Influence of ammonia gas exposure on microstructure of nanocrystalline titanium nitride powder synthesized from titanium dioxide

In this study, we investigated the preparation conditions of titanium nitride (TiN) through nitridation of nano-sized titanium dioxide (TiO₂) without particle agglomeration. Synthesis of nanocrystalline TiN powder was attempted via ammonia (NH₃) nitridation of nanocrystalline TiO₂ powder. The nitridation behavior was investigated using thermogravimetry (TG) in an NH₃ atmosphere. Non-isothermal TG experiments showed that nitridation of the nanocrystalline TiO₂ powder began at ³750°C. Two types of experiments were performed using isothermal TG. In the first experiment, an argon atmosphere was used while heating at 5 °C/min. On reaching the holding temperature (900 or 1,000°C), the atmosphere was changed to NH₃/Ar (50/50 kPa). This atmosphere was used throughout the second experiment. The first experiment produced a nitride powder with severely agglomerated particles. In the second experiment, nano-sized powder particles with inhibited agglomeration were obtained, and long holding time of 6 h at 900 or 1,000°C was effective in obtaining the small nitrided particles.