Measurement of Carbon on Cold-Rolled Steel: A Comparative Study Using Surface Analytical and Coulometric Methodologies

Direct oxidation carbon dioxide coulometry was carried out on three steels that had been manufactured by different processes. Electron spectroscopy for chemical analysis (ESCA) and secondary ion mass spectroscopy showed the types of carbon and at what depth it had been removed by the oxidation technique. The oxidations were carried out at 450 and 600 deg. C. All detectable surface carbon was removed from all the steels at the lower temperature, while iron oxide layers 200 and 2000 nanometers in thickness, approximately, were produced at these respective temperatures, which showed that near-surface carbon from such depths was oxidized in the coulometry. However, the oxidation technique at 450 deg. C, measured chiefly surface carbon, whilst the subsequent 600 deg. C coulometry measurement is comprised entirely of near surface carbon and reflected differences in manufacture. 26 refs.