Electrolytic polarization curve

Introduction

The electrochemical polarization curves were first introduced by Michael Faraday in 1834. Since then, the electrochemical polarization curves have been used for the study of materials’ corrosion behaviors. This method of research is typically applied for analyzing metallic materials when measuring the oxygen and hydrogen levels absorbed in the metal’s surface. An electrochemical polarization curve is a very important tool for assessing the level of corrosion of a material and helps us to understand the effects of different surface conditions in relation to material corrosion.

Description of Electrochemical Polarization Curves

An electrochemical polarization curve is constructed using an electrode material and a reference electrode. Both the electrode materials and reference electrode are placed in an electrolytic solution of the same environment where the corrosion process is desired to be studied. Current is then passed through the electrode material and reference electrode in order to measure the various aspects of the corrosion process.

This data is then plotted on a graph in order to create the actual electrochemical polarization curves. The figure measured is called the ‘corrosion potential’ and it is measured by the system’s ability to produce a current that can influence the corrosion rate. The position of the point in the graph indicates the extent of damage a material has sustained as a result of corrosion.

Purpose of Electrochemical Polarization

The purpose of electrochemical polarization is to measure the level of corrosion that material has experienced. This is achieved by measuring the potential difference between the metal and its environment, and then comparing this value to that of the metals to the reference electrode in the electrolytic solution.

The electrochemical polarization curves can also be used to determine the level of protection that materials may have. These curves can also be used to identify areas that are prone to corrosion, by measuring the electrochemical difference between different locations.

Conclusion

Electrochemical polarization curves are a useful tool for studying and analyzing material’s corrosion behavior. This method is used to measure the corrosion rate a material may have experienced, and provides an insight into the protection it may have against further corrosion. This technique is also employed to identify areas that are vulnerable to corrosion and can therefore be used to make improvements to the material in order to prolong its lifespan and prevent corrosion.

Electrode polarization curves are widely used to characterize electrochemical reactions. This type of curve provides valuable information about the kinetics of the electrochemical reaction and its thermodynamics. Electrode polarization curves are obtained in a three-electrode system, which consists of a working electrode, a reference electrode and a counter electrode. An external bias is applied between the working and counter electrodes and the resulting current is measured. By varying the bias potential, a current-potential curve can be obtained which clearly shows the distribution of electrochemical processes occurring at the electrode surface. This information can then be used to design catalytic microreactors, fuel cells and other electrochemical systems.

The shape of an electrode polarization curve is also determined by the type of electrochemical reaction occurring – for example, the anodic or cathodic polarization of an electrode in an electrolyte solution or the decrease in current reaction caused by the development of a protective film on an electrodes surface. The form of the curve depends on the type of reaction and its kinetics, the solution concentration of species involved in the reaction and the electrode overpotential caused by kinetic effects.

In general, the current at the working electrode increases with applied bias potential; this is known as the forward polarization region. At the beginning of the forward polarization process the current supplied by the electrolyte is low, this is referred to as the limiting current. When the bias potential reaches a certain point, known as the half-wave potential, the current reaches its maximum value. This is followed by a decrease in current in the so-called reverse polarization region. At the end of the reverse polarization region the current is again very low and this is the so-called cutoff potential.

Electrode polarization curves can therefore provide valuable insight into the underlying reaction kinetics and thermodynamics. By interpreting their shape, parameters such as the exchange current density, the potential of zero electron-transfer and the standard rate of electron transfer can be calculated. As well as providing essential kinetic information, electrode polarization curves allow engineers to design efficient electrochemical systems.