Using Electrochemical Noise to Obtain More Information From Conventional Corrosion Test Methods

摘要

Within corrosion research, the analysis of electrochemical noise offers a simple, sensitive and virtuallyrnnon-destructive measuring technique for assessment of the corrosion susceptibility of metallic materialsrnand for the investigation of corrosion processes. The present status of knowledge concerning noiserndiagnostics in corrosion processes permits the application of this method not only to experimental tasksrnin the laboratory, but also to special problems in the context of practical corrosion monitoring.rnFurthermore, specific advantages of the technique enable its use to an increasing extent in supporting orrnimproving conventional corrosion testing. The advantages here include obtaining additional informationrnand shortening testing times (together with associated savings in resources such as manpower, energy,rnchemical reagents, etc.), thus resulting in state-of-the art corrosion testing.rnIn this paper, it is shown, with the aid of three examples taken from the routine work of a corrosionrnlaboratory, how conventional testing methods and investigation procedures can be enriched by thernapplication of electrochemical noise techniques. In the first example, current noise measurement using arnzero-resistance ammeter is used to investigate the development of corrosion over time during salt-sprayrntesting, thus making assessment of the test samples better and more quantifiable. During potentiostaticrnexperiments, in the second example, additional noise diagnostics permits conclusions as to criticalrnregions of potential and chloride concentration, as well as the effect of inhibitors, to be drawn within thernshortest possible testing period. Detection of the initiation processes of corrosion (e.g. incipient pitting) isrnnot possible simply using the conventional method of total current measurement. In the third example,rnthe testing requirements for the determination of critical pitting temperatures can be reducedrnconsiderably and, in particular, the evaluation of the noise signals can be carried out so as to eliminate