Electrothermographic Investigation of Rapid Exothermic Gas–Solid Reactions in Refractory Materials

Abstract

This study presented the formation and oxidation of refractory materials investigated with a high-speed electro-thermographic method specifically designed to probe rapid exothermic gas–solid reactions. Thin metallic wire specimens of Ta or tantalum carbide (TaC, Ta₂C) coated Ta served as both heating elements and reactants, enabling controllable heating of specimen up to 5 × 10⁵ K/s under various gas environments. Real-time measurements of electrical parameters and temperature at 10 kHz captured reaction dynamics across 900–2500 K. Two distinct heating modes were employed: (i) temperature-controlled (isothermal or linear heating) and (ii) power-controlled, which simulates quasi-isothermal reaction conditions. This dual approach allowed detailed exploration of TaC/Ta₂C coating synthesis on Ta wires and identification of the critical parameters separating slow oxidation from ignition of tantalum and tantalum carbides. Gravimetric measurements provided kinetic data on carbidization and oxidation across varied experimental conditions, while rapid quenching of specimens preserved intermediate states for ex-situ characterization by X-ray diffraction and electron microscopy.