Analysis of Iron Corrosion Products Using Mössbauer Spectroscopy

A brief outline of Mössbauer spectroscopy is presented, and previous work on its application to the field of corrosion is summarized. Practical corrosion products formed under a variety of conditions are identified using the Mössbauer effect, and in some cases the Mössbauer data have been complemented by X-ray diffraction analysis. α-FeOOH, γ-FeOOH, γ-Fe₂O₃, and Fe₃O₄ are found in atmospheric corrosion products; Fe₃O₄, γ-Fe₂O₃, α-FeOOH, FeCO₃, and perhaps γ-FeOOH on buried pipelines; Fe₃O₄, γ-Fe₂O₃, α-FeOOH, β-FeOOH, and perhaps γ-FeOOH on buried structures; Fe₃O₄ in boiler superheaters, and γ-Fe₂O₃, Fe₃O₄, α-FeOOH, and possibly γ-FeOOH on heat exchangers, and α-FeOOH, γ-FeOOH, γ-Fe₂O₃, Fe₃O₄, and sometimes Zn_xFe_3-xO₄ in galvanized potable water pipe. The ability of the Mössbauer effect to distinguish these oxides and hydrated oxides provides the corrosion engineer with a valuable method for analyzing iron corrosion products.