Study on reaction mechanism for the synthesis of vanadium nitride by carbothermic reduction nitridation method

Abstract

Vanadium nitride (VN), as a typical transition metal nitride, has widespread applications in various fields due to its high melting point, high hardness, and excellent thermal and chemical stability. In this study, VN was synthesized through the carbon thermal reduction nitridation method using V2O3 as the main material, and the reaction mechanism was thoroughly examined. Thermodynamic analysis, coupled with thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), revealed that the reaction mechanism was not simply a direct nitridation process nor a two-step coupling of reduction and carburization. Instead, it was the result of multiple reaction mechanisms working in conjunction. Direct nitridation of V2O3 occurred throughout the entire reaction process, while indirect nitridation of VO and VC also occurred with the variation of temperature. A kinetic model was constructed based on the material thermal weight loss curve and revealed that in the carbothermal reduction nitridation system of V2O3, the solid phase reaction followed a three-dimensional diffusion model, with an activation energy of 160.244 kJ/mol, while the gas phase reaction with the solid phase followed a one-dimensional interface model, with an activation energy of 169.015 kJ/mol.