Inter-particle neck growth kinetics of vanadium carbide powder during initial stages of conventional and spark-plasma sintering has been investigated. Vanadium carbide (V8C7) micron-size powder has been subjected to both Free Pressureless Spark Plasma Sintering (FPSPS) and conventional sintering dilatometry. While the latter resulted not to be effective in the consolidation process, FPSPS procedure proved to be successful in terms of the initial stages of densification and inter-particle neck evolution, even without applying an external load. FPSPS was conducted with and without holding time, in order to obtain experimental data on the inter-particle contact growth for different temperature regimes. The neck sizes derived from scanning electron microscopy observations were utilized in the inverse regression of the surface diffusion equation and led to the calculation of the value of the surface diffusion activation energy for the vanadium carbide powder. 

http://www.sciencedirect.com/science/article/pii/S0263436813001418