Metallurgy Commons^™

The Effect Of Near-Surface Metallurgy On The Machinability Of Cast Iron, William Dewey Peach

Masters Theses

"The increasing performance and durability of cutting tool inserts have created metallurgical challenges for production foundries to produce near-net shaped castings within strict dimensional tolerances. In order for foundries to take full advantage of the increased cutting speed capabilities, it becomes necessary to reduce machining allowances and produce much more stable casting surfaces. To accomplish this, a better understanding of the complex microstructures formed within the first 0.120 in. (3 mm) of the mold/metal interface (as-cast surface) is necessary. The goal of the work presented here was to examine the microstructures formed in the near-surface region of gray iron castings, …

Thermal Characterization And Vibration Of Solder Alloys, Brandon Lee Brinkmeyer

Masters Theses

"Recent legislation and growing environmental concerns have forced the electronics industry to discontinue the use of tin-lead (SnPb) solder. Although the legislation did not directly affect aerospace and defense industries, future transitions to lead-free (LF) solders are inevitable. Differences exist between these high reliability systems and consumer electronics, first of which is a very small production rate and a long life cycle which often leads to repair or rework procedures which introduce the potential for mixing of SnPb and LF solder. In this study, Sn-3Ag-0.5Cu (SAC305) was mixed with Sn-37Pb solder in amounts of 0, 25, 50, 75, and 100 …

Elevated Temperature Behavior Of A Magnesium Based Bulk Metallic Glass, Neal C. Ross

Masters Theses

"Bulk metallic glasses are a new material set that possess interesting and exceptional engineering properties. Their study has been a major focus of research in metallurgy since the early 1990s, and recently their properties have led to application in specialized applications. Limitations including material cost, maximum attainable cast diameters, and high density have prevented the widespread use of these materials. In particular, the high density of most bulk metallic glasses has significantly reduced their appeal to the aerospace community. In an effort to overcome this, research is being performed on producing lower density glass forming systems based on magnesium and …

Age Strengthening Of Gray Cast Iron: Alloying Effects And Kinetics Study, Thottathil Viswanathan Anish

Masters Theses

"Age strengthening of gray cast iron has become a critical issue with metal casters trying to optimize their process for the closest conformance to properties. This necessitated more robust and precise methods to predict age strengthening. Most foundries use age strengthening behavior to cast at hight carbon equivalents to facilitate smaller gating systems. Also, it is well known in the casting industry that the tool life improves with aging. Hence these foundries require a model to predict aging behavior and accelerate the mechanism from days to hours. This research focuses on the methods of composition adjustments to control aging properties, …

Texture And Residual Stresses On Nanocomposite Coatings, Hussam E. Aikhasawneh

Masters Theses

Nickel was electroplated on cold-rolled 2024-T3 aluminum. The coating was done with reinforcement by nanoparticles of y-alumina or silicon carbide. For comparison, nickel-only coatings were done too. Rectangular samples were coated in nickel sulfamate bath with no particles to determine the optimum coating conditions. The optimized parameters were the current density, time of coating, and agitation rate. After coating conditions were established, composite samples were coated using these conditions. The coated layer was characterized by measuring: thickness, residual stresses, and crystallographic preferred orientation. The coated layer was tested by SEM for evaluation of the quality of the coatings. The presence …

Microstructural Characterization Of Rapidly Solidified And Extruded Ti-Al-Nb Alloys, Danny Joe Edwards

Masters Theses

"Two titanium alloys have been characterized using transmission and scanning electron microscopy, X-ray diffraction, and optical metallography techniques. Both of these alloys were rapidly solidified by melt spinning, the resulting ribbons pulverized, and the powders then extruded into cylindrical billets. The alloys are based on the compositions Ti-21.3Al- 9 Nb-0.6-Mo-2.6V and Ti-13.2Al-2.6Nb-0.5Mo-0.9V-0.5Zr-3.1B in atomic percent. The first alloy was examined in both the as-extruded condition and in the annealed condition (looo0c for 12 hours). The second alloy was examined in the as-extruded condition only.

For the first alloy, the as-extruded microstructure consisted of a B2 matrix with alpha-2 particles at …

Fluid Dynamics Of An Atomizer Nozzle, Bhaskar Sengupta

Masters Theses

"A pilot plant gas atomizer was designed and assembled at the Center of Pyrometallurgy, U.M.R., to produce metal powders. The pilot plant utilizes a confined, annular, supersonic nozzle to yield spherical metal powders (aluminum and zinc alloys have been atomized) of average size of 15μm in diameter.

A cold model of the atomizing nozzle was constructed to simulate the pilot plant. First, the high-speed gas flow was studied and later, modelling of the atomizing process was carried out by using water as the atomized liquid. This work has investigated the complex gas flow in the converging-diverging nozzle and around the …

Effects Of 0.5 Weight Percent Boron On Cobalt Aluminide, Kevin Thomas Slattery

Masters Theses

"A study was made on the effects of adding 0.5 weight percent boron to the ordered intermetallic Cobalt Aluninide. Thirty gram (30g) specimens were induction melted in an pure argon atmosphere and cast into a copper alloy bar mold. The addition of boron raised the modulus of rupture from 30.1 to 44.3 ksi; increased the Knoop microhardness from 543 to 693; reduced the average grain size from 190 to 70 microns; and gave a more equiaxed grain structure. X-ray diffraction detected the presence of a second phase, AlB , 12 in the material containing boron. Scanning electron micro-scopy revealed that …

Influence Of Prior Deformation On Structure And Properties Of Heat Treated Aluminum Casting Alloy, Chungwei Hsia

Masters Theses

"A1 356 alloy is extensively used for a wide variety of casting applications. The structure is composed of primary dendrites and eutectic silicon formed during the eutectic reaction. It has long been recognized that the shape of the eutectic silicon significantly affects the ductility of the alloy. Traditionally, the morphology of the silicon is changed by certain chemical and/or thermal processes to improve the ductility. Mechanically deforming the castings to "modify" the shape of silicon has been shown by this research to be an effective alternative method to improve the spheroidization rate of eutectic silicon during heat treatment. The best …

Reductive Stripping Of Iron(Iii) From Di(2-Ethylhexyl) Phosphoric Acid, Byron G. Belew

Masters Theses

"Unwanted impurities, present in raw materials, are often coextracted along with desired constituents during leaching. If left unchecked, impurity levels may increase in hydrometallurgical process streams until their presence has deleterious effects upon subsequent unit processes. Due to its abundance and ease of extraction, the presence of ferric iron in solvent extraction circuits has always been a problem. The technique proposed herein constitutes a novel approach to remove iron from zinc hydrometallurgical circuits; but the principles employed may find a variety of applications.

This research investigated the reduction and stripping of ferric iron from di(2-ethylhexyl) phosphoric acid into a …

Characterization Of The Fluid-Dynamic Mixing Of A Bottom Gas-Injected Channel Reactor Using Low-Temperature Modelling, Jay Bernett Gassel

Masters Theses

"Variables influencing the mixing in a single-phase (30.5 x 60 x 606 cm) and a two-phase (20 x 40 x 200 cm) channel reactor model were studied. Tracer and/or neutral density particle techniques were used to determine an eddy diffusivity, De, for the system(s). Three bubbler arrangements were investigated in the one-phase work. A separate apparatus was developed to withstand the corrosiveness of the tetrachloroethylene used in the two-phase work.

Both the electrical conductivity tracer technique and the neutral density particle technique were shown to be feasible experimental techniques for determining an eddy diffusivity in the systems studied. Decreasing liquid …

Formability Of 356 Aluminum, Karol Krumrey Schrems

Masters Theses

"Although aluminum casting alloys are not often thought of as being formable, this thesis examines this possibility. Aluminum alloy 356 was cast in permanent molds and subsequently deformed by rolling (providing compressive loading) and bending (providing tensile loading). Cold forming was found to be very limited, while forming at elevated temperatures was comparatively easy and permitted reductions of up to 90%. Tensile properties and microstructures were examined in detail. Forming breaks up the eutectic silicon and intermetallic compounds. The yield strength and tensile strength increased almost linearly with increasing total percent reduction. The elongation at first increases with total percent …

The Use Of Computerized Data Acquisition Techniques To Measure The Kinetics Of A Batch Flotation Process, Jose Antonio Barrera-Godinez

Masters Theses

"The flotation response of a lead ore was measured by utilization of a computer driven data acquisition system. A symmetric, fast and automatic froth removal and weighing system was attached to a conventional laboratory flotation cell. The rate controlling mechanisms were identified by manipulation of the froth removal rate, (FRR), froth layer thickness, (FT), and air flow rate, (AFR). The production of froth, water, solids and value in addition to value recovery and concentrate grade were determined as a function of time of flotation.

The flotation response was controlled by events dependent of AFR when using shallow froths of less …

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 …

Electrogalvanizing And Drawing Of Steel Wires, Thomas Joseph O'Keefe Jr.

Masters Theses

"The effects of varying current density, temperature, Zn⁺² and licorice concentrations on the morphology of the zinc deposited on steel wire have been studied and compared. The plated wires were then drawn and evaluated in terms of required drawing energy and zinc loss during processing of up to 40% reduction in area. Scanning electron microscope and X-ray diffraction were used to evaluate the electrodeposits"--Abstract, page ii.

The Role Of Boron In So32 And So43 Steels, Sunil S. Moghe

Masters Theses

"In this project study was conducted with the goal of understanding the role of boron involved in structure-toughness property relationship for SO32 and SO43 steels. For a standard heat-treatment of austenitizing (1 hr.) at 1700°F, water quenching and 1 hr. tempering at 1150°F SO32 steel (with 37 ppm B) lacked in toughness, while SO43 steel (with 2 ppm B) showed good toughness. In both steels all the boron was present in the form of "soluble boron" i.e., Fe₂₃ (B,C)₆ borocarbide. Experiments were carried out to study the effect of various heat treatment parameters on the precipitation behavior of …

Solid Solubility Of Sulfur In Transition Metal Oxides And Stability Of Sulfates Relevant To Roasting Processes, Zeynal Karakus

Masters Theses

"Two types of sulfur equilibration experiments were carried out in this study using either a conventional thermal gravimetric analysis (TGA) technique or a horizontal tube furnace apparatus. Samples were equilibrated with flowing SO₂-O₂ gas mixtures of either 58% SO₂ or 10% SO₂.

The types of experiments were:
1. Investigation of the extent of solid solution of sulfur in ZnO, NiO, CuO, and Fe₂O₃ over a wide range of temperature.
2. Studies of compound or solid solution formation between binary sulfate mixtures of Fe-Zn, Cu-Zn, Ni-Zn, Fe-Cr, and Cd-Zn by TGA.

The …

Ion Implantation For Improvement Of Wear Properties Of Steels, Kenneth W. Burris

Masters Theses

"Previous research on ion implantation at U.M.R. has dealt with the development of a modified Falex Lubricant Tester as a valid wear test and its use in dose curve determination. Our recent work uses Auger surface analysis and scanning electron microscopy to gather support for a model that will tie together some of the many theories proposed as to why ion-implantation improves the surface related mechanical properties of steels"--Abstract, page ii.

The Effect Of Selected Alloying Elements On The Hardness And Microstructure Of Ductile Cast Iron, Chi-Hua Edward Tseng

Masters Theses

The effects of cooling rate and alloying element on the matrix structure, nodule count and hardness have been studied in this investigation.

Recommendations for producing ferritic ductile iron have been made and the relationship between hardness and pearlite percentage has been obtained in this study.

Separation Of Mineral Particles In Cyclones Under The Influence Of A Magnetic Field, Kwasi Amoako-Gyampah

Masters Theses

"The separation of mineral particles in a cyclone under the influence of a magnetic field was investigated using an electromagnetic - cyclone arrangement. Feed pulps of dolomite and magnetite were used in the study. Two different cyclone types were investigated: An air-type cyclone arrangement and a conventional cyclone arrangement. Magnetic field strengths of 0 to 3000 gauss (0 - 0.3 Tesla) were used in the study by varying the current through the coils of the electromagnet .

The parameters evaluated in the study were the grades and recoveries of the magnetic concentrates produced, the enrichment ratios, the improvement in recoveries …

Drawing Characteristics Of Electrogalvanized Steel Wires., Chi-Yuan Tsao

Masters Theses

"As a means of investigating the often adverse drawing behavior of electrogalvanized steel wire, drawing experiments were conducted on a variety of industrially-supplied and laboratory-prepared electroplated steel wires. Back-flow and shaving appeared to be the mechanisms by which sizeable zinc losses occurred. Performance during drawing and the quality of the product depended upon both the characteristics of the plating and the drawing process variables. Grain size, grain texture, and surface 'flatness' can affect the required drawing force, surface finish and level of zinc retention. Low die angles and large reductions offered greatest efficiencies with minimum zinc loss"--Abstract p. ii

A Metallurgical Evaluation Of The Mi Vida Prospect: A Mixed Copper Sulfide-Carbonate Ore Body, Sells, Pima County, Arizona, Kevin Michael Kenney

Masters Theses

"A copper-prospect in south-central Arizona has been evaluated on a metallurgical basis. Primary chalcocite and secondary covellite, plus the copper oxides malachite and brochantite, constitute the economic mineralization. The deposit outcrops as a steeply dipping (70°SW), intensely brecciated, copper-bearing quartz vein with discontinuous lenticular ore shoots.

Acid leaching techniques alone and in conjunction with froth flotation utilizing four copper oxide specific collectors were used to evaluate the amenability of this ore to processing. Direct acid leaching was examined and found to be ineffective. Removal of the chalcocite by froth flotation with xanthate was easy and gave better results to subsequent …

Recovery Of Lead From Lead Smelter Mattes, Cheng-Ping Chang

Masters Theses

"A by-product of lead smelting is a matte which consists mostly of lead and copper sulfides. Experiments were conducted to determine the feasibility of removing lead from molten matte by adding iron as a reducing agent. The effectiveness of iron at 1000 and 1100°C was a function of matte composition, but not of temperature except near iron saturation. The lead content of matte could be decreased to as low as 9.0 to 11.6 wt pct (2.3 to 3.0 at. pct) at 1000°C, depending on composition. The effect of oxygen in the matte on lead recovery from iron-saturated mattes was also …

Pelletizing Of A Lead Sinter Machine Feed, Hung-Yang Tsai

Masters Theses

"A typical lead sinter machine feed can be pelletized in a drum pelletizer using tap water as a binding liquid. The green pellets produced have return sinter as cores, and an outer layer of new material and fluxes. The moisture content of the pellets produced is about 5%. The pelletizing procedure developed used raw materials from the Amax Lead Smelter, with only a minor amount of feed preparation. The importance of proper moisture control, use of binders, method of adding moisture, speed of pelletizing drum, etc. were investigated. The stability of pellets under extreme storage conditions was also determined"--page ii.

Molybdenum Stability In Coal Slags At 1400⁰C: Corrosion Properties For Mhd Electrode Applications., Kenton Brian Wright

Masters Theses

"Molten coal slag corrosion studies conducted on molybdenum at 1400°C used static and stirred slag experiments and electrical current experiments to parallel electrode conditions of slagging duct MHD generators. Crucibles containing molybdenum and slag were exposed to combustion-type gases in a tube furnace. Carbon monoxide-carbon dioxide gas mixtures controlled oxygen partial pressures at selected values between 10^-11 and 10^-3 atm. Metallograph and microprobe examination of polished sample sections defined corrosion characteristics.

At 1400°C, molybdenum metal is stable below 10^-9 atm oxygen pressure. Molybdenum dioxide is stable at higher pressure, but volatile molybdenum trioxides prevent formation of stable …

Processing Of Copper Refinery Anode Slimes, Shrirang Anant Kulkarni

Masters Theses

"A study of commercial copper refinery anode slimes has been conducted to evaluate the separation of valuable metals contained in the slimes. The slimes contain substantial quantities of Ag, Sn, Au, Pb, and Cu. The values were present principally as AgCl, SnO₂, Au, PbSO₄, Cu and CuSO₄.

A Roast-Leach-Roast-Leach (RLRL) technique solubilized up to 91 pct of the Ag and 99 pct of the Cu from raw slimes.

The Pb-Sn separation was investigated using the following hydrometallurgical techniques: 1) DETA (diethylene triamine) leaching; 2) NaOH leaching; 3) (NH₄)₂CO₃ leaching; …

Electroless And Chemical Metal Deposition On Human Tooth Enamel., Richard Doyle Christie

Masters Theses

"Initial investigations have confirmed the feasibility of depositing an adherent metal film onto tooth enamel. Such films might be used as pit and fissure sealants in preventive dentistry, with denture or orthodontic work, as an intermediate substrate with various organic or inorganic restorative materials, or other such areas. The process employs chemical solutions containing ions of the metal to be deposited and suitable reducing agent solutions.

To date, metallic copper and silver films have been plated onto teeth in vitro. The deposits are quite adherent and appear to exhibit the conductivity, crystal structure, luster, hardness, and other chemical and physical …

Variables Affecting The Rate Of Solution Of Mold Inoculants In Cast Iron, Jose Osorno Fonnegra

Masters Theses

"The purpose of this investigation was to measure the effectiveness of an inoculant alloy reacting with molten cast iron in a reaction chamber properly located in the gating system.

The chemical composition of the gray iron was held constant while several metallurgical factors were varied to produce test samples with different cementite thicknesses. These chill depths were measured as an indication of the inoculation effectiveness.

Appreciable differences in chilling tendency were observed within the different variables studied. The results indicate that pouring temperature, as well as the other variables studied, are of considerable importance when dealing with inoculation of gray …

The Spheriodization Of Tool Steels., Siri Ram Rai

Masters Theses

"Four different tool steels--AISI 01, Sl, A9 and Tl5--were obtained in the 1/2-inch diameter hot rolled and air-cooled condition from the steel mill. The lower critical temperatures of these steels were determined. The spheroidization of each steel by three different spheroidizing procedures was evaluated with the use of hardness testing and metallographic techniques. Isothermal annealing completely spheroidized each steel yielding coarse carbides and low hardness. Cyclic annealing was an effective spheroidization procedure only for 01 and Tl5 steels. Hardening and tempering resulted in rather fine spheroidized structures in these steels. The total time consumed to produce the best spheroidized structures …