OXIDATION OF Fe3O4 ON IRON AND STEEL SURFACES.

On weathering steel, carbon steel, and pure iron, two sets of samples were polished and coated with an Fe//3O//4 paste. One set was moistened daily with distilled water and allowed to dry in air. The second set was treated in a similar manner except that every other day, a 0. 1M Na//2SO//4 solution was used. In samples treated only with distilled water, Fe//3O//4 was oxidized to gamma -FeOOH on both the weathering and carbon steel surface, but oxidation of Fe//3O//4 was not observed on the iron surface. On all samples treated with 0. 1M Na//2SO//4, Fe//3O//4 was oxidized initially to gamma -FeOOH which converted to alpha -FeOOH after several weeks. The initial oxidation of Fe//3O//4 is proposed to occur by a reaction with H//2O//2 produced from reduction of O//2.