When a semiconductor film is irradiated by gamma rays, excited electrons are transferred to abase metal in contact with the film, resulting in a drop of corrosion potential. The authors propose a corrosion mitigation method based on radiation induced surface activation (RISA) phenomena by supplying gamma rays from outside the material, or based on a self-excited methodology activating the film and/or the base metal. The corrosion potential of ZrO2 coated SUS304L was shifted down to the range between -90 mV and -300 mV vs. SSE by gamma-ray irradiation. The corrosion potential was further shifted down to -600 mV when a CoCr intermediate layer was inserted between the ZrO2 spray coating film and the SUS304L base metal. Iron specimens with a spray coating film of TiO2, ZrO2, and Al2O3 were immersed in a 3 wt% sodium chloride aqueous solution. Pitting and general corrosion were observed on both the specimens kept in a darkroom and illuminated with ultraviolet rays. Pitting and general corrosion were, however, suppressed on all three specimens irradiated with gamma rays.
