The Thermal Behaviors And Their Correlations By Adding Metal Hydride To Explosives

In order to explore the correlations between thermal behaviors,and the effect of metal hydride on energetic materials" thermal behavior and safety performance,three empirical methods and adiabatic detonation calorimeter were used to determine heat of detonation of desensitizing RDX,TNT and composite explosives containing Mg(BH4)2.Heats of combustion and decomposition were tested by bomb calorimeter and DSC.Mechanical sensitivity and thermal stability were also analyzed in this paper.The results show that Mg(BH4)2 can improve the energy of explosive significantly.With the increase of mass fraction of Mg(BH4)2,the combustion heat of composite explosives gradually increased and the combustion efficiency decreased.When the mass fraction was about 30%,the heat of detonation of desensitizing RDX and TNT reached the maximum.However,due to Mg(BH4)2 increased the thermal conductivity of the system,and the composite explosive was more negative oxygen,the heat of decomposition reduced.Compared the error between values of calculation and experiments,the minimum free energy method was more accurate to determine the explosion products.The addition of Mg(BH4)2 changed the reaction mechanism of explosives.When discussing the correlation between thermal behaviors of explosives,it should be divided into two cases.For compound explosives,there are three types of relationship between heats of combustion and detonation according to the oxygen balance.And there is a linear interdependence between heats of combustion and decomposition.In this paper,the calculation errors of seven common explosives are less than 10%.For composite explosives containing Mg(BH4)2,the relationship between heats of combustion and detonation is in accordance with the Boltzmann function,and there exists a quartic polynomial relationship between heats of combustion and decomposition.The results of mechanical sensitivity show Mg(BH4)2 reduced the characteristic height of drop hammer of desensitizing RDX to 18.14cm,and increased friction sensitivity from zero to 12%.Even TNT,which has low mechanical sensitivity itself,after addition of Mg(BH4)2,the friction sensitivity increased from 4%to 36%.But Mg(BH4)2 had no effect on thermal sensitivity.DSC data and kinetic parameters obtained by Ozawa method showed that the activation energy of desensitizing RDX didn’t change significantly,but Mg(BH4)2 had a tendency to accelerate its secondary decomposition.The activation energy of TNT/Mg(BH4)2 was higher than that of TNT,which was because the dehydrogenation of Mg(BH4)2 affect the dehydration process of TNT,thus inhibiting the decomposition reaction.