D. B. Lempert

Energetic capabilities of high-density composite solid propellants containing zirconium or its hydride

A comparative analysis of ballistic efficiency of various propellants containing Al, or Zr, or ZrH2 is performed. The analysis is carried out for compositions including various oxidizers and binders and, when applied to missiles, for different volume and mass characteristics. Replacement of aluminum with zirconium or its hydride is demonstrated to increase the missile velocity (or payload mass) almost for all compositions of composite solid propellants if the ratio of the propellant volume to the mass of the empty structure is smaller than approximately 1.0–1.4 liters/kg.

Novel trinitroethanol derivatives: high energetic 2-(2,2,2-trinitroethoxy)-1,3,5-triazines

The multicomponent reaction of 2,4,6-trichloro-1,3,5-triazine with potassium trinitromethane and trinitroethanol was exploited for the first synthesis of the hetaryl trinitroethyl ether, 2,4-bis(2,2,2-trinitroethoxy)-6-trinitrometyl-1,3,5-triazine 13. The use of compound 13 as a scaffold for the synthesis of substituted trinitroethoxytriazine by sequential nucleophilic substitution processes is described. A number of trinitroethoxytriazines bearing a range of functional groups, including 2,4,6-tris(2,2,2-trinitroethoxy)-1,3,5-triazine 16, have been prepared. There has been no previous incorporation of the trinitroethoxy moiety to a heteroaromatic ring. All trinitroethoxytriazines were fully characterized using IR and multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC), and, in some cases, 16, 20 and 21, with single crystal X-ray structuring. When compared to the aliphatic trinitroethoxy compounds, the trinitroethoxytriazines show better energetic performance as calculated. The impact sensitivities and ignition points of the novel oxygen and nitrogen-rich triazines were measured. The ability of the applied trinitroethoxytriazines in solid composite propellants as well as in gas generant compositions for airbag inflators was evaluated. The straightforward preparation of these ethers highlights them as valuable new environmentally friendly and high-performing nitrogen and oxygen-rich materials.

Comprehensive assessment of physicochemical properties of new energetic materials

The review presents original methodological approaches and summarizes the results of research into the assessment of relationships between the structure of energetic organic compounds and their main physicochemical properties. A large number of experimental values of these parameters were statistically analyzed, and a database of the properties of explosives and rocket propellant ingredients was created. Based on the analysis and integration of these data, approaches were developed to evaluate the fundamental properties of energetic compounds of different chemical classes, such as the enthalpy of formation, the molecular crystal density, and the sensitivity to mechanical impacts. The explosive and ballistic characteristics were calculated. The comprehensive assessment was made of the possible applications of new substances and those poorly characterized by experimental methods.

The energetic potential of azo- and azoxyfurazan nitro derivatives as components of composite rocket propellants

The energetic potential of solid composite rocket propellants on the basis of solid and liquid nitro derivatives of azo- and azoxyfurazans was studied by using thermochemical calculations. Quantitative relationships were established between the energetic parameters of propellants, the selected binder, and the properties of the studied component. It was shown that the studied solid nitrofurazans can serve as the foundation of metal-free compositions of solid composite rocket propellants, giving specific impulse over 263 s, while the use of liquid nitrofurazans as plasticizers of the binder can improve the ballistic effectiveness of rocket propellants containing aluminum hydride by 2–4 s.

Possibility of using gas-generating compositions for increasing the rocket propulsion efficiency

A possibility of ballistic efficiency of space rockets with main rocket propulsion engines by means of developing a system of gasification of unburned residues in propellant tanks with the use of gas-generating compositions with self-sustained combustion is considered. The criterion for choosing gas-generating compositions is the increment of the characteristic velocity of the rocket stage acquired due to combustion of gasified propellant residues. The results of the present study show that the proposed method of gasification of liquid propellant residues increases the energy characteristics of the rocket.

Combustion of zirconium-containing model compositions of solid propellant

The features of combustion of model compositions of a composite solid rocket propellant containing zirconium at a concentration of up to 40 wt % are investigated. Burning rates at pressures of from 20 to 80 atm and the parameters of the combustion law are measured. Comparison with combustion of similar aluminum-based compositions is carried out. Compositions with compound (zirconium along with aluminum in various proportions) metal fuels are investigated. The application of zirconium as a metal fuel is shown to substantially increase the burning rate in comparison with compositions based on aluminum.

Synthesis of methoxy-NNO-azoxyethene

The first representative of the alkoxy-NNO-azoxy olefin series, viz., methoxy-NNO-azoxyethene, was synthesized by the pyrolysis of 1,1-bis(methoxy-NNO-azoxy)ethane.

Pyrazolyltetrazoles—a High-Enthalpy Backbone for Designing High-Energy Compounds: An Experimental Study of the Enthalpy of Formation

The standard enthalpies of combustion and formation of isomeric nitropyrazolyltetrazoles have been measured by combustion calorimetry. Positional isomerism has been shown to have a significant effect on thermochemical characteristics. The contributions of some explosophore groups and moieties to the total heat content of the molecules have been determined. These contributions can be used to correctly calculate the enthalpy of formation of both known and hypothetical energy-intensive compounds.

Bipyrazole bearing ten nitro groups – a novel highly dense oxidizer for forward-looking rocket propulsions

Taking into account the manifold requirements for future rocket industry breakthroughs, the scientific community is currently focusing on the design of novel higher performance, high-tech and environmentally more acceptable materials compared with conventional propellant ingredients for liquid, solid, gelled, and hybrid propellant systems. Earlier, considerable efforts were made to find environmentally friendly chlorine free alternatives to ammonium perchlorate (AP) which is still the main oxidizer for solid propellants; however, success in this way is extremely rare. In this work, a novel oxygen-rich energetic material, 4,4′,5,5′-tetranitro-2,2′-bis(trinitromethyl)-2H,2′H-3,3′-bipyrazole (11), was obtained by N-alkylation of 4,4′,5,5′-tetranitro-2H,2′H-3,3′-bipyrazole (9) with bromoacetone and subsequent nitration. X-ray single-crystal diffraction confirmed its structure and revealed a unique high crystal density of 2.021 g cm−3 at room temperature, introducing it into the top three of the densest CHNO compounds known. This high density material has an attractive positive oxygen balance, acceptable sensitivity, and enthalpy of formation (on a unit of weight) similar to CL-20, with calculated specific and effective impulses exceeding those of AP and ADN, making it a competitive replacement for AP as a green energetic oxidizer for diverse propellants.

Energy potential of solid composite propellants based on 1,1-diamino-2,2-dinitroethylene

To obtain new formulations for solid composite propellants for creating composites with low sensitivity to mechanical stress and improved thermal stability, the energy potential of composites based on 1,1-diamino-2,2-dinitroethylene (FOX-7) and additionally containing a hydrocarbon or active binder, aluminum, and inorganic oxidant was studied. A formulation with 60% FOX-7 and 19 vol % active binder can be created which is characterized by a specific impulse Isp ~ 251 s, density ~1.91 g/cm3, and Tc below 3600 K. The composites containing FOX-7 have smaller specific impulse values than the same formulations with HMX: by 10 s at 60% FOX-7 and by 4 s at 30% HMX.