Anodic Behaviour of Binary Iron–Silicon Alloys

Abstract

Cyclic voltammetry was used to investigate the anodic behaviour of binary alloys of iron and silicon. Both pure and cast iron were studied, alloyed with pure Si. The media used for the tests included 1M NaCl, 1 M Na₂SO₄ and 1M H₂S₄, all at room temperature. Both annealed and unannealed alloys were used.

The results show that pure iron-based alloys show a higher corrosion resistance than the analogous castiron alloys and that, while NaCl is the most aggressive medium, there is little difference between sulphuric acid and its neutral salt. Separate cyclic voltammetric experiments using repetitive scanning indicate that the passivation is largely irreversible. The implications of all these findings on previous studies are considered. Volumetric measurements of evolved gaseous oxygen suggest that under potentiostatic control, where thin films are formed, corrosion rates are much higher than in the steady-state under galvanostatic control.