Abstract
In the present work, the oxidation reactions: Co + 1/2O2 → CoO, 3CoO + 1/2O2 → Co3O4 and Ni + 1/2O2 → NiO were induced by mechanical milling. These oxidation reactions were carried out under air atmosphere and with the addition of methanol as a process control agent to avoid excessive agglomeration of the original metallic powders. Characterization of product phases has been done using x-ray diffraction, scanning electron microscopy, transmission electron microscopy and microanalysis by energy dispersive x-ray spectrometry. Oxidation of cobalt produced CoO and Co3O4 phases; the addition of methanol delayed the formation of the Co3O4 phase. For nickel, the product phases were NiO and a residual amount of Ni. Cobalt powders were more easily oxidized than Ni powders, probably as a result of their smaller initial particle size. The resulting crystallites in the oxide particle had sizes smaller than 20nm in both cases.
Original language | English |
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Pages (from-to) | 281-286 |
Number of pages | 6 |
Journal | Materials Science Forum |
Volume | 386-388 |
State | Published - 2002 |
Event | Proceedings of the International Symposium on Metastable, Mechanically Alloyed and Noncrystalline Materials (ISMANAM) - Ann Arbor, MI, United States Duration: 24 Jun 2001 → 29 Jun 2001 |
Keywords
- Mechanochemical reactions
- Nanocrystals
- Transition metal oxides