Effect of mechanical activation of high specific surface area aluminium with PTFE on composite solid propellant

This study deals with the mechanical activation of pyral with PTFE. Pyral is a flake-like aluminium particle with a large specific surface area (∼22.5 m2/g). This paper, through a variety of tests like the TGA, DSC, particle size analysis, SEM analysis and other tests tries to establish that this mechanically activated aluminium is a good replacement for conventional aluminium used in a solid propellant. Burn rates were also measured at pressures ranging from 10 to 70 bar using a modified Crawford bomb. The burn rates of solid propellants prepared with this mechanically activated pyral powder were found to be higher than that of non-activated pyral powder and much higher than that of those reported in literature with similar mechanically activated aluminium. This has been explained to be due the large specific surface area of aluminium used in these experiments which undergo exothermic fluorination reactions with PTFE. Two phase losses and slag accumulation are the two problems encountered when aluminium is used in composite solid propellants. Slag accumulation has shown a significant reduction with the use of this activated powder over non-activated pyral.