Analysis of TiB2 powders oxidation in the air

The kinetic parameters of TiB2 powders oxidation of different dispersions were estimated by Coats-Redfern and Ozawa-Flynn-Wall methods. Based on the isoconversional method, it was found that the investigated reaction is most likely of the fractional order and the activation energy E-A dependence during the oxidation reaction is of the complicated behavior. Using the Coats-Redfern method the E-A values were estimated for four temperature ranges: E-A congruent to 300-400 kJ/mol (<750 K, alpha congruent to 5-7 %), 190 kJ/mol (750-820 K), 75 kJ/mol (820-1,000 K), and EA congruent to 16...26 kJ/mol (1,000-1,400 K) at high alpha values. A thickness, composition, and microstructure of the scale are changing continuously with temperature (T) increase. These changes lead to the variations of the mechanism of the oxygen diffusion transport to the reaction area.