Synthesis and Characterization of Vanadium Carbide Nanoparticles

Abstract

Research on nanomaterials is a step towards miniaturization of technology that contributes significantly towards a sustainable usage of raw materials and energy. Properties of nanoparticles are different than bulk and often superior to their conventional polycrystalline form. The variation in properties is because of microstructure which is determined by the chemical composition, grain size, atomic structure and crystallographic orientation. Nanoparticles, due to their smaller size and large surface to volume ratio, exhibit interesting novel properties which include nonlinear optical behaviour, increased mechanical strength, enhanced diffusivity, high specific heat, magnetic behaviour and electric resistivity etc. Therefore, more emphasis is being given on the development of new processes for the synthesis of nano materials on large scale. It is well known fact that use of vanadium carbide in nano range enhances its mechanical, chemical and physical properties. Other than the conventional types, nano VC finds its applications as catalyst in many devices. Currently, synthesis of vanadium carbide is done at high temperatures (> 1000 ºC) and involves many intermediate steps. Therefore, there is a need to develop new synthesis routes to obtain the product at relatively lower temperature than the reported ones. Literature review gives an idea on the work done on direct synthesis of nanocrystalline vanadium carbide from different precursors, which include the formation of mixed/impure phases also (VC and V2C). Keeping in view these technological challenges, the present work is undertaken to synthesize pure nano vanadium carbide from V2O5 as precursor at relatively lower temperature by thermo-chemical/mechano-chemical route. The work reported here is innovative in nature to obtain pure phase (VC or V8C7) using these techniques. The techniques adopted for their synthesis are mild and of industrial importance as the processes developed are economical in nature. The as-synthesized vanadium carbide nano powders were mixed with WC and Co followed by consolidation and sintering at different temperatures. The control in the grain growth of WC-Co-VC composite has been observed during sintering. The variation in microstructure and hardness with variation in sintering temperature has been observed. The present work deals with the synthesis and characterization of nano vanadium carbide(s) by thermo-chemical/mechano-chemical route. Also, suitability of the obtained vanadium (xvii) carbide has been checked in WC-Co cermets as grain growth inhibitor (GGI).