Crevice corrosion control for stainless steel using radiation-induced surface activation

When a semiconductor film is irradiated by γ-rays, excited electrons are transferred to a base metal in contact with the film, resulting in cathodic-anodic reactions and surface activation of the metal oxide film. The authors first produced radiation-induced surface activation (RISA) in 2000 and have used it in the development of a new corrosion protection method. This report describes a corrosion mitigation technique based on RISA to prevent crevice corrosion in stainless steel, using low-intensity radiation. Experimental results show that an electrode potential of -100 mV vs. Ag/AgCl was produced and maintained on TiO₂-coated SUS304 stainless steel specimens immersed in artificial seawater and in close contact with a small, sealed ⁶⁰Co source (external irradiation) or activated by neutron irradiation to become self-exciting, with no corrosion observed for more than 7 days. In contrast, the potential of a specimen without a radiation source decreased to less than -280 mV vs. Ag/AgCl and crevice corrosion occurred beneath the O-ring within a few days. The corrosion control mechanism was explored by measurement of dissolved oxygen and iron ions in the solution.