Study On Thermal Decomposition And Mechanical Sensitivity Of Perovskite Energetic Materials

The perovskite energetic compounds were prepared by the assembly of high energy oxidants?NaClO₄,KClO₄?and triethylenediamine?DABCO?using perchlorate as bridging ligand.They have the advantages of excellent theoretical detonation performance,good thermal stability,simple synthesis and low production cost,the perovskite structure itself has the functions of controllable and replaceable components,which makes it have certain advantages in the future application of energetic materials.However,there is no research report on the thermal and safety properties of this kind of energetic materials.In order to promote the early application of this kind of energetic materials in military and engineering fields,two kinds of perovskite energetic materials?H₂dabco?[Na?ClO₄?₃]??H₂dabco?[K?ClO₄?₃]?DAP-1?DAP-2?as the research objects in this paper,and the specific contents are as follows:?1?The perovskite energetic materials DAP-1 and DAP-2 were prepared by the one-pot method,and their structural composition was characterized by XRD and FT-IR.The results showed that the diffraction peak position of the prepared sample coincides with the peak position of the spectrum in the standard card?CCDC:1528107,1528106?,indicating the successful synthesis of the perovskite energetic materials DAP-1 and DAP-2;SEM-EDS combination test on the sample morphology and surface elements shows that DAP-1 is a polygonal block structure with sharp edges and corners,and the size range of 400?600?m,and DAP-2 is a cube with equal length and edge,and the size range 60?200?m,C,N,O,Cl,M?Na⁺,K⁺?elements were detected on the surface of both compounds.?2?The thermal decomposition properties of the perovskite energetic materials DAP-1and DAP-2 were studied by TG-DSC.The results show that the extrapolation starting point temperature of the exothermic peaks of DAP-1 and DAP-2 is T₀>330?,combined with the TG curve,it can be found that there there is no obvious weight loss step before the exothermic decomposition peaks appear in DAP-1 and DAP-2,which indicates that the perovskite framework structure composed of Na⁺,K⁺and ClO₄^-anion has good thermal stability.During the exothermic process,a large amount of heat is released,and the unit exothermic amounts are 3000 J·g^-1 and 2815 J·g^-1.The reason for the difference of heat release between DAP-1 and DAP-2 is that the formation enthalpy of NaCl and KCl is different,and the radius of Na⁺ion is smaller,which makes the structural tension of anion framework in DAP-1 stronger than that in DAP-2.The heat difference in the exothermic process shows that the heat release during the DAPs exothermic process is not only determined by the energy released by the covalent bond break,but also related to the structural tension in the perovskite structure.?3?The thermal decomposition test was carried out by high pressure differential scanning calorimeter?PDSC?under two static high pressure conditions.The results showed that there was no significant difference in the extrapolation starting temperature of the exothermic curve under the pressure conditions of 6 MPa and 8 MPa,and DAP-1 and DAP-2 still have good thermal stability under two high pressure conditions?T₀>340??,but the exothermic curve at 8 MPa is sharper than that at 6 MPa,and the unit exothermic energy(5512 J·g^-1,4502 J·g^-1)is significantly higher than 4588 J·g^-1,2877 J·g^-1 at 6 MPa.The apparent activation energy of DAP-1 and DAP-2 at 8 MPa is slightly lower than that at6 MPa,indicating that the increase of pressure makes DAP-1 and DAP-2 easier to be heated to the activation state and has a more intense exothermic process.?4?The mechanical ball milling method was used to refine DAP-1 and DAP-2,and the morphology and thermal decomposition performance were characterized.The results showed that after ball milling,the sample particle size became significantly smaller and the size distribution range was 0.1?2?m,which is quasi-spherical or ellipsoid.Thermal decomposition results show that the exothermic peaks of DAP-1 and DAP-2 after ball milling have moved forward in different degrees compared with the raw materials.The apparent activation energy values of 160.933 kJ·mol^-1 and 163.045 kJ·mol^-1 are lower than the raw material of 168.599 kJ·mol^-1,173.346 kJ·mol^-1?Kissinger method?.After ball milling,the characteristic drop heights of DAP-1 and DAP-2 were 63.86 cm and 60.63 cm,which reduced the impact sensitivity compared with the raw materials?51.07 cm and 36.79 cm?,but the friction sensitivity between the raw material and the refined sample were both 100%,and there was no change.