Development of New Flowsheet for the Synthesis of Nano Zirconium Carbide (ZrC)

Abstract

Scientist for the past two centuries have been fascinated by carbides due to their unique physical, chemical and mechanical properties. It is because of their high melting point that they form refractory carbides and falls in the category of ultra high temperature ceramics (UHTC). Their hardness is also very high due to which they find use in production of drill bits and cutting tools. Among these carbides, ZrC is a very significant compound due to its distinctive features and thus is useful for industrial applications. Keeping this in mind, ZrC nanopowders were synthesized in the present study via a carbothermal-reduction technique by using ZrO2 as a precursor for Zr and C6H14 as a C source along with Mg as a reductant. Various experiments were performed by varying temperature (600, 700, and 800 °C), holding time (2.5 and 7.5h), and in the later stages varying the C content to observe the changes in the morphology of the compound. All the synthesis was done in a sealed stainless steel autoclave in a furnace at a heating rate of 5 °C/min. Synthesized samples were characterized by X-ray diffraction, scanning electron microscope and transmission electron microscope. The thermal analysis was done using thermal gravimetric analysis/ differential scanning calorimetry. XRD results illustrated that heating the precursors at 700 °C with a holding time of 10h is optimum condition to produce single phase ZrC. The nanoparticles produced have an average size of about 26 nm having a C layer engulfed structure. The factors influencing the synthesis of ZrC have been discussed in the present work.