Fabrication of nano-TiN powder by pyrolysis conversion of TiO_2 in a fluidized bed furnace

摘要

Nano-structure TiN powders were prepared by using anatase-TiO_2 and graphite mixtures as the precursor. Prior to thermal conversion, the mixture of TiO_2 and graphite was milled in a high energy attritor to enhance the validity of carbothermic reduction. The nano-TiN powders were thermal converted by introducing N_2 into a low pressure circulated fluidized-bed reactor which was previously evacuated to the pressure around 10~(-1) torr. The formation of TiN compound is greatly enhanced by high-energy milling due to the reduced crystallite size, large grain boundary area, presence of amorphous phases and the increased defect concentration in the powder reactants given by the high-energy milling. The experiment results evidenced that the carhothermic reduction could not be occurred if the powder mixture of TiO_2 + graphite had not been undergone a severe milling.