Engineering Commons^™

Impact Of A Microwave Curing Process On Tensile Strength Of Selected Carbon Fiber Composites, Brian B. Balzer

All-Inclusive List of Electronic Theses and Dissertations

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown. The research study describes the statistical procedure and analysis of data to answer the specific question for the experimental trials: What is the effect on the tensile strength of cured CF composite samples due to the relationship of the autoclave …

Determination Of Three-Dimensional Grain Boundary Connectivity From Two-Dimensional Microstructures, Megan Frary

Materials Science and Engineering Faculty Publications and Presentations

The connectivity of so-called "special" and "general" grain boundaries at a quadruple node is known to be nonrandom as a result of crystallographic constraints. Although a quadruple node is a three-dimensional feature, there exist two-dimensional features which are topologically identical. Therefore, the distribution of these two-dimensional features may be used to determine the three-dimensional connectivity. Computer simulations of a three-dimensional microstructure which is virtually serial sectioned are used to validate the proposed approach.

High Temperature Heat Exchanger Project: Quarterly Progress Report April 1, 2007 Through June 30, 2007, Anthony Hechanova

Publications (NSTD)

• Ceramatec Sulfuric Acid Decomposer. Modeling with different reacting flow channel configurations (ribbed-surface channels, hexagonal channels, and diamond-shaped channels) was performed. The probability of failure for the one channel geometry with different reacting flow channel configurations was calculated to be zero in the three principal directions for all of the cases.

• Bayonet Heat Exchanger. The Matlab code for calculating the probability of failure using a two-dimensional axisymmetric model of the bayonet decomposer was developed. The probability of failure was calculated for the inner and outer SiC walls, and the intermediate quartz wall of the decomposer and found to be …

Guidelines For The Application Of Recycled Concrete Aggregate In The Egyptian Construction Industry, Ahmed Moustafa Essam Aly Kamel

Archived Theses and Dissertations

Construction industry is one of the most important fractions of economy worldwide. This industry consumes enormous amounts of raw materials and produces considerable waste. The optimization of construction material usage not only saves costs but also can significantly contribute towards sustainable development. The concept of recycling the construction and demolition rubble is being addressed in this study as a solution. The recycling of concrete, resulting from both the construction activities and the demolition activities, in order to be used as a source of aggregate is being focused upon in this study. Although the idea of using recycled concrete has been …

49th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 49th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-endorsed by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Breckenridge, Colorado, July 22-26, 2007.

Additive-Assisted, Cerium-Based, Corrosion-Resistant E-Coating, James O. Stoffer, Thomas J. O'Keefe, Eric L. Morris, Xuan Lin, Scott A. Hayes, Pu Yu

Chemistry Faculty Research & Creative Works

Corrosion resistance of metallic components such as stainless steel components of vehicles, and especially aluminum- based components of aircraft, is enhanced by application of an e-coat paint or primer which is enhanced by incorporation of cerium ions into the e-coat electrolytic bath. The resulting overall coating includes a cerium-based layer under a cerium-enhanced e-coat paint or primer layer.

Physisorption Of Nucleobases On Graphene: Density-Functional Calculations, Gowtham S, Ralph H. Scheicher, Rajeev Ahuja, Ravindra Pandey, Shashi P. Karna

Data Science Publications

We report the results of our first-principles investigation on the interaction of the nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) with graphene, carried out within the density-functional theory framework, with additional calculations utilizing Hartree-Fock plus second-order Møller-Plesset perturbation theory. The calculated binding energy of the nucleobases shows the following hierarchy: G>A≈T≈C>U, with the equilibrium configuration being rather similar for all five of them. Our results clearly demonstrate that the nucleobases exhibit significantly different interaction strengths when physisorbed on graphene. The stabilizing factor in the interaction between the base molecule and graphene sheet is …

Processing And Properties Of Palm Oil-Based Rigid Polyurethane Foam, S Chuayjuljit, T Sangpakdee, O Saravari

Journal of Metals, Materials and Minerals

Rigid polyurethane (PU) foam has been prepared from palm oil-derived polyol. The polyol was synthesized by transesterification reaction of palm oil and pentaerythritol using calcium oxide as a catalyst. The obtained palm oil-based polyol was reacted with commercial polymeric diphenylmethane diisocyanate in the presence of water (blowing agent), N,N-dimethylcyclohexylamine (catalyst) and polydimethylsiloxane (surfactant) to produce rigid PU foam. The effects of the amount of the catalyst and surfactant on foam properties (i.e. density, compressive strength and thermal behaviors) were studied. It was found that the density of the foams decreased whereas the compressive strength increased with the increasing amount of …

Removal Of Adsorbed Moisture On Iron Powders By Rice Husk Ash, T Luangvaranunt, S Jearwun, K Kondoh

Journal of Metals, Materials and Minerals

Rice husk ash was proposed to be used for removal of adsorbed moisture on iron powders to enhance their flow characteristic. It was produced by burning of rice husk at 700°C for 1 h, using a slowly increasing of heating rate (5°C/min). The burning condition was determined from thermal gravitation analysis of rice husk. The obtained rice husk ash contained 99.7% amorphous silica with large specific surface area of 295 m2 /g. Rice husk ash was effective in removal of adsorbed moisture on iron powders. Adsorption characteristic was found to be isothermal monolayer adsorption. The treated iron powders can be …

Rational Design And Investigation Of Polypeptide Multilayer Films And Capsules, Ling Zhang

Doctoral Dissertations

Three major concerns in the science of materials today are control over structure and function at the molecular level, biodegradability, and scalability of production. Polymeric materials, notably polyelectrolyte multilayer films, have shown considerable promise in all these areas, and for rational development of multifunctionality. Polypeptides constitute an especially interesting class of polyelectrolyte, given their inherent biodegradability, means of control over structure, methods of large-scale synthesis, and ability to encode biological information. Relatively little is known, however, about polypeptide multilayer films, despite recent advances in the general area.

In this dissertation, ten heteropolypeptides were designed and synthesized by Fmoc chemistry. These …

Use Of Pp-G-Ma Prepared By Solution Process As Compatibilizerin Polypropylene/Polyamide 6 Blends, S Chongprakobkit, M Opaprakasit, S Chuayjuljit

Journal of Metals, Materials and Minerals

In this work, polypropylene grafted maleic anhydride (PP-g-MA) prepared by solution process was used as a compatibilizer for polypropylene (PP)/polyamide 6 (PA6) blends. PP with melt flow index (MFI) of 10 g/10 min was grafted with maleic anhydride (MA) using benzoyl peroxide (BPO) as an initiator and toluene as a solvent. The effects of BPO and MA concentration on the grafting degree of MA onto PP were studied. The grafting degree was determined by a back-titration procedure whereas the formation of graft copolymers was confirmed by FT-IR technique. It was found that the maximum extent of grafting achieved was 0.87%. …

Analysis Of The Influence Of The Loading Rate On The Mechanical Properties Of Microalloyed Steel, M Mihalikova

Journal of Metals, Materials and Minerals

The aim of this paper is to analyse the influence of the loading rate in the range from 1 to 1000 mm/min, which corresponds to the tensile machine working range, on the strength properties and the formability characteristics obtained on standard and notched test bars made of steel strips. The combination of the loading rate and the test bar type made it possible to obtain the relationship of monitored variables in the strain rate interval from 10-4 to 10 s-1. In this interval, the strength properties of the tested strips thickness of 1, 1.5 and 1.8 mm increase exponentially, but …

Effect Of Solution Annealing Temperature On Structure And Mechanical Properties Of En Aw 2024 Aluminium Alloy, M Fujda, R Mišičko, L Rusňáková, M Sojko

Journal of Metals, Materials and Minerals

The effect of solution annealing temperature on the change of microstructural and mechanical properties of EN AW 2024 aluminium alloy was investigated using a metallographic analysis, Vickers hardness measurement and tensile test. An intensive growth of solid solution grains was the result of the increase of solution annealing temperature by the finely dispersed particles dissolved during applied annealing process. The role of these finely dispersed particles was to inhibit the recrystallization process and grain growth of solid solution matrix through its pinning effect on the migrated solid solution grain boundaries. Observed changes of the microstructure involved the strength decline and …

Surface Treatment Of Powder Material By Metal Coatings - Study Of Corrosion Properties, Z Fečková

Journal of Metals, Materials and Minerals

Coatings by one-component Ni and two-component Ni-Co were electrodeposited onto Fe powder particles from a sulphate-based electrolyte. The coatings were deposited under galvanostatic conditions at 25o C. A fluidized bed arrangement was applied. The influence of cathodic current intensity and electrolysis time on the composition of metal coating was studied. The amount of deposited metals increased with the current intensity and with the electrolysis time. Scanning electron microscope and optical microscope were used to characterize the metal coatings. Voltammetric measurements have been conducted in order to characterize the electrochemical behaviour of Ni and Ni - Co coatings in two corrosion …

Powder Injection Moulding Of Cemented Carbides: Feedstock Preparation And Injection Moulding, N Chuankrerkkul, P F. Messer, H A. Davies

Journal of Metals, Materials and Minerals

A composite binder system, successfully developed earlier for powder injection moulding of stainless steels, CoCrMo and NiCrSiB alloys, has been adapted for tungsten carbide-cobalt (WC-Co) cemented carbides. The binder consists of a major fraction of polyethylene glycol (PEG), which can be removed rapidly by leaching with water, a minor fraction of a finely dispersed polymethyl methacrylate (PMMA), which retains rigidity of the components and sometimes with stearic acid (SA) to act as a lubricant. The adjustments made to powder characteristics, binder compositions and process parameters to achieve successful injection moulding are reported. Feedstocks containing a powder loading of the WC-Co …

Fatigue Performance Enhancement Of Steels Using Mechanical Surface Treatments, P Juijerm, I Altenberger

Journal of Metals, Materials and Minerals

Mechanical surface treatments (mainly deep rolling) were performed on various steels, such as austenitic stainless steel AISI 304 and normalized plain carbon steel SAE 1045. To evaluate the effectiveness of the mechanical surface treatments, mechanically surface treated specimens were cyclically deformed at room temperature using push-pull stress-controlled fatigue and compared to the non-surfacetreated condition as a reference state. Additionally, the concept, methods and effect of selected mechanical surface treatments will also be addressed in this paper. It was found that mechanical surface treatments can dramatically enhance the fatigue performance of metallic materials as compared to the non-surface-treated condition due to …

Glassification Of Electric Arc Furnace Dust By Using Fly Ash Or Bagasse Ash, S Polsilapa, P Wangyao

Journal of Metals, Materials and Minerals

Electric arc furnace (EAF) dusts contain significant quantities of iron and zinc found almost entirely as iron oxide, zinc oxide and zinc ferrite. The dust has been classified as a hazardous waste due to the relative high lead, cadmium and hexavalent chromium contents. An option for treating EAF dust with an economic and uncomplicated process is by using ashes. Silica in ashes has the ability to incorporate a variety of elements in a nonleachable form in the dust. In this study, the EAF dust was mixed with fly ash or bagasse ash in several ratios. All mixed samples were heated …

Microstructural Characterization Of Aluminum Powder Liquid Coating On In 738 Superalloy, P Visuttipitukul, N Limvanutpong, V Krongtong, P Wangyao

Journal of Metals, Materials and Minerals

The powder liquid coating method was proposed for aluminizing of nickel-based superalloy grade IN738 in this study. Slurries for the coating consisted of aluminum and alumina (Al2O3) powder with various weight ratios in the range from 3:7 to 10:0. The slurries were pasted onto the IN738 specimens, which were subsequently dried and heated under argon atmosphere. Macrostructures of coated samples were observed. Surface and cross-sectional microstructures were studied by OM and SEM. Qualitative analysis and composition mapping were analyzed by EDS. Phase identification of coated surface was done by GIXD, at the incident angle of 2 degrees. The results showed …

Om Study Of Effect Of Hip And Heat Treatments On Microstructural Restoration In Cast Nickel-Based Superalloy, Gtd-111, P Wangyao, V Krongtong, W Homkrajai, N Panich, G Lothongkum

Journal of Metals, Materials and Minerals

The present work aims at studying and searching for the effect of repairing conditions on microstructural restoration. It also seeks to investigate into the most suitable and practicable repairing condition, which could provide the desired microstructural characteristics by rejuvenation method of hot isostatic pressing (HIP), followed by 12 heat treatment conditions for long-term serviced gas turbine blades, cast nickel-based superalloy grade GTD-111 operated by Electricity Generating Authority of Thailand (EGAT). During solution treatment, coarse carbides and over-exposed coarse gamma prime precipitates, which had formed previously during service, would dissolve into the matrix. Then specimens were processed through a series of …

Effect Of Powder Mixture Conditions On Mechanical Properties Of Sintered Al2o3-Ss 316l Composites Under Vacuum Atmosphere, R Tongsri, S Asavavisithchai, C Mateepithukdharm, T Piyarattanatrai, P Wangyao

Journal of Metals, Materials and Minerals

Al2O3-SS 316L composites belong to new generation materials which should be characterized by a specified combination of properties. This study is concerned with the effect of the preparation method of the starting mixed powders upon the properties of Al2O3-SS 316L composites sintered under vacuum atmosphere. The composites were produced using powder mixtures with various weight shares between Al2O3 and SS 316L as well as varying size of Al2O3 particles. The mixtures were prepared by a conventional mechanical mixing. It was found that the addition of Al2O3 particles resulted in a slight decrease in the sintering density, the ultimate tensile strength …

Self-Assembly And Characterization Of Germanium Quantum Dots On Silicon By Pulsed Laser Deposition, Mohammed S. Hegazy

Electrical & Computer Engineering Theses & Dissertations

Self-assembled Ge quantum dots (QD) are grown on Si(100)-(2×1) by pulsed laser deposition (PLD). In situ reflection-high energy electron diffraction (RHEED) and post-deposition atomic force microscopy (AFM) are used to study the growth dynamics and morphology of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400°C using a Q-switched Nd:YAG laser (λ = 1064 mu, 40 ns pulse width, 23 J/cm2 fluence, and 10 Hz repetition rate). At low film thicknesses, but clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing …

Corrosion Stress Relaxation In Pure Magnesium And Die-Cast Mg Alloys, Y B. Unigovski, L Riber, E M. Gutman

Journal of Metals, Materials and Minerals

The effect of corrosive solutions on stress relaxation behavior of pure Mg and its alloys is studied. Pure magnesium shows a crucial corrosion stress relaxation in 3.5wt.% NaCl even at room temperature in comparison with tests in air. Die-cast Mg alloys AZ91D, AM50 and AS21 at room temperature show a relatively small stress decrease both in air and in different corrosive media. At elevated temperature, all studied die-cast Mg alloys show a strong stress relaxation in a 3.5 % NaCl corrosive solution. In a corrosive environment, the highest sensitivity to stress relaxation was observed both in the alloy with the …

Pvd Coatings Applied On The Tool Steels, M Hagarová, D Jakubéczyová, M Vojtko

Journal of Metals, Materials and Minerals

The paper deals with the properties of thin coatings deposited on the tool steels. The TiAlN coat was applied by PVD technology on the Vanadis steel produced by powder metallurgy. Development of a new technology of coat deposition is connected with adequate evaluation of coated parts. The quality of a thin coating - substrate system was determined by measuring properties.

Sub-Surface Corrosion Research On Rock Bolt System, Perforated Ss Sheets And Steel Sets For The Yucca Mountain Repository — Quarterly Technical Report No. 12, Dhanesh Chandra, Jaak J.K. Daemen

Publications (YM)

This 12th report shows the work done in accordance to cooperative agreement of University of Nevada system for the Task 019 “Subsurface Corrosion Research on Rock Bolt System, Perforated SS Sheets and Steel Sets for the Yucca Mountain Repository”, the overall objective of which is to conduct corrosion research and predict the durability of rock-bolts and other underground metallic roof supports. We are performing oxidation tests using Thermogravimetric Analyzer (TGA), and Potentiodynamic and immersion tests to determine the corrosion rates of rock bolts. In this quarter: Potentiodynamic tests were performed to determine corrosion rates (CR) of 4340 Steel in pure …

Optimal Utilization Of Timber Poles As Structural Members Of Formwork, Ladislaus Lwambuka

Tanzania Journal of Engineering and Technology (TJET)

Timber poles of the type “Mirunda” are commonly used in East Africa as formwork support structures for casting of reinforced concrete slabs, beams and canopies. It is also widely known that the “Mirunda” poles as structural members of formwork are massively used without any structural consideration and guidance. This common practice has resulted into wastage of natural resources and escalated construction costs. This study has attempted to establish the load bearing capacity of randomly selected “Mirunda” poles through laboratory testing. Using an existing construction site as a case study, the results have been used to establish the actual number of …

Double Statistical Distribution Of Conductivity And Aspect Ratio Of Inclusions In Dielectric Mixtures At Microwave Frequencies, Marina Koledintseva, Richard E. Dubroff, Robert W. Schwartz, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

An analytical model of a composite dielectric presented in this paper is the extension of Maxwell Garnett formulation. It takes into account the simultaneous statistical (Gaussian) distribution of conductivity and aspect ratio of inclusions. The inclusions are randomly oriented elongated conducting spheroids at concentrations below the percolation threshold. The formulation presented herein is limited to microwave frequencies. However, taking subtle frequency-dependent effects that play important part at optical frequencies into account is straightforward. Some results of computations of microwave complex effective permittivity of composites with different input parameters have been obtained using analytical and numerical integration in Maple 10 software. …

Final Report: Second Generation Waste Package Design Study, L. S. Armijo, Mano Misra, Piyush Kar

Publications (YM)

The objectives of this project activity are: to review the current YMP baseline environment and establish corrosion test environments representative of the range of dry to intermittently wet conditions expected in the drifts as a function of time. to demonstrate the oxidation and corrosion resistance of A588 weathering steel and reference Alloy 22 samples in the representative dry to intermittently dry conditions. to evaluate backfill and design features to improve the thermal performance analyses of the proposed second-generation waste packages using existing models developed at UNR.

Radio Frequency Mems Switch Contact Metal Selection, Ronald A. Coutu Jr., Paul E. Kladitis, Robert L. Crane, Kevin D. Leedy

AFIT Patents

A method for selecting metal alloys as the electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This method includes a review of alloy experience, consideration of equilibrium binary alloy phase diagrams, obtaining thin film material properties and, based on a suitable model, predicting contact electrical resistance performance. After determination of a candidate alloy material, MEMS switches are conceptualized, fabricated and tested to validate the alloy selection methodology. Minimum average contact resistance values of 1.17 and 1.87 ohms are achieved for micro-switches with gold (Au) and gold-platinum (Au-(6.3 at %)Pt) alloy contacts. In addition, `hot-switched` life cycle test results …

Prime Modules: Teaching Introduction To Materials Engineering In The Context Of Modern Technologies, Stacy Gleixner, Elliot Douglas, Olivia Graeve

Faculty Publications

This paper discusses the progress of curriculum development under an NSF, CCLI-EMD sponsored work, “Development of Project-Based Introductory to Materials Engineering Modules” (DUE # #0341633). A multi-university team of faculty is developing five lecture modules for use in Introductory to Materials courses. This course is required by most engineering programs in the U.S., with an annual enrollment of 50,000 students. This freshman/ sophomore class is an ideal place to excite students about their engineering majors and expose them to real world engineering experiences. PRIME Modules are being developed that teach the fundamentals of a traditional introduction to materials engineering course …

Collaborative Design Of Project-Based Learning Courses: How To Implement A Mode Of Learning That Effectively Builds Skills For The Global Engineer, Richard N. Savage, Jonathan Stolk, Linda Vanasupa

Materials Engineering

Success for tomorrow’s engineers necessitates the design of curricula that promote awareness of the broader impacts of engineering, enhances systems thinking, reflects sustainable engineering practices, and helps prepare students to make an impact in the global community. Project-based learning approaches that emphasize student learning rather than instructor teaching may be a key to successful development of “global engineers.” Evaluations of project-based courses show increases in student motivation, problem-solving ability, communication and teaming skills, knowledge retention, and capacity for self-directed learning. Despite these reported benefits, curriculum-wide implementations of project-based learning are rare, probably partly due to the traditional emphasis on technical …