Materials Science and Engineering Commons^™

An Analysis Of Texture Resulting From Thermomechanical Processing Of Ti-6al-V, David J. Brock

Masters Theses

An investigation of texture and microstructure formation in Ti-6Al-4V after thermomechanical processing and heat treating was performed. X-ray diffraction was used to measure prismatic and pyramidal pole figures. These pole figures were used to calculate basal pole figures, which showed significant changes in texture from heavy rolling and near or above β-transus heat treatments. Primary texture components were found to be strengthened by near β-transus heat treatments. For heavily rolled material, above β-transus heat treatments were found to reverse the primary texture components order of dominants. Heavy rolling was found to reduce the RD component and strengthen the TD.

Synthesis And Characterization Of Silicon Dioxide Films Using Diethyl Silane And Oxygen, Kiran Kumar

Theses

This study focuses on producing thin and thick silicon dioxide films towards the fabrication of integrated optical sensor capable of monitoring and determining in-situ, the concentration of numerous analyze species simultaneously. In this study, diethylsilane (DES) has been used as a precursor to produce silicon dioxide films by low pressure chemical vapor deposition. The films were synthesized with two different flow ratios of oxygen to DES in the temperature range of 550°C to 800°C at a constant pressure of 200mTorr. The films deposited with lower oxygen to DES flow ratio have very high growth rate but suffer from high tensile …

The Solution Of Hypersingular Integral Equations With Applications In Acoustics And Fracture Mechanics, Richard S. St. John

Mathematics & Statistics Theses & Dissertations

The numerical solution of two classes of hypersingular integral equations is addressed. Both classes are integral equations of the first kind, and are hypersingular due to a kernel containing a Hadamard singularity. The convergence of a Galerkin method and a collocation method is discussed and computationally efficient algorithms are developed for each class of hypersingular integral equation.

Interest in these classes of hypersingular integral equations is due to their occurrence in many physical applications. In particular, investigations into the scattering of acoustic waves by moving objects and the study of dynamic Griffith crack problems has necessitated a computationally efficient technique …

Effect Of Temperature And Strain Rate On The Mechanical Behavior Of Al/Sic Particulates Metal Matrix Composites, Mohamed Mahmoud Zaki Emara

Archived Theses and Dissertations

No abstract provided.

An Expert System Approach For Process Planning Of Rotational Components, Sherif Salah Raslan

Archived Theses and Dissertations

No abstract provided.

Plasma Enhanced Chemical Vapor Deposition Of Diamondlike Carbon Films Using Acetylene, Sriram Vishwanathan

Theses

This study is focussed on the synthesis and characterization of diamondlike carbon (DLQ films deposited on silicon wafers and glass by plasma enhanced chemical vapor deposition (PECVD), using acetylene (C₂H₄) as a precursor. The process parameters, such as temperature, pressure, power and reactant gas flow rate have been systematically varied and their effects on the film growth rate and properties were investigated. The optimized deposition condition appeared to be at 150°C, 200mTorr, 200 Watts and flow rate = 25 sccm. For these conditions, the films were hard and found to have good adhesion to the substrate, …

Characteristics And Performance Of R413a As An Alternative Refrigerant To R12, Waleed Mahmoud El-Nahas

Archived Theses and Dissertations

No abstract provided.

Mechanical Properties, Structure, And Corrosion Characteristics Of Al And Al-Zn Coated Steel Sheets, Farraj El Shammari

Archived Theses and Dissertations

No abstract provided.

Melt Hydroperoxidation Polypropylene With Potential Application In Pollution Control, Zeena Cherian

Theses

The primary objective of this study is to introduce tertiary hydroperoxide functional groups into polypropylene (PP) melt by injecting air. This was done first by mixing additive free polypropylene powder with air in a batch mixer. The influence of air flow rate, temperature, mixing time and rotor RPM on the concentration of hydroperoxide groups were studied. Iodometric analysis and fourier transform infrared spectroscopic analysis were the techniques used to detect and quantify the concentration of hydroperoxide groups. In the second phase of the study, hydroperoxide groups were introduced in polypropylene through reactive processing in a single screw extruder. It was …

The In0.75ga0.25as/In0.52al0.48as/Inp Hall Effect Magnetic Field Sensor, Oleg Mitrofanov

Theses

The magnetic field sensor is produced from III-V group semiconductor materials. The structure is designed for molecular beam epitaxy growth technique (MBE) on the semiinsulating InP substrate. The sensitive element is the In_0.75Ga_0.25As/In_0.52Al_0.48As heterostructure. The sensor uses the classic Hall effect in two-dimension electron gas (2DEG) formed at pseudomorphic strained epilayer of In_0.75Ga_0.25As. Properties of the 2DEG are preferential for the Hall effect sensor performance. Comparatively to bulk, electron mobility is higher. The device combines high magnetic field sensitivity and temperature stability. The sensor is designed for operation …

Low Pressure Chemical Vapor Deposition Of Boron Nitride Thin Films From Triethylamine Borane Complex And Ammonia, Narahari Ramanuja

Theses

Boron nitride thin films were synthesized on Silicon and quartz substrates by low pressure chemical vapor deposition using triethylamine-borane complex and ammonia as precursors. The films were processed at 550°C, 575°C and 600°C at a constant pressure of 0.05 Torr at different precursor flow rates and flow ratios.

Several analytical methods such as Fourier transform infrared spectroscopy, x- ray photo-electron spectroscopy, ultra-violet/visible spectrophotornetry, ellipsometry, surface profilometry and scanning electron microscopy were used to study the deposited films. The films deposited were uniform, amorphous and the composition of the films varied with deposition temperature and precursor flow ratios. The stresses in …

Platinized Tin Oxide: A Low-Temperature Oxidation Catalyst, Erik Joshua Kielin

Dissertations, Theses, and Masters Projects

Some combinations of noble metal and reducible metal oxide possess a synergistic level of activity for the catalytic oxidation of CO at lower temperatures and partial pressures of O2 than can be obtained by either component alone. The most promising candidates, Au on MnO2 and Pt on SnO 2, were investigated for the effects on activity of noble metal loading, of reductive pretreatment at elevated temperature, and of reaction gas mixture composition. Optimum activity was obtained at a noble metal loading of 28% Au/MnO2 and 17% Pt/SnO2. Both catalysts benefitted from reductive CO pretreatment at 125??C. Both catalysts showed enhanced …

The Role Of Adsorbed Oxygen In Secondary Emission From Metallic Substrates, Scott Gregory Walton

Dissertations, Theses, and Masters Projects

Low energy, ion- and photon-induced secondary electron and anion emission from metallic substrates has been investigated as a function of adsorbate coverage. Sodium positive ions (Na+), with kinetic energies up to 500 eV, and photons, with energies up to 23 eV, are utilized to initiate secondary emission. The principal adsorbate is oxygen with coverages ranging from none to a few monolayers.;For ion-induced emission, the secondary electron and negative ion absolute and relative yields from 302 stainless steel and polycrystalline tungsten (W) have been measured as a function of both impact energy and oxygen coverage. Additionally, the yields from a "technical" …

An Evaluation Of The Aws Entry Level Welder Training Program, John R. Rice

Dissertations and Theses @ UNI

The purpose of this study was to evaluate the effectiveness of a training program for Entry Level Welders and to provide this information to the American Welding Society (AWS), industry, and educators. The problem of this study was to evaluate the AWS Entry Level Welder Training Program (ELWTP) by obtaining the opinions of faculty members who taught the program and welders who had completed the program.

Two groups comprised the research population for this study. The first group consisted of faculty members who were actually involved in teaching the course at institutions accredited by the AWS to offer the curriculum. …