Defense Tech Briefs - Measuring Corrosion-Related Properties of Coupled Metals

Subscribe to Defense Tech Briefs

Home

Tech Briefs

Physical Sciences

Measuring Corrosion-Related Properties of Coupled Metals

Naval Research Laboratory, Washington, DC

Jul 31 2007

Page 1 of 2

The working electrode in an EIS apparatus is made of coupled metals.

Amethod and apparatus have been conceived for using electrochemical impedance spectroscopy (EIS) for determining rates of corrosion of coupled metals. EIS has been used heretofore for determining rates of corrosion of single metals. However, many structures used in corrosive environments include different metals in electrical contact. Moreover, the concept of using a sacrificial metal to suppress or reduce the corrosion of another metal is applied in some structures. The coupling of two different metals can affect the rates of corrosion of both. Hence, there is a need to extend EIS to coupled metals.

This EIS Apparatus resembles a conventional EIS apparatus in most respects. In this case, the working electrode is a specimen of two coupled metals.

In most respects, the present method and apparatus for EIS testing of coupled metals are essentially the same as the conventional method and apparatus EIS testing of a single metal. The apparatus (see figure) includes a three-electrode electrochemical cell filled with an electrolyte that simulates the corrosive environment to which the metal specimen is exposed in use (e.g. an aqueous solution of NaCl to simulate seawater). One of the electrodes, denoted the working electrode, is the metal specimen to be tested. The portion of the working electrode exposed to the electrolyte can be coated or uncoated, depending on whether or not one intends to examine the anticorrosion effect of a coating material. The working electrode may be either a conventional single-metal specimen or a coupled-metal specimen. A typical coupled-metal specimen consists of a circular cylindrical plug of a first metal embedded tightly, with its end face flush, in a matching cylindrical hole in a plate of a second metal. Preferably, the second-metal plate area exposed to the electrolyte is about three times the area of the exposed end face of the first-metal plug.

<< Start < Prev 1 2 Next > End >>

Dedicated to helping you design better products in a digital world... your guide to the latest tools & techniques for digital prototyping, simulation, and analysis of the real-world performance of your ideas.

Visit the Digital Design Center

>> Most Popular

>> Related Items

>> Most Searched

>> New Download

Microwave & RF Technology Download the FREE PDF issue here

>> Newsletter

>> Syndicate