Study On Thermal Stability Of Mixtures Of Metal Hydride And Explosives

Adding metal hydrides which have a high calorific value (MgH2, Mg(BH4)2) to high explosive is expected to improve the detonation properties of explosives, but it also may change the explosives security and bring challenge for the safety of explosives use. In order to explore the thermal stability of different oxygen balance explosive (TNT, RDX, AN) with MgH2 and Mg(BH4)2, in this thesis the differential scanning calorimeter (DSC) and accelerating rate calorimetry (ARC) were used to test the mixtures of the above three explosives and metal hydride respectively. Calculation for the activation energy, pre-exponential factor and other kinetic parameters and discussion for changes in the mechanism of thermal decomposition of explosives have been carried out.The results show that MgH2 and Mg(BH4)2 decrease the initial decomposition temperature and the apparent activation energy of TNT, there are major changes in the DSC decomposition mechanism of TNT, the sharp exothermic peak is turned into a slow rising trend, this shows MgH2 and Mg(BH4)2 can reduce the reaction severity of TNT in reducing the reaction temperature. The effects of MgH2 and Mg(BH4)2 for RDX exothermic temperature are not obvious, however, changes in the activation energy of exothermic peak shapes may explain the occurrence of the change in RDX decomposition mechanism, so the danger cannot be ignored. The addition of MgH2 makes the thermal decomposition process of AN into two sections and advances the initial temperature of the first exothermic section greatly, which shows that MgH2 has a significant role in promoting the decomposition of AN, and then heat release decreased obviously at the same time, therefore, no matter from the thermal stability or from the blast energy point of view, it is not recommended to use AN mixed with MgH2. ARC test results show, Mg(BH4)2 significantly increase the decomposition rate of AN, so the danger should not be ignored as well. To make a long story short, MgH2 or Mg(BH4)2 has certain influence on the thermal stability of TNT, RDX, and AN. Therefore, before the metal hydrides are used as high-energy explosives additives, the thermal stability of metal hydride and explosive mixture must be improved to ensure the safe use of the process.