Preparation of vanadium-nitrogen alloy at low temperature by a coupled electric and thermal field

Abstract

Vanadium-nitrogen alloy was prepared at 900 °C by a coupled electric and thermal field using vanadium pentoxide and carbon black powder as raw materials. The effect of different alternating current densities and reaction time on the material phase and chemical composition of nitridation products was investigated. It was demonstrated that the current densities had a great influence on the formation of vanadium nitride (VN) phase and the content of nitrogen in the final products. The nitriding process could be basically completed within 4 h when the current density was 35.37 A/cm2 at 900 °C of equipment temperature, and the highest value nitrogen content of up to 17.99 wt% in the product was obtained. VN began to transform into V(N1-xCx) solid solution when the current density rose to over 35.37 A/cm2, resulting in the nitrogen content of the products decreased. The Joule heating effect was used to explain the reaction mechanism, and the real temperature distribution of the samples was simulated and calculated by computer, and the simulation results showed that the real temperature distribution of the sample was obviously inhomogeneous.