Energy Release Characteristics of Impact-Initiated Energetic Materials
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0896-H03-08.1
Energy Release Characteristics of Impact-Initiated Energetic Materials
Richard G. Ames Naval Surface Warfare Center, Dahlgren Division ABSTRACT Impact-initiated energetic materials are a class of energetic materials that are formulated to release energy under highly dynamic loads. Under quasi-static or static loads, however, the materials are intended to be inert and carry a material classification of 4.1 flammable solid. In general, these materials are formed by introducing metal powders into a polymer binder but a number of binderless varieties exist (primarily pressed/sintered intermetallics and thermites). Most of the materials are sufficiently insensitive so as not to produce a self-sustaining reaction; as such, they require the mechanical work of a high-strain-rate plastic deformation process to provide the energy required to drive the reaction. Traditional initiation techniques such as exploding bridge wires or flame initiation are not sufficient to maintain a reaction in this class of materials. This paper presents a brief overview of the energy release characteristics of this class of materials, including a discussion of the material formulations, initiation phenomena, and a discussion of the manner in which the material properties affect the energy release characteristics. INTRODUCTION The Naval Surface Warfare Center, Dahlgren Division (NSWC-DD) has been investigating impact-initiated energetic materials for a variety of applications. These materials are different from traditional energetic materials (explosives and propellants, for example) in that they are also required to have significant mechanical strength. Furthermore, they are also required to be sufficiently insensitive so as to carry a classification of 4.1 flammable solid. The combined requirements of strength and reactivity have led to the creation of a number of novel materials and novel diagnostic techniques. Though the strength properties are easy to obtain, the energy release characteristics of this class of materials are difficult to measure. Because the reaction efficiencies are a strong function of the impact process, static analysis techniques such as bomb calorimetry are not sufficient. As such, a novel diagnostic technique has been developed and is able to measure the energy release provided by these materials during the impact process. This paper will present a description of the energy release testing technique, results for a family of representative material types, and comparison between the theoretical content and measured energy release as a function of binder strength, material density, and specimen mass. MATERIAL TYPES This overview paper provides data collected for four basic materials. All of these materials include a metal powder that is mixed into a fluoropolymer binder and consolidated via a press/sintering process. This formulation process produces materials with even distributions of the metal powder within the fluoropolymer binder at near theoretical maximum density
0896-H03-08.2
(TMD). Polytetrafluor
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