Materials Science and Engineering Commons^™

Electrical Activation Studies Of Silicon Implanted Aluminum Gallium Nitride With High Aluminum Mole Fraction, Elizabeth A. Moore

Theses and Dissertations

This research demonstrates a method for producing highly conductive Si-implanted n-type aluminum gallium nitride (Al_xGa_1-xN) alloys, and represents a comprehensive analysis of the resulting material's electrical and optical properties as a function of Al mole fraction, anneal temperature, anneal time, and implantation dose. Highly conductive alloys are critical to the fabrication of devices operating in deep UV, high-temperature, high-power, and high-frequency environments, and thus this research is significant in regard to the application of such devices. The Al_xGa_1-xN wafers of this study, with Al concentrations of 10 to 50%, were implanted at …

Ultrahydrophobic Surface Modification Of Polymeric Fibers And Inorganic Substrates, Karthik Ramaratnam

All Dissertations

The wettability of a solid surface is a very important property, and is governed by both the chemical composition and the geometrical microstructure of the surface. Wettability and repellency are important properties of solid surfaces from both fundamental and practical aspects. The wettability of the solid surface is a characteristic property of materials and strongly depends on both the surface energy and the surface roughness. These properties may be approached by mimicking hydrophobic structures created by nature on lotus leaf surface. The lotus effect is based on surface roughness caused by different microstructures together with the hydrophobic properties of the …

Investigation Of Structure And Properties Of Novel Multi-Layer Clay Nanocomposite Films Produced Controllably By Continuous Chaotic Advection Blending, Chaitra Mahesha

All Dissertations

Polymer nanoclay composites have been studied extensively in the past decade due to the excellent combination of properties they can offer at low loadings of clay. Despite robust research, the potential enhancements that nanoclays are theoretically predicted to offer have not been achieved. Such potential improvements in mechanical and gas barrier properties are realized only when the internal structure of the nanocomposite is optimized in terms of arrangement and orientation of nanoclay within the matrix. The mixing-based approach and the accompanying complex flow fields of conventional processing techniques widely used to produce nanoclay composites are unable to control the internal …

College Of Engineering Senior Design Competition Fall 2007, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge.

The senior design competition helps to focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects …

Synthesis, Structure And Characterization Of Silver Doped Diamond Like Carbon Thin Films, Pankaj Jyoti Hazarika

Material Science and Engineering Theses - Archive

Diamond like carbon (DLC) films have gained grounds in the biomedical field as an inert, biocompatible, low friction and wear resistant coating and are widely used in heart valves, coronary artery stents, dental implants, knee prosthesis and other vascular devices. In addition, Ag nanoparticles/films can prevent the formation of biofilm on biomedical implants by degrading the metabolic activities like permeability and respiration and also impair DNA replicability. Thus, Ag-doped DLC (Ag-DLC) can serve as a multifunctional bio coating combining desirable antibacterial and physical/ mechanical characteristics. In the present study, Ag-DLC films were synthesized utilizing a hybrid Plasma CVD and Magnetron …

Synthesis And Characterization Of Ferromagnetic Nanoparticles, Kazuaki Yano

Material Science and Engineering Theses - Archive

Ferromagnetic nanoparticles and their bimagnetic nanoparticles with uniform size distribution have drawn great attention in the past decades because of their unique magnetic properties and potential applications in high density recording media, exchange-spring permanent magnets and biotechnology. In this thesis, synthesis and characterization of ferromagnetic nanoparticles (FePt, Sm-Co system) and bimagnetic nanoparticles (FePt/Fe3O4, FePt/Au) are reported. FePt nanoparticles with different sizes and compositions were successfully synthesized via chemical synthesis. FePt particle size was tuned to a range of from 3 nm to 8 nm with 1 nm accuracy by changing the surfactant to Pt precursor ratio. By optimizing the amount …

Surface Patterning Of Biodegradable Polymer In Tissue Engineering By Applying Photolithography, Lee-Chun Su

Material Science and Engineering Theses - Archive

The prevalence of cardiovascular disease and inherent problems with current surgical therapies has prompted major efforts in the field of vascular tissue engineering. While there have been significant advances towards creating functional blood vessel substitutes, the fabrication of a vascular graft with mechanical, structural and functional properties similar to native vessels has not yet been achieved. We have presented an observation of a new biodegradable polymer utilized on the research of tissue engineering. Our idea was to create a structure to imitate blood vessel muscles in vitro and also to guide the cells when they start spreading and trying to …

Thermally Activated Sulfurization Scheme For Cuins2 Solar Cells, Karan Agrawal

Material Science and Engineering Theses - Archive

Chalcopyrite Solar Cells are now being fabricated on flexible (polymer) substrates. However, CuInS2 solar cells have not been fabricated on the polymer substrates on the commercial scale due the sulfurization temperature which limits the use of polymer substrates during fabrication. To overcome this problem a thermally activated sulfurization process for the manufacture of CuInS2 solar cells from the Cu-In bilayers is described in this work. This sulfurization process can be employed for lower temperature for the formation of the absorber layer. For the sulfurization, the Cu-In bilayer with different compositions is prepared by thermal evaporation in which the In-rich film …

Prediction Of Tensile Strength For Sandwich Injection Molded Short-Glass-Fiber Reinforced Thermoplastics, S Patcharaphun, G Mennig

Journal of Metals, Materials and Minerals

This present paper provides a modified rule-of-mixtures relationship which allows for the calculation of ultimate tensile strength (UTS) as a function of the area fraction between skin and core layers. The effects of fiber length and fiber orientation within the skin and core layers on the tensile strength of conventional and sandwich injection molded short-glass-fiber reinforced polypropylene have been studied in detail. The present theory is then applied to existing experimental results and the agreement is found to be satisfactory

Ferroelectric Glass-Ceramic Sintering Aid For Lead Titanate Ceramics, P Sooksaen, I M. Reaney, D C. Sinclair

Journal of Metals, Materials and Minerals

Silicate-based glass that devitrifies on heating to form ferroelectric lead titanate has been developed. The potential for use as sintering aid in PbO-based electroceramics has been evaluated by studying the densification of PbTiO3 (PT) with increasing wt% addition of glass powder. As the wt% glass content increased, the density increased, the maximum and room temperature relative permittivity decreased and there was also a decrease in Tc and the c/a ratio. The decrease in Tc is believed to be due to increased clamping from neighbouring grains as the density of the PT increases. The decrease in maximum and room temperature relative …

Surface Modification Of Microfluidic Devices, P Kumlangdudsana, S T. Dubas, L Dubas

Journal of Metals, Materials and Minerals

Microfluidic is a multidisciplinary which encompasses the fields of physics, chemistry, nanotechnology, engineering, and biotechnology. It has been developed extensively for many applications such as handling biological entities such as DNA separation, immunoassay, cell sorting, biosensors, and enzymatic assays due to the potential offered by miniaturizing, high throughput of analysis, low cost of fabrication, multiplex functionality and portability. The surface modification of microfluidic devices has also been a major focus in research to help to enhance their efficiency. There is a variety of surface modification methods and in this paper we reviews and presents an overview of the surface modification …

An Investigation On The Corrosion Resistance And Stress Corrosion Cracking Of Ductile Ni-Resist Cast Irons In Desalination Plants., Yahya Abdulla Alzafin

Theses

Two cases of stress corrosion cracking failures of brine pumps casings have been reported. These pumps are installed in two desalination plants located on the coast of Arabian Gulf in UAE. The materials of construction of failed parts are Ni-Resist Ductile Irons (NDI) and the environment is brine, which is concentrated seawater. Two brands of pumps had different lives to total failure; one lived 18 years while the other lasted only 5 years. The failed parts of former pumps were made out of NDI material as per American standard ASTM A439 D2 (designated D material) whereas those of latter pumps …

Using Science, Engineering, And Education To Address Water Supply Challenges In The Highlands Of Guatemala, Andrew Curtis Elmore, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

The Guatemalan Highlands is a Popular Destination for Non-Government Organizations Interested in Performing Relief Projects. U.S.-Based Organizations Such as Rotary International, Engineers Without Borders, and Various Religious Organizations Travel to Guatemala to Conduct Humanitarian Activities Which May Be Effective for the Short Term, But It is Not Clear that the Efforts Have a Systematic Impact. Students and Faculty at the University of Missouri-Rolla Have Systematically Studied Water Supply Issues Including Undergraduate and Graduate Research Projects and Undergraduate Engineering Courses Such as International Capstone Design. Materials Engineers Have Been Involved in the Study of Ceramic-Based Water Treatment Devices. These Microfilters Have …

Diffusion-Free Back Contact Solar Cells On S-Passivated Si(100) Substrates, Guanghua Song

Material Science and Engineering Dissertations - Archive

A diffusion-free back contact solar cell is proposed in this work. The textured front-side of this cell is coated with ~100 nm thermal SiO2 to enhance the light trapping meanwhile reduce the surface recombination velocity (SRV). The back-side of this cell is finger-patterned, using a diffusion-free junction as its emitter region and Al-Si alloy as its base contact. The diffusion-free junction is made by a Schottky contact between low work-function metal aluminum (Al) and sulfur (S)-passivated p-type Si(100) surface. Solution-based S passivation is one of the experimental realizations of the "valence-mending concept". Previously developed MBE (molecular bean epitaxy) selenium (Se) …

The Microgeometry Parameters Of Uncoated And Zinc-Coated Cold Rolled Steel Strips, J Bidulská, T Kvačkaj, V Bodák, R Bidulský

Journal of Metals, Materials and Minerals

The microgeometry of surface is arithmetically expressed by the arithmetical mean deviation of the profile, Ra and peak count, Pc. Roughening of working rolls was achieved by using the technology EDT (Electric Discharge Texturing) and SBT (Shot Blast Texturing). The paper shows the relationship between the basic microgeometry parameters and the adjustment technology of working rolls. Zinc-coated cold rolled steel strips, uncoated cold rolled steel strips and the Ra, Pc parameters were measured using the tangent profilometer "Hommel Tester T1000". Measurements of Ra and Pc showed the scatter for SBT and EDT rolls, respectively. EDT can provide a considerably greater …

Zn Coatings For Temporary Protection Applied By Peening Technology, J Brezinnová

Journal of Metals, Materials and Minerals

This paper presents actual investigation results of an experiment that aimed at verifying the possibility of applying zinc on steel surface by peening technology using zinc-coated cut wire. A suitable method for obtained zinc layers and evaluation of their corrosion resistance was determined. Accelerated laboratory tests with presence of SO2 and long term working tests in atmospheric conditions were used. Creation of incoherent zinc coatings was established on the bases of metallographic and spectral analysis. The process of cold zinc by peening may serve as temporary anticorrosion protection of steel surface.

Microstructure And Mechanical Properties Of En Aw 6082 Aluminium Alloy Prepared By Equal-Channel Angular Pressing, M Fujda, T Kvačkaj

Journal of Metals, Materials and Minerals

The mechanical properties and microstructure of EN AW 6082 aluminium alloy subjected to severe plastic deformation (SPD) and natural ageing are compared with those of extruded and artificially aged state (initial state) and quenched state of alloy after solution annealing. Quenched state of alloy was deformed at room temperature by equal channel angular pressing (ECAP) following route C up to three passes. Polyedric microstructure of quenched state was considerably changed by SPD. Deformation bands with different amount of deformation were observed in microstructure of ECAPed state, which indicated non-uniform deformation across the cross-section of ECAPed specimen. Ultimate tensile strength (UTS) …

Experimental Methods Of Assessment Of Pvd Coatings Properties, M Hagarová

Journal of Metals, Materials and Minerals

The paper investigates the properties of thin coatings deposited by Physical Vapour Deposition (PVD) technology. This is a modern technology of depositing thin coatings onto the surface of machine parts. Technological procedures of deposition of thin coatings undergo constant improvement. At the same time, new types of coatings are developed. These developments necessitate evaluation of structure, composition and properties of the coatings. The basic methods of determination of properties of thin coatings include determination of their thickness and hardness, structure and chemical analysis, adhesioncohesion and tribological properties.

Fatigue Performance Of High-Temperature Deep-Rolled Metallic Materials, P Juijerm, I Altenberger

Journal of Metals, Materials and Minerals

High-temperature deep rolling was developed from conventional deep rolling (deep rolling at room temperature) and performed on various metallic materials, such as austenitic stainless steel AISI 304, normalized plain carbon steel SAE 1045, aluminium alloys (non-precipitation-hardenable AA5083 and precipitation-hardenable AA6110). The fatigue performance of high-temperature deep-rolled specimens was investigated using stress-controlled fatigue tests and compared with the conventionally deep-rolled condition. It was found that high-temperature deep rolling effectively enhances the fatigue performance of steels. However, for aluminium alloys, the beneficial effects of high-temperature deep rolling are not pronounced due to the different strengthening mechanisms in aluminium alloys.

Finite Element Analysis Study On Effect Of Indenter Tip Radius To Nanoindentation Behavior And Coatings Properties, N Panich, P Wangyao, S Surinphong, Y K. Tan, Y Sun

Journal of Metals, Materials and Minerals

This paper mainly focuses on the study of factors that affect the nanoindentation process and the determination of mechanical properties of coating film using computational finite element (FE) analysis. Attempts have been made in order to show the effect of indenter tip radius on the nanoindentation process of both hard and soft coating systems. It has been proved that larger load is required to reach a specific penetration depth when the indenter tip radius increases. Besides, the change in tip radius led to a more severe effect on hard coating system compared to soft coating system. Furthermore, pile- up and …

Om Study Of Effect Of Hip And Heat Treatments On Microstructural Restoration In Cast Nickel Based Superalloy, In-738, O Wangyao, W Homkrajai, V Krongtong, N Panich, G Lothongkum

Journal of Metals, Materials and Minerals

The present work aims at studying and searching for the most suitable and practicable repairing condition for microstructural restoration, 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 made of cast nickel base superalloy grade IN-738 operated by Electricity Generating Authority of Thailand (EGAT). During heat treatment process, coarse carbides and overexposed coarse gamma prime precipitates, which had formed previously during service, would dissolve into the matrix during solution treatment. Then specimens were processed through a series of precipitation aging, which re-precipitated …

Primary Analysis Of Effective Permeability Of The Flame In Burning Natural Gas, R Jaroslav, R Magdalena

Journal of Metals, Materials and Minerals

This paper presents a method of analysis of effective permeability of the flame in burning natural gas. In order to conduct a complex analysis, it is necessary to determine this parameter as a special case of the process of quasi-plasma nature for the purpose of investigating the options for application of suitable industrial methods applied in similar cases. We observed the synergy of solenoid parameters of the plasma part of the flame with ceramic materials without any special additional customization of the measurement device. The processed results of measurement demonstrate additional requirements necessary for measurement technology. The method was applied …

Electrochemical Oxidization Of Herring Sperm Dna And Its Interaction With Histone, Juan Xu, Gui-Ping Huang, Hong Li, Wei Zhu

Journal of Electrochemistry

The voltammetric behavior of herring sperm DNA at glassy carbon electrode and its interaction with histone have been investigated by using cyclic voltammetry,differential pulse voltammetry,and fluorescence measurement.In the potential range of 0.20 V to 1.25 V,it is found that an irreversible oxidative peak is exhibited in acid solution,but in the neutral or alkaline solution two oxidative peaks are observed.Oxidative peak potential values show a negative shift with increasing pH via a slope of-57 mV·pH-1 and a linear relation with DNA concentration in the range of 0.45 to 8.20 mmol·L^-1.In the presence of histone,the oxidative peak current of DNA …

Eiectro-Oxidation Of Methanol On Pdnio/C Catalyst In Alkaline Medium, Mei-Li Wang, Lin Sang, Cheng-De Huang

Journal of Electrochemistry

The electro-oxidation of methanol in alkaline electrolyte at in-house synthesized PdNiO/C and Pd/C catalysts and the effect of heat treatment on the structure and performance of catalysts were studied by cyclic voltammetry,chronoamperometry,chronopotentiometry and X-ray diffraction methods.It is shown that when the reduction temperature is 70℃ and the ratio between Pd and Ni is 8∶2,The PdNiO/C catalyst presents a highest activity for methanol electrooxidation.Calcining can increase the particle size and crystallinity of catalysts,but decrease the dispersion and activity of catalysts, too.Besides,the NiO is disengaged from Pd lattice by heat-treatment.The optimal PdNiO/C catalyst shows higher catalytic activity and much better poisoning resistance …

Preparation And Properties Of High Capacity Lifepo4, Jun Li, Gui-Tang Lai, Hui-Min Huang, Da-Guang Li, Xin-De Xia

Journal of Electrochemistry

Carbon-doped LiFePO₄/C and pure phase LiFePO₄ cathode materials were prepared by liquid-state precipitation reaction. The results of XRD, SEM, elemental analysis,FTIR and A.C.impedance tests show that the samples have had olivine structure and a 3.4V discharge platform.The tapped density of LiFePO₄/C sample could reach 1.46g/cm³, the initiate discharge capacity is 144.6mAh/g at 0.1C,which remained capacity is 93.2% after 20 cycles. The first discharge capacity is 133.5mAh/g at 1C and the capacity decreased 8.76% after 20 cycles.

Electrochemical Behavor Of Zinc-Indium Alloy Electrodes In Concentrated Alkaline Solution, Zhi-Lin Wang, Xiao-Ge Zhang, Rong-Gui Du, Chang-Jian Lin

Journal of Electrochemistry

The electrochemical behavior of zinc-indium alloy electrodes in 35%KOH solutions has been investigated by electrochemical methods including the potentiodynamic polarization and discharge measurements under constant current density.The results indicate that the anodic current density and passive current density increase after the indium addition.The discharge measurement shows that the addition of indium shortens the time to passive state for the Zn alloy compared to pure zinc at a large discharge conditions,that is the addition of indium may enhance the electrochemical activity of Zn alloy electrodes.It is found that the anodic dissolution of zinc-indium alloy electrodes in the concentrated KOH solution occurs …

Study On The Corrosion Of Chlorine Condenser By Electrochemical Method, Bin Xiang, Wen Chen, Wen-Zhang Huang, Shao-Hua Xing, Sheng-Tao Zhang

Journal of Electrochemistry

Corrosion of condenser is very seriously in chlorine-alkali industry,which could lead to fatal disaster.The most commonly used material in low pressure condenser includes steel of 16MnR,10#,and welding rod of J507.Electrochemical analysis of the three materials in 29.9%(by mass) calcium chloride(CaCl₂) solution was carried out.The corrosion current density icorr and impedance parameters of the three materials in 29.9% CaCl₂ solution were estimated separately.The result showed that in the tripartite phase regions where the 10# seamless tube and 16MnR armor plate were jointed by welding,the weld was firstly eroded and suggested that the chlorine condenser should be examined and …

Determination Of Malathion Based On Carbon Nanotubes Modified Electrode Incorporating Acetylcholinesterase, Lu Zhang, Yao-Dong Zhang, Hong-Lan Qi

Journal of Electrochemistry

A biosensor for determination of organophosphorus pesticide based on the acetylcholinesterase and multi-wall carbon nanotubes modified electrode is fabricated.Under the optimal conditions,the chronoamperometric current at +0.70V(vs.SCE) increased linearly with the concentration of malathion in the range from 6.0×10^-10 to 6.0×10^-9 mol·L^-1 with a detection limit of 1.0×10^-10 mol·L^-1.The recoveries of malathion in lake water is 97% to 105% determinated by this method.

Ion-Implanting Modification Of Layered Manganese Dioxide And Its Electrochemical Performance, He-Ning Huang, Dong-Ping Lv, Xing-Kang Huang, Qi-Wei Zhang, Yong Yang

Journal of Electrochemistry

Layered MnO₂(δ-MnO₂) was prepared by thermal decomposition of potassium permanganate.Ti was ion-implanted into such δ-MnO₂ by physical techniques,forming a composite(δ-MnO₂-Ti).These materials were characterized by XRD,SEM,XPS techniques and their electrochemical proprieties were investigated.The results showed that the layered structure of δ-MnO₂ did not been destroyed after Ti ion implantation,and the implanted Ti element was mainly Ti⁴⁺ as indicated by XPS.Both of the first and the highest discharge specific capacities of the ion-implanted layered MnO₂(δ-MnO₂-Ti),compared to those of δ-MnO₂,were improved significantly.

Electrochemical Behavior And Determination Of Luteolin At A Glassy Carbon Electrode, Ai-Lin Liu, Shao-Bo Zhang, Xiao-Sha Wu, Li-Ping Li, Yang-Yuan Cao, Li-Ying Huang, Xin-Hua Lin

Journal of Electrochemistry

The electrochemical behavior of luteolin was studied by voltammetry at a glassy carbon electrode in phosphate buffer solution.The results exhibited that the well-defined redox peak of luteolin is observed and the electrode process is adsorption-controlled.The charge transfer coefficient(α) was calculated as 0.66 in phosphate buffer solution(pH 4.0).The relationships between oxidation peak current and the concentration of luteolin are linear in the range of 1.0×10^-8 ～ 5.0×10^-6 mol·L^-1 by differential pulse voltammetric method.The detection limit had been estimated as 1.0×10^-8 molL^-1.This method can be used for the determination of luteolin with satisfactory results.