Anodic dissolution and electrocatalytic properties of Fe 60Co 20Si 10B 10 amorphous alloy in 1 M KOH

The anodic dissolution and the electrocatalytic properties of Fe 60Co 20Si 10B 10 (Vitrovrac 7600, G14) amorphous alloy in de-aerated 1 M KOH aqueous solutions were investigated at 25 and 70°C by different electrochemical techniques (cyclic voltammetry, cathodic polarisation, and galvanostatic transients). The results obtained show that voltammograms for the amorphous alloy change with time becoming stable after 20-25 cycles between -1900 and +100 mmV vs saturated sulphate electrode. Comparisons among voltammograms for polycrystalline iron, cobalt and the amorphous alloy, suggest that the first step of the anodic dissolution of the amorphous alloy is cobalt dissolution. The stable voltammogram of the amorphous alloy is quite similar to that of pure iron in the same environment, suggesting that after 20-25 cycles only iron dissolves. The electrocatalytic properties of the amorphous alloy vs the hydrogen evolution reaction in 1 M KOH increases by increasing the number of cycles which have been attributed to a porous Fe 3O 4 layer covering the amorphous surface. © 1994

Electrochemical and electrocatalytic behaviour of iron-base amorphous alloys in 1 M KOH at 25°C

The electrochemical and the electrocatalytic properties of Fe60Co20Si10B10 (Vitrovac 7600, G14), Fe40Ni40P14B6 (AC), Fe681 4Ni101 2Cr51 4Zr8B12 (BCC) and of Fe60Ni10Cr10Zr8B12 (BDI) iron base amorphous alloys in deaerated 1 M KOH aqueous solution and at 25°C was investigated. Poor electrocatalytic activity was exhibited by the amorphous alloys in the as-quenched state, while enhanced electrocatalytic activity was observed after anodic oxidation in situ at constant current density. The more active the amorphous alloy is in the alkaline solution, the better is its catalytic activity. The catalytic activity generally increases by increasing the oxidation current. This result has been attributed to an increase in the active surface of the catalyst after the anodic treatment rather than to an enhancement of the electronic properties of the surface. The G14 alloy exhibited the best catalytic properties among the alloys investigated. After an anodic treatment with a charging current of 0.5 mA cm-2 for 2 min, this alloy shows catalytic activity comparable to that of pure polycrystalline Pt in the same environment. © 1993

EFFECTS OF WATER AND IONS ON THE ELECTROCHEMICAL AND MECHANO-ELECTROCHEMICAL BEHAVIOUR OF METALLIC MATERIALS IN ORGANIC SOLVENTS.

Comparable working conditions and different surface characterization techniques were used to study corrosion behaviour of different materials in different organic solvents. Nickel was investigated with the purpose of studying the evolution of corrosion resistance and the aptitude to passivation as a consequence of water presence. Stability towards stress-corrosion of iron and low-alloyed steel passive films in acid anhydrous environments in the presence of Cl ions and water show the competition between defects nucleation and repassivation of the protective oxide. The electrochemical behaviour of iron and stainless steel in alcoholic solutions of different chain length in the presence of water and Cl ion under controlled fluid-dynamic conditions showed the effects of the chain length related to corrosion resistance and diffusion phenomena