Bestimmung von Argon neben Stickstoff und Sauerstoff in pulvermetallurgisch hergestellten Werkstoffen mit einem modifizierten Trägergas-Heißextraktionsgerät

The modification of a commercial carrier-gas fusion instrument for the simultaneous determination of argon is described. In order to separate argon from nitrogen, a gas-chromatographic column with molecular sieve was incorporated between the absorption traps for H2O and CO2 and the thermal conductivity detector. A computing integrator was used for the evaluation of the detector signals. The calibration was done by introduction of defined volumes of dry air into the carrier-gas line. The conditions for the liberation of argon from samples of ODS-alloys and the separation from the other extracted gases were optimized. Results of analysis of powders and compact samples were compared with the results obtained by means of a vacuum-fusion instrument. In the concentration range 25 to 50 μg/g argon the relative standard deviations were 1.5 to 3% (six determinations). With powders of 3 to 5 μg/g relative standard deviations of about 8% were achieved. The limit of detection for 1 g samples was found to be ca. 0.5 μg/g.