Engineering Commons^™

Electrochemical Monitoring Of Electrogalvanizing Solutions, Thomas J. O'Keefe, S. F. Chen, E. R. Cole, M. Dattilo

Materials Science and Engineering Faculty Research & Creative Works

The corrosion resistance of steel is vastly improved when a zinc cathodic protective layer is applied. In recent years there has been renewed interest in producing this galvanized coating electrolytically. As with many deposition processes, the control of the operating parameters is very important in order to produce good quality zinc coatings. The homogeneity, ductility and smoothness of the zinc layer are critical. These factors are usually influenced by the electrochemical nature of the solution and organic additives are often used to assist in control. Studies on the polarization behavior of solutions for electro galvanizing electrolytes were made. Cyclic voltammetry …

28th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 28th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, August 3-7, 1986.

Isolation And Characterization Of The Dimers Formed In The Free-Radical And Anionic Initiated Polymerization Of Alpha-Methylstryene, Kevin S. Bosman

Masters Theses

No abstract provided.

Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Preparation Of Perovskite Pb(Mg1/3nb2/3)03 Using Pb3nb208 And Mgo, Jyoti P. Guha, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The synthesis of perovskite Pb(Mg1/3Nb2/3)O3 from an equimolar mixture of Pb3Nb208 and MgO was studied by solid‐state reaction techniques. An addition of 1 wt% excess MgO to the stoichiometric composition enhances the formation of the cubic perovskite phase. The absence of free PbO in the initial starting materials minimizes the volatilization loss during firing, thereby reducing the possibility of any compositional change and resulting in a substantial improvement of the perovskite phase purity over the conventional mixed‐oxide processing. Copyright © 1986, Wiley Blackwell. All rights reserved

A Study Of Problem Lead-Zinc Ores Of Southeast Missouri In Terms Of Mineralogy And Galena Oxidation, Michael G. Schroer

Masters Theses

"Recovery problems encountered at some of the St. Joe Lead Company's milling facilities prompted the study of 6 different ores. High and low grade ores had characteristics that varied from poor lead - zinc selectivity to excessive lead losses to the flotation tailings. Three ores from both the Fletcher and Viburnum mills were studied through flotation tests, mill water analysis, and ore analysis using an ore microscope.

The major cause for poor recovery was found to be due to ore oxidation. Not only was lead, in the form of oxides, reporting to the tails, but high levels of copper ions …

Characteristics Of A Stirred Bed Reactor Used For Gas-Solid Reactions, Christine Joy Beyke

Masters Theses

“A fluidized bed gas-solid reactor was designed and tested in which most of the fluidization energy is provided by a helical stirrer, with gas being used primarily as a reactant. The bulk gas in which the particles are suspended is practically constant in composition except for the area immediately adjacent to the gas inlet. The reactor is capable of withstanding temperatures up to at least 800°C and can be used with a wide range of flow rates. It is intended primarily as a laboratory tool, with the potential to be scaled up to multikilogram size.

The reactoor is a useful …

Influence Of Oxygen Activity On The Lattice Parameters And Thermal Expansion Of Mg And Sr-Doped Lacro₃, Sutham Srilomsak

Masters Theses

"Lanthanum Chromite, when used as the fuel cell interconnector material is exposed to extremely different oxygen activities on its two surfaces. In addition, it must also form coherent boundaries with the fuel electrode (anode) and air electrode (cathode) layers. In order to accomplish these functions the acceptor doped LaCrO₃ must not only be chemically stable over large oxygen activity ranges, but also have good thermal expansion coefficient of match with both the anode and cathode. Therefore, the objective of this study is to investigate these requirements for Mg and Sr doped LaCrO₃. The study was divided into …

The Effect Of Oxygen Partial Pressure On Oxygen And Carbon Incorporation In Czochralski Grown Single Crystal Silicon, Paul Shane Carter

Masters Theses

"The study herein detailed was made to determine the effect of varying the oxygen partial pressure of a Czochralski type crystal pulling furnace using conventional hardware and remelt silicon on the level of incorporated oxygen and carbon in the single crystal. The oxygen partial pressure was measured by a zirconia type oxygen sensor and controlled by additions of hydrogen or carbon dioxide to the argon purge gas. The oxygen and carbon incorporation measurements were made by the Fourier Transform Infrared (FTIR) method, using the American Standard for Testing Materials (ASTM) standard calibration.

During the study boules which were zero dislocation …

An Investigation Of The Low Voltage Failure Mechanism In Multilayer Ceramic Capacitors, Christopher John Brannon

Masters Theses

"Enhanced leakage current was induced into multilayer ceramic capacitors by the introduction of micro-cracks. These cracks extended from the surface through the electrode layers and were formed by means of thermal shock. The capacitors were then exposed to a low voltage bias and a humid atmosphere. Results indicated that a simple electrolytic solution mechanism may be responsible for the increased conduction, and that the proposed dendritic growth mechanisms may be more complex than necessary"--Abstract, p. ii

Reaction During Sintering Of Barium Titanate With Lithium Fluoride, Jyoti P. Guha, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The reactions occurring during sintering of stoichiometric BaTiO₃ with small additions of LiF were studied at temperatures between 700° and 900°C. BaTiO₃ reacts with LiF to form a cubic solid solution and Li₂TiO₃ During sintering, the cubic solid solution coexists with Li₂Ti0₃ and forms a liquid phase at 740°± 5°C. The occurrence of a liquid phase at this temperature results in an enhancement of the sintering process and leads to the development of a highly dense microstructure. Copyright © 1986, Wiley Blackwell. All rights reserved

Glass Experiments In Space, Norbert J. Kreidl

Materials Science and Engineering Faculty Research & Creative Works

Current and potential glass research under microgravity includes studies of minimum cooling rate, homogeneous nucleation, diffusion, surface tension and enrichment, fining without buoyancy, avoidance of liquid phase separation, gel synthesis, composites and uniform micro balloons. The experiments do not just anticipate space fabrication but will also provide information and innovation encouraging advanced processing on earth. © 1986.

Reply, Paul W. Angel, Chandra S. Ray, Delbert E. Day

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Tspc/Dc Measurements On Barium Titanate, Harlan U. Anderson, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

Thermally-stimlated polarization / depolarization current (TSPC / DC) measurements were made on high-purity doped and undopod BaTiO3 as a function of applied field, heating rate, dopant level, and Ba:Ti ratio. The form of the TSPC/DC curves is dependent upon both the resistive and ferroelectric properties of BaTiO3. For TSPC spectra, current peaks are exhibited due to the change in in magnitude and direction of the spontaneous polarization with changing crystal structure. In particular, whether the phase transition is first or seoond order influsnaes the existence and magnitude of the current peaks. TSDC measurements are essentially dynamic pyroelectric measurements and as …

Oxidation Kinetics Of Polycrystalline Srtio₃ And Lacro₃, Chi-Kung Jerry Yu

Doctoral Dissertations

"The oxidation kinetics of polycrystalline SrTiO₃ and LaCrO₃ were determined by measuring the time and temperature dependence of the weight and conductivity change of reduced samples. A region of fast diffusion followed by a reduced diffusion tail was observed in the TGA measurements. This observation can be interpreted as the initial diffusion along the boundaries and then spreading out into the lattice. The absence of the tail in the conductivity measurements is due to the high electron and hole mobility at the boundaries. The electrical conductivity and TGA results on Nb-doped LaCrO₃ show that at low oxygen …

Silicon-On-Insulator Technology By Crystallization On Quartz Substrates, Helmut Baumgart

Electrical & Computer Engineering Faculty Publications

The purpose of the novel zone-melting recrystallization process (ZMR) is to produce single crystalline Si films on Si02 of high crystalline perfection, which are suitable for device fabrication and subsequent industrial applications. However, silicon films grown on amorphous insulating substrates without seeding contain regularly spaced subgrain boundaries as their predominant growth defect and to a lesser degree twin boundaries and some grain boundaries. Detailed materials studies have revealed the core structure of these extended defects and the fundamental mechanisms responsible for subgrain boundary formation. The nature and origin of subgrain boundaries is reviewed and a model for polygonization of the …

Relationships Between Casting Features And Cavity Fill Time, Gate Velocity, And Gate Area For Aluminum Die Castings, Hsin-Yen Chen

Dissertations and Theses @ UNI

The purpose of this study was to investigate the relationships between casting features (including weight, average thickness, surface area, and outside diameter) and casting process variables (including cavity fill time, gate velocity, and gate area) for aluminum die castings. Historical data of good quality aluminum round castings of the Kiowa Corporation in Marshalltown, Iowa, were used in the correlation analysis. The correlation analysis consisted of determining the following:

(1) the correlation of one casting process variable and one casting feature.

(2) the multiple correlation of one casting process variable and a combination of several casting features.

The results of statistical …

Utilization Of A Carbon-Dioxide Laser To Form An Amorphous Metallic Layer On Gray Cast Iron With Various Amount Of Boron, Majid Torkzadeh Tabrizi

Dissertations and Theses @ UNI

The study of the amorphous metals in important because of their technological usefulness. One class of these materials, iron-based metallic glass, has shown great promise in application because of the superior chemical, mechanical, electrical, and magnetic properties of these materials.

This study was conducted to examine the capability of a medium-powered carbon-dioxide laser to form an amorphous metallic layer on the surface of a ferritic gray cast iron in order to improve the wear and corrosion resistance of engineered components. Boron was used as an alloying element for the retardation of nucleation and for the formation of the amorphous metallic …

An Assessment Of The Possible Use Of Air Cushion Systems To Assist The Development Of Egyptian Deserts, Baha Elsayed Attia Abulnaga

Archived Theses and Dissertations

No abstract provided.

Microencapsulation As An Alternative To Emulsification For Preparing As A For Use In Papermaking, William J. Corriveau

Masters Theses

The sizing chemical ASA is emulsified to make i t compatible with the papermaking process. Unfortunately, emulsified ASA is chemically reactive with water at the elevated temperatures found in papermaking systems. As an alternative, encapsulated ASA was made and investigated for its stability towards water at elevated temperatures.

A handsheet procedure was developed to analyze emulsified and encapsulated ASA. It was concluded that the procedure gave statistically reproducible results. Investigations with the procedure revealed important variables concerning the laboratory and m ill application of ASA. Evidence indicated that retention of ASA was critical to sizing development.

Encapsulated ASA made for …

Effect Of Grain Characteristics On Liquefaction Potential—In Search Of Standard Sand For Cyclic Strength, Isao Ishibashi

Civil & Environmental Engineering Faculty Publications

Since the original Monterey 0 sand, which had been used for cyclic triaxial testing system calibration, is not available any more, the search for an alternative sand was started. In order to provide useful information for the above purpose, liquefaction potentials were evaluated for Monterey 0 and 0/30 sands and for ASTM Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube) (C 109) Ottawa sands from various sources. The results clearly indicated that the liquefaction potential was very sensitive to slight changes in material properties (mean grain size, coefficient of uniformity, sphericity, and volume decrease …

New Specimen Design For Studying The Growth Of Small Fatigue Cracks With Surface Acoustic Waves, Blair London

Materials Engineering

The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate-type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25-μm deep surface pit produced by an electrospark machine. The importance of studying these

27th Rocky Mountain Conference

Rocky Mountain Conference on Magnetic Resonance

Program and abstracts from the 27th annual meeting of the Rocky Mountain Conference, co-sponsored by the Rocky Mountain Section of the Society for Applied Spectroscopy and the Rocky Mountain Chromatography Discussion Group. Held in Denver, Colorado, July 14-18, 1985.

Removing Fluoride From Drinking Water By Organic Polymers, Eleni Davou Achilleos

Civil & Environmental Engineering Theses & Dissertations

Fluoride is a substance that can provide beneficial or detrimental effects depending on the total amount ingested. Naturally occurring high fluoride concentrations exist in many drinking water supplies. The fluoride removal methods developed in the past have been found to be either impractical and/or not cost effective.

The purpose of this study was to determine whether organic polymers can effectively remove fluoride. The water used in this study contained naturally occurring fluoride concentrations between 4.5 to 5.5 mg/1 and it was collected from the City of Franklin, Virginia, water supply system. Laboratory jar test procedures, which simulated a conventional water …

Electronic Absorption Spectra Of Ni (Ii) In Sodium Phosphate And Sodium Fluorophosphate Glasses, Tarek Mostafa Sami Genena

Archived Theses and Dissertations

No abstract provided.

Deformation And Fracture Of Some Aluminium-Magnesium Alloys Under Impact Compressive Loading, Mohamed Ibrahim Hamed

Archived Theses and Dissertations

No abstract provided.

Ion-Exchange And Surface Properties Of Titania Gels From Ti (111) Chloride Solutions, Suzan I Khairy Seleem

Archived Theses and Dissertations

No abstract provided.

Structural Self-Shadowing And Its Effects On The Thermal-Structural Behavior Of Orbiting Trusses, Jack Mahaney

Mechanical & Aerospace Engineering Theses & Dissertations

The determination of structural shadowing is described. The computation of environmental heat loads for slender structural members in earth orbit is described, and two methods for finite element thermal analysis are described . The effects of self-shadowing on the thermal structural behavior of single truss members and two different trusses are presented. In each case the shadowing produces a noticeable effect on the temperature distributions on truss members, and on the deformations of the trusses.

Flake Aligner Including Reciprocating Baffles, Tauno B. Kilpela

Michigan Tech Patents

Apparatus for forming a loosely felted mat of elongated wood flakes, the wood flakes being aligned in parallel relation and parallel to the longitudinal direction of the mat. The apparatus includes a former for depositing wood flakes on a support surface in a uniformly dispersed, loosely felted relation, and a plurality of vertically oriented baffles positioned below the former and in mutually parallel alignment. The baffles are reciprocated in the direction of the mat to cause flakes lying across the baffles to fall between the baffles and to be aligned with the longitudinal direction of the mat.

High-Temperature Redox Behavior Of Doped Srtio3 And Lacro3, Harlan U. Anderson, M. M. Nasrallah, B. K. Flandermeyer, A. K. Agarwal

Materials Science and Engineering Faculty Research & Creative Works

The stability of high-temperature fuel cell electrodes to their ambient environment is important for the long-term reliability of fuel cells. In this report the behavior of oxide electrode materials as a function of oxygen activity and temperature is considered. Models for the oxidation-reduction behavior of both p- and n-type oxides are presented. These models take into account the absorption and evolution of oxygen which take place as oxygen activity is varied. The resulting instability in electrical conductivity is explained as a consequence of changes in carrier concentration due to variability in ionic defect concentration. The proposed models are applied to …