Improvements in the combustion method for the determination of low carbon contents in steel

For the reliable determination of carbon contents of a few μg/g in low and ultra-low carbon steels by the combustion method with commercially available carbon analyzers special measures as surface cleaning by chemical etching, pre-treatments of crucible and accelerator materials, or in-situ desorption of contaminations have to be taken. A new technique including firstly, the pre-burning of copper for degassing the ceramic crucible and, secondly, the desorption of carbonaceous contaminations from the surface of the sample and the Cu-accelerator by placing together into the still hot crucible yields a detection limit of about 0.5 μg/g carbon. The technique was checked with granular and compact iron samples, and the results were compared with those of investigations with special devices for fractionated, temperature controlled combustion.