Preparation of Energetic Composites Materials via Sol-Gel

In this research, nitrocellulose / magnesium borohydride nanomaterials (NC / Mg(BHx)y) nanoenergetic composite materials are synthesized through sol-gel method and the freeze-drying technology. Among them, nitrocellulose (NC) is used as a gel matrix to load Mg(BHx)y particles. Scanning electron microscopy (SEM) results show that Mg(BHx)y is embedded and uniformly dispersed in the NC matrix. The particle size of the high-energy composite material is about 2 μm. The results of FT-IR showed that the hydrogen storage alloy was successfully loaded around the NC without destroying the cellulose structure. The composite material decomposition reaction (Temperature-Time) curve is obtained through the adiabatic accelerated calorimeter (ES-ARC) test.

Fabrication of Energetic Composites with 91% Solid Content by 3D Direct Writing

Direct writing is a rapidly developing manufacturing technology that is convenient, adaptable and automated. It has been used in energetic composites to manufacture complex structures, improve product safety, and reduce waste. This work is aimed at probing the formability properties and combustion performances of aluminum/ammonium perchlorate with a high solid content for direct writing fabrication. Four kinds of samples with different solid content were successfully printed by adjusting printing parameters and inks formulas with excellent rheological behavior and combustion properties. A high solid content of 91% was manufactured and facile processed into complex structures. Micromorphology, rheology, density, burning rate, heat of combustion and combustion performance were evaluated to characterized four kinds of samples. As the solid content increases, the density, burning rate and heat of combustion are greatly enhanced. Based on 3D direct writing technology, complex energetic 3D structures with 91% solid content are shaped easier and more flexibly than in traditional manufacturing process, which provides a novel way for the manufacture of complicated structures of energetic components.

Computational Investigation of Crack-Induced Hot-Spot Generation in Energetic Composites

The sensitivity of polymer-bonded explosives (PBXs) can be tuned through adjusting binder material and its volume fraction, crystal composition and morphology. To obtain a better understanding of the correlation between grain-level failure and hot-spot generation in this kind of energetic composites as they undergo mechanical and thermal processes subsequent to impact, a recently developed interfacial cohesive zone model (ICZM) was used to study the dynamic response of polymer-bonded explosives. The ICZM can capture the contributions of deformation and fracture of the binder phase as well as interfacial debonding and subsequent friction on hot-spot generation. In this study, a two-dimensional (2D) finite element (FE) computational model of energetic composite was developed. The proposed computational model has been applied to simulate hot-spot generation in polymer-bonded explosives with different grain volume fraction under dynamic loading. Our simulation showed that the increase of binder phase material volume fraction will decrease the local heat generation, resulting in a lower temperature in the specimen.