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- 2013 (23) (entfernen)
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- Vortrag (17)
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Schlagworte
- Electrochemical noise (2)
- Pitting corrosion (2)
- Stainless steel (2)
- A. Stainless steel (1)
- B. Potentiostatic (1)
- C. Passivity (1)
- C. Pitting corrosion (1)
- Cathodic reaction (1)
- Detektion korrosionsempfindlicher Oberflächen (1)
- Duplexstahl (1)
Eingeladener Vortrag
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Mit den vorliegenden Untersuchungen konnte die grundsätzliche Eignung des Verfahrens zur Beurteilung der Passivschichtstabilität nachgewiesen und Grenzen der Anwendbarkeit aufgezeigt werden. Es sind verschiedene Einflüsse in Parameterstudien gezielt untersucht und mit bekannten Methoden zur Beschreibung der Korrosionsbeständigkeit verifiziert worden. Das KorroPad Prüfverfahren wirkt vorrangig oberflächenspezifisch und eignet sich in einem Temperaturbereich
von +5 bis +50°C zur vergleichenden Prüfung von nichtrostenden Stahloberflächen hinsichtlich ihrer Korrosionsbeständigkeit. Der Feuchtlagerung frisch bearbeiteter Oberflächen vor einer KorroPad-Prüfung kommt dabei eine große Bedeutung zu, um eine sichere Differenzierung von korrosionsanfälligen und -beständigen Oberflächen zu gewährleisten.
Electrochemical noise measurements on anodically polarised type 304 stainless steel surfaces in contact with buffer solutions of neutral pH were performed to study the effect of chloride ions in the nucleation of pitting corrosion. Passive layer stability and susceptibility to pitting corrosion after pickling and passivation at different environmental conditions were also investigated by means of electrochemical current noise measurements under cathodic and anodic polarisation. According to the obtained experimental results pits nucleate independently on the presence of chloride ions. It has been also shown that protectiveness of stainless steel surfaces after pickling strongly depends on the relative humidity of the environment in which the surface is subsequently passivated.
Electrochemical noise (EN) enables corrosion research and monitoring in real time and with high sensitivity. In the case of submicroscopic nucleation events of pitting corrosion it has been observed that the cathodic process plays a decisive role in the mechanism as well as in the origin of EN signals, which depend not only on the metallic dissolution reaction but also on the electron-consuming process. EN signals arising from the nucleation process of localized corrosion on stainless steels can only be recorded due to the inhibition effect on the cathodic process achieved by the spontaneous formation of the passive layer. In consequence, passive layer stability becomes a significant factor in influencing EN signals. The way in which the passive layer stability affects the acquisition and analysis of EN signals arising from pitting corrosion on stainless steels is discussed in detail.