Efficient construction of double-shelled Ammonium perchlorate based energetic microunits with multiple performance via solvent evaporation method

Ammonium perchlorate (AP) is the most widely used oxidant in composite solid propellants (CSPs). The comprehensive performance of CSPs is closely related to the thermal properties, hygroscopicity, mechanical properties and sensitivity properties of AP. Nevertheless, there remain substantial difficulties in the preparation of AP with a variety of superior properties. The construction of core-shelled AP-based energetic microunits is considered to be an effective strategy to tackle this issue. In this study, AP@graphite@F2603 double-shelled energetic microunits were prepared by successively coating nano-graphite and F2603 on the surface of AP using a solvent evaporation method. The results demonstrated that both graphite and F2603 could be uniformly and tightly coated on the surface of AP. AP@1%graphite@0.6 %F2603 double-shelled energetic microunits exhibited an excellent 4-in-1 comprehensive performance in terms of thermal decomposition, hygroscopicity, mechanical properties, and sensitivity. AP@1%graphite@0.6 %F2603 shows a decrease in peak high temperature decomposition from 439.8 to 427.6 degrees C, the water contact angle (WCA) enhances from 0 to 75 degrees, the H50 values (impact sensitivity) increases from 23.7 to 42.6 cm, and the compressive strength improves from 79.05 to 86.56 MPa compared with raw AP. Additionally, the desensitization mechanism of the AP-based energetic microunits is also discussed. AP-HTPB propellant containing AP@1%graphite@0.6 %F2603 keeps good combustion state under atmospheric pressure with burning rate and sensitivity reduced by 8.3 % and 26.4 % than that containing AP, respectively. These very inspiring findings provide a straightforward yet effective technique for large-scale production and application of high-performance AP-based energetic microunits in tunable burning rate and low sensitivity AP-HTPB propellants.