A Proposed R-T Model for Atmospheric Corrosion of Metallized Film in AC Capacitors

Atmospheric corrosion is a significant issue affecting the storage quality of metallized film capacitors (MFCs). Oxygen and moisture in the atmosphere permeate among the layers in capacitor, initiating oxidation on the surface of metal layer, which increases the electrode resistance. In this work, a resistance–time model is proposed to study the atmospheric corrosion mechanism of nano-scaled Al–Zn metal layer. The analysis results point out that it is the barrier of metal–oxide interface that affects the anticorrosion ability. Moreover, the metal composition is studied as a factor influencing the anticorrosion ability, revealing that the enhancement gained by adjusting the composition tends to saturate once the Al content exceeds 10 wt.%. Therefore, in terms of MFCs for ac applications, the Al content in electrode should be controlled within 10 wt.% as a compromise between the atmospheric and electrochemical corrosion.