Validation of a kinetic model of diffusion for complete oxidation of bismuth powder: influence of granulometry and temperature

The kinetics of complete oxidation of bismuth powder by air has been investigated by thermogravimetric studies under isothermal conditions in the range 729–968 K. Particles size was chosen in the 35–375-μm range. We have been able to carry out the full oxidation of the powder far above the bismuth metal melting point (544.3 K) without coalescence of the particles. A quantitative interpretation based on the diffusion of reactants through the oxide layer has been proposed. The activation energy calculated from the Arrhenius law is close to 139 kJ mol−1.