Kinetics and mechanisms of interactions of nitrogen and carbon monoxide with liquid niobium

The kinetics and mechanisms of interactions of N2 and CO with liquid niobium were investigated in the temperature range of 2,700 to 3,000 K in samples levitated in N2/Ar and CO/Ar streams. The nitrogen absorption and desorption processes were found to be second-order with respect to nitrogen concentration, indicating that the rate controlling step is either the adsorption of nitrogen molecules on the liquid surface or dissociation of absorbed nitrogen molecules into adsorbed atoms. The carbon and oxygen dissolution in liquid niobium from CO gas is an exothermic process and the solubilities of carbon and oxygen (CCe, COe in at%) are related to the temperature and the partial pressure of CO. The reaction CO → [C] + [O] along with the evaporation of niobium oxide takes place during C and O dissolution, whereas C and O desorption occurs via CO evolution only