The formation mechanism of nanocrystalline TiC from KCl–LiCl molten salt medium

Abstract

In this research, an attempt was made to artificially synthesis bulk nanocrystalline TiC using molten salt bath medium. To do so, titanium powder and carbon black (CB) were mixed as precursors with prepared KCl–LiCl eutectic composition and the effect of the synthesis temperature and dwelling time were studied on the final powder. The X-ray diffraction (XRD) patterns revealed that the increase of the temperature and dwelling time has a considerable effect on the purity and crystallinity of the final TiC. Based on results attained from simultaneous thermal analysis (STA) and microscopic micrographs (TEM and SEM), the mechanism of TiC synthesis was determined as “template growth”. The XRD and STA analyses results showed that by increasing the temperature up to 950 °C, some intermediate phases such as LiTiO2 and TiClx (x = 2 and 3) were formed. The results of Rietveld refinement showed that with increasing the temperature from 815 to 950 °C, the crystallite size of the final product decreased from 75 to 30 nm and the lattice parameter of TiC powder increased from 4.298 to 4.324 Å (The lattice parameter of TiC is 4.327 Å). The Energy Dispersive X-ray Spectroscopy (EDS) declared that the nanocrystalline TiC synthesized at 950 °C was with maximum accordance with the composition of the stoichiometric compound.