Oxidation of Metals

, Volume 17, Issue 1–2, pp 55–76 | Cite as

Kinetics and mechanisms of the oxidation of cobalt at 600–800°C

  • H. S. Hsu
  • G. J. Yurek
Article

Abstract

Two-phase layered scales comprising CoO and Co3O4 formed on cobalt during oxidation at 600°, 700°, and 800°C and at oxygen partial pressures in the range 0.001–1 atm. The kinetics, which were obtained by thermogravimetric analysis, obeyed a parabolic rate law after an initial, non-parabolic stage of oxidation. The monoxide consisted of relatively large grains (∼10 μ) and the spinel comprised small grains (⪝3 μ) for all conditions of oxidation. Grain boundary diffusion of cations played a significant role in the growth of the spinel layer. Thermogravimetric data and the steady-state ratio of the oxide layer thicknesses were employed to calculate the rates of thickening of the individual oxide layers and the rate of oxidation of CoO to Co3O4.

Key words

oxidation cobalt diffusion grain boundaries Co3O4 

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Copyright information

© Plenum Publishing Corporation 1982

Authors and Affiliations

  • H. S. Hsu
    • 1
  • G. J. Yurek
    • 1
  1. 1.The Corrosion LaboratoryMassachusetts Institute of Technology Cambridge

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