DETERMINATION OF NITROGEN-CONTENT IN VANADIUM POWDER BY INERT-GAS FUSION OF GRAPHITE-ADDED PELLETS

A graphite-addition pelletizing technique proposed by the authors has been successfully applied to the determination of nitrogen in the ppm range in powdered vanadium. Complete extraction of total nitrogen from pellets of 5 mm diameter weighing from 0.1 to 0.5 g with graphite add ition of more than atomic ratio of 1 or above requires an impulse furn ace heating at about 3000 degrees C within the 100-s gas collection. T he results obtained by the proposed method were in agreement with thes e obtained by the Kjeldahl method for higher content sample, and showe d slightly higher results for the samples containing 0.02 to 0.04 mass % nitrogen. From the results of the investigations of the effect of an impulse heating power on the extractability of nitrogen, the crucible aspects after use, and X-ray identification of the products formed in the crucible, nitrogen from the pellet with a 1 : 1 atomic ratio of g raphite was released at about 2900 degrees C in a solid state, accompa nying complete formation of a VC phase. Residual nitrogen in the sampl e can be extracted at about 3000 degrees C in a melting or half-meltin g state of the pellet. From these results, the separation of peaks can be observed by a two-step technique; the first step at about 2900 deg rees C for 50 s and the second step at about 3000 degrees C for next 6 0 a power supply. The extraction of nitrogen from a VC pellet was also reported.