Determination of carbon in uranium carbide using catalytic oxidation by manganese dioxide

Abstract

The oxidation of uranium carbide in oxygen is initiated at 548 K, but the reaction is only 80–85% complete even at 673 K in oxygen after 30 min. In this work, the oxidation of uranium carbide with manganese dioxide and potassium nitrate in oxygen and argon atmospheres was studied. With manganese dioxide at 653 K, the oxidation reaction in an oxygen atmosphere was quantitative. This reaction was therefore used for the determination of carbon in uranium carbide. The carbon content of samples determined by the present method agreed well with that obtained using a conventional combustion method. The recovery of carbon from a mixture of U3O8 and graphite was negligible. However, when an intimate mixture of graphite and uranium carbide was analysed, the contribution of the graphite (free carbon) to the calculated carbon content was significant. Hence free carbon was found to interfere seriously. Similar experiments carried out with potassium nitrate gave very low recoveries of carbon at 623 K, and at higher temperatures the recoveries were inconsistent.