Surface modification of iron plates by ion implantation

Application of ion implantation to the modification of electrochemical properties of metal surfaces is briefly reviewed. The ion implantations of Ar+, N2+, O2+, Zn+, Cu+, Ni+, Cr+, Ti+, and Si+ into substrates were carried out by means of a RIKEN 200 kV Ion Implanter. Concentration-depth profiles of the implanted element were measured by a secondary ion mass spectrometry (SIMS). The electrochemical properties of the ion implanted specimens were studied by means of multi-sweep cyclic voltammetry. A 0.5 mol.dm-3 sodium acetate buffer (pH 5) solution was utilized as a mild corrosion atmosphere. The relationship between the composition of the surface layer and electrochemical dissolution properties was discussed. The anodic dissolution of the iron electrodes was remarkably suppressed by the ion implantation of Cr, Si, and Ti with a dose of 1 x 1017 ions.cm-2. The concentration-depth profiles and the cyclic voltammograms were measured for Ni+-Cr+ and Cr+-O2+ double-implanted iron specimens. Oxidation of chromium by the additional O2+-implantation depressed the anodic dissolution of the Cr-implanted iron electrode. These results suggest that the ion implantation is effective in making a corrosion inhibited surface layer on iron. (author)