Oxidation kinetics and thermophysical properties of gamma irradiated silicon hexaboride

摘要

Silicide hexaboride (SiB6) compound with a purity of 99.5% was irradiated using Co-60 gamma radioisotope under the atmospheric pressure with a dose rate (D) of 0.27 Gy/s at the 9.7, 48.6, 97.2, 145.8 and 194.4 kGy doses at room temperature. The oxidation kinetics, diffusion velocity, and depth of oxidation of the SiB6 compound were determined by using a differential scanning calorimetry (DSC) in the temperature range of 920 <= T <= 1270K. The maximum thickness of the B2O3 and SiO2 oxide layers was deter- mined on the surface of SiB6 from the caloritmetric analyzes. The thickness of the formed oxide layers was found in the range of 10 nm and 60 nm. The activation energy of oxide layers formed on the surface as observed from Arrhenius plots was found to increase up to 49.8 kJ mol(-1) with respect to absorption dose of SiB6 samples in the temperature range between 950 K and 1270 K. The results have revealed that it has been observed a change in thermodynamic functions (Delta S, Delta H, and Delta G) from room temperature up to 1270 K. (C) 2019 Published by Elsevier B.V.