Other Materials Science and Engineering Commons^™

He+ Ion Irradiation On Tungsten Surface In Extreme Conditions, George I. Joseph, Jitendra Tripathi, Sivanandan S. Harilal, Ahmed Hassanein

The Summer Undergraduate Research Fellowship (SURF) Symposium

Higher melting point (3695K), lower sputtering yield and most importantly, lower in-bulk, and co-deposit retention at elevated temperature makes tungsten (W) as a potential candidate for plasma-facing component (PFC) in the international thermonuclear experimental reactor (ITER)-divertor. Helium ion (He⁺) bombardment on W can cause wide variety of microstructural evolution, such as dislocation loops, helium holes/bubbles and fibre-form nanostructures (Fuzz) etc. In this work, 100 eV He⁺ ion irradiation, at temperature ranges from 500°C to 1000°C, will be performed on mechanically polished mirror like W surfaces. The surface modification and compositional analysis, due to ion irradiation, will be …

Simulation Of Bio-Inspired Porous Battery Electrodes, Raju Gupta, R. Edwin Garcia, Rui Tu

The Summer Undergraduate Research Fellowship (SURF) Symposium

Advancement of technology has led to the increase in use of electronic devices. However, longer life of the rechargeable battery used in electronic devices is one of the biggest issue and demand in the world of electronic devices at present. Battery's performance is affected by the orientation, arrangement, shape and size, and porosity of the materials out of which battery electrodes are made. The goal of this project is to develop a set of numerical libraries that allow developing material micro structures that will allow increasing the performance of rechargeable batteries. We focused on the development of an algorithm that …

Development Of Electron Microscopy Analysis And Simulation Tools For Nanohub, Mingxuan Lu, Chang Wan Han, Benjamin P. Haley, Volkan Ortalan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Electron microscopy has a crucial role in the field of materials science and structural biology. Although electron microscopy gives lots of important results and findings, some additional simulations and image processing/reconstruction is required to get more information from the data that are collected from the experiments. For this purpose, researchers are using IMOD¹ and QSTEM² for electron microscopy analysis and simulation. IMOD is a set of programs used for tomographic reconstruction and 3D visualization and QSTEM is used for quantitative simulations of TEM and STEM images. However, IMOD and QSTEM are hard to install or use for beginners …

Simulation Of Bio-Inspired Porous Battery Separators, Yumeng Xie, Edwin Garcia, Aniruddha Jana

The Summer Undergraduate Research Fellowship (SURF) Symposium

Li-Ion rechargeable battery is one of the most-used rechargeable batteries around the industry of the world. The battery is most used in most electronic devices, electrical cars. But the battery separator is one of the mainly problem that limits the service life. If we can find the way to improve the performance of the battery separator, we can highly increase the service life of the Li-Ion battery. The goal of the project 'Simulation of Bio-Inspired Porous Battery Separators' is to generate a tool for users in order to create computer models of bio-inspired porous structures that resemble porous separators layer …

Photo-Sensitivity Of Large Area Physical Vapor Deposited Mono And Bilayer Mos2, Baoming Wang, Christopher Muratore, Andrey A. Voevodin, M. Amanul Haque

Chemical and Materials Engineering Faculty Publications

We present photosensitivity in large area physical vapour deposited mono and bi-layer MoS2 films. Photo-voltaic effect was observed in single layer MoS2 without any apparent rectifying junctions, making device fabrication straightforward. For bi-layers, no such effect was present, suggesting strong size effect in light-matter interaction. The photo-voltaic effect was observed to highly direction dependent in the film plane, which suggests that the oblique deposition configuration plays a key role in developing the rectifying potential gradient. To the best of our knowledge, this is the first report of any large area and transfer free MoS2 photo device with performance comparable to …

Monte Carlo Modeling Of Ion Beam Induced Secondary Electrons, Uk Huh

Doctoral Dissertations

Modeling ion beam induced secondary electron (iSE) production within matter for simulating ion beam induced images has been studied. When the complex nature of ion beam interactions with matter is account for, a detailed quantitative model of the ion interactions with matter, Monte Carlo simulation will be the best choice to be able to compute and predict iSE yields faster and more accurately. In order to build Monte Carlo simulation software incorporated with a reliable database of stopping power tables, for wide variety of range of materials, there have been numerous attempts to experimentally measure ion stopping power tables and …

Low Temperature Thermally Activated Cvd Of Silicon On Molybdenum For Oxidation Protection, Brian C. Jolly

Masters Theses

The United States Global Threat Reeducation Initiative (GTRI) is promoting the production of molybdenum-99 without the use of uranium-235. One possible route, called neutron capture technology, is through the activation of molybdenum-98 via irradiation. GE-Hitachi has identified a location within their boiling water reactors for molybdenum-98 irradiation, but the elevated temperatures present risk oxidizing the molybdenum. This work explored using a silicon coating to protect the molybdenum from oxidation. With silane gas as the precursor, chemical vapor deposition was employed to produce the silicon coating. Characterization was performed and showed a discrete silicon layer was deposited with little to no …

Fabrication And Characterization Of Cu-Co Alloy Nanoparticles Via Pulsed Laser Dewetting, Shaofang Fu

Masters Theses

The fabrication and characterization of Cu[Copper]-Co[Cobalt] alloy nanoparticles are addressed in this thesis. First, Cu-Co alloy thin films with total thickness of ~10 nm [nanometer] were deposited on both 100 nm SiO₂ [silicon dioxide] coated silicon wafers and quartz substrates using RF magnetron sputtering system. Three structures were studied in this work: (1) ~10 nm co-sputtered Cu-Co alloy thin film. (2) ~5 nm (at center) Cu thin film covered by ~5 nm (at center) Co thin film. (3) ~5 nm (at center) Co thin film covered by ~5 nm (at center) Cu thin film. In addition, ~10 nm pure …

Finite Volume Numerical Analysis Of The Thermal Property Of Cellular Concrete Based On Two And Three Dimensional X-Ray Computerized Tomography Images, She Wei, Yang Yonggan, Xie Deqing, Zhang Yunsheng

International Conference on Durability of Concrete Structures

Cellular concrete is one kind of lightweight concrete, which are widely used in thermal insulation engineering project. In this study, a three dimensional (2D and 3D) finite-volume-based models was developed for analyzing the heat transfer mechanisms through the porous structures of cellular concretes under steady-state heat transfer condition and also for investigating the differences between 2D and 3D modeling results. 2D and 3D reconstructed pore networks were generated from the microstructural information measured by a 3D image captured by X-ray computerized tomography (X-CT). In addition, the 3D-computed value of the effective thermal conductivity was found to be in better agreement …

Overview Of Instruments For Investigating Dust Interactions On Small Solar System Bodies By Landers And Rovers, Ryan L. Kobrick, Jeffrey A. Hoffman, Kenneth W. Street Jr., Douglas L. Rickman

Publications

Small Solar System bodies such as asteroids, comets and Mars' moons Phobos and Deimos have relatively unknown regolith environments. It is hypothesized that dust preserved in the regolith on the surfaces will have similar mechanical properties to lunar dust because of similar formation processes from micrometeoric bombardment, low relative gravity for slow settling times, and virtually no weathering because there is no atmosphere.

Material Composition And Toxicology Of Cosmetic Products, Hilda Gonzalez

Materials Engineering

In today’s modern society, the U.S. Food and Drug Administration regulates many industries to protect consumers’ health; the cosmetics industry is not one of them. Through self-regulation, companies continue to sell products for topical use on the body that have been known to contain toxic chemicals with little to no testing on the effects they have on the human body. The purpose of this project was to determine the content of such known toxins in five different brands of face powders. X-Ray Diffraction (XRD) was used to verify the primary component and Inductively Coupled Plasma-Optical Emissions Spectroscopy (ICP-OES) was used …

Prediction Of Tribological Behavior Of Candidate Materials For Rotor Seals, John W. Franzino, Will F. Michul

Materials Engineering

To reduce high costs associated with manufacturing and testing materials for rotor seals, a procedure needs to be developed to quickly and accurately test candidate materials as they are released. The test should reduce the amount of fabrication required and model working conditions in order to accurately assess the tribological behavior of candidate materials. A possible solution was examined that utilized a rig meant to model operational stresses and wear. Compression modulus data was then taken in order to quantify the accumulation of damage due to microcracking, the primary mode of failure, through a damage index parameter. Testing results concluded …

Development Of Low Temperature, Aqueous Synthesis Method Of Lead Sulfide Quantum Dots, Albert Nakao, Colin Yee

Materials Engineering

Quantum dots have become an active area of research in the past decade due to their unique properties. Quantum confinement effects allow for efficient spectral conversion and size tunable fluorescence and absorption peaks. Near infrared spectral converting lead sulfide quantum dots have potential applications in solar power, biological imaging and communications technology. However at Cal Poly, lead sulfide dots have not been synthesized. The quantum dot synthesis currently adapted at Cal Poly encompasses organometallic precursors at high reaction temperatures, producing cadmium selenium dots. The organometallic approach has been found to produce nanocrystals with high quality photoluminescence, but due to its …

Electrochemical Characterization Of Precious Metal Braze Alloys Using Potentiodynamic Polarization, Maxwell Glen Martin, Mason Gregory Morgan, Matthew David Vance

Materials Engineering

This study aimed to characterize the electrochemical behavior of six precious metal braze alloys by performing potentiodynamic polarization tests (ParStat 2273) based on ASTM Specifications G5 and G59. To determine the extent to which the alloys will contribute to galvanic corrosion in a marine environment (3.5 wt% NaCl), corrosion analysis software was used to produce fitted Tafel lines to determine the open circuit potential, V_oc, for each alloy. The V_oc values for the alloys were found to be -66.58 mV for Gold ABA, 13.01 mV for Nicoro^®, -39.00 mV for Nioro^®, 23.4 mV …

An Investigation Into The Properties And Fabrication Methods Of Thermoplastic Composites, Ann E. Livingston-Peters

Master's Theses

As applications for thermoplastic composites increase, the understanding of their properties become more important. Fabrication methods for thermoplastic composites continually improve to match designs specifications. These advanced thermoplastics have begun to show an improvement in mechanical properties over those found in thermoset composites commonly used in industry. Polyaryletherketones (PEK) have high service temperatures, good mechanical properties, and improved processing capabilities compared to thermoplastics used in the past making them important to the aerospace industry. The wide range of types of PEK make them suitable for a variety of applications, but selection of specific chemistries, processing parameters, and composite stack-ups determine …

Developent Of A Phospholipid Encapsulation Process For Quantum Dots To Be Used In Biologic Applications, Logan Grimes

Master's Theses

The American Cancer Society predicts that 1,665,540 people will be diagnosed with cancer, and 585,720 people will die from cancer in 2014. One of the most common types of cancer in the United States is skin cancer. Melanoma alone is predicted to account for 10,000 of the cancer related deaths in 2014. As a highly mobile and aggressive form of cancer, melanoma is difficult to fight once it has metastasized through the body. Early detection in such varieties of cancer is critical in improving survival rates in afflicted patients. Present methods of detection rely on visual examination of suspicious regions …

Influence Of Nanofiller Morphology On The Viscoelastic Properties Of Cnf/Epoxy Resins, Liberata Guadagno, Marialuigia Raimondo, Khalid Lafdi, Annalisa Fierro, Salvatore Rosolia, Maria Rossella Nobile

Chemical and Materials Engineering Faculty Publications

In this paper we discuss the viscoelastic properties of CNF/Epoxy-Amine Resins for structural applications. The use of reactive diluent inside the unfilled and nanofilled epoxy mixture as proven to be of benefit to strongly decrease the viscosity.

A First-Principles Examination Of Dopants In Hfo2, Daniel Cunningham

Honors Scholar Theses

A systematic first-principles study using density functional theory was performed on dopants in HfO2, a material with great importance as a high-k dielectric. Sixteen dopants were tested, most of which came from the fourth period of the periodic table (K-Ge, Al and Si). The relative stability of the monoclinic, tetragonal, and cubic phases were calculated for HfO2 with each dopant in order to determine which dopants tend to stabilize which phases. It was found that the most important factor in determining relative phase stability of doped HfO2 was the ionic radius of the dopant, where dopants smaller than Hf tend …

Ab Initio Studies Of Proton Transport In Proton Exchange Membranes, Jeffrey Keith Clark

Doctoral Dissertations

A molecular-level understanding of the factors that contribute to transport properties of proton exchange membranes (PEMs) for fuel cell applications is needed to aid in the development of superior membrane materials. Ab initio electronic structure calculations were undertaken on various PEM ionomer fragments to explore the effects of local hydration, side chain connectivity, protogenic group separation, and specific side chain chemistry on proton dissociation and transfer at low hydration. Cooperative interactions between both intra- and inter-molecular acidic groups and hydrogen bond connectivity were found to enhance proton dissociation at very low degrees of hydration. The energetics associated with proton transfer …

Synthesis And Characterization Of Magnetic Nanowires Prepared By Chemical Vapor Deposition, Siwei Tang

Doctoral Dissertations

Various metal silicide and germanide magnetic nanowires were synthesized using a home-built CVD [chemical vapor deposition] system. The morphology, composition, and magnetic properties of the nanowires were studied and correlated with growth parameters such as temperature, pressure, time, and source-substrate distance.

One of the compositions targeted for synthesis was MnSi [manganese silicide]. In bulk, this material orders helimagnetically at T_c [curie temperature] = 30K, with a helical pitch of about 20 nm. After extensive study, we learned that the thickness of the silicon dioxide layer on the substrate is a critical parameter for the growth of MnSi nanowires. An …