscopy (EIS) was utilized to delve into the corrosion inhibition of eutectic Cu-Ag alloy and its components (Cu and Ag) in an aqueous, aerated 0.1 M KNO3 solution. This alloy plays a major role in the water cooling of central processing units in data storage centers. Two organic inhibitors, namely, 1,2,3-benzotriazole (BTA) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD), were utilized in this study. The corrosion inhibition slowly evolved over time as diagnosed by an increase in the charge transfer impedance and the gradual tendency of the Nyquist profiles to arc toward the real axis. This trend was attributed to the gradual formation of organometallic passivation layers. The EIS data underlined the specific affinity of BTA and DMTD toward the Cu and Ag surfaces, respectively. A transition of the double-layer equivalent circuit element from ideal capacitance to a constant phase element was observed for the alloy compared to the pure metals. This was attributed to the heterogeneity induced by Cu-rich and Ag-rich phases in the alloy and by the formed oxides/protective film on the alloy surface. The EIS study demonstrated that both BTA and DMTD can provide sufficient corrosion inhibition to Cu-60Ag alloy with DMTD being significantly more effective.
Electrochemical Behavior of Sn-Ag Alloys in Sodium Fluoride Solutions
Materialwissenschaft und Werkstofftechnik, 2006
Passivation and corrosion behavior on Ag, Sn and Sn-Ag alloys were studied using various electrochemical techniques, i.e. opencircuit, potentiodynamic polarization and impedance measurements. The specimens were polarized between -1000 and 500 mV vs. saturated calomel electrode (SCE) in naturally oxygenated NaF solution of different concentrations. The results of potentiodynamic polarization showed that each of i corr and i c increases with increasing either Sn% or Fconcentration. EIS measurements under open circuit conditions confirmed well this behavior. The ef-fect of temperature was also studied in 0.5M NaF at temperature range of 291K to 333K. The corrosion current i corr was observed to increase with temperature for the same electrode. The activation energy was calculated according to Arrhenius equation and its value was found to decrease considerably with increasing the Sn content in the alloy.
Electrochemical corrosion properties of metal alloys
This study concerns an investigation of the corrosion behavior of 316 stainless steel, CoCrMo and Ti6Al4V alloys in simulated body conditions (ringer lactate) at 37 C by the use of Tafel plots, mixed potential and electrochemical impedance spectroscopy (EIS). Ti6Al4V alloy has the highest corrosion resistance followed by CoCr alloy. Ti6Al4V–CoCrMO was the best couple for galvanic corrosion with the minimum galvanic potential and current values according to mixed potential theory and Tafel method. It was concluded that Ti6Al4V was the most suitable material for implant applications in the human body.
Electrochemical studies of copper–aluminum–silver alloys in 0.5 M H2SO4
Electrochimica Acta, 2001
ABSTRACT The electrochemical behavior in 0.5 M H2SO4 at 25°C of a CuAl(9.3 wt%)Ag(4.7 wt%) alloy submitted to different heat treatments and an annealed CuAl(9.7 wt%)Ag(34.2 wt%) were studied by means of open circuit potential (Emix) measurements, potentiodynamic polarizations and cyclic voltammetry. SEM and EDX microanalysis were used to examine the changes caused by the electrochemical perturbations. The steady state potentials observed for the studied samples were correlated in terms of the phases present in the alloys surface. The resulting E/I potentiodynamic profiles were explained in terms of the potentiodynamic behavior of pure copper and pure silver. The presence of aluminum decreased the extent of copper oxidation. In the apparent Tafel potential region, two anodic Tafel slopes were obtained: 40 mV dec−1 in the low potential region and 130 mV dec−1 in the high potential region, which were related with the electrochemical processes involving copper oxidation.