Metallurgy Commons^™

Solidification Modeling Of Centrifugal Casting, Stephen M. Lane

Opportunities for Undergraduate Research Experience Program (OURE)

This paper describes the methodology used to estimate the solidification time of castings produced by processes in which normal thermal analysis cannot be used, such as centrifugal casting. This methodology utilizes the relationship between microstructure, in particular secondary dendrite arm spacing (SDAS), and freezing time. Using this method it is shown that position within the casting and casting geometry affect the SDAS and freezing time. However, the SDAS did not vary across the wall section due to differences in filling pattern compared to sand casting. Further research is necessary to determine filling pattern effects on microstructure.

Electrochemical Technique For Evaluating Surface Area Of A Treated Copper Foil, Gregory Lea

Opportunities for Undergraduate Research Experience Program (OURE)

In order to increase the strength of copper foil bonded to a polymeric substrate material, a dendritic layer is electrodeposited onto the foil. Treating the foil in this manner causes its surface to be rough and porous, thus providing for better penetration of the adhesive and a greater surface area for bonding. The process is particularly helpful in the manufacturing of printed circuit cards, due to the added bond strength which greatly enhances the durability of the printed circuit cards.

The Influence Of Matrix Microstructure, G. M. Vyletel, J. E. Allison, David C. Van Aken

Materials Science and Engineering Faculty Research & Creative Works

The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and artificially aged 2219/TiC/15p and unreinforced 2219 Al were investigated utilizing plastic strain-controlled and stress-controlled testing. The cyclic response of both the reinforced and un-reinforced materials was similar for all plastic strain amplitudes tested except that the saturation stress level for the composite was always greater than that of the unreinforced material. The cyclic response of the naturally aged materials exhibited cyclic hardening and, in some cases, cyclic softening, while the cyclic response for the artificially aged materials showed no evidence of either cyclic hardening or softening. The …

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 Study Of Fatigue Failure In Superalloys Using Positron Annihilation, D. Hoeckelman, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

This study shows there are significant changes occurring in the open volume defect concentration during fatigue cycling as measured by the S parameter. These changes are dependent upon the stress ratio, R = σmin/σmax, the maximum stress, σmax, and the number of fatigue cycles. The decline in the S parameter is due to the elimination of the residual vacancies. This decline is followed by an increase due to the generation of dislocations and the formation of small microcracks. This is followed by a decline in the S parameter due to growth of the microcracks ultimately leading to failure. Copyright © …

Galvanic Stripping Of Fe⁺³ And Pb⁺² Ions And Dissolution Of Metallic Fe, Zn, Pb And Cd Using Di(2-Ethylhexyl)Phosphoric Acid, Luis Miguel Chia Aquije

Doctoral Dissertations

"Two systems were evaluated using the principles of the galvanic stripping process. One of them, the removal of Pb⁺² ions from di-2(ethylhexyl) phosphoric acid (D2EHPA) was performed using metallic zinc. The other, the removal of Fe⁺³ ions from D2EHPA used metallic iron as reductant and was performed simultaneously with the organic phase using a slightly acidic aqueous solution of hydrochloric acid. In addition, the dissolution of metallic zinc, iron, lead, and cadmium in D2EHPA was studied in order to better understand the anodic step in the mechanism of the galvanic stripping process.

Increased temperature was found to dramatically …

Investigation Of Fatigue Behavior In Notched Cross-Ply Titanium Metal Matrix Composite At Elevated Temperature, Robert P. Baker

Theses and Dissertations

The objective of this research was to investigate the initiation and progression of damage which develops in notched (0/90)_2S SCS-6/Ti-15-3 at elevated temperature. Testing consisted of a monotonic tensile test at 427°C followed by fatigue testing performed under load control with a stress ratio of 0.1 at a frequency of 10 Hz. A crack was defined to have initiated when it had attained a length greater than or equal to 0.124 mm. Crack initiation and progression was monitored by strain and modulus observations and visual inspection via telemicroscope. The cracks were recorded with edge and face replicas. Metallographic and …

Open And Filled Hole Static Tensile Strength Characterization Of Metal Matrix Composite Scs-9/Β21s, Jacob T. Roush

Theses and Dissertations

SCS-9/β21s has a reduced gauge thickness, in comparison with other metal matrix composites, due to a smaller diameter fiber. This reduced gauge thickness makes it an attractive candidate for the skin of hypersonic vehicles. Tensile testing of (0/90)_2s and (O/±45/90)_s laminates was performed at room temperature, 482°C, and 650°C. Both notched and unnotched specimens were tested. Notched specimens, open and filled hole, had a width-to-diameter ratio of six. Materials 7075-T6 and Mar-m-246 were used as pins in the filled hole tensile testing. Analytical work was completed to predict material properties, elastic and plastic stress concentration factors, residual stresses, …

Electrochemical Evaluation Of The Adherence Of Zinc To Aluminum Cathodes, Jang Sop Han, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

Excess fluoride ions in zinc electrolyte are known to cause problems with the removal of electrowon zinc from aluminum blanks. The mechanisms responsible for this undesirable adherence were studied. Acid zinc sulfate electrolyte similar to that employed in zinc electrowinning was used. Using electrolyte containing various fluoride ion concentrations, the initial nucleation and growth morphology of zinc and the aluminum electrode surface were examined using scanning electron microscopy. Electrochemical tests were also carried out in various solutions to obtain a better understanding of the polarization behavior of the system. © 1992.

The Effect Of Additives On The Nucleation And Growth Of Copper Onto Stainless Steel Cathodes, M. Sun, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

A potentiostatic technique has been used to study the effects of chloride ion, glue, and thiourea on the initial electrodeposition of copper. A stainless steel (AISI 304) rotating disc electrode (RDE) with an electrolyte containing 40 g/1 Cu²⁺ and 180 g/1 H₂SO₄ at 40 °C was employed. The current transients from the potential step measurements for the additive-free electrolyte could be fitted to a model that assumed progressive nucleation followed by growth of three-dimensional (3-D) centers under diffusion control. The growth mechanism and the type of nuclei were also confirmed by scanning electron microscopy (SEM) of …

The Degradation Of Aluminium Cathodes By Fluoride Ion During Zinc Electrowinning, J. S. Han, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The influence of fluoride ions on aluminum cathode surface degradation during zinc electrowinning has been studied. Electrolyte with a composition similar to that employed in plant operations has been used. A direct correlation is shown between the electrolyte fluoride content and the number of deposition cycles possible before zinc removal becomes difficult. The role of initial nucleation and starting electrode morphology is discussed in terms of the degree of adherence observed. Electrochemical tests have also been made on the electrodes at various stages of the process in an attempt to gain a better fundamental understanding of the mechanisms responsible for …

Stimulation Of Amorphizing Reactions In Co-Si Multi-Layers, Jeanne K. Jackson

Opportunities for Undergraduate Research Experience Program (OURE)

Co-Si multi-layer specimens do not normally amorphize. To possibly stimulate amorphization, Ti was added by evaporation and the specimens were annealed at 300 and 400 degrees Celsius. The results showed that amorphization occurred at 400 degrees Celsius in the presence of Ti, but did not occur at 300 degrees Celsius. Further research would be necessary to conclude whether the amorphization was stimulated by the addition of Ti or the temperature increase.

Effect Of Ultrasound On Acidified Brine Leaching Of Double-Kiln Treated Eaf Dust, J. A. Barrera-Godinez, Thomas J. O'Keefe, Johh L. Watson

Materials Science and Engineering Faculty Research & Creative Works

The U.S. steel industry produces approximately 500,000 tons/year of electric arc furnace (EAF) dust, which is classified as a hazardous waste. Increasing disposal costs of these dusts have encouraged studies to investigate treatment processes to render the material non-hazardous, and to possibly recover metal values. This research project was designed to examine the hydrometallurgical recovery of zinc from EAF dusts that have been treated by a double kiln fuming process. The test work consisted essentially of acidified brine leaching of the pelletized calcine to determine the influence of traditional conditions, such as acid concentration, temperature and agitation, plus the application …

Sme Annual Meeting. Phoenix, Usa. February 22-27, 1992, Johh L. Watson

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Solvent Extraction Reagent Entrainment Effects On Zinc Electrowinning From Waste Oxide Leach Solutions, M. Neira, Thomas J. O'Keefe, Johh L. Watson

Materials Science and Engineering Faculty Research & Creative Works

A considerable quantity of metal-containing waste oxide is generated by the primary metal industry, and under increased environmental regulation, treatment of these wastes has become viable. Hydrometallurgical processing is often appropriate and one potential treatment process for zinc oxide wastes involves leaching the oxide with an acid, purifying by a solvent extraction operation, and recovering metallic zinc by electrowinning the purified leach solution. The purification stage is frequently critical and the introduction of a solvent extraction organic reagent into the flowsheet can be detrimental to downstream processes. The object of this study was to determine the effect of organics, entrained …

Development Of An Automated Ultrasonic Inspection Cell For Detecting Subsurface Discontinuities In Cast Iron, John Scott Burningham

Dissertations and Theses @ UNI

Manufacturing of value added products by companies in todays global marketplace requires the vendors to meet certain minimum standards, SAE, ASTM, ISO, etc. In a global economy, as a manufacturer for the year 2000 and beyond, preferred vendors will become ISO 9000 certified to maintain a market share of produced goods.

An automated inspection cell was developed for the inspection of cast iron ports to detect subsurface discontinuities. The cell consists of an ultrasonic flaw detector (UFD), transducer, robot, immersion tank, computer, and software. Normal beam pulse-echo ultrasonic nondestructive testing is performed on each rough casting.

Using test blocks and …

A Wear Analysis Study Of Selected Alternative Foundry Tooling Materials Using Impact Abrasion Testing, L. Fred Vondra

Dissertations and Theses @ UNI

The purpose of this study was to simulate the wear characteristics of foundry tooling using an impact abrasion test apparatus. The wear characteristic was exhibited by non-metallic materials and was measured as a function of percentage weight loss and was benchmarked against Class 30 gray iron. The research question focused on whether or not a non-metallic material exists that exhibits comparable or superior wear characteristics to Class 30 gray iron for possible consideration as tooling materials for foundry applications. The information obtained adds to knowledge and is useful to foundry professionals in making tooling decisions.

The 34 test materials were …

Crack Growth Rate Modeling Of A Titanium-Aluminide Alloy Under Thermal-Mechanical Cycling, John J. Pernot

Theses and Dissertations

In this study, a model is developed to predict crack growth rates in a titanium-aluminide alloy under thermal-mechanical fatigue (TMF). This TMF crack growth rate prediction model, which requires only isothermal data to define its parameters, is distinguished from earlier models in two ways. First, it accounts for mechanical-fatigue and environmental crack growth rate contributions while it also considers a retardation mechanism thought to be caused by creep blunting of the crack tip. This is the first study to account for such a retardation mechanism during TMF. The second uniqueness of the model is that its general form can account …

Measuring Hydrogen In Galvanized Steels, Timothy O'Hearn

Opportunities for Undergraduate Research Experience Program (OURE)

There has been much investigation in the past concerning ways to eliminate the embrittling effects of hydrogen in galvanized steel components. Such galvanized parts are used extensively in the automotive industry. One solution that is commonly used is to anneal the galvanized parts at approximately 200 degrees Celsius for 4 to 24 hours. This annealing process does restore the ductility. However, very few if any experiments have been done to measure the amount of hydrogen released and the temperature dependence of the hydrogen release. This investigation is part of an on going effort to measure the hydrogen released from galvanized …

Calculated Point Defect Properties Of The Intermetallic Compounds Nickel Titanium (Niti) And Iron Titanium (Feti), Russell T. Lutton

Theses and Dissertations

Atomistic simulation with a modified version of the DYNAMO code was used to calculate the point defect properties of the intermetallic compounds nickel titanium and iron titanium. The calculated energies are believed to be experimentally accurate to within +/- 0.1 eV. Vacant Ni or Fe lattice sites were preferred and had energies of 6.356 eV for NiTi and 5.899 eV for FeTi. Removing a Ti atom resulted in a neighboring antisite defect caused by migration of a Ni or Fe atom into the vacant Ti site. These configurations had energies of 7.024 eV for NiTi and 6.336 eV for FeTi. …

Effects Of Sample Orientation On The Corrosion Of Zinc In Ammonium Sulfate And Sodium Hydroxide Solutions, D. Abayarathna, Edward Boyd Hale, Thomas J. O'Keefe, Y. M. Wang, D. Radovic

Physics Faculty Research & Creative Works

The corrosion and electrochemical properties of three zinc single crystal surfaces with different orientations have been investigated. In near-neutral 1 M (NH₄)₂SO₄, the corrosion rates on all three surfaces were found to be similar. However, the SEM morphologies of the corresponding corroded surfaces were markedly different from each other, but consistent with preferential attack of {1120} surfaces. In alkaline 0.5 N NaOH solution, the three sample orientations showed significantly different reactivities, with the (1120) surface exhibiting the highest reactivity and corrosion rate. Here, passivation ultimately occurred and the difference in the corrosion performance of …

Positron Study Of Defects And Diffusion Induced Grain Boundary Migration In A Pb-Sn System, A. Belaidi, Hollis P. Leighly, H. Aourag, B. Khelifa, M. Oubadi, A. Elias

Materials Science and Engineering Faculty Research & Creative Works

The Pb-Sn system discloses a remarkable effect at the intermediate α → α + β phase boundary. The observation of the sharp transient peak in the S-parameter curve which is analogous to those found in thermal capacity curves is, as far as the authors are aware, unique in such positron measurements. This effect is interpreted in terms of positron trapping in defects associated with the strains accompanying the initial stage of transformation. This short note offers a new approach to the underlying phenomenon published in J. Phys. F. Met. Phys., 12 (1982) 813 by A. Belaidi, H. P. Leighly Jr. …

Surface Treatment Of Cast Iron By Adding Different Alloying Elements To Form Metallic Glass Structure Layer Using An Industrial Carbon Dioxide Laser, Mohammad Riahi

Dissertations and Theses @ UNI

Wear and corrosion are the two factors that make utilization of metals very costly. Extraordinary amount of time and money is spent to replace metallic parts affected by either wear or corrosion. Cast iron that is used very widely in a host of different industrial products is one such metal. Among the various methods used to improve the properties of metals, production of amorphous metals is highly noticeable. This process is done by treating the base metal in a certain technique which produces a metal that is more resistant to wear and corrosion.

This study was conducted to examine the …

Technological Upgradation Policies Of The Steel Industry And Impact Of The Steel Industry In The Indian Economy, K K Saxena, Binayak Rath

IIMB Management Review

In India, the iron and steel industry in general occupies an important Position among the manufacturing industries. The priorities attached to this sector can be explained from the Second Five Year Plan document which mentioned that the expansion of iron and steel industry has obviously the highest priority than other industries because the tempo of progress of the economy. Hence, Second Plan onwards the industry has made a rapid stride in our economy. A number of Integrated Steel Plants (ISPs) in the public sector have been set up to boost up production. Today these ISPs contribute a significant portion of …

Investigation Of Damage Mechanisms In A Cross-Ply Metal Matrix Composite Under Thermo-Mechanical Loading, Joel J. Schubbe

Theses and Dissertations

Metal matrix composites (MMCs) are rapidly becoming strong candidates for high temperature and high stiffness structural applications such as the Advanced Tactical Fighter (ATF). This study systematically investigated the failure modes and associated damage in a cross-ply, [0/90]_2s SCS6/Ti-15-3 metal matrix composite under in-phase and out-of-phase thermomechanic fatigue. Initiation and progression of fatigue damage were recorded and correlated to changes in Young's Modulus of the composite material. Experimental results show an internal stabilization of reaction zone size but degradation and separation from constituent materials under extended cyclic thermal loading. Critical to damage were transverse cracks initiating in the 90° …

Electrochemical Evaluation Of Copper Deposition With Gas Sparging, D. A. Uceda, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The influence of gas sparging during copper electrolysis was studied using standard electrochemical techniques. The polarization behavior of acid copper electrolytes was determined in the presence and absence of gas sparging on vertical electrodes. Tracer ion techniques were employed to determine the effect of gas sparging and forced circulation of the electrolyte on the mass transfer characteristics of the system. In addition to the potentiodynamic scans, 3-h copper deposits were produced for morphology and orientation studies. The effect of current density and temperature on deposition were also studied. The polarization experiments have shown that a mass transfer component becomes evident …

The Effects Of Lead On The Electrochemical And Adhesion Behavior Of Zinc Electrodeposits, Vijay Srinivasan, J. Sami Cuzmar, Thomas J. O'Keefe

Materials Science and Engineering Faculty Research & Creative Works

The presence of excessive lead in zinc sulfate electrolytes can lead to problems related to both processing efficiency and the properties of the metal produced. For example, poor adhesion can occur in electrogalvanized steel when it is heated in the temperature range of 215 °C to 280 °C if lead is present in the deposit. The duration of heating necessary to induce the peeling of the zinc was found to be dependent on the temperature, time, and concentration of lead in the electrolyte and the plating parameters. The presence of lead slowed the formation of the intermetallic, and the peeling …

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 …

Comments On The Papers By Kê And Su, Hollis P. Leighly

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.