THE IMPROVEMENT OF THE LOCALIZED CORROSION-RESISTANCE OF STAINLESS-STEEL BY CERIUM

Rotating disc assemblies are employed to study the cathodic electrode process and its inhibition by cerium implantation into UNS S31603 stainless steel in a solution of 0.6 M NaCl + 0.1 M Na2SO4. The reduction of oxygen and protons on both gold and untreated steel are shown to be controlled by the mass transport processes in solution. Cerium implantation effectively inhibits the cathodic reduction, reducing the cathodic current by more than two orders of magnitude. The cathodic reduction of oxygen and protons on ion-implanted stainless steel is thus controlled primarily by charge transfer at the electrode. Thermodynamic data suggests that the highly stable cerium oxide may be responsible for blocking the active sites for both cathodic and anodic reactions.