Oxidation of Niobium Silicides Obtained by Self-Propagating High-Temperature Synthesis

Abstract

Niobium silicide-based composites are promising materials for high-temperature structural applications, such as gas turbines. One attractive method for their fabrication is mechanically activated self-propagating high-temperature synthesis (MASHS). However, oxidation resistance of niobium silicides produced by MASHS has not been studied yet. In this present work, the oxidation of Nb/Nb5Si3 composites obtained by MASHS was investigated by using non-isothermal thermogravimetric analysis (TGA) and differential scanning analysis (DSC). Both techniques have shown that the oxidation starts at about 500 °C and the materials become fully oxidized at 750 – 800 °C. Model-based analysis of the TGA data has shown that the Avrami-Erofeev nucleation and three-dimensional diffusion models exhibit the best fit with the TG curves and predict similar values of the apparent activation energy, 193 and 212 kJ/mol, respectively.