Shock tube ignition studies of a mixed powder of DAP-4 and nanometric boron
摘要
Boron (B) is considered as a high-energy additive for solid propellants owing to its high mass and volumetric calorific values. DAP-4, a novel solid energetic material, exhibits excellent detonation performance and strong oxidizing properties, making it a promising high-energy oxidizer for solid propellants. To explore the ignition and combustion characteristics of DAP-4-based boron-containing high-energy materials, mixed powders of DAP-4 and nanometric boron (nano-B) materials with varying mass ratios were prepared through mechanical blending. X-ray diffraction (XRD) analysis confirmed the crystalline structure of the DAP-4/nano-B mixed powder and the absence of additional compounds or phases. Scanning electron microscope (SEM) observations revealed that nano-B particles effectively adhered to the surface of the DAP-4 particles, with the density of attached nanometric boron increasing as its content in the samples increased. Elemental mapping and Energy Dispersive X-ray Spectroscopy (EDS) further validated this surface modification. TG-Differential Scanning Calorimetry (DSC) analysis indicated good compatibility between DAP-4 and nano-B, with minimal mutual influence during thermal decomposition under heating. The ignition and combustion characteristics of the DAP-4/nano-B mixed powders were investigated using a shock tube at temperatures of 2200–3100 K and pressures of 0.1 MPa and 0.5 MPa. Results showed that both ignition delay time and burn time decreased with increasing temperature, whereas pressure had a negligible effect. As the boron content increased from 0 to 30%, the ignition delay time decreased, while the burn time initially decreased and then increased. Overall, the addition of nano-B effectively enhanced the combustion of DAP-4/nano-B mixed powders. In practice applications, the ignition and combustion performance of DAP-4 can be tailored by adjusting the mass fraction of boron powder.