Self-propagating high-temperature synthesis of AlN–TiC powder composition using sodium azide and C2F4 fluoroplastic

Producing powder compositions using conventional processing technology can lead to the formation of large agglomerates and, therefore, makes it difficult to obtain a uniform microstructure. The production of composites by self-propagating high-temperature synthesis can reduce costs and the number of technological stages, as well as lead to obtaining composites that are more homogeneous. Synthesis by the combustion of mixtures of powder reagents of sodium azide (NaN₃), fluoroplastic (C₂F₄), aluminum and titanium with different ratios of reagents in a nitrogen gas atmosphere at a pressure of 4 MPa was used for the production of a highly dispersed powder ceramic AlN–TiC composition. Thermodynamic calculations have confirmed the possibility of synthesis of AlN–TiC compositions of different formulations in combustion mode. The dependences of temperature and combustion rate on the composition of the initial mixtures of reagents were experimentally determined for all stoichiometric reaction equations. The study have shown that the experimentally found dependences of combustion parameters on the ratio of the initial components correspond to the theoretical results of thermodynamic calculations. The formulation of the synthesized composition differs from the theoretical composition by a lower content of target phases and the formation of Al₂O₃, Na₃AlF₆ and TiO₂ side phases. The powder composition consists of aluminum nitride fibers with a diameter of 100–250 nm and ultradisperse particles of predominantly equiaxed and lamellar shapes with a particle size of 200–600 nm. As the combustion temperature increases to produce the largest amount of titanium carbide phase, the particle size increases to the micron level.