OXIDATION OF VANADIUM BY CARBON-DIOXIDE

The oxidation of vanadium by CO//2-CO mixtures (0. 25 less than P(CO//2)/P(CO) less than 9) in the temperature range 1025-1225 degree C leads simultaneously to the growth of a thin external layer of V//2O//3 above a thick VO scale and to the dissolution of oxygen in the metal. This dissolution, which is particularly significant at the beginning of the reaction ( alpha less than 0. 2), is associated with the formation of the alpha , alpha prime (or V//9O) and beta phases. The parabolic kinetics are controlled by a mainly cationic diffusion process (E equals 49 plus or minus 5 kcal mol** minus **1) where the VO phase plays a preponderant role.