Oxidation behavior of nano-scaled and micron-scaled TiC powders under air

• Oxidation behavior under air of several batches of TiC nano- and micropowders
• Kinetics and mechanisms observed using DTA–TGA and in-situ temperature XRD
• Oxidation reactions: i) TiC → TiCxO1 − x up to TiO, ii) → Ti3O5, iii) → TiO2
• Shift of oxidation temperature for nano compared to micropowders
• Discussion of the role of the oxygen trapped in the powder

The oxidation behavior of several batches of TiC nanopowders and micropowders under air has been studied. Using TGA, the oxidation of nanopowders is completed faster and at a lower temperature compared to micropowders. This is related to the higher specific surface area of the nanopowders. Using an amount of powder of about 41.6 mg through DTA, three different exothermic peaks were observed for both kinds of powders. Correlated to the in-situ temperature XRD diffractograms, these peaks were attributed to the following oxidation reactions: i) TiC → TiCxO1 − x up to TiO, ii) → Ti3O5, and iii) → TiO2. The same successive oxide phases for nanopowders and micropowders were observed, meaning that the oxidation mechanism is similar in both cases but with a shift of temperature. In this article, the role of the oxygen trapped in the powder and the effect of powder quantity on the oxidation kinetics and on the occurrence of one or three oxidation peaks are discussed.

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