Reliability of electrochemical noise measurements: Results ofround-robin testing on electrochemical noise

tSixteen laboratories have performed electrochemical noise (EN) measurements based on two systems.The first uses a series of dummy cells consisting of a “star” arrangement of resistors in order to validatethe EN measurement equipment and determine its baseline noise performance, while the second sys-tem, based on a previous round-robin in the literature, examines the corrosion of aluminium in threeenvironments. All participants used the same measurement protocol and the data reporting and analysiswere performed with automatic procedures to avoid errors. The measurement instruments used in thevarious laboratories include commercial general-purpose potentiostats and custom-built EN systems.The measurements on dummy cells have demonstrated that few systems are capable of achieving instru-ment noise levels comparable to the thermal noise of the resistors, because of its low level. However, itis of greater concern that some of the instruments exhibited significant artefacts in the measured data,mostly because of the absence of anti-aliasing filters in the equipment or because the way it is used.The measurements on the aluminium samples involve a much higher source noise level during pittingcorrosion, and most (though not all) instruments were able to make reliable measurements. However,during passivation, the low level of noise could be measured by very few systems.