Analyzing equilibrium kinetics of surface reactions in energetic materials
Abstract
The goal of this proposal is to develop the capability to analyze thermochemical kinetics from energetic material reactions. Students studying inorganic synthesis for advancing the science of metal fuel combustion rely on knowledge of equilibrium kinetics to inform material design strategies. Analyzing the heat flow and mass loss from an equilibrium reaction enables deconvolution of the complex steps that are masked under rapid heating rate and combustion conditions. Knowledge of thermochemistry under equilibrium enables identification of important processes that can be controlled when synthesizing a new formulation. For example, the measured apparent activation energy of a reaction describes its ignition sensitivity. Phase changes or pre-ignition reactions (PIR) introduce pathways for mechanisms that control the rate of energy release. Activation energy, phase changes, and the PIR are metrics that can be determined from measurements using thermal equilibrium instrumentation such as differential scanning calorimetry (DSC) and a thermal gravimetric analyzer (TGA). Our research is focused on synthesizing metal fuel particles with inorganic passivation shells. Acid-base precipitation reactions are one approach to altering the traditional alumina passivation shell on aluminum particles. Introducing hydration on the alumina shell enables new chemical synthesis strategies for transforming the shell chemistry. Thermochemical properties of the new shell chemistry influence the global reaction of the metal particles. Experimental plans include analysis of reaction kinetics of metal core- inorganic shell particles to inform synthesis of new solid fuels. The Jupiter 449 STA is a combined differential scanning calorimeter and thermal gravimetric analyzer (DSC-TGA) that provides measurements of heat flow and mass change associated with equilibrium kinetics (e.g., slow heating rate analysis, i.e., < 40 K/min). Students will design and perform experiments using the proposed simultaneous thermal analyzer (STA), NETZSCH STA 449 Jupiter and be trained on its safe use and operation. Knowledge gained from using the STA will translate to DOD laboratories because a DSC-TGA is a standard thermochemical diagnostic system in most materials laboratories. By using DSC-TGA and developing skill sets involving reaction kinetics and thermal analyses of reacting materials, students will more easily transition into DoD employment. By working on research projects directed towards national security applications, students will be more prepared for careers as engineers and scientists throughout the DOD enterprise.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2023
- Source ID
- W911NF2310318
Entities
People
- Michelle L. Pantoya
Organizations
- Army Contracting Command
- Texas Tech University
- United States Army