Metallurgy Commons^™

Ignition Of A Plasma Discharge Inside An Electrodeless Chamber: Methods And Characteristics, Mounir Laroussi

Electrical & Computer Engineering Faculty Publications

In this paper the generation and diagnostics of a reduced pressure (300 mTorr to 3 Torr) plasma generated inside an electrodeless containment vessel/chamber are presented. The plasma is ignited by a guided ionization wave emitted by a low temperature pulsed plasma jet. The diagnostics techniques include Intensified Charge Coupled Device (ICCD) imaging, emission spectroscopy, and Langmuir probe. The reduced-pressure discharge parameters measured are the magnitude of the electric field, the plasma electron number density and temperature, and discharge expansion speed.

Microstructural Evaluation Of Aluminium Alloy A365 T6 In Machining Operation, Bankole I. Oladapo, S. Abolfazl Zahedi, Francis T. Omigbodun, Edwin A. Oshin, Victor A. Adebiyi, Olaoluwa B. Malachi

Electrical & Computer Engineering Faculty Publications

The optimum cutting parameters such as cutting depth, feed rate, cutting speed and magnitude of the cutting force for A356 T6 was determined concerning the microstructural detail of the material. Novel test analyses were carried out, which include mechanical evaluation of the materials for density, glass transition temperature, tensile and compression stress, frequency analysis and optimisation as well as the functional analytic behaviour of the samples. The further analytical structure of the particle was performed, evaluating the surface luminance structure and the profile structure. The cross-sectional filter profile of the sample was extracted, and analyses of Firestone curve for the …

Direct Strength Approach To Predict The Flexural Strength Of Cold-Formed Z-Section Purlins On Sloped Roofs, Ali Parva, Michael W. Seek

Engineering Technology Faculty Publications

In this study, the strength of cold-formed Z-section purlins is predicted considering the effects of roof slope in real roof systems. The study applies to simple span purlins with torsion restraints at support locations and at paired locations along the length of the member. A previously developed method has shown through comparisons to base tests that when the biaxial bending and torsion stresses are incorporated into the analysis, the Direct Strength Method can accurately predict the strength of a purlin. These stress distributions can deviate substantially from the constrained bending approximation typically assumed in analysis and therefore impacts the local …

Impact Of Clip Connection And Insulation Thickness On Bracing Of Purlins In Standing Seam Roof Systems, Michael W. Seek, Daniel Mclaughlin

Engineering Technology Faculty Publications

The flexural strength of purlins in standing seam roof systems is highly dependent upon the extent to which the sheathing provides lateral and torsional restraint. Typical models to predict the restraint provided by the sheathing assume that the plane of lateral resistance occurs at the top flange of the purlin. In reality, depending on the configuration of the clip and the amount of insulation located between the purlin and the clip, the plane of lateral resistance and corresponding center of rotation shifts above the top flange. This distance, referred to as the effective standoff, is important to evaluate the effectiveness …

The Effect Of Temperature On The Optical Absorptive And Reflective Behavior Of Metals, Thomas A. Hunyady

Mechanical & Aerospace Engineering Theses & Dissertations

In the five decades since its invention, the laser has been used to commercially process materials in an increasingly diverse number of ways. The precise control over the delivery of the incident energy that is afforded by a laser allows for a wide variety of applications. All of these processes depend in some way on two important physical properties of the material being treated. These properties are known as the optical reflectivity and absorptivity of a material. The values of each of these properties are different for each material and are influenced by a number of factors, including surface roughness, …

Effect Of Cr3+ And So42- On The Structure Of Rust Layer Formed On Steels By Atmospheric Corrosion, Masato Yamashita, Hitoshi Uchida,, Desmond C. Cook .

Physics Faculty Publications

The effect of chromium ion (Cr³⁺) and sulfate ion (SO₄^2-) on the structure of the rust layer formed by thin electrolyte-film corrosion of low-alloy steels has been examined. By using X-ray diffraction spectroscopy, it was found that coexistence of Cr³⁺ and SO₄^2- in the electrolyte film covering the steel surface quickly forms the Cr-goethite (α-(Fe _1-X, Cr_X)OOH) layer which has been known as the final protective rust layer. Scanning vibrating electrode measurements showed that the rust layer formed under the electrolyte film containing Cr³⁺ and SO₄^{2- …}

Quantitative Analysis Of Ultra-Fine Goethite In Rust Layer On Steel Using Mossbauer And X-Ray Diffraction Spectroscopy, Masato Yamashita, Toshihei Misawa, H. E. Townsend, D. C. Cook

Physics Faculty Publications

We have proposed determination procedure of the relative amounts of rust constituents of steel. Mossbauer spectroscopy provides the relative amounts of crystalline rust constituents including ultra-fine crystals. A quantitative analysis of ultra-fine crystals is possible with the resolution of several percent by comparing the Mossbauer results with the relative amounts of rust constituents determined by X-ray diffraction spectroscopy.

Characterization Of Iron Oxides And Atmospheric Corrosion Of Steel, Sei Jin Oh

Physics Theses & Dissertations

The study of corrosion behavior was performed using three different analytical techniques, which provided information on the formation, development and layering of iron oxides on the corrosion products as a function of atmospheric conditions, exposure time and type of steel. In particular, the protective layer formed on weathering steel was investigated as a function of different amounts of alloying elements in the steel, atmospheric conditions and exposure times. Combined together, the results provided a better understanding of the atmospheric corrosion behavior of steel, and formed a part of database of the atmospheric corrosion characteristics.

Accurate characterization of the iron oxides …

Mechanical Alloying Of Nitrogen Into Iron Powders, J. Rawers, D. Govier, D. C. Cook

Physics Faculty Publications

Mechanical alloying of nitrogen into bcc-fe powder is a very effective and efficient means of obtaining very high concentration of nitrogen in micron-size iron particles. Mechanical alloying increases the concentration of nitrogen in the iron powder far in excess of the bcc-Fe lattice low nitrogen solubility, however most of the infused nitrogen resides on the nano-size grain boundaries and in nano-size bct-fe that forms during mechanical alloying.

Identification And Characterization Of The Iron-Zinc Intermetallics Formed In Galvanneal Steel, Richard Frederick George Grant

Physics Theses & Dissertations

The demand to improve the corrosion resistance of steel sheet, particularly for use within the automotive industry, has led to a dramatic increase in the use of coated steels in place of cold-rolled sheet steel. Galvanneal steel results from the post annealing of the zinc-coated steel sheet, in which iron and zinc are interdiffused to form an iron-zinc alloy coating. Within this alloy coating, four main iron-zinc phases, Zeta, Delta, Gamma-1, and Gamma may be present. Manufacture of the most suitable coating requires identifying which phases form during the galvannealing process, an understanding of the properties of each phase and …

Superheating Of Bi(0001), E. A. Murphy, H. E. Elsayed-Ali, J. W. Herman

Electrical & Computer Engineering Faculty Publications

Superheating of Bi(0001) by about 90 K above the bulk melting temperature is observed using time-resolved reflection high-energy electron diffraction with ∼200-ps time resolution. Larger temperature excursions above the bulk melting temperature result in melting accompanied by irreversible laser damage to the surface. The rhombohedral structure of Bi leads to very different behavior of material parameters upon melting as compared with fcc metals. Therefore, our observation of the superheating of Bi(0001), together with the previously observed superheating of Pb(111), suggests the generality of the superheating phenomenon.

A Method For Improving The Accuracy In Phase Change Heat Transfer Data Through Increased Precision In Thermophysical Property Determinations, John Philip Drummond

Mechanical & Aerospace Engineering Theses & Dissertations

Wind tunnel model materials typically have thermophysical properties that vary with both position and temperature. A numerical study using a finite difference representation of the heat conduction equation has been performed on several of these model materials to determine their thermal response under a specified heat loading. This study has confirmed the feasibility of using an effective thermophysical property to account for the existence of variable thermal properties when a model undergoes aero­ dynamic heating. The effective property, when used in the reduction of phase-change heat transfer data, forced agreement of the actual transient behavior of a model with the …