Introducing Tetrazole Salts as Energetic Ingredients for Rocket Propulsion

Two tetrazole salts, hydroxylammonium 2-dinitromethyl-5-nitrotetrazolate (HADNMNT) and dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (HATO), were synthesized and characterized. HADNMNT is a new compound, whose structure was determined by 15N NMR experimentally and GIAO calculation, the thermal decomposition temperature, the explosion probabilities of impact sensitivity, and friction sensitivity of which were tested to be 141.9 °C, 96 %, and 100 %, respectively. The detonation parameters of HADNMNT were predicted to be equal to those of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX). It was found theoretically that HADNMNT is a potential oxidizer for composite propellants to replace ammonium perchlorate (AP), 1,3,5-trinitro-1,3,5-triazinane (RDX), HMX, and 2,4,6,8,10,12-hexanitro-,2,4,6,8,10,12-hexazaisowurtzitane (CL-20). Safety tests for HATO were performed, and results showed that HATO exhibits excellent thermal stability (the decomposition temperature is 230.3 °C, and the volume of the released gas is 0.30 mL·g−1 at 100 °C for 48 h) and low mechanical sensitivities (the explosion probabilities of impact sensitivity and friction sensitivity are 16 % and 24 %, respectively). The compatibilities of HATO with hydroxyl-terminated polybutadiene (HTPB), AP, RDX, and aluminum powder (Al) were reexamined to be good, using the vacuum stability test. Results from comparative study of HATO and RDX as ingredient for composite propellant showed that the composite propellant composed HATO offer the advantages of high burning rate and low mechanical sensitivities.