Transition Metal Carbohydrazide Nitrates: Burn-rate Modifiers for Propellants

摘要

This paper discusses the synthesis and characterisation of cobalt (Co), nickel (Ni) and copper (Cu) carbohydrazide nitrates. In differential scanning calorimetry (DSC), the complexes exhibited exothermic decomposition indicating their energetic nature. The commencement of decomposition was observed at 220℃ for Ni complex, and at 160℃ for Co complex whereas that of Cu complex occurred at 75℃. In view of the better thermal stability, Ni and Co complexes were selected for further study. The activation energy of decomposition of Ni and Co complexes were found to be 47 kcal/mol and 60 kcal/mol respectively. Impact and friction sensitivity test results revealed relatively lower vulnerability of carbohydrazide cobalt nitrate. Its incorporation in an ammonium perchlorate (AP)-based composite propellant led to 9-19 per cent enhancement whereas that of carbohydrazide nickel nitrate resulted in 28-74 per cent enhancement in burning rates in the pressure range 1.9 MPa to 8.8 MPa. Exothermic decomposition of the coordination complexes on propellant surface and involvement of metal at molecular level formed on decomposition of the complexes in combustion environment of composite propellant may be attributed to the catalytic effect of this class of compounds on the lines of reported literature.