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Inhibitor containing plasmaelectrolytic oxide layers on magnesium alloy AZ31

Thursday (09.11.2017)
09:35 - 09:55
Part of:

Plasmaelectrolytic oxide (PEO) layers afford a high corrosion and wear protection on light wight alloys based on aluminum, titanium or magnesium. However, due to the thermochemical nature of the process the formed oxide layer shows a number of micropores or microholes. Although these pores and holes do not pass the complete oxide layer they are weak spots in view of the long-time corrosion protection. To improve the corrosion protection the PEO layer can be coated by polymers which means that a second production step is necessary. An alternative approach is the incorporation of corrosion inhibitors in the oxide layers simultaneously to the PEO process. Such a one-step process is the object of the present work. The result would be a one-step process. A zeolite carrier containing cerium ions was indicated as a promise inhibitor, which forms a stable suspension in combination with a KOH based electrolyte. The PEO was carried out as current modulated technique. The resulting oxide layers were investigated by SEM/EDX measurement to describe the morphology and chemical composition. The cerium incorporation was additionally proofed by RFA measurements. Regarding the electrochemical behavior the PEO samples of AZ31 were investigated by linear sweep voltammetry. The influence of cerium could be clearly shown by an extended passive range as well as a lower passive current density.

Dr.-Ing. Michael Schneider
Fraunhofer Institute for Ceramic Technologies and Systems IKTS
Additional Authors:
  • Kerstin Kremmer
    Fraunhofer-Institut für Keramische Technologien und Systeme IKTS
  • Daria Tabatabai
  • Dr. Wolfram Fürbeth