Corrosion Behaviour of Pure Chromium in H₂SO₄ Solutions

Abstract

The corrosion behaviour of 99.83% pure Cr in H₂SO₄ solutions was investigated by corrosion rate and electrochemical measurements. Particular attension was given to effects of concentrations and temperature of acids.
Cr exhibited much better corrosion resistance in 50%H₂SO₄ than that for Fe-Cr alloys and Ti at low temperatures up to 350 K. A wide passive potential range with low passive current densities was observed for Cr. The corrosion potential for Cr was nobler and more stable than those for Fe-Cr alloys and Ti. The high corrosion resistance is based on spontaneous passivation due to high stability of air formed oxide film. Cr was, however, severely corroded similary to Fe-Cr alloy and Ti under high temperature conditions higher than 350 K. The corrosion potential shifted to less noble side as a result of depassivation, and then active dissolution of Cr occurred continuously.