Effects of carbon dots and their composites on the burning performance of HMX-CMDB propellant

Designing efficient, stable dual-functional combustion catalysts remains a key challenge in developing next-generation solid propellants, particularly in achieving wide pressure plateau combustion. Herein, we synthesize a series of carbon dot-based catalysts (CDs-1, CDs-2, CDs/Cu) via oxidative etching and hydrothermal methods, and employ them to replace conventional carbon black (CB) at 0.65 wt% loading in the preparation of HMX-CMDB propellants. Systematic evaluation through combined thermochemical analysis (50–350 °C), laser ignition diagnostics (50–350 W/cm 2 ), and combustion chamber testing (4–18 MPa) reveals remarkable catalytic enhancements. The optimized CDs/Cu catalyst demonstrates multifunctional superiority: (1) 7.4 °C reduction in HMX-CMDB decomposition temperature at 10 °C/min (from 205.2 °C to 196.0 °C); (2) 66.7% decrease in laser ignition delay (from 45 ms to 15 ms); (3) 190.9% burning rate increase at 4 MPa (from 4.61 mm/s to 13.41 mm/s); (4) lower pressure exponent of 0.02 within 4–18 MPa range. Notably, CDs-1 induces stable “Plateau” combustion (4–14 MPa), while CDs/Cu achieves “Mesa” effects (8–12 MPa) via synergistic thermal feedback mechanisms-both phenomena ensure stable operation of the engine. Mechanistic studies integrate thermochemical kinetics, ignition combustion process, combustion flame structure and combustion wave temperature distribution trends, which establish a new paradigm for the study of high efficiency combustion catalysts for solid propellants. Three kinds of novel carbon dots-based nanomaterials(CDs-1, CDs-2 and CDs/Cu)were prepared and characterized, and their application in HMX-CMDB propellant after replacing carbon black was studied and discussed. • Three new combustion catalysts (CDs-1, CDs-2 and CDs/Cu) were obtained and applied in HMX-CMDB propellants. • Compared with traditional carbon black, the effects of three catalysts on the thermal decomposition, laser ignition and burning rate of HMX-CMDB propellant were studied. • The thermal synergy mechanism of CDs/Cu can effectively increase the burning rate and reduce the pressure exponent. • The catalytic mechanisms of CDs and CDs/Cu were analyzed.