Registration is open for The Penn State University’s 24th Annual Corrosion Short Course scheduled for June 7-12, 2020 at the University Park Campus in State College, PA (USA). Gamry Instruments will be a co-sponsor for the course. Philadelphia, PA, January 27, 2020 – Registration is now open for the annual Penn State University Corrosion Short Read more about Gamry Instruments to Co-Sponsor the 24th Annual Penn State University Corrosion Short Course[…]
NACE Corrosion 2020 to feature a presentation by Gamry Instruments’ David Loveday This Conference dates have been updated to: June 14-18, 2020 Warminster, PA, October 14, 2019 – NACE Corrosion 2020, the world’s largest conference and exposition on corrosion, is being held March 15-19, 2020 at the George R. Brown Convention Center in Houston, TX. Read more about Gamry Instruments’ Presentation at NACE CORROSION 2020 Conference dates have been updated to June 14-18, 2020[…]
Corrosion: Fundamentals and Experimental Methods When: June 5-10, 2016 Where: Penn State University Park Campus Registration is open for the annual Penn State University Corrosion Short Course being held at Penn State University Park Campus June 5-10th. Now in its 20th year, the course will cover the fundamentals of corrosion and various electrochemical techniques. Lectures Read more about 20th Annual Penn State University Corrosion Short Course[…]
Why Use Electrochemical Techniques for Corrosion Measurement? Corrosion is an electrochemical process. A broad range of electrochemical techniques have been developed specifically for corrosion measurement. Electrochemical techniques are fast. Electrochemical techniques are sensitive. Nevertheless, there are some Corrosion Engineers who don’t use electrochemical techniques…probably because they don’t understand them. Electrochemical Techniques and Corrosion Corrosion is Read more about Electrochemical Techniques for Corrosion Measurement[…]
According to a new report released by the American Road & Transportation Builders Association (ARTBA), 58,495 of the 609,539 bridges in America have been found to be ‘structurally deficient”. This key finding is based on the ARBTA analysis of the U.S. Department of Transportation’s recently-released 2015 “National Bridge Inventory” database. According to the ARBTA Report Read more about Nearly 10% of US Bridges Considered Structurally Deficient[…]
Corrosion can be viewed as the natural return of metals to their ores and will occur anywhere a galvanic cell or field can be or has established. To establish the field all that is needed is two dissimilar metals that are connected directly or indirectly by an electrolyte, such as water. This is the same Read more about Corrosion as an Electrochemical Process[…]
The various parameters that are typically listed in the specifications of potentiostats are explained in this Technical Note originally posted by Gamry Instruments. There are many important factors that pertain to buying a potentiostat, and the old adage “The more the better” really does not apply when researching the potentiostat to fit your experiment. There Read more about Understanding Potentiostat Specs[…]
Corrosion: Fundamentals and Experimental Methods Registration is now open for the 2015 Corrosion Short Course being held at Penn State University Park Campus June 7-12th. The course, now in it’s 19th year, will cover the fundamentals of corrosion and various electrochemical techniques. Lectures and laboratories will be used to illustrate how electrochemical techniques are applied, Read more about Penn State University Corrosion Short Course[…]
by 3 Different Techniques
We began with a simple LPR (Polarization Resistance) experiment. The results are shown to the right. Analysis of the data within 5 mV of Eoc gave the line shown in red. It corresponds to an Rp value of 687 ohm. Using the default beta values of 120 mV/decade yields a corrosion rate of 5.77 mpy in this electrolyte. This estimate can be refined if better estimates of the beta values are known. More about this shortly!
Many of the following ‘references’ are available at Amazon.com and can be viewed at our Bookstore. DC Electrochemical Test Methods, N.G. Thompson and J.H. Payer, National Association of Corrosion Engineers, 1440 South Creek Drive, Houston, TX 77084-4906. Phone: 281-228-6200. Fax: 281-228-6300. ISBN: 1-877914-63-0. Recommended! Principles and Prevention of Corrosion, Denny A. Jones, Prentice-Hall, Upper Saddle Read more about References on Corrosion Theory and Electrochemical Corrosion Tests[…]
In the previous post (Electrochemical Corrosion Measurements Primer) we pointed out that Icorr cannot be measured directly. In many cases, you can estimate it from current versus voltage data. You can measure a log current versus potential curve over a range of about one half volt. The voltage scan is centered on Eoc. You then fit the measured data to a theoretical model of the corrosion process.
The model we will use for the corrosion process assumes that the rates of both the anodic and cathodic processes are controlled by the kinetics of the electron transfer reaction at the metal surface. This is generally the case for corrosion reactions. An electrochemical reaction under kinetic control obeys Equation 1-1, the Tafel Equation.
Most metal corrosion occurs via electrochemical reactions at the interface between the metal and an electrolyte solution. A thin film of moisture on a metal surface forms the electrolyte for atmospheric corrosion. Wet concrete is the electrolyte for reinforcing rod corrosion in bridges. Although most corrosion takes place in water, corrosion in non-aqueous systems is not unknown.
Corrosion normally occurs at a rate determined by an equilibrium between opposing electrochemical reactions. The first is the anodic reaction, in which a metal is oxidized, releasing electrons into the metal. The other is the cathodic reaction, in which a solution species (often O2 or H+) is reduced, removing electrons from the metal. When these two reactions are in equilibrium, the flow of electrons from each reaction is balanced, and no net electron flow (electrical current) occurs. The two reactions can take place on one metal or on two dissimilar metals (or metal sites) that are electrically connected.
Figure 1-1 diagrams this process. The vertical axis is potential and the horizontal axis is the logarithm of absolute current. The theoretical current for the anodic and cathodic reactions are shown as straight lines. The curved line is the total current — the sum of the anodic and cathodic currents. This is the current that you measure when you sweep the potential of the metal with your potentiostat. The sharp point in the curve is actually the point where the current changes signs as the reaction changes from anodic to cathodic, or vice versa. The sharp point is due to the use of a logarithmic axis. The use of a log axis is necessary because of the wide range of current values that must be displayed during a corrosion experiment. Because of the phenomenon of passivity, it is not uncommon for the current to change by six orders of magnitude during a corrosion experiment.