Electrochemical corrosion behavior of an amorphous Co-Cr-Si-B alloy under various conditions

This study was undertaken to measure the electrochemical corrosion of an amorphous Co70Cr5Si10B15 (at. %) alloy ribbon under various conditions, including 0.052-M HCl, 0.068-M NaCl, and for various values of the pH and the oxygenation time. With increasing temperature, the corrosion potentials decreased toward a higher negative value, the current density at the primary passivation potential was relatively higher, the corrosion current density and the corrosion rate increased, and the width of the passive region decreased over a given range of temperature. The corrosion resistance was inversely proportional to the corrosion rate. The corrosion potential in 0.068-M NaCl was lower than that in 0.052-M HCl at all temperatures studied, and a passive region was not formed. Both the corrosion potential and the passive region showed only slight variations with the oxygenation time. The corrosion sensitivity under 0.052-M HCl was 0.776. Under 0.052-M HCI the corrosion rate was relatively high, and the corrosion resistance small.