Raman Study of Surface Reaction of Iron with Peroxide Ion in the Melts

Otori, Norikazu; Furukawa, Tomohiro  

We have investigated corrosion reaction on surface of steel with NaO powder using in situ Raman spectroscopy. The obtained spectra showed corrosion reaction occurs under 833 K and the corrosion product was identified as NaFeO. A reaction mechanism for the corrosion based on the above results was presented that the system of Fe + NaO produces corrosive melt under 833 K so that it spreads over the surface and the corrosion products distribute homogeneously on the surface. The corrosion reaction in homogeneous powder mixture of Fe and NaO has also been investigated using Raman spectroscopy with the help of XRD and DTA methods. The corrosion products were identified as the double oxides whose compositions correspond to the stoichiometric ratio of Na to Fe in the starting materials, while the products from the surface reaction of steel with NaO tend to have a specified composition of NaFeO. The difference can reasonably be explained using the mechanism presented above. It was found from the DTA measurements that NaO has particularly strong corrosivity for iron, in contrast to NaO and NaOH.