Thermokinetic study of the oxidation of ZrAl3 powders

The oxidation kinetics of ball milled ZrAl3 powder was investigated by thermogravimetry at temperatures up to 1100 image C. The non-selective oxidation of ZrAl3 results in the formation of image-Al2 O3, tetragonal and monoclinic ZrO2. Non-isothermal and isothermal measurements were simultaneously used in a multivariate non-linear regression analysis to determine the kinetic reaction parameters. The oxidation process is well described by a generalized n-dimensional Avrami type rate equation, according to a diffusion limited growth reaction with an apparent activation energy of 244 kJ/mol. Significant improvement of the fit quality of the kinetic data is achieved through a two-step kinetic model indicating a complex oxidation mechanism.