Preparation of titanium nitride: Microwave-induced carbothermal reaction of titanium dioxide

Carbothermal reduction and nitridation of TiO₂ was performed in a 2 kW, 2.45 GHz microwave furnace. Carbon, generally added for the removal of oxygen from TiO₂ lattice also served as the low-temperature susceptor in these experiments. At temperatures >1200°C, the mixtures started reacting vigorously (self-burn), which was never observed with the respective pure compounds. In the self-burning state, the minimum duration required for complete titanium nitride transformation was ∼20 min with stoichiometric amounts of carbon. With excess C, the transformation duration dropped to just 1 min. CO removal and subsequent Ni fixation occur more directly in microwave-induced reactions than in conventional nitridation procedures. Intermediate formation of successive Magneli phases (Ti_2nO_2n-1) was not found in the microwave-induced reactions. The combination of microwave processing and combustion makes this route of economical interest.