Corrosion inhibition effects of metal cations on SUS304 in 0.5 M Cl− aqueous solution

The corrosion characteristics of SUS304 exposed to 0.5 M Cl− aqueous solution containing different metal cations were studied with immersion tests, surface analysis and electrochemical tests. The mechanism of corrosion with metal cations was clarified by the XPS analysis results together with the hard and soft acid and base (HSAB) concept and the passive films structure. It is supposed that metal cations with large hardness make a layer by chemical bonding with the passive films. The passive films are protected by the metal cation layer from Cl− attack, and consequently corrosion reactions are inhibited.