Study of the anodic behaviour of iron at high potentials in solutions containing chloride ions

✍ Scribed by A. Ríus; R. Lizarbe

• Publisher: Elsevier Science
• Year: 1962
• Tongue: English
• Weight: 447 KB
• Volume: 7
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(62)85001-4

✦ Synopsis

Abstraet--Galvanostatic and potentiostatic polarization curves of an iron electrode in H2SO4 electro-lyti¢ baths containing KC1 from N/50 to N[500 have been determined. When the concentration of the electrolyte is N/250 or less, the galvanostatic curves show, for a certain value of c.d., a shift of potential; this value of the c.d. depends on the speed of getting the polarization curve and for a steady velocity on the KC1 concentration and temperature of the electrolyte. If the KC1 concentration is higher than N/250, once passivation has taken place gas evolution starts which disappears rapidly and a dark layer covers the electrode. At the same time the potential takes less positive values and osciUates.

When the KC1 concentration in the electrolyte is smaller than N/250 the potentiostatic polarization curve does not seem to be affected on its active part by the Cl-ions. The shift of passivation takes place at 150 mV and the c.d. reduces at some ~tA. At higher values of potential gas evolves and the transpassive part of the polarization curve begins. For potentials higher than +2000 mV dark spots appear on the anodic surface. At the same time the evolution of gas and the c.d. diminishes.

In the descending curves (galvanostatic and potentiostatic) and below the critical c.d. of passivation, two poorly defined waves appear. The first is at about +1600 mV and the second at +1200 inV.