Propellant grade ultrafine aluminum powder by RF induction plasma

Abstract A continuous process of synthesizing ultrafine aluminum powder (UFAP) having high yield rate using RF induction plasma is reported in the current work. The processing parameters (powder injection probe position; powder feed rate; flow rates of gases for plasma forming, quenching and passivation) were varied systematically to evaluate their influence on the size and distribution, and metallic Al content of the synthesized powder. The UFAP was characterized using X–ray diffraction and, scanning and transmission electron microscopes. The metallic aluminum content of UFAP was evaluated using hydrogen gas evolution technique and its thermal behavior was studied using simultaneous thermo–gravimetric and differential scanning calorimetry under static air. UFAP with an average particle size varying between 220 and 400 nm was obtained under different processing conditions and a maximum metallic Al content of 89.2% was obtained at a high powder feed rate. Among the parameters studied, increased powder feed rate, plasma forming gas flow rate and the position of the powder injection probe had a significant effect on the particle size, distribution and the metallic Al content of the synthesized UFAP.