New Jersey Institute of Technology Digital Commons @ NJIT Dissertations Electronic Theses and Dissertations Summer 8-31-2019 Improving boron for combustion applications Kerri-lee Annique Chintersingh New Jersey Institute of Technology Follow this and additional works at: https://digitalcommons.njit.edu/dissertations Part of the Aerospace Engineering Commons, Chemical Engineering Commons, and the Materials Science and Engineering Commons Recommended Citation Chintersingh, Kerri-lee Annique, "Improving boron for combustion applications" (2019). Dissertations. 1420. https://digitalcommons.njit.edu/dissertations/1420 This Dissertation is brought to you for free and open access by the Electronic Theses and Dissertations at Digital Commons @ NJIT. It has been accepted for inclusion in Dissertations by an authorized administrator of Digital Commons @ NJIT. For more information, please contact [email protected]. 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Please Note: The author retains the copyright while the New Jersey Institute of Technology reserves the right to distribute this thesis or dissertation Printing note: If you do not wish to print this page, then select “Pages from: first page # to: last page #” on the print dialog screen The Van Houten library has removed some of the personal information and all signatures from the approval page and biographical sketches of theses and dissertations in order to protect the identity of NJIT graduates and faculty. ABSTRACT IMPROVING BORON FOR COMBUSTION APPLICATIONS by Kerri-lee Annique Chintersingh Boron has received much attention as a potential additive to explosives and propellants due to its high theoretical gravimetric and volumetric heating values. The challenge, however, is that boron particles tend to agglomerate, have lengthy ignition delays and very low combustion rates. Prior research indicates that boron’s long ignition delays are due to its inhibiting naturally occurring oxide layer, impeding the diffusion of reactants for oxidation. For combustion, current studies report that boron particles have two consecutive stages, but the actual reaction mechanism is poorly understood. Despite many years of relevant research, quantitative combustion data on micron-sized boron particles are limited and most of the proposed modifications of boron powder for its improved ignition and combustion substantially diminish the energy density of the produced composites. Such modifications affect low-temperature oxidation kinetics, and thus, aim to reduce the ignition delay rather than accelerate high-temperature reactions affecting combustion rates and efficiencies. The objectives of this research are to achieve higher burn rates for boron powders without jeopardizing their thermochemical performance, safety and stability, and to develop an experimentally validated model adequately describing boron oxidation kinetics that can be used in practical simulations for a broad range of temperatures. The study is also aimed to close the gap in data for combustion of fine boron particles in varying oxidizing environments. In this work, burn times as a function of particle size, ignition delays and temperatures of commercial and modified boron powders are collected from optical emissions and images of single particles burning in air, steam, and gases formed by combusting hydrocarbons. In each case, the oxidizing gas environment is described accounting for thermodynamic equilibrium and using computational fluid dynamics. Unlike previous work, the complex morphology of boron aggregates is explicitly accounted for by correcting for their fractal dimension. The fractal dimension is determined by scanning electron microscopy (SEM) image analysis by box counting and diffusion limiting cluster morphology theories. Strategies to modify boron’s heterogeneous reactions by functionalizing its surface by organic solvents and using transition metals as “shuttle catalysts” are explored. It is found that washing boron with acetonitrile removes hydrated surface oxide and reduces ignition delays while preventing rapid aging and re-oxidation at ambient conditions. Doping boron with less than 5wt% transition metals (Fe or Hf) by high energy ball milling or wet synthesis, accelerates surface reaction rates leading to shorter particle burn times compared to the starting commercial powder. A kinetic model is derived from low-temperature thermo-analytical measurements to describe the oxidation of complex aggregated boron particles accounting for their surface morphology. Comparison with particle combustion experiments shows that the same model can describe reactions at high temperatures typical of the full-fledged boron combustion, suggesting that the same heterogeneous reactions govern both ignition and combustion of boron. It is found that the morphology of as received boron powders comprising micron-sized agglomerates of finer primary particles does not always change to spherical droplets even at temperatures exceeding the boron melting point. This leads to variation in burn rates and temperatures for various particles. IMPROVING BORON FOR COMBUSTION APPLICATIONS by Kerri-lee Annique Chintersingh A Dissertation Submitted to the Faculty of New Jersey Institute of Technology in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering Otto H. York Department of Chemical and Materials Engineering August 2019 Copyright © 2019 by Kerri-lee Annique Chintersingh ALL RIGHTS RESERVED APPROVAL PAGE IMPROVING BORON FOR COMBUSTION APPLICATIONS Kerri-lee Annique Chintersingh Dr. Edward L. Dreizin, Dissertation Advisor Date Distinguished Professor of Chemical and Materials Engineering, NJIT Dr. Robert B. Barat, Committee Member Date Professor of Chemical and Materials Engineering, NJIT Dr. Mirko Schoenitz, Committee Member Date Associate Professor of Chemical and Materials Engineering, NJIT Dr. Alexei Khalizov, Committee Member Date Associate Professor of Chemistry and Environmental Science, NJIT Dr. Suhithi Peiris, Committee Member Date Senior Scientist, Munitions Directorate, United States Air Force Research Laboratory BIOGRAPHICAL SKETCH Author: Kerri-lee Annique Chintersingh Degree: Doctor of Philosophy Date: August 2019 Undergraduate and Graduate Education: • Doctor of Philosophy in Chemical Engineering, New Jersey Institute of Technology, Newark, NJ, 2019 • Bachelor of Engineering in Chemical Engineering, University of Technology, Jamaica, Kingston, Jamaica, 2013 Major: Chemical Engineering Presentations and Publications: Publications: Y. Sun, K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Reactive Shell Model for Boron Oxidation, Journal of Physical Chemistry 123, p.11807-11813 (2019). K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Doped Boron with Iron: Preparation and Combustion in Air, Combustion and Flame 200, p. 286-295 (2019). K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Combustion of Boron and Boron-iron Composite Particles in Different Oxidizers, Combustion and Flame 192, p. 44-58 (2018). X. Liu, K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Reactive Composite B-Mg Powders Prepared by Mechanical Milling, Journal of Propulsion and Power 34, p. 787-794 (2017). K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Oxidation Kinetics and Combustion of Boron Particles with Modified Surfaces, Combustion and Flame 173, p. 288-295 (2016). iv K.-L. Chintersingh, Q. Nguyen, M. Schoenitz, E.L. Dreizin, Combustion of Boron Particles in Products of an Air-acetylene Flame, Combustion and Flame 172, p. 194-205 (2016). K.-L. Chintersingh, Q. Nguyen, M. Schoenitz, E.L. Dreizin, Combustion of Boron Particles in Products of an Air-Acetylene Flame. 2016 Spring Technical Meeting, Eastern States Section of the Combustion Institute (ESSCI), Princeton University, New Jersey. Liu, X., Chintersingh, K.-L., Schoenitz, M., Dreizin, E.L. Composite B·Mg Powders Prepared by Mechanical Milling. 2016 Spring Technical Meeting, ESSCI, Princeton University, New Jersey. Presentations: K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Transition Metal Catalysts for Boron Combustion. Presented at the American Institute of Chemical Engineers (AIChE) Annual Meeting, Pittsburgh, PA, November 2018 K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Doping Boron for Improved Ignition and Combustion. Presented at the Gordon Research Conference (GRC) on Energetic Materials, Newry, ME, June 2018. K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Doping Boron for Improved Ignition and Combustion. Presented at the Gordon Research Seminar (GRS) on Energetic Materials, Newry, ME, June 2018. K.-L. Chintersingh, M. Schoenitz, E.L. Dreizin, Doping Boron with Iron for Better Combustion. Presented at the Materials Research Symposium (MRS) Fall Meeting & Exhibit, Boston, MA, November