Burning rate modulation for composite propellants by interfacial control of Al@AP with precise catalysis of CuO

Burning rate modulation is a critical but challenging technology for solid propellants’ design. Great efforts have been made to synthesize and utilize catalysts to modify the pressure exponent (n), but poor catalytic efficiency and lower energy level of conventional catalysts limit their further applications. In this research, interfacial control of Al@AP together with precise catalysis of CuO is represented for the purpose of pressure exponent reduction and combustion performance improvement. The core-shell structured Al@AP and Al@AP/CuO composites were prepared and applied into HTPB/Al/AP composite propellants. These prepared propellants have the same formula but different micro-structures of ingredients, leading to varied combustion performance, in terms of the burning rates, combustion wave structures, flame spectra, agglomeration processes of Al particles and condensed combustion products. The investigation results show that by using interfacial control of Al@AP and precise catalysis of CuO, the n of involved propellants over 1–4 MPa can be greatly decreased from 0.42 to 0.21 and the agglomeration of Al could be effectively inhibited. In addition, propellants based on Al@AP and Al@AP/CuO interfacial controls of this research are summarized and compared together with those based on Al@RDX published recently, to present overall characteristics of interfacial control techniques, which could lead to the development of new smart controllable propellants.