Tungsten Carbide by Electrothermal Explosion under Pressure: Accompanying Phase Transformations

Abstract

Phase transformations taking place during synthesis of WC by electrothermal explosion (ETE) were investigated within the following range of process parameters: T = 293–3700 K, 49.8–50.2 at % C, P = 96 MPa, V = 10 V, I = 20 МА/m², sample diameter of 20 mm. The thermogram of the ETE process was subdivided into four stages (I–IV). Stage I, warmup, temperature range of 293–563 K, endothermic reaction (isothermic plateau), input electric energy Q = 2.96 kJ, specific input energy Е = 111.6 kJ/mol. Low-temperature stage II, 563–1190 K, ignition, Q = 5.46 kJ, Е_а = 109.2 kJ/mol. High-temperature stage III, 1190–2695 K, eutectoid decay, order–disorder transformation, Q = 14.25 kJ, Е_а = 424 kJ/mol. Stage IV, melting, 2695–3695 K, Q = 14.31 kJ, Е_а = 143.2 kJ/mol. The rate of ETE reaction is highly sensitive to applied pressure, concentration of reagents, sample shape, oxide film, etc. Variation in E affords facile control of the ETE process.