Materials Science and Engineering Commons^™

Oxidation Modeling By Means Of Molecular Dynamics, Chaiyod Soontrapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

Oxidation modeling is normally engineered to study systems at macroscopic scales, mostly in analytical forms based on diffusion theories. The associated time scale is usually in months, days, or minutes, and the length scale is in the order of microns. In this dissertation, oxidation modeling is performed at atomistic scale with the time and length scales in picoseconds and angstroms, respectively, using molecular dynamics. Molecular dynamics simulations generate trajectories of each atom or particle in a system according to the laws of physics. Studying oxidations under the atomistic point of view can offer new insights on atomic behaviors and influencing …

Tensile Strength And Failure Criterion Of Analog Lithophysal Rock, James A. Nott

UNLV Theses, Dissertations, Professional Papers, and Capstones

This project determines the tensile strength of lithophysal analog rock and presents failure criteria that can be used by geotechnical engineers to evaluate underground structures in rock. The physical and mechanical properties that are related to the failure criterion, such as porosity, compressive strength and modulus of elasticity, are also discussed. Experimental tensile tests were made using direct uniaxial and indirect Brazilian tests. Three 4-inch specimens were fabricated and tested in direct uniaxial tensile tests using Hydro-Stone TB. The results showed that the elastic tensile modulus of elasticity was within two percent of existing data for the compressive modulus of …

Study Of Corrosion Of Materials In The Sulfur-Iodine Hydrogen Production Cycle, Thao Trung Ho

UNLV Theses, Dissertations, Professional Papers, and Capstones

Hydrogen is of great interest since the availability of traditional fossil fuels is in decline. Strictly speaking, hydrogen is not a primary source of energy but is an energy carrier, since energy typically must be used from another source (electricity, natural gas, coal, etc.) to produce it. Of hydrogen production techniques, the Sulfur-Iodine thermochemical water splitting process (S-I cycle), which was proposed by General Atomics (GA), is promising with its simplicity and high efficiency. Most of the chemicals are recycled except water. However, the S-I cycle operates in a harsh, corrosive environment in the presence of a mixture of iodine …

Effects Of Mechanical And Metallurgical Variables On Creep, Fracture Toughness And Crack Growth Behavior Of Alloy 617, Muhammad Hasibul Hasan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Nickel base Alloy 617 has been identified to be a suitable structural material for heat exchanger applications in both hydrogen and electricity generation using nuclear heat. A maximum operating temperature of 950°C has been specified by department of energy (DOE) for both applications to achieve a maximum possible efficiency. Therefore, an extensive investigation has been pursued to evaluate time-dependent-deformation (Creep) of this alloy as functions of temperature and applied load. The results indicate that this alloy exhibited severe creep deformation, characterized by development of an instantaneous tertiary creep region at 850 and 950°C under applied stresses corresponding to its 35% …

Mse News 2009, Department Of Materials Science And Engineering, Michigan Technological University

Department of Materials Science and Engineering Annual Reports

Table of Contents

• MSE Department Welcomes Engineering Fundamentals Chair
• MSE Department Welcomes New Professor
• Steel
• MSE Program Shines in US News Rankings
• MSE Alumnus Excelled in Mining Industry
• Student News
• Staff News
• Faculty News
• Alumni News

Model For Alumina Nanopore-Based Optical Filter, Nathan Lehman, Rama Venkat, Robert A. Schill

Electrical & Computer Engineering Faculty Research

Alumina nanopore structures find applications in magnetic sensors, optical filters, and various biological devices. In this work, we present a ray-optics model for the optical filter. We present a detailed simulation and a simplified analytical expression for the reflectance as a function of the alumina parameters such as pore diameter, pore density, alumina thickness, and a function of the wavelength and angle of incidence of the illuminating plane electromagnetic wave. The reflectance vs wavelength in the range of 400–800nm obtained from the simulation and the analytical expression are compared with that of the experiments for thin and thick alumina. All …

Freeze Casting Of Bioactive Glass And Ceramic Scaffolds For Bone Tissue Engineering, Qiang Fu

Doctoral Dissertations

"The main objectives of this dissertation were to explore the production of bioactive ceramic and glass scaffolds with oriented pore architectures by unidirectional freezing of suspensions, and to characterize the mechanical and biological performance of the scaffolds. Freezing of aqueous suspensions of hydroxyapatite (HA) or bioactive 13-93 glass particles resulted in the formation of scaffolds with a lamellar-type microstructure (pore width = 5-30 µm). The addition of polar organic solvents (such as 60 wt% dioxane) to the aqueous suspensions markedly changed the morphology and size of the oriented pores, giving scaffolds with a columnar-type microstructure and larger pre width (90-110 …

Microstructural Influence On Dynamic Properties Of Age Hardenable Femnal Alloys, Ryan A. Howell

Doctoral Dissertations

"A lightweight castable alloy was sought to reduce the MIL-PRF-32269 class II cast steel perforated armor's weight with the requirement that the material had to be manufactured utilizing existing foundry technology and without incurring large alloy cost increases to meet property requirements. Literature on wrought age hardenable Fe-Mn-Al-C alloys suggested this alloy system could achieve weight reduction through high aluminum concentrations with the highest reported strengths exceeding 2 GPa for a Fe-30Mn-9Al-0.9C composition. Even though ballistic testing had not been conducted on this system, high strain rate data of wrought alloys showed excellent work hardenability; greater than existing ballistic metals. …

Material Flow And Microstructure Evolution In Friction Stir Welding Of Aa6111 Alloy Sheets, Manasij Kumar Yadava

Doctoral Dissertations

"Material flow and microstructure evolution are the two important aspects of the Friction stir welding (FSW) technique, which control the properties and performance of the friction stir welds. The present work investigates these two aspects of the FSW with main emphasis on the friction stir lap joints (FSLJs) on the AA6111 sheets. Due to the characteristic material flow during FSW, the faying surfaces in FSLPs are deposited in and around the weld nugget and create unavoidable defects. These defects reduce the load carrying thickness of the joints by providing an easy path for the weld failure. Therefore, to control the …

The Role Of Friction Stir Processing On The Microstructure And Mechanical Properties Of A Cast Aluminum Alloy, Saumyadeep Jana

Doctoral Dissertations

"Al-7Si-0.6Mg is one of the most important cast aluminum alloys because of its attractive mechanical properties and high castability. Microstructurally, the alloy consists of primary aluminum dendrites with eutectic Si particles in the interdendritic region. This makes the alloy quasi-brittle in nature which affects the ductility of the alloy to a great extent. In order to improve the ductility, the eutectic Si particles need to be refined which so far has been achieved by chemical and/or thermal modification. Friction stir processing (FSP) on the other hand can achieve the same through plastic deformation, and therefore replace the cast structure with …