Influence of Prepolarization on the Electrochemical Behavior of Iron-Carbon Alloys

CORROSION ◽  
1968 ◽  
Vol 24 (6) ◽  
pp. 163-171 ◽  
Author(s):  
G. C WOOD ◽  
G. C. SOLTZ
Keyword(s):  
Sulfuric Acid ◽  
Carbon Content ◽  
Noble Metal ◽  
Acid Concentration ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Rest Potential ◽  
Cathodic Pretreatment ◽  
Time Required

Abstract The influence of anodic and cathodic prepolarization of electrodes, containing respectively 0.03, 0.48, and 1.3 percent carbon, in de-aerated N and 0.1 N sulfuric acid at 25 C (77 F) on the subsequent open circuit potential-time curves has been determined. Anodic pretreatment always lowers and cathodic pretreatment raises the initial potential on these curves. Magnitude of the potential shift and time required to resume the rest potential are larger the higher the prepolarizing time. The influence of carbon content and acid concentration is complex. Special experiments have indicated the importance of specimen, and especially solution history, and have permitted an interpretation in terms of polarization diagrams. The most likely explanation is the influence of sulfide or noble metal or metalloid ions derived from the alloy or possibly the solution in altering the number of active anodic sites. This is achieved by an increase in the degree of hydrogen poisoning or by accumulation or plating out of metals or metalloids.

Prediction and Measurement of Corrosion Rates of Stainless Steel in Concentrated Sulfuric Acid

CORROSION ◽  
10.5006/0709 ◽  
2013 ◽  
Vol 69 (6) ◽  
pp. 543-550 ◽  
Author(s):  
S. Jones ◽  
K. Coley ◽  
J. Kish
Keyword(s):  
Stainless Steel ◽  
Sulfuric Acid ◽  
Corrosion Behavior ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Electrochemical Techniques ◽  
Open Circuit ◽  
Corrosion Rates ◽  
Transient Nature ◽  
Concentrated Sulfuric Acid

When exposed to concentrated sulfuric acid, stainless steel exhibits unique electrochemical behavior. This behavior can be observed as an oscillation in open-circuit potential between the active and passive states. The transient nature of the corrosion behavior under these conditions results in a distinct challenge for measuring and predicting corrosion rates. Using a series of commercial alloys with various nickel contents, this paper outlines the utilization of electrochemical experimentation to refine the prediction of corrosion rates. The paper also discusses some of the difficulties associated with many traditional electrochemical techniques such as potentiodynamic scans when used for characterizing systems that undergo oscillations in open-circuit potential.

Effect of Bi Addition on the Electrochemical Behavior of Zinc Electrodes in Concentrated Alkaline Solutions

2013 ◽  
Vol 805-806 ◽  
pp. 1240-1249
Author(s):  
Hong Xia Liang ◽  
Fu Rong Li ◽  
Zhi Lin Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Linear Polarization ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Exchange Current ◽  
Zinc Electrode ◽  
Current Densities ◽  
Scanning Electron

The electrochemical behavior of zinc electrode with bismuth addition in 35%KOH solutions has been investigated systematically by electrochemical methods including linear polarization, potentiostatic polarization, potential-time measurements at a constant current density, combining the observations of scanning electron microscopy (SEM). Linear polarization results showed that the open circuit potential shifted positively with increasing bismuth content, which is explained based on the gassing data and change in the exchange current of the zinc electrode. Addition of bismuth increased the exchange current of zinc reaction and caused an increase in the measured open circuit potential. Galvanostatic results showed that the addition of bismuth shortened the passivation time. Scanning electron microscopy images showed that the addition of bismuth aggravated the corrosion of zinc electrode which may be responsible for the increased tendency to passivation at high current densities. It has been found that at low current densities the reaction kinetics may be increased by addition of Bi, which is general agreement with the discharging test of actual alkaline batteries.

Characterization of a Microfluidic Based Direct-Methanol Fuel Cell

2008 ◽  
Author(s):  
Isaac B. Sprague ◽  
Prashanta Dutta ◽  
Su Ha
Keyword(s):  
Sulfuric Acid ◽  
Fuel Cell ◽  
Soft Lithography ◽  
Open Circuit Potential ◽  
Internal Resistance ◽  
Open Circuit ◽  
Operating Conditions ◽  
Methanol Concentration ◽  
Dimethyl Siloxane ◽  
Direct Methanol

The performance of a membraneless laminar flow micro fuel cell was evaluated under different operating conditions. The fuel cell was microfabricated in poly-dimethyl-siloxane using standard soft-lithography techniques. It used methanol solution as the fuel for the anode side, and oxygen saturated sulfuric acid for the cathode. The parameters studied were the methanol concentration and the concentration of sulfuric acid in the anode stream. The performance was characterized by V-I plots, stability of open circuit potential, and anode polarization curves. Our results show that the power output of the device decreases with increase in the methanol concentration. It is shown that these trends are caused by the cell’s internal resistance to proton transport. The addition of sulfuric acid to the fuel significantly decreases this resistance. The device open circuit potential was not stable over extended operation, and could drop by more than 150 mV in 72 hours.

scholarly journals The Basics of Hydrogen Uptake in Iron and Steel

2021 ◽  
Author(s):  
Mathias Truschner ◽  
Anton Trautmann ◽  
Gregor Mori
Keyword(s):  
Sulfuric Acid ◽  
Sodium Chloride ◽  
Hydrogen Content ◽  
Open Circuit Potential ◽  
Armco Iron ◽  
Hydrogen Uptake ◽  
Open Circuit ◽  
Iron And Steel ◽  
Thermal Conductivity Cell ◽  
Cathodic Charging

AbstractArmco iron and L80 steel (according to API 5CT) were charged under various conditions due to often not knowing the exact amount of hydrogen absorbed during operation and laboratory charging. These two materials were charged in sodium chloride (NaCl), sulfuric acid (H2SO4), both with and without addition of thiourea (CH4N2S), and in H2S (NACE TM0177) at open circuit potential.Additionally, cathodic charging was done in sodium chloride and sulfuric acid, both with thiourea added at a current density of 1 mA/cm2. The charging time was between 2 and 336 h for both methods. Prior to the charging, the specimens were cleaned in acetone and the bulk hydrogen content of the two materials was determined. After charging, the specimens were ground with a silicone carbide paper and the hydrogen content was measured with a thermal conductivity cell after hot extraction at 950 °C.Most of the immersion tests at open circuit potential resulted in hydrogen concentrations of up to 1 wt. ppm, while the cathodic charging led to values of up to 4 wt. ppm. In addition, the NACE TM0177 test provided the highest hydrogen concentrations and was the only test to show higher hydrogen concentrations for Armco iron than for L80 steel.

Anodic Porous Zirconium Oxide Prepared in Sulfuric Acid Electrolytes

2006 ◽  
Vol 512 ◽  
pp. 205-210 ◽  
Author(s):  
Hiroaki Tsuchiya ◽  
Jan M. Macak ◽  
Irina Sieber ◽  
Patrik Schmuki
Keyword(s):  
Sulfuric Acid ◽  
Porous Structure ◽  
Zirconium Oxide ◽  
Open Circuit Potential ◽  
Sweep Rate ◽  
Open Circuit ◽  
Potential Sweep ◽  
Self Organized ◽  
Electrochemical Condition ◽  
Ordered Porous

We report the formation of self-organized porous ZrO2 layers by anodization of Zr in H2SO4 electrolytes. Anodization at 20 V after a potential sweep from open-circuit potential with a defined sweep rate results in tube-like porous ZrO2. In particular, under optimized electrolyte condition and polarization, a highly ordered porous structure is obtained. Furthermore, sponge-like porous ZrO2 is also fabricated under a specific electrochemical condition.

Study on the Electrochemical Behavior of Al-6Zn-0.02In-1Mg-0.03Ti Sacrificial Anodes for Long-Term Corrosion Protection in the Ocean

CORROSION ◽  
10.5006/3404 ◽  
2020 ◽  
Vol 76 (4) ◽  
pp. 366-372 ◽  
Author(s):  
Mingkun Yang ◽  
Yan Liu ◽  
Zeyao Shi ◽  
Xiaodan Lv ◽  
Bin Liu ◽  
...  
Keyword(s):  
Mass Loss ◽  
Corrosion Product ◽  
Cathodic Protection ◽  
Electrochemical Behavior ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Output Current ◽  
Alloy Anode ◽  
Sacrificial Anodes

After 10 y of service in the ocean, the long-term performance of Al-6Zn-0.02In-1Mg-0.03Ti aluminum alloy sacrificial anodes for steel piles was characterized by mass loss in addition to optical and electron microscopy analysis. The electrochemical behavior was conducted by open-circuit potential with potentiodynamic and potentiostatic polarizations. The results showed that cathodic protection potential was in the range of −0.960 VCSE to −1.103 VCSE. The corrosion type and consumption rate of the alloy anode were related to the output current. In harsh corrosion environments, the alloy anode showed uniform corrosion and lost more mass due to voltage output, therefore more current is needed to fulfill cathodic protection. Otherwise, localized corrosion and less mass loss were observed. The alloy anodes were covered by marine creatures and corrosion product. The corrosion product contained amorphous Al(OH)3 and MgAl2(CO3)(OH)·xH2O which became more crystalline from outside to inside of the alloy anode. A translucent corrosion product was found on the alloy anode surface which contained amorphous Al(OH)3·xH2O with S, along with AlxCly(OH)z·mH2O. The electrochemical performance of the alloy anode was strongly reduced by the coverage of corrosion product. Consequently, the open-circuit potential of the alloy anode increased and the output current decreased. The effect of corrosion product thicknesses on the anodic activation is not remarkable.

scholarly journals Adsorption characteristics of albumin on gold and titanium metals in Hanks’ solution using EQCM

2004 ◽  
Vol 18 (4) ◽  
pp. 545-552 ◽  
Author(s):  
J. A. Lori ◽  
T. Hanawa
Keyword(s):  
Bovine Serum Albumin ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Open Circuit Potential ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Open Circuit ◽  
Rest Potential ◽  
Before And After ◽  
Titanium Surfaces ◽  
Adsorption Desorption

The adsorption of Bovine Serum Albumin (BSA) on gold and titanium surfaces in Hanks’ solution was monitored using the electrochemical quartz crystal microbalance (EQCM) technique. The changes in mass and open circuit potential at rest potential and mass and current at constant potentials were measured before and after the introduction of BSA.The mass of BSA adsorbed on titanium reached a steady value within one hour, while the albumin adsorbed on gold continued to increase. The amount of BSA adsorbed by titanium increased with concentration and stabilized at 0.8 mg/ml while that on gold did not stabilize. This indicates a monolayer of the protein on titanium and multi-layer on gold. The adsorption of BSA on gold and titanium was accelerated by the charge of potential.The time before stabilizing the adsorption‒desorption phenomena also increased with the BSA concentration.

Experimental Analysis of a Single Cell Flowing Electrolyte-Direct Methanol Fuel Cell

2011 ◽  
Author(s):  
Nasim Sabet-Sharghi ◽  
Cynthia A. Cruickshank ◽  
Edgar Matida
Keyword(s):  
Sulfuric Acid ◽  
Fuel Cell ◽  
Single Cell ◽  
Acid Concentration ◽  
Direct Methanol Fuel Cell ◽  
Sulfuric Acid Concentration ◽  
Open Circuit ◽  
Membrane Electrode ◽  
Direct Methanol ◽  
Methanol Fuel Cell

A single cell flowing electrolyte - direct methanol fuel cell (FE-DMFC) was studied experimentally. Nafion® NRE-212 was used in the membrane electrode assembly (MEA). The flowing electrolyte channel was formed by a polyethylene porous material. The active area of the fuel cell was approximately 25 cm2. Effects of varying flowing electrolyte conditions (channel thickness, sulfuric acid concentration, channel pressure), methanol concentration, and fuel cell temperature on the overall performance of the cell were studied. It was observed that stopping the flowing electrolyte caused a reduction in the open circuit voltage as well as the current of the cell, indicating that the methanol crossover affected the cell performance. Also, it is presented that a thicker flowing electrolyte channel results in lower power density, and sulfuric acid concentration of 2 molar (18%) was found to be the most advantageous. Raising operating temperature resulted in much better performance of the cell. Increasing flowing electrolyte pressure slightly decreased the performance.

scholarly journals Electrochemical behavior of tantalum in potassium hydroxide solutions

2018 ◽  
Author(s):  
Irena Ljubomir Mickova
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Behavior ◽  
Potassium Hydroxide ◽  
Open Circuit Potential ◽  
Cathodic Polarization ◽  
Film Formation ◽  
Open Circuit ◽  
Passive Region ◽  
M 10 ◽  
Stable Passive

<p class="PaperAbstractTitle"><em>The electrochemical behavior of tantalum in various concentrations of KOH solutions <br /> (0.1 M - 10 M), was investigated using the evolution of the open circuit potential in time, cyclic voltammetry and ellipsometric measurements. Depending on KOH concentrations, the open circuit potential measurements have shown three distinct behaviors concerning oxide film formation on the electrode surface and its dissolution. The cyclic voltammetry measurements were performed in various potential ranges, from -1.4 to 8 V, different concentrations of KOH solutions (0.1-10 M) and sweep rates ranging from 0.005 V/s to 1 V/s. In the passive region, very stable passive films were formed, which reduction has not been possible during cathodic polarization even at highly concentrated KOH solutions. In the trans-passive region, the very strong peak at 1.65 V was monitored, which nature and chemical composition is still not well known. </em></p>

scholarly journals Galvanic Corrosion of Copper / Nickel-Chrome Alloy in an Agitated Sulfuric Acid Solution

2018 ◽  
Vol 21 (1) ◽  
pp. 133
Author(s):  
Samar S. Hussein ◽  
Basim O. Hasan ◽  
Naseer A. Al-Haboubi
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Sulfuric Acid Solution ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Galvanic Corrosion ◽  
Corrosion Current ◽  
Open Circuit ◽  
Flow Conditions ◽  
Galvanic Current

Galvanic corrosion of Nickel-Chrome alloy (Ni-Cr alloy) and Copper (Cu) coupled in 5% sulfuric acid solution was investigated. The effects of agitation velocity, temperature, and time on the galvanic corrosion current and the weight loss of both metals in both free corrosion and galvanic corrosion were investigated. The trends of open circuit potential (OCP) of each metal and galvanic potential (Eg) of the couple were also determined. The results showed that Cu was cathodic relative to Ni-Cr alloy in galvanic couple and the corrosion potential of the couple (Ni- Cr alloy /Cu) was between the values of the two single components because the OCP of copper shifted to positive with the increase in velocity. Under stagnant conditions initially the galvanic current was more negative then shifted to the positive with time. The corrosion of Ni-Cr alloy decreased with time because the passivation layer was formed on the surface. Under flow conditions, the galvanic current sharply shifted to the negative direction (increase galvanic current from Ni-Cr alloy (anode) to Cu (cathode) during the first few minutes.

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