Influence of Calcium on the Thermal Oxidation of Ca-Doped CoO and of CaO-Coated Cobalt

Year 2025, Volume: 36, 11 - 20

Nacer Halem Zohra Halem Ouardia Halem Mariora Abrudeanu Georgette Petot-Ervas

Abstract

The present study concerns the influence of calcium on the thermal oxidation of Ca-doped Co1-xO
and of CaO-coated cobalt. We have found that calcium enhanced the thermal oxidation of Co1-xO single crystals
while a CaO coating leads to a decrease of the oxidation kinetic of cobalt polycrystals, at T<1200°C. From a
formal treatment, based on the thermodynamic of irreversible processes, we have shown that the increase of the
thermal oxidation of Ca-doped Co1-xO is due to the increase of the diffusion coefficient of cobalt in Ca-doped
samples, while the beneficial effect of a CaO coating on the cobalt oxidation is due to the shift of the Co/Co1-xO
phase boundary to higher PO2, leading to a decrease of the driving force of diffusion in the oxide scale.

Keywords

Oxygen chemical potential gradient , Diffusion driving force , Diffusion , Kinetic demixing

References

• Halem, N., Halem, Z., Halem, O., Abrudeanu, M., & Petor-Ervas, G. (2025). Influence of calcium on the thermal oxidation of Ca-doped CoO and of CaO-coated cobalt. The Eurasia Proceedings of Science, Technology, Engineering and Mathematics (EPSTEM), 36, 11-20