EQUILIBRIA BETWEEN CERIUM OR NEODYMIUM AND OXYGEN IN MOLTEN IRON

Autoradiographs show that there is an obvious reaction between Ce and Nd in liquid iron and the MgO/CaO crucible wall. For reaching the Ce-O, Nd-O equilibrium, a long melting period and the addition of rare earth elements (RE's) in several batches were needed to ensure the full reaction between the RE's in the melt and crucible wall. The dissolved Ce or Nd content in iron was measured by means of radioactive isotopes141Ce or147Nd and electrolysis in the organic electrolyte. The oxygen activity was measured by solid electrolyte sensors made of ZrO2(MgO) tube. The relationships between the equilibrium constants and the temperatures for reactions Ce2O3 (s) = 2[Ce] + 3[O], CeO2 (s) = [Ce] + 2[O], and Nd2O3 (s) = 2[Nd] + 3[O], as well as the corresponding thermodynamic parameters, have been determined. © 1990 The Minerals, Metals & Material Society.