NOISE DIAGNOSTICS AT CORROSION PROCESSES PART 1 - EVALUATION OF A ROUND-ROBIN TEST

The Institute of Materials Engineering and Materials Testing of the Un iversity of Magdeburg (IWW) organised a round robin test on the measur ement of electrochemical noise (EN) and obtained the participation of 17 organisations (universities, commercial firms, R&D laboratories) fr om 5 countries. The experiment involved the investigation of EN signal s from aluminium and stainless steel exposed under conditions in which pitting corrosion can occur. The data provided by the participants we re analysed at IWW according to various criteria. Evaluation methods i ncluded visual inspection of the noise in the potential or current ver sus time curves, calculation of the standard deviation, counting of tr ansients and transformation of the measurements into the frequency dom ain. Almost all of the participants were able to detect differences in EN behaviour during different stages of the experiment qualitatively. Quantitative evaluation, however, revealed a more complex situation. At times, differences in measured EN signal intensity of two orders of magnitude were obtained as a result of different apparatus used (sens itivity, frequency range, etc.). Nevertheless, the fact that more than half of the participants reported data within a relatively narrow sca tterband is a positive result. The experience gained from the round ro bin test provides a basis for further development of EN as a tool both for the fundamental understanding of various aspects of corrosion and for the solution of practical problems of corrosion protection, in pa rticular in the area of corrosion monitoring.