Corrosion of metals by contact with metal oxides

The corrosion of metals in aqueous solutions is influenced by contact with metal oxides. The electrode potential of metals fully covered with metal oxides stands either at the potential of metal oxide formation or at the flat band potential of metal oxides: the latter predominates if no metal ion transfer occurs across the metal/oxide interface. When a metal electrode is partially covered with metal oxides, the corrosion potential of the metal shifts in the cathodic direction if the oxide is of n-type and in the anodic direction if the oxide is of p-type. Such a shift in the corrosion potential of metals leads to reducing the corrosion in case of n-type oxides and to accelarating the corrosion in case of p-type oxides. Under the exposure to radiation metallic copper in contact with p-type copper oxides corrodes even if no oxygen is present in the environment.