Das anodische und kathodische Verhalten des Eisens in sulfathaltigen Elektrolyten. Chaire d'Electrochimie,Faculté des Sciences,Strasbourg, France

The anodic and cathodic behaviour of iron in sulphate containing electrolytes The formation of Fe₂(SO₄)₃ on passive iron at p_H = 1 appears probable from a thermodynamical point of view. At high SO₄^2? concentrations the equilibrium system contains but low concentrations of Fe³⁺, and no Fe²⁺ ions, a fact showing the relatively elevated stability of the Fe₂(SO₄)₃ layer on passive iron. In slightly acid solution (p_H = 4) the passivity of the iron is determined by iron oxide layers. The formation of FeSO₄ from metallic iron and sulphate ions is restricted to the transpassive zone (p_H 4 to 7), in alkaline solutions even to the active zone. In the p_H region 2 to 14 the passive layer on iron has about the same composition in the systems Fe|H₂O + SO₄^2? and Fe|H₂O.