Carbonitridation of mechanically activated mixtures of zircon and carbon

•Formation temperature of ZrN and ZrC decreased to 1400°C in the five hours milled sample.•Either ZrC or ZrN were observed in the heating of 6:1 C:Zircon samples under argon/nitrogen atmospheres.•Amount of tetragonal zirconia increased in nitrogen atmosphere.•Percentage of tetragonal zirconia increased at higher C:Zircon ratios. Two different stoichiometries of zircon (ZrSiO4) and activated carbon (C:zircon molar ratios of 3:1 and 6:1) were milled together at for 5h and subjected to thermo-gravimetric analysis (TGA). TGA runs were performed under argon and nitrogen atmospheres. The main mass loss reaction started at around 1200°C in all samples, but the mass loss was greater in the 6:1 C:zircon ratio samples in nitrogen. X-ray diffraction (XRD) of the residues showed the decomposition of zircon was nearly complete. Traces of ZrN along with monoclinic and tetragonal forms of zirconia were observed in the nitrogen atmosphere, however only zirconia was present after heating in argon. Heating the 6:1 C:zircon molar ratio sample for 1h at 1400°C in argon resulted in the formation of ZrC and SiC, in nitrogen ZrN was formed.