Particle Engineering Research Center

Obscurants

Engineered Particulates - Army Research Projects

P.I. K. W. Powers
PERC Team Members: K. W. Powers, A. Ranede, N. Stevens, S. Tedeschi, Y. Lee, Y. Rabinovich, H. El-Shall

Aluminum flakes used for obscurantContinuing from the successful completion of the Next Generation Obscurants for the US Army project, the Particle Engineering Research Center Army Obscurants Team is continuing its research direction in several new and exciting areas.

Many particles once dispersed in air have the tendency to be prone to explosive combustion. The conditions required for a dispersion of particles to deflagrate include fuel, air, ignition, dispersion and confinement. Typically of these 5 conditions, only the fuel (particles) can be modified or controlled to minimize explosive behavior. The Army Obscurants Team is addressing this issue for metallic obscurant particles by employing a variety of coatings that are engineered for the systems under investigation.

The performance of these obscurants is highly dependent on the physical properties of the particles not limited to, but including particle shape, size, electrical conductivity and so on. Recent findings at PERC have shown that the drying method has a prominent result on dispersability when forming an obscurant cloud. PERC researchers have developed several advanced drying methods including supercritical CO2 drying and sublimation CO2 drying. These methods produce dry, highly dispersible powders in a manner that is non-destructive to the particles original morphology. Research is continuing in this area to improve the speed of which the final product can be obtained as well as the quality (dryness).

The dispersability of particles is related to the degree of attraction or repulsion that two or more particles experience. Ideally, for optimum dispersion of particles, the attractive forces between particles needs to be kept to a minimum. Current research by PERC Obscurants Team is directed at controlling the interparticle forces by employing tailored coatings on the surfaces of the desired particle. Many coatings thus far have shown to add a two fold benefit by reducing attractive capillary forces as well as contributing to the overall passivation of a particle.

The PERC obscurants team was awarded funding to develop a new candidate for a visible wavelength obscurant. This new product will be build upon the foundation of knowledge developed during the Infrared Obscurants Program.