Combustion and thermal studies on Al/Ti/Ni/Zr composite modified double-base systems

Slurry-cast metallized ammonium perchlorate (AP)-composite modified double-base (CMDB) propellants incorporating Ni, Ti, and Zr were studied. Aluminized formulations were investigated as reference. Selected ballistic modifiers, namely, copper chromite (Cu-chromite)/ferric oxide (Fe2O3)/ferric acetyl acetonate (FeAA)/basic lead salicylate (BLS) + Cu2O + carbon black (C-black) combinations were also evaluated for their effectiveness. An acoustic emission technique was applied to determine the burning rates in the pressure range of 1-10.8 MPa, and thermal data were generated by applying differential thermal analysis, thermogravimetry, and differential scanning calorimetry techniques. The control formulation based on 30% AP dispersed in a 70% double base matrix, gave stable combustion in the entire pressure range studied. Inclusion of metals (2.5-17.5% at the expense of AP) resulted in a decrease in the burning rates with the increase in metal content. Ni-based formulations exhibited burning rates superior to aluminized formulations particularly with high metal content. The overall best burning-rate results were obtained with Zr, followed by Ti. Among ballistic modifiers, Cu-chromite was found to be the most effective, followed by the BLS + Cu2O + C-black combination. An interesting composition with super-burning-rate characteristics (10-60 mm/s in the 1-10.8 MPa pressure range) emerged during the research. Thermal studies show the heat sink effect of metals. However, Ni, Ti, and Zr appear to produce compensating heat feedback to a greater extent than Al. Cu-chromite appears to be highly effective in facilitating both condensed- and gas-phase combustion reactions.