Hybrid Aluminum and Porous Si as High Performance Energetic Materials
Abstract
Abstract: Hybrid Aluminum and Porous Si as High Performance Energetic Materials Overview and Future Naval Relevance Aluminum (Al), due to its high volumetric energy density, is an important fuel component of propellants used for naval weapon systems, and methods to increase the speed and efficiency of its combustion process are a critical military need. Previous research has addressed this need by reducing Al particle size to nanoscale for a faster transport process. While nanosized Al particles show higher energy release rates and combustion efficiency, high manufacturing costs and high dead mass render that approach not suited to practical application. Our research goal is to increase the energy release rate and combustion efficiency of Al particles by hybridizing micron-sized Al particles with porous Si (p-Si) particles. We hypothesize that adding p-Si particles to Al particles will significantly increase the energy release rates and combustion efficiencies of Al particles. Our justification is based on four scientific facts. First, p-Si can readily be ignited and has an extremely high energy release rate, with a reported burning rate up to 3050 m/s. Second, the rapid combustion of p-Si releases huge amounts of heat and gas (50% more gas than black powder) that can potentially melt Al and/or blast Al particles into smaller pieces, significantly accelerating the combustion process of Al particles. Third, p-Si has volumetric energy density comparable to Al so that the overall volumetric energy density remains high, enhancing delivered energy in compact volumes. Finally, p-Si can be conveniently coated with different materials to reduce the environmental sensitivity of the overall hybrid fuel, improving resistant to catastrophic failure in extremely stressful environments. The proposed hybrid Al/p-Si fuel directly addresses the ONR’s need to provide improved performance with acceptable insensitivity characteristics for explosives, propellants and reactive materials, supports weapon systems technology and will provide long-range maritime dominance. Statement of Work To test our hypothesis, we will synthesize various hybrid Al/p-Si fuels and characterize the effects of key properties of p-Si (e.g., mass percentage, size, porosity and surface functionalization) on the ignition, heat release and combustion efficiency of such hybrid fuels. Our research objectives are to: 1) synthesize and prepare a range of well-defined hybrid Al/p-Si particle composites as samples for combustion studies, 2) measure the reaction onset temperature and heat release characteristics of the hybrid fuel and study their dependence on the properties of p-Si using simultaneous TGA/DSC, 3) measure the heat release rate of the hybrid fuel and study its dependence on the properties of p-Si using a constant volume vessel, and 4) measure the burning rate of the hybrid fuel and study its dependence on the properties of p-Si using a microchannel coupled with high speed imaging. Expected Outcome At project’s end, we will be able to quantify the effect of adding p-Si on the combustion performance of Al micron particles. In addition, we will develop new synthesis routes for the scalable production of energetic fuels and new characterization tools for testing small quantities of energetic fuels. Potentially, we will obtain scaling relations between the ignition temperature, heat release rate, burning rate of the proposed hybrid Al/p-Si fuel and the various properties of p- Si, including mass percentage, size, porosity and surface passivation. The obtained fundamental knowledge will guide the design of next-generation propellant fuels having enhanced combustion performance and acceptable insensitivity. The proposed research leverages the PI’s background in synthesis and in the characterization of Al and p-Si based energetic materials.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512028
Entities
People
- Xiaolin Zheng
Organizations
- Office of Naval Research
- Stanford University
- United States Navy