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Full-Text Articles in Engineering
Feedstock Powders For Reactive Structural Materials, Daniel Hastings
Feedstock Powders For Reactive Structural Materials, Daniel Hastings
Dissertations
Metals as fuels have higher energy density per unit mass or volume compared to any hydrocarbon. At the same time, metals are common structural materials. Exploring metals as reactive structural materials may combine their high energy density with attractive mechanical properties. Preparing such materials, however, is challenging. Requirements that need to be met for applications include density, strength, and stability enabling the component to sustain the structure during its desired operation; added requirements are the amount and rate of the energy release upon impact or shock. Powder technology and additive manufacturing are approaches considered for design of reactive structural materials. …
Improving Boron For Combustion Applications, Kerri-Lee Annique Chintersingh
Improving Boron For Combustion Applications, Kerri-Lee Annique Chintersingh
Dissertations
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 …
Synthesis And Characterization Of Novel Boron-Based Nanostructures And Composites, Rajen B. Patel
Synthesis And Characterization Of Novel Boron-Based Nanostructures And Composites, Rajen B. Patel
Dissertations
A number of nanomaterials have been synthesized by using a method that has been previously utilized to make pure boron nanostructures through the addition of different reactant gases to the process. This method was pioneered by Iqbal-Liu and will be referred to as the IL method in this dissertation. The IL method successfully created boron nanowires, boron nanoflakes, and boron nanotubes. In this dissertation, by adding methane, hydrogen sulfide, and ammonia to the process, an entire family of nanomaterials is prepared. These include nanowires, nano-heterostructures, and thin nanoplatelets of a variety of elemental compositions. These materials can be integrated with …
Low Energy Implantation Of Boron With Decaborane Ions, Maria Angela Albano
Low Energy Implantation Of Boron With Decaborane Ions, Maria Angela Albano
Dissertations
The goal of this dissertation was to determine the feasibility of a novel approach to forming ultra shallow p-type junctions (tens of nm.) needed for future generations of Si MOS devices. In the new approach, B dopant atoms are implanted by cluster ions obtained by ionization of decaborane (B10H14)vapor. Each B atom carries only ~9% of the cluster kinetic energy and the B dose per unit charge is 10 times larger than in the case of monomer ion beams. Thus, the problems of spacecharge, limiting the extraction and transport of low energy (< = 1 keV) beams of B+ ions, can …