Engineering Commons^™

Development Of Lignin Carbon Fiber And Reinforced Composites, Nathan Kieran Meek

Masters Theses

The aim of this work is to develop lignin carbon fiber for composite applications. This included mechanical testing of single lignin carbon fiber (LCF), interfacial shear strength determination for LCF-resin systems using single fiber fragmentation, x-ray diffraction for the evaluation of microstructural parameters, and finally composite manufacturing and testing. Through these focused areas of analysis, the carbon fiber is thoroughly characterized and composite performance is evaluated. This effort was a collaboration with the Center for Renewable Carbon (CRC) and the Civil and Environmental Engineering Department. LCF produced by the CRC resulted in fibers having tensile strength of 250-800 MPa and …

Lignin Maximization: Analyzing The Impact Of Different Feedstocks And Feedstock Ratios Using Organosolv Fractionation, Marc Banholzer

Masters Theses

Over-exploitation of fossil fuels coupled with increasing pressure to reduce carbon emissions are prompting a transition from conventional petrochemical feedstocks to sustainable and renewable sourced carbon. The use of lignocellulosic biomass as a feedstock for integrated biorefining is of current high interest, as separation into its component parts affords process streams of cellulose, hemicellulose and lignin, each of which can serve as a starting point for the production of biobased chemicals and fuels. Given the large number of potential sources of lignocellulosic feedstocks, the biorefinery will need to adapt to the supplies available over a normal growing season. Of particular …

Fluorochlorozirconate Glass Ceramics For Computed Radiography, Adam Wesley Evans

Masters Theses

Heat treating fluorochlorozirconate (FCZ) glasses nucleates nanocrystals in the glass matrix, resulting in a glass ceramic that has optical properties suitable for use as a medical imaging plate. As the temperature of heat treatment rises, the resulting FCZ glass-ceramic becomes increasingly more opaque as the size of the orthorhombic phase BaCl­₂[barium chloride] nanocrystals grow within the glass matrix. This opaqueness negatively affects imaging. The effect of adding Fe³⁺[iron] on the valence state of zirconium and overall glass quality was investigated.

Samples were synthesized and characterized with differential scanning calorimetry to determine the temperature of the orthorhombic …

Evaluation Of The Potential For Weld-Related Cracking In Cast 20cr-32ni-1nb Heat-Resistant Stainless Steel, John William Bohling

Masters Theses

Steam reforming of hydrocarbons is an important process for the production of hydrogen for industrial needs, such as ammonia synthesis. Due to the high temperature conditions (700 °C–900 °C), reformer furnace components require materials with excellent creep properties and thus highly alloyed austenitic stainless steels are typically employed. For reformer outlet manifolds, a cast, heat-resistant stainless steel with the composition 20Cr-32Ni-1Nb (ASTM A351 Grade CT15C) is widely used. However, after service exposure this alloy exhibits problems with liquation cracking in the base metal heat-affected zone (HAZ) during repair welding. In the work presented herein, two heats of material from centrifugally-cast …

Thermal Characteristics Of Lithium Indium Diselenide And Lithium Indium Gallium Diselenide Neutron Detection Crystals, Dustin Carroll Giltnane

Masters Theses

Tracking special nuclear materials (SNM) has never been more important than in the 21^st century where information is transferred rapidly around the globe. Tracking SNM is important to nuclear power, weapons, medicine, and science. Neutron and gamma ray detection are the primary methods of detecting SNM. Increased movement and availability of SNM have increased the demand for radiation detection systems beyond the capacity of traditional neutron detection technologies (³He) [Helium three]. Many alternative neutron detection materials are being considered, including ⁶LiInSe₂ [Lithium Indium Diselenide grown with lithium enriched in lithium six] and its derivative ^{6 …}

Modeling And Experimental Investigation On The Influence Of Radiation Defects On Helium Behavior In Bcc Iron, Zuya Huang

Masters Theses

Fe-based alloys are important structural materials for both fission and fusion energy. For fusion applications, the challenges of radiation-induced changes in microstructure, properties and performance is further challenged by the concomitant production of helium from (n, alpha) nuclear reactions and fusion reactions. Due to the lack of a volumetric, high flux 14-MeV neutron source, studying these phenomena require the use of computational materials modeling and novel experimental methods. In this thesis, molecular dynamics (MD) simulations was used to investigate the synergistic interactions of helium with prismatic dislocation loops characteristic of those observed in neutron irradiated iron to determine how the …

Cell Contraction, De-Adhesion, And Shape Effects Investigated By Cohesive Model With Finite Element Simulations, Margarita Vladimirovna Semenova Petrova

Masters Theses

Cell adhesion is a complex mechanism, and different factors control this process including surface morphology, chemical, and mechanical interactions. These aspects are usually combined to achieve robust adhesion between surfaces. The later stage in bio-adhesion process involves the formation of molecular bonds through diffusion or interpenetration of molecules at the interface. In order to create contact, cells sense their physical environment by applying mechanical forces or responding to them via traction force. The force is transmitted through cell skeleton. However, how this force is transmitted is mostly unknown. Also, there are still many open questions about fracture mechanism in bio-adhesive …

Magnetron Sputtering And Corrosion Of Ti-Al-C And Cr-Al-C Coatings For Zr-Alloy Nuclear Fuel Cladding, Devin Alan Roberts

Masters Theses

The disaster at the Fukushima Daiichi Nuclear Power Plant in March 2011 bought renewed focus to the issue of corrosion in nuclear fuel cladding applications. This thesis reports on the background behind these issues, the investigation strategy, and the analysis of experiments focused on mitigating oxidation of Zr-alloy fuel cladding. This thesis seeks to develop magnetron sputtered Ti-Al-C and Cr-Al-C coatings for Zr-alloy substrates and characterize the as-deposited and corroded samples.

Ti-Al-C and Cr-Al-C coatings were deposited onto ZIRLO, Si, and Al₂O₃ [Aluminum Oxide] substrates under various sputtering conditions. A combinatorial sputtering method was employed to refine …

Study Of Magneto-Optical Behaviors At A Ferromagnetic/Organic Semiconductor Interface, Jeremy Tyler Tisdale

Masters Theses

Organic materials have been widely studied for the last 20 years to use for photovoltaic applications. Organic photovoltaic materials have shown promising properties for solar cells, such as very low cost, flexibility, easy fabrication methods, etc. Although power conversion efficiencies for organic-based solar cells have exponentially grown in the last decade, up to about 13% in early 2016, it is still optimal to increase these efficiencies. In order to raise efficiencies, it is important to study the fundamental mechanisms inside organic materials that lead to photovoltaic properties. This thesis reports the magneto-optical effects on the p-type organic semiconductor, tetracene, from …