Oxidation behavior and kinetics of Al2O3–TiC–Co composites

The oxidation behavior of nano-sized Al2O3–TiC–Co composite sintered at different temperature was investigated at 200–1000 °C in air for 25 h. Microstructures and phase compositions of oxidation surfaces were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that the oxidation reaction would take place when oxidation temperatures are 800 °C and 1000 °C. The oxidation resistance of Al2O3–TiC–Co composite increased with the sintering temperature rising when the sample was oxidized at 800 °C and 1000 °C. The mechanism of oxidation has been analyzed using thermodynamic and kinetics considerations. The oxidation kinetics follows a rate that is faster than the parabolic rate law at 800 °C and 1000 °C. The activation energy of the composite for oxidation in the range of 800 °C to 1000 °C was found to be 142.21 kJ/mol.

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► The oxidation behavior of Al2O3–TiC–Co composites is studied from 200 to 1000 °C.
► The oxidation resistance of composites increased with sintering temperature increasing.
► The oxidation kinetics of the composites did not follow the parabolic-rate law.
► The rate is slightly faster than the parabolic-rate law at 800–1000 °C.
► The rate constant k decreased with sintering temperature going up at 800 °C–1000 °C.