Engineering Science and Materials Commons^™

Mechanical Properties And Microstructure Evolution Of Thermally Treated Laser Powder Bed Fusion Alsi10mg, Jorge Merino-Gomez

Open Access Theses & Dissertations

The optimization of mechanical properties with thermal postprocessing treatments was investigated in this study across a wide variety of variants. The relationship between heat treatments and the impacts on the mechanical properties and microstructure of printed materials is a crucial part of additive manufacturing. As a result, the current paper provides a comprehensive overview of postprocess heat treatments for Laser Powder Bed Fusion fabricated AlSi10Mg alloy, including stress relief anneals at 190 and 285 degrees Celsius for 2 hours, hot isostatic pressing at 515 degrees Celsius for 3 hours, hot isostatic pressing + T6 treatment for 6 hours, and final …

Influence Of Leading Edge Oscillatory Blowing On Time-Accurate Dynamic Store Separation, Ryan G. Saunders

Theses and Dissertations

The primary objective of this research is to support the static and dynamic characterization and the time-accurate dynamic load data acquisition of store separation from a cavity with leading edge oscillatory blowing. Developing an understanding of, and potentially controlling, pitch bifurcation of a store release is a motivation for this research. The apparatus and data acquisition system was used in a two-part experiment to collect both static and dynamic testing data in the AFIT low speed wind tunnel in speeds of 60, 100, and 120 mph, from Reynolds numbers varying from 5.5x10⁴ to 4.6x10⁵, depending on reference …

Tailoring The Mechanical And Optical Properties Of Silicon-Niobium-Nitride Composite Coatings, Cristian Orozco

Open Access Theses & Dissertations

Nitride nanocomposite thin films have generated significant attention as a result of their robust mechanical properties, excellent triobology, and good chemical (corrosion) stability. Due to their excellent hardness and high wear resistance NbN coatings have found use in a wide variety of applications such as the coating of cutting tools and to strengthen the surface mechanical properties of superconducting cavities. The mechanical properties of NbN can be further improved through mixing with Si3N4, leading to the formation of a nanocomposite structure. NbN-Si3N4 nanocomposite coatings have been actively studied due to their high hardness, high elastic modulus, and high resistance to …

Mechanical Properties And Degradation Of High Capacity Battery Electrodes: Fundamental Understanding And Coping Strategies, Yikai Wang

Theses and Dissertations--Chemical and Materials Engineering

Rechargeable lithium ion and lithium (Li) metal batteries with high energy density and stability are in high demand for the development of electric vehicles and smart grids. Intensive efforts have been devoted to developing high capacity battery electrodes. However, the known high capacity electrode materials experience fast capacity fading and have limited cycle life due to electromechanical degradations, such as fracture of Si-based electrodes and dendrite growth in Li metal electrodes. A fundamental understanding of electromechanical degradation mechanisms of high capacity electrodes will provide insights into strategies for improving their electrochemical performance. Thus, this dissertation focuses on mechanical properties, microstructure …

Additive Manufacturing With High Density Polyethylene: Mechanical Properties Evaluation, Calvin Wampol

Electronic Theses and Dissertations

High-density polyethylene is a common recyclable plastic that has a large potential as an additive manufacturing material due its economic and environmental benefits. However, high-density polyethylene has undesirable thermal properties that cause the material to shirk and not adhere to the printing bed during an additive manufacturing processes. Researchers have attempted to combat these thermal properties but have only created novel filaments of high-density polyethylene without being able to create 3D printed specimens for mechanical property testing. This paper presents several methods to create 3D printed specimens with pure high-density polyethylene filament on a fused filament fabrication type 3D printer. …

Tungsten Doping Induced Superior Mechanical Properties Of Hafnium Oxide For Energy Applications, Ann Marie Uribe

Open Access Theses & Dissertations

Hafnium oxide, or hafnia, is a high temperature refractory material with good electrical, chemical, optical, and thermodynamic properties. The effects of dopants have been widely studied, especially after the discovery of ferroelectricity induced in hafnia thin films. While attractive and used in the opto-electronic, memory devices, and semiconductor industries, there is a lack in the literature on enhancing the mechanical properties of hafnium oxide, specifically through doping it with tungsten, another material of interest particularly for future high temperature device applications. Thus, this work aimed to grow hafnia thin films doped with varying amounts of tungsten. The samples were grown …

Experimental And Analytical Characterization Of Regenerated/Nano Cellulose Composites, Issam I A Qamhia

Theses and Dissertations

Fiber-reinforced composite materials are increasingly used for structural and engineering purposes. In particular, composites reinforced with natural fiber systems are becoming more and more popular due to their biodegradability and abundance; added to that other properties such as transparency, dimensional stability and good mechanical behavior. However, major issues remain to properly understand their behavior and enable their widespread use.

In this thesis, the mechanical behavior of cellulose fiber/epoxy composites is investigated. The natural fiber systems studied fall into three categories: unidirectional regenerated cellulose fibers, triaxially braided quasi-isotropic regenerated cellulose fibers and micro-fibrillated cellulose in the form of nanocellulose scaffolds. Different …

Characterization Of High-Purity Niobium Structures Fabricated Using The Electron Beam Melting Process, Cesar Adrian Terrazas

Open Access Theses & Dissertations

Additive Manufacturing (AM) refers to the varied set of technologies utilized for the fabrication of complex 3D components from digital data in a layer-by-layer fashion. The use of these technologies promises to revolutionize the manufacturing industry. The electron beam melting (EBM) process has been utilized for the fabrication of fully dense near-net-shape components from various metallic materials. This process, catalogued as a powder bed fusion technology, consists of the deposition of thin layers (50 - 120µm) of metallic powder particles which are fused by the use of a high energy electron beam and has been commercialized by Swedish company Arcam …