Effects of Nano-sized Energetic Ingredients in High Performance Solid Gun Propellants

Unique propellant configurations, such as fast-core designs, require a layered propellant with tailored burn rate. The use of these layered propellants is expected to improve the energy management during the ballistic cycle and hence increase the muzzle velocity. These new propellants under development have different thermochemistry from that of traditional nitrocellulose-based propellants. The layered propellant is typically stacked as laminated disks in the cartridge chamber. Layered propellants (also called fast-core propellants) consist of an inner layer of fast burning high-impetus propellant imbedded in two layers of slower burning low-impetus propellant. Propellant geometries are tightly controlled such that the fast burning inner-core layer does not start burning until the volume available has slightly increased due to the projectile motion. This allows the pressure to be maintained at a high level for a relatively long duration. Advances in energetic materials have been made in all types of composite propellant ingredients, including binders, oxidizers, and metal additives. Special processing techniques of functionally graded energetic materials have also been developed in recent years. The goal of this study is to develop a pair of layered propellants through a "materials-by-design" approach for use in a fast-core gun propulsion application. A pair of baseline propellants was initially developed and named as ME (moderate energy) propellant with a relatively slow burning rate and HE (high-energy) propellant with a fast burning rate. Modifications of these propellants with different ingredients have been made such that the burning rate ratio between fast and slow burning propellants is suitable for use in applications requiring layered propellants (~ 3:1).
Prepared in collaboration with the Pennsylvania State University, University Park, PA and the University of Maryland, College Park, MD. Presented at the Army Science Conference (25th), "Transformational Army Science and Technology - Charting the future of S&T for the Soldier," held in Orlando, Florida on 27-30 Nov 2006. Published in proceedings of the same. See also ADM002075.