Synthesis of zirconium nitride from zircon sand by transferred arc plasma assisted carbothermal reduction and nitridation process

Abstract

This paper reports the experimental results on synthesis of zirconium nitride from zircon sand through transferred arc plasma processing via carbothermal reduction and nitridation reaction. A mixture of zircon sand and carbon was processed in a transferred arc set-up in a stream of nitrogen gas. The influence of the amount of carbon and processing parameters such as input power and processing time on zirconium nitride phase formation and product morphologies were investigated by means of XRD and SEM-EDS respectively. Thermodynamic calculations were performed using free energy minimization technique to predict the conditions under which zirconium nitride is formed when zircon is processed in nitrogen atmosphere. Conversion diagrams were constructed for the ZrSiO4-C-N2 system with different mole ratios of carbon. The experimental results show that the optimum mole ratio of carbon to zircon to convert zircon to zirconium nitride by this process is 1:4. Further, the results show that the plasma input power has a greater influence on the formation of zirconium nitride rather than the processing time. Experimental observations show that the optimum processing parameters for effective formation of zirconium nitride from zircon are 10 kW of plasma input power and 5 min of processing time under nitrogen environment.