An Automatic Polarization Apparatus for Electrochemical Corrosion Studies

CORROSION ◽  
1969 ◽  
Vol 25 (12) ◽  
pp. 515-519 ◽  
Author(s):  
W. D. HENRY ◽  
B. E. WILDE
Keyword(s):  
Cathodic Polarization ◽  
Reference Electrode ◽  
Electrochemical Corrosion ◽  
304 Stainless Steel ◽  
Constant Current ◽  
Voltage Source ◽  
Potential Range ◽  
Alloy Development ◽  
Corrosion Studies ◽  
Potentiodynamic Anodic Polarization

Abstract Statistical alloy development programs in which electrochemical screening techniques are used require facilities to produce precision polarization data. Conventional equipment and techniques presently available for such programs are not entirely satisfactory. Therefore, modifications were made to readily available commercial equipment to significantly improve the attainable sensitivity and reproducibility. This paper describes in detail the procedures necessary to produce an apparatus that automatically measures and records anodic and cathodic polarization curves over an applied potential range of ±2.0 volts. Traverse rates between 2 × 10−3 and 3 × 104 volts per hour are attainable and can be used to polarize electrodes through zero volts (with respect to reference electrode) without the necessity of manual switching. A special mode switch is described in detail with which the basic electronic potentiostat can be used as a constant current or constant voltage source by manual selection. The results obtained from three typical polarization experiments: (1) potentiodynamic anodic polarization, (2) galvanodynamic cathodic polarization, and (3) galvanodynamic linear polarization of AISI Type 304 stainless steel in hydrogen saturated 1N H2SO4 at 25 C (77 F), showed the performance of the apparatus to be equal to or superior to that of conventional manual procedures.

An Assembly for Electrochemical Corrosion Studies in Aqueous Environments at High Temperature and Pressure

CORROSION ◽  
1967 ◽  
Vol 23 (11) ◽  
pp. 331-334 ◽  
Author(s):  
B. E. WILDE
Keyword(s):  
Test Specimen ◽  
Reference Electrode ◽  
Electrochemical Corrosion ◽  
High Temperature And Pressure ◽  
Aisi Type ◽  
Corrosion Studies ◽  
External Reference ◽  
Aqueous Environments ◽  
Temperature And Pressure ◽  
Type 304

Abstract An assembly is described, in which electrochemical corrosion measurements can be carried out in aqueous environments up to 314 C (598 F) and 105.5 kg/cm2. Test specimen mounting and corrosive environment containment procedures are discussed. A techniqie for using a high pressure electrolyte bridge with an external reference electrode is described. The performance of the system is demonstrated by potentiostatic anodic, cathodic and linear polarization experiments carried out on AISI Type 304 steel in dilute chloride solutions at 289 C.

Electrochemical (Corrosion) Behavior of Amorphous/Microcrystalline Ion Plated Fe-Cr Alloy Films

CORROSION ◽  
1982 ◽  
Vol 38 (6) ◽  
pp. 314-318 ◽  
Author(s):  
Welville B. Nowak ◽  
Boniface A. Okorie
Keyword(s):  
Electrochemical Corrosion ◽  
Passive Layer ◽  
Current Data ◽  
Constant Current ◽  
Potential Range ◽  
Potential Region ◽  
Crystalline Substrate ◽  
Electrochemical Corrosion Behavior ◽  
Transient Data ◽  
Current Relaxation

Abstract Amorphous and microcrystalline thin films of chromium-bearing iron alloys produced by ion plating exhibit high resistance to localized (pitting) corrosion in neutral NaCl aqueous solutions. The films are produced by thermal evaporation of the alloys through an argon glow discharge onto Ebrite (Fe-Cr) substrates maintained at low temperatures. Potentiodynamic tests indicate that the ion plated films exhibit a Tafel-like behavior in the “passive” potential range, whereas Ebrite and melt-spun amorphous alloys of composition similar to the films have a constant current passive region. Transient current data obtained from tests at successively higher potentiostatic voltages (V) show that such currents decrease exponentially with time. The current relaxation time constant (τ) of the films are five to ten times larger than those of Ebrite, and increases rapidly with V up to about 0.3 V, decreasing slowly thereafter. For the Ebrite substrate, τ shows only increasing values, but with a sharp discontinuity in the V versus τ curve at about 0.4 V. Transient data obtained for bulk amorphous Metglas 2826A above 0.5 V shows that the variation of τ with V is similar to that of the ion plated films. The results indicate that it takes longer to complete the passive layer on the ion plated films than on the crystalline substrate; the decrease in τ with increasing V in the middle potential region may be related to the amorphous or amorphous/microcrystalline structure of Metglas 2826A and the ion plated films. The results are consistent with a change in the character of the passive layer at 0.3 to 0.4 V.

scholarly journals Analysis of the Influence of the Cathodic Polarization Value on the Amount of Hydrogen Sorption of Al-Sm with the Alloy of Electrochemical Measurements

2020 ◽  
Vol 20 (4) ◽  
pp. 206-213
Author(s):  
Viktoriya O. Lukyanova ◽  
◽  
Irina Yu. Gots ◽  
Keyword(s):  
Cathodic Polarization ◽  
Diffusion Constant ◽  
Hydrogen Sorption ◽  
Constant Current ◽  
Potential Range ◽  
Hydrogen Atoms ◽  
Diffusion Kinetic ◽  
Recombination Mechanism ◽  
Constant Diffusion ◽  
Adsorption Of Hydrogen

The effect of cathodic polarization on the rate of hydrogen sorption from an aqueous organic electrolyte on an Al-Sm alloy using the potentiostatic and potentiodynamic methods were studied. The obtained data allowed us to calculate the diffusion-kinetic characteristics of this process, such as the interstitial constant, diffusion constant CН √ D, constant current iconst, diffusion coefficient D and adsorption of hydrogen atoms G. The number of nuclei decreases, but their mass and radius increase in the potential range from –2.0 V to –2.4 V. The adsorption of hydrogen on the surface increases; which confirms that predominance of the discharge of hydrogen atoms occurs at more negative potentials according to the recombination mechanism.

scholarly journals Corrosion potential of 304 stainless steel in sulfuric acid

2006 ◽  
Vol 71 (5) ◽  
pp. 543-551 ◽  
Author(s):  
Bore Jegdic ◽  
Dragutin Drazic ◽  
Jovan Popic
Keyword(s):  
Stainless Steel ◽  
Sulfuric Acid ◽  
Cathodic Polarization ◽  
Corrosion Potential ◽  
Electrochemical Corrosion ◽  
Passive Layer ◽  
Open Circuit ◽  
Anodic Peak ◽  
304 Stainless Steel ◽  
Metal Dissolution

The potentiodynamic study of the electrochemical behavior of austenitic 304 stainless steel in deaerated aqueous sulfuric acid of pH 1 revealed that the steel achieved a stable corrosion potential of ca. - 0.350 V (SCE) independent of whether the electrode had previously been cathodically "activated" or anodically passivated. It was also shown that the experimentally observed anodic peak was not the usually obtained anodic passivation peak, as is the case with a number of metal, but an artifact due to the anodic oxidation of hydrogen absorbed during the previously employed cathodic polarization and hydrogen evolution, intended to activate the initially passive surface, or even hydrogen absorbed on the open circuit potential. It was shown that this potential establishes and electrochemical corrosion potential of the Wagner-Traud type due to the evolution of cathodic hydrogen on a passivated steel surface and anodic metal dissolution through the passive layer. It was impossible to activate 304 stainless steel in sulfuric acid of pH 1 by cathodic polarization, and the usually observed anodic peak obtained under these conditions should not be considered as an active metal dissolution process and a passivation anodic peak, but rather as an artifact due to the electrochemical oxidation of the in the steel absorbed hydrogen.

scholarly journals Transient Current Density in a Pair of Long Parallel Conductors

2021 ◽  
Vol 11 (15) ◽  
pp. 6920
Author(s):  
Oldřich Coufal
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Current Density ◽  
Circular Cross Section ◽  
Transient Current ◽  
Constant Current ◽  
Voltage Source ◽  
Sinusoidal Voltage ◽  
Steady State Current ◽  
Maximum Current

Two infinitely long parallel conductors of arbitrary cross section connected to a voltage source form a loop. If the source voltage depends on time, then due to induction there is no constant current density in the loop conductors. It is only recently that a method has been published for accurately calculating current density in a group of long parallel conductors. The method has thus far been applied to the calculation of steady-state current density in a loop connected to a sinusoidal voltage source. In the present article, the method is used for an accurate calculation of transient current using transient current density. The transient current is analysed when connecting and short-circuiting the sources of sinusoidal, constant and sawtooth voltages. For circular cross section conductors, the dependences of maximum current density, maximum current and the time of achieving steady state on the source frequency, the distance of the conductors and their resistivity when connecting the source of sinusoidal voltage are examined.

scholarly journals Adaptive Smart Control Method for Electric Vehicle Wireless Charging System

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2685 ◽  
Author(s):  
Lingbing Gong ◽  
Chunyan Xiao ◽  
Bin Cao ◽  
Yuliang Zhou
Keyword(s):  
Control System ◽  
Control Method ◽  
Characteristic Curve ◽  
Constant Current ◽  
Voltage Source ◽  
Wireless Charging ◽  
Charging Time ◽  
Multi Stage ◽  
Smart Charging ◽  
Smart Control

In order to shorten the wireless charging time of electric vehicles (EVs) and achieve stable charging, an adaptive smart control method for EV wireless charging is proposed in the paper. The method dynamically tracks the rechargeable battery state during the whole charging process, realizes multi-stage charging of constant current (CC) or constant voltage (CV) by switching two kinds of compensation networks of bilateral L3C and L3C-C, and regulates the charging voltage and current to make it as close as possible to the battery charging characteristic curve. This method can be implemented because the voltage source connected to the coupler and the compensation networks of bilateral L3C and L3C-C have the CC and CV source characteristics, respectively. On the basis of the established adaptive smart control system of EV wireless charging, the experiments of wireless data transmission and adaptive smart charging were conducted. The results showed that the designed control system had a response time of less than 200 ms and strong anti-interference ability and it shortened the charging time by about 16% compared with the time using traditional charging methods, thereby achieving a fast, stable, safe, and complete wireless charging process.

scholarly journals Electrochemistry of active chromium, part III: Effects of temperature

2003 ◽  
Vol 68 (11) ◽  
pp. 871-882 ◽  
Author(s):  
Jovan Popic ◽  
Dragutin Drazic
Keyword(s):  
Corrosion Rate ◽  
Hydrogen Evolution ◽  
Anodic Dissolution ◽  
Electrochemical Corrosion ◽  
Potential Range ◽  
Temperature Dependences ◽  
Hydrogen Evolution Reactions ◽  
Effects Of Temperature ◽  
Best Fit ◽  
Anomalous Dissolution

It was shown that the temperature in the range 20 ? 65 ?C has considerable effects on the electrochemical anodic dissolution of chromium in the active potential range as well as on the electrochemical hydrogen evolution reactions on bare and oxide covered chromium surfaces. Also, the chemical dissolution of chromium is strongly affected. The apparent energy of activation for anodic dissolution is 63.1 kJ mol-1, for hydrogen evolution on a bare Cr surface 19.5 kJ mol-1, for the same reaction on an oxide covered surface 44.0 kJ mol-1 and for the chemical ("anomalous") dissolution 66.9 kJ mol-1. The temperature dependences of the total corrosion rate, and the electrochemical corrosion rate alone, are presented in polynomial forms with the appropriate constants obtained by the best fit of the experimental data. For the hydrogen evolution reaction on both bare and oxide covered chromium, the Volmer-Heyrovsky reaction mechanism with the second step as rate determining was proposed.

Effects of Cathodic Protection on Cracking of High-Strength Pipeline Steels

2010 ◽  
Author(s):  
M. Elboujdaini ◽  
R. W. Revie ◽  
M. Attard
Keyword(s):  
Hydrogen Embrittlement ◽  
Cathodic Protection ◽  
Cathodic Polarization ◽  
Water Solution ◽  
Reference Electrode ◽  
High Strength ◽  
Point Of View ◽  
Pipeline Steels ◽  
Different Levels ◽  
Reduction Index

A comparison was made between four strength levels of pipeline steels (X-70, X80, X-100 and the X-120) from the point of view of their susceptibility to hydrogen embrittlement under cathodic protection. The main aim was to determine whether the development of higher strength materials led to greater susceptibility to hydrogen embrittlement. This was achieved by straining at 2×10−6 s−1 after cathodic charging in a simulated dilute groundwater solution (NS4) containing 5% CO2/95% N2 (pH approximately 6.7). The results showed quantitatively the loss of ductility after charging, and the loss of ductility increases with strength level of the steel. All four steels exhibited a loss of ductility at overprotected charging potential and an increasing amount of brittleness on the fracture surface. Ductility in solution was measured under four different levels of cathodic protection, ranging from no cathodic protection to 500 mV of overprotection with respect to the usually accepted criterion of −850 mV vs. Cu/CuSO4 reference electrode. Experiments were carried out by straining during cathodic polarization in a simulated dilute ground water solution (NS-4 solution). Strain rates used were 2×10−6 s−1. After failure, the fracture surfaces were characterized by examination using scanning electron microscopy (SEM). Under cathodic protection, all four steels showed loss of ductility and features of brittle fracture. The loss of ductility under cathodic polarization was larger the greater the strength of the steel and the more active (i.e., more negative) the applied potential. The Ductility Reduction Index (DRI) was defined to quantify the reduction in ductility.

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