Synthesis of nanocrystalline TaC powders via single-step high temperature spray pyrolysis from solution precursors

Nanocrystalline powders for high temperature ceramics (HTC) and ultra-high temperature ceramics (UHTC) are important materials for aerospace and other important industrial applications. In this study, a low cost, single-step synthesis method for nanocrystalline HTC and UHTC powders is reported, which is based on high temperature spray pyrolysis (HTSP) process. The synthesis starts with solution of oxide and carbon precursors dissolved in common organic solvents, which are broken into fine droplets (e.g., via a nebulizer). The droplets then go through processes of solvent removal, thermolysis, and rapid in situ carbothermal reduction (CTR), all in one single pass in a tube furnace operated at high temperature. The synthesis method was demonstrated successfully using the example of tantalum carbide (TaC) from precursors of tantalum chloride (TaCl5) and phenolic resin in a single-step HTSP process with maximum temperature of 1650 degrees C in one pass that finished within minutes, yielding agglomerated nanocrystalline TaC UHTC powders.