APPLICATION OF SPECTRAL EMISSIVITY OF TC4 ALLOY IN OXIDATION KINETICS STUDY

The oxide growth rate on the TC4 alloy surface is an important indicator in oxidation kinetics study. The aim of this study was to determine the rate constant and reaction activation energy of TC4 alloy during oxidation via emissivity measurements. An experimental device was constructed to investigate the emissivity as a function of the heating time at temperatures of 873, 903, 943 and 973 K. Based on the characteristics of the spectral emissivity, the oxide thickness is estimated by using the theory of thin film radiation effect. The parabolic relation of thickness with time was found, and then the parabolic rate constants in all cases were evaluated by the least square method according to the Wagner's theory. Finally, all these results were plugged into the Arrhenius equation, resulting in an oxidation activation energy of 271 kJ/mol. The good agreement between the experimental values and those reported in other literatures suggests the applicability of emissivity measurement in the study of the oxidation kinetic of TC4 alloy.