Within the Centre for Corrosion Technology, facilities exist for conducting localised corrosion tests. These techniques have allowed researchers to examine specific phenomena related to corrosion degradation, such as organic coating delamination, stress corrosion cracking, pitting corrosion and repassivation. The range of equipment available includes a scanning vibrating electrode (SVET), scanning kelvin probe (SKP) and scanning droplet cell (SDC).

Scanning Vibrating Electrode

The SVET is used to measure the corrosion of conducting materials immersed in an electrolyte. The surface of the corroding material consists of anodic and cathodic sites, resulting in potential gradients forming in the solution. These are measured by a microelectrode which is vibrated perpendicular to the sample surface, hence the name given to this technique. A simple calibration procedure can also allow the measured potentials to be converted to corrosion currents.

Scanning Kelvin Probe

The SKP is capable of examining conducting and semi-conducting materials and has the benefit that tests can be performed in humid or gaseous environments. The Kelvin probe measures the work function of a material, which can in turn be related to its corrosion potential, Ecorr.

Scanning Droplet Cell

The scanning droplet cell is not a technique, but is a piece of equipment that allows a full range of electrochemical tests to be performed within a small droplet of electrolyte, typically around 1mm diameter. The electrolyte is constantly replenished, the solution being fed through a capillary arrangement, whereby the spent electrolyte is also removed.

External Links

• Further details of localised corrosion measurement techniques are available on the Electrochemical Scanning Probe Network (ESPNET) website
• Equipment manufacturer Uniscan Instruments also have more information on their website

For more information please contact Matt Kitchen