Research Highlights

Project Highlights 

Our studies of energetic material combustion continue with great success owing largely to creative and resourceful graduate students that persevere with passion. Our groundbreaking research is based on new directions for improving fuel particle combustion: (1) one focus is on using surface chemistry from the alumina shell passivating an aluminum (Al) particle to increase energy release rates (Army Research Office ARO); and, (2) the other focus alters the stress state within the core-shell Al particle towards greater reactivity (Office of Naval Research ONR). We have also expanded our projects to (3) characterize biocidal formulations for the destruction of chemical warfare agents (Defense Threat Reduction Agency DTRA); (4) characterize penetration and impact events of structural reactive materials (Air Force Research Lab, AFRL); (5) develop advanced combustion characterization diagnostics (DOE, DoD, Industry); and, (6) develop technology to print materials with functionally tailored density gradients(Army Research Lab, ARL).

1. Exothermic Surface Reactions: Catalysis to Promote Reactivity

The Holy Grail for metal particle combustion is to harness the enormous chemical potential energy stored within metal fuel particles at time scales relevant to a detonation event. Diffusion controlled reactivity limits Al energy release potential but with the advent of nanotechnology and development of nanoparticles, time scales for diffusion-controlled kinetics could approach detonation. In the 15 years we've been studying nanoparticle combustion, we have learned nanoparticles cannot achieve reactivity at detonation time scale by themselves. But, we have transformed the inert alumina passivation shell surrounding the Al core into a highly oxidizer rich salt, called aluminum iodate hexahydrate (AIH)through surface chemistry. The AIH coated Al particles are stable under ambient conditions and improve the detonation velocity of TNT by 30 %! Exploiting surface chemistry to harness energy release at faster time scales and
promote greater power is a goal of this project. ARO

2. Optimizing Reactivity by Pre-Stressing

Annealing and quenching Al particles affects the mechanical properties at the core-shell interface and influences reactivity. We determined annealing conditions to optimize stress-state but learned that quenching rate more strongly influences interface core-shell properties that also affect reactivity. Specifically, quenching at rates on the order of 1000 K/min delaminates the core from the shell. Delamination promotes reactivity especially under impact loading conditions. ONR

3. Defeating Chemical Warfare Agents

Our group was founded on characterizing the reactivity of energetic composites. This project is at the core of our mission. We partnered with Indian Head Naval Surface Warfare Center, D. Carl Brothers, who is a synthetic chemist and creating new iodine
polymer binders. These materials have great potential to neutralize biological threats, particularly anthrax. We are characterizing these materials for combustion performance and have patented the formulations. This project is poised to make an impact on the next generation of energetic materials! DTRA

4. Impact and Penetration at High Velocities

Ballistics is a natural extension for reactive material characterization, especially materials designed for structural applications. We are studying the fragmentation and combustion of new formulations designed for improved reactivity upon high velocity
impact and penetration. Our propellant gun launches projectiles at up to 1500 m/s and diagnostics help us resolve ignition, fragmentation, and overall reactivity. AFRL

5. Additive Manufacturing 

We extended our work on films to address the next generation need in processing energetic materials. Our goal is to develop a printer that can print multiple materials with a tailored density gradient. This project includes both hardware and software development. ARL

6. Temperature

Temperature is a fundamental combustion property that is difficult to quantify in high energy reactions and over fast durations. We are advancing our capabilities of measuring
temperature by developing two new diagnostics: (1) a 4-channel pyrometer, and (2) software that will enable our high speed cameras to capture thermal distributions. Our goal is to measure temperatures that resolve ignition events as low as 600K and flames in excess of 3000 K. DOD