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Kinetics of the alpha-Fe2O3 formation on Fe3O4 between 400 degree C and 570 degree C studied by means of X-ray diffraction with grazing incidence

Lectures and posters.
Untersuchung der Kinetik der alpha-Fe2O3-Bildung auf Fe3O4 im Temperaturbereich zwischen 400 Grad C und 570 Grad C mittels Röntgenbeugung bei streifendem Einfall

Nickel, H.:
7. Arbeitstagung Angewandte Oberflächenanalytik 1992. Lectures and posters
Berlin: Springer, 1993 (Fresenius' journal of analytical chemistry 346)
Arbeitstagung Angewandte Oberflächenanalytik (AOFA) <7, 1992, Jülich>
Fraunhofer ICT ()
corrosion; difference method; Fe-ARMCO; Fe2 O3 formation; grazing incidence; in situ study; iron; oxidation; thin layer; x-ray diffraction

The formation of alpha-Fe2O3 on Fe3O4 during the oxidation of iron below 570 deg. C occurs very slowly and the scales are so thin that they cannot be detected by microscopy. X-ray diffraction with grazing incidence, equipped with a high temperature device, allows an 'in situ' study of the alpha-Fe2O3 formation even the initial reactions. The formation of alpha-Fe2O3 was studied in isothermal experiments at 400, 450, 500 and 550 deg. C. alpha-Fe2O3 could already be detected at the beginning of the experiments. The difference method, a numerical treatment for kinetic evaluation, yields curves showing the growth of the alpha-Fe2O3 layer. Fitting the parabolic time law to these curves yields the rate constants.