Full transition from metal to ceramic by direct oxidation of metallic cobalt powder

The study deals with the direct oxidation kinetics of micronic cobalt metal particles and its simulation for the complete transition from metal to ceramic. The simulation was also experimentally verified. All the three possible interfaces, Co/CoO, CoO/Co3O4 and Co3O4/O2 (air), have been taken into consideration for the simulation. The complete oxidation kinetics has been investigated from the thermogravimetric studies under isothermal conditions in the temperatures 973–1173 K. A quantitative interpretation based on the diffusion of Co or oxygen ions through the grown oxide layer has been proposed. The activation energy for the oxidation kinetics calculated from the Arrhenius law was 161 ± 20 kJ mol−1.