Durgesh Kumar Pandey

Hexammine metal perchlorates as energetic burning rate modifiers

Abstract Four transition metal hexammine perchlorates namely, [Cu(NH3)6](ClO4)2, [Co(NH3)6](ClO4)2, [Ni(NH3)6](ClO4)2 and [Zn(NH3)6](ClO4)2 have been prepared, characterized and used as ballistic modifiers in the combustion of hydroxy terminated polybutadiene (HTPB)-Ammonium perchlorate (AP) composite solid propellants. Burning rate was considerably enhanced with [Co(NH3)6](ClO4)2 and [Cu(NH3)6](ClO4)2 whereas moderately with [Ni(NH3)6](ClO4)2 and [Zn(NH3)6](ClO4)2 at low concentration (2% by wt). [Co(NH3)6](ClO4)2 was found to accelerate the burning rate by three fold at two percent concentration and it can be exploited as potential energetic burning rate modifier for HTPB-AP propellants. Further, ignition delay studies showed that the deflagration of propellants and AP was accelerated by these additives.

Thermal Studies on Energetic Compounds

The nitrate complexes of copper, nickel and zinc with diethylenetriamine (dien) i.e. [Cu(dien)2](NO3)2, [Ni(dien)2](NO3)2·2H2O and [Zn(dien)2](NO3)2 have been prepared and characterised. Thermal studies were undertaken using TG-DTG, DSC, ignition delay (tid) and ignition temperature (IT) measurements. Impact sensitivity was measured using drop mass technique. The kinetic parameters for both non-isothermal and isothermal decomposition of the complexes were evaluated by employing Coats-Redfern (C-R) method and Avrami-Erofeev (A-E) equations (n=2 and 3), respectively. The kinetic analysis, using isothermal TG data, was also made on the basis of model free isoconversional method and plausible mechanistic pathways for their decomposition are proposed. Rapid process was assessed by ignition delay measurements. All these complexes were found to be insensitive towards impact of 2 kg mass hammer up to the height limit (110 cm) of the instrument used. The heat of reaction (?H) for each stage of decomposition was determined using DSC.

Studies on energetic compounds: Part 35: kinetics of thermal decomposition of nitrate complexes of some transition metals with propylenediamine

Abstract Five bis(propylenediamine)metal nitrate (BPMN) complexes such as [M(pn) 2 ](NO 3 ) 2 (where M = Cr, Mn, Ni, Cu, Zn, and pn = propylenediamine) have been prepared and characterized by gravimetric methods, infrared and elemental analysis. Their thermal decomposition has been studied using simultaneous thermogravimetry -differential thermal analysis in atmospheres of nitrogen and air to examine the effect of the atmosphere on the thermolysis of these complexes. Several measurable changes were recorded in the mode of decomposition of all these complexes when the atmosphere was changed from nitrogen (inert) to air (reactive). However, as indicated by thermoanalytical techniques, the thermal stability of these complexes decreases in the order: Cr > Mn > Zn > Ni > Cu. Isothermal thermogravimetry, over the temperature range of deamination (ie, the loss of an amine ligand) has been performed for all the complexes. An analysis of the kinetics of deamination of these complexes was made using a model fitting procedure, as well as an isoconversional method independent of any model. The merits and demerits of both kinetic approaches have been discussed. The ignition delay (t id ) was measured to investigate the trends of rapid thermolysis. All these complexes were found to be insensitive to an impact test in which a hammer (2 kg weight) was used.

Kinetics and mechanism of thermolysis of hexammine metal perchlorates

Abstract The thermal decomposition studies on four transition metal hexammine perchlorates, viz. [Cu(NH3)6](CIO4)2, [Co(NH3)6](CIO4)2, [Ni(NH3)6](CIO4)2 and [Zn(NH3)6](CIO4)2. have been carried out using Thermogravimetry (TG), derivative thermogravimetry (DTG) and explosion delay (DE) measurements. Although, the kinetics of thermolysis of these complexes were evaluated by fitting isothermal TG data in nine mechanism-based kinetic models but the contracting area (n=2) and contracting cube (n=3) give the best fits. It has been observed that deammination takes place at lower temperatures and ammine metal perchlorates and/or metal perchlorates are formed as intermediates which decompose to metal oxides at higher temperatures. The decomposition pathways for hexammine metal perchlorates have also been suggested.