Materials Science and Engineering Commons^™

Bubble Template Synthesis Of Hollow Gold Nanoparticle, Chivarat Muangphat

Material Science and Engineering Dissertations - Archive

Recently, a new synthesis method for creating hollow gold nanoparticles by using electrochemically hydrogen nanobubbles as a template was discovered in our research group. Hollow gold nanoparticles with well-controlled, tunable dimension and morphology can be synthesized using various synthesis conditions. Such hollow gold nanoparticles exhibit unique optical properties that can be tuned by changing the nanoparticle structures. The objective of this study is to understand the formation mechanism of hollow gold nanoparticles synthesized using bubble template synthesis method. The synthesis process can be divided into two main processes: the formation of hydrogen nanobubble and the reduction of gold ions on …

The Effects Of Microstructure On The Mechanical Properties Of Hard Transition Metal Silicon Nitride Nanocomposite Coatings, Jessica Mooney

Material Science and Engineering Dissertations - Archive

In this body of work, the examination of two different transition metal silicon nitride (MeSiN) systems using two different methods of physical vapor deposition (PVD) allowed for the development of a detailed understanding between the processing conditions, the micro-scale and nano-scale morphology, and the mechanical properties of the as-deposited thin film nanocomposite coatings. TiSiN coatings processed using the high-energy Arc deposition technique had hardness values of up to 33.6 GPa, and a previously unidentified (TiSi)N FCC crystalline phase, likely present due to the amounts of energy employed during coating processing, was discovered via intensive low angle X-Ray diffraction (XRD) and …

Ultrasonic Propagation And Scattering In Pearlitic Steel, Hualong Du

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Diffuse ultrasonic backscatter measurements have been especially useful for extracting microstructural information and for improving flaw detection in materials. In this dissertation, this approach is applied to inspection of railroad wheels. To improve the wear resistance, the tread surfaces of railroad wheels are usually quenched with water to increase the hardness. The pearlite phase of iron, characterized by alternating ferrite and cementite phases, is created by the quenching and the lamellar spacing within grains increases progressively from the quenched tread surface to deeper locations due to the non-uniform cooling rate. The quench depth is an important parameter governing the wheel …

Scrap Dissolution In Molten Iron Containing Carbon For The Case Of Coupled Heat And Mass Transfer Control, Ajay Kumar Shukla, Brahma Deo, D. G.C. Robertson

Materials Science and Engineering Faculty Research & Creative Works

The scrap dissolution in an actual process like the BOF is affected both by mass transfer and heat transfer. In this paper, the mass transfer of carbon in liquid melt is considered along with heat transfer. The approaches used in this paper to model the scrap dissolution phenomenon include the application of Green's function, quasi-static, integral profile, and the finite difference approach for different Biot numbers. Mass transfer coefficients are calculated using the Chilton-Colburn's analogy for the case of forced convection. Since the quasi-static approach requires the least computational time, it is used for a detailed parametric study, including the …

Monodentate, Bidentate And Photocrosslinkable Thiol Ligands For Improving Aqueous Biocompatible Quantum Dots, Hiroko Takeuchi

Graduate Theses and Dissertations

Water-soluble Quantum Dots (QDs) are highly sensitive fluorescent probes that are often used to study biological species. One of the most common ways to render QDs water-soluble for such applications is to apply hydrophilic thiolated ligands to the QD surface. However, these ligands are labile and can be easily exchanged on the QD surface, which can severely limit their application. As one way to overcome this limitation while maintaining a small colloidal size of QDs, we developed a method to stabilize hydrophilic thiolated ligands on the surface of QDs through the formation of a crosslinked shell using a photocrosslinking approach. …

Heat Treatment Of Steel Parts In Different Media, Sc Maidargi, V Rani

Journal of Metals, Materials and Minerals

This study reports an investigation of the effect of different media (oil and polymer) on the properties of different grade steel parts. Steel parts after manufacture, will not have the desired properties like wear resistance, tensile strength, surface and core hardness. To attain these, heat treatment processes like Case Hardening (CH) or Through Hardening (TH) were carried out in sealed quench furnace and rotary furnace. The microstructure of the steel part influences the hardness of the same. The required microstructure is Fine Tempered Martensite (FTM) and the Quench media has a very important role in achieving this. Using different grades …

Influence Of Microstructure On The Propagation Of Fatigue Cracks In Inconel 617, Benjiman Michael Albiston

Boise State University Theses and Dissertations

Inconel 617 is a candidate material for use in the intermediate heat exchanger of the Next Generation Nuclear Plant. Because of the high temperatures and the fluctuations in stress and temperature, the fatigue behavior of the material is important to understand. The goal of this study was to determine the influences of the microstructure during fatigue crack propagation. For this investigation, Inconel 617 compact tension samples, fatigue tested by Julian Benz at the Idaho National Laboratory, were obtained. The testing conditions included two environments at 650 °C (lab air and impure-He) and varied testing parameters including: loading waveform (triangular, trapezoidal), …

Impact Of Alkaline Doping And Reducing Conditions On Lafeo3, Geoffrey L. Beausoleil

Boise State University Theses and Dissertations

Efficient and reliable materials for gas separation, syngas production, and hybrid nuclear power plants must be capable of reliably operating at a high-temperature range of 700-1000°C and under exposure to highly oxidizing and reducing conditions. Candidate materials for these applications include alkaline metal doped lanthanum ferrite.

In the first study, the impact of A site substitution by different alkaline metals on lanthanum ferrite (LMF, M=Ca, Sr, and Ba) was investigated. The study focused on thermal expansion near the Néel transition temperature and a magneto-elastic contribution to thermal expansion was identified for each sample. Iron oxidation, Fe³⁺ to Fe^{4+ …}

Fabrication Of Chitosan/Titanium Dioxide Composites Film For The Photocatalytic Degradation Of Dye, P Norranattrakul, K Siralertmukul, R Nuisin

Journal of Metals, Materials and Minerals

The investigation of the chitosan film as a polymer matrix for titanium dioxide (TiO2) dispersion was carried out. Chitosantitanium dioxide composite films were prepared by solution casting, using Chitosan, TiO2, Arquad T50 HFP as surfactant. The mixture of 1.0 g chitosan in 100 mL acetic acid was prepared, subsequently with the addition of TiO2. The solution was then cast onto an acrylic mold and allowed to air-dry. The external morphology of the composite film revealed the high dispersion of TiO2 in the polymer matrix. Three types of crosslinking agent; glutaraldehyde, citric acid, and itaconic acid were studied. It was found …

Sio2-Included Cesium Polyoxotungstate Catalysts For Oxidation, W Trakarnpruk, W Kanjina

Journal of Metals, Materials and Minerals

SiO2-included cesium polyoxotungstate catalysts were synthesized by a sol-gel method and characterizied by FTIR, XRD and N2 adsorption isotherms. XRD patterns prove that the cesium polyoxotungstate is uniformly dispersed in the silica network. The catalysts were used in oxidation of cyclohexane with H2O2. The products are cyclohexanol and cyclohexanone. The catalysts prepared by using a copolymer surfactant show higher surface area and exhibit higher activity. These catalysts are truly heterogeneous and can be reused at least 3 times.

Crystallization Of Carnallite From Kcl-Mgcl2 Brine Solutions By Solvent Evaporation Process And Its Structural And Mechanical Characterization, J Podder, S Gao, R W Evitts, Rw Besant, D Matthews

Journal of Metals, Materials and Minerals

Carnallite crystals have been synthesized from brine solutions at room temperature (23C) by solvent evaporation growth technique to show the effect of the concentration of potassium chloride (KCl) and magnesium chloride (MgCl2) on the growth, structural and mechanical properties of the crystal. Transparent and pseudo-hexagonal shape carnallite crystals with the dimension of 4 5 2 mm to 16 13 3 mm were grown. The crystals were characterized by powder X-ray diffraction and the lattice parameters were found to be a = 9.598 b = 16.141and c = 22.519 space group: Pnna, Z: 12, ? = ? = ? = 90 …

Effect Of Heat Treatment On Phase Transformation Of Tio2 And Its Reflectance Properties, K Archaapinun, N Witit-Anun, P Visuttipitukul

Journal of Metals, Materials and Minerals

Titanium dioxide (TiO2) anti reflection coating film applied for solar cell application, gains more interest due to the insufficient energy problems today. Titanium dioxide can be found in several forms, and the most stable phase is rutile. This research aims to study effect of heat treatment on phase transformation of TiO2 and its effect on reflectance property. Titanium dioxide film was coated on silicon wafer by DC magnetron sputtering to obtain 190 nm and 420 nm thicknesses. Then, it was heat treated at 900C for 1 and 4 hours under ambient atmosphere. Phases and surface morphologies before and after heat …

Investigation Of Supersaturated Silver Alloys For High Hardness Jewelry Application, S Praiphruk, G Lothongkum, E Nisaratanaporn, B Lohwongwatana

Journal of Metals, Materials and Minerals

Sterling silver is one of the most widely used precious metal alloys in jewelry industry. 92.5 wt% silver content is the standard for sterling products, while 7.5 wt% is reserved for other alloying elements. Because the mechanical properties of pure silver such as yield strength and hardness are extremely low. In the bounds of 7.5 wt% solute addition, different approaches have been introduced in order to improve the properties of sterling silver. For example, to increase the hardness of the jewelry pieces, metallurgists introduced age hardening, cold working, and surface treatments. We reported on the trend of intrinsic hardness increase …

Comparison Of Ball-On-Disc And Taber Wear Tests In Assessing Wear Performance Of Electrolessly-Deposited Alloys, K Theeratatpong, S Danchaivijit, Y Boonyongmaneerat

Journal of Metals, Materials and Minerals

In the industry, a Taber wear test is commonly employed to assess the wear resistance of coatings, which are applied on a panel of relatively large scales. On the other hand, other wear testing methods, such as ball-on-disc, is preferred in laboratory settings, as they require smaller test specimens and can determine coefficient of friction. In this study, we systematically compare the differences of Taber wear and ball-on disc by evaluating with an electrolessly-deposited Ni-P alloy systems. The Taber wear shows purely abrasive wear, whereas the ball-on-disc test offers a complex blend of wear mechanisms, and provides the coefficient of …

Unification Of The Negative Electrocaloric Effect In Bi1/2Na1/2Tio3-Batio3 Solid Solutions By Ba1/2Sr1/2Tio3 Doping, Sarir Uddin, Guang-Ping Zheng, Yaseen Iqbal, Rick Ubic, Junhe Yang

Materials Science and Engineering Faculty Publications and Presentations

The microscopic mechanisms of the negative electrocaloric effect (ECE) of the single-phase (1−x)(0.94Bi_1/2Na_1/2TiO₃-0.06BaTiO₃)-xBa_1/2Sr_1/2TiO₃ (BNT-BT-BST) perovskite solid solutions fabricated via the sol-gel technique are explored in this study. Dielectric and mechanical relaxation analyses are employed to investigate the ferroelectric and structural transitions of the samples. The electrocaloric properties of the samples were measured by thermodynamics Maxwell relations. The difference between the depolarization temperature (T_d) and the maximum dielectric constant temperature (T_m) was found to decrease with increasing BST content. Doping with BST stabilized the …

Synthesis And Characterization Of Polymer Layers For Control Of Fluid Transport, Fehime Vatansever

All Dissertations

The level of wetting of fiber surface with liquids is an important characteristic of fibrous materials. It is related to fiber surface energy and the structure of the material. Surface energy can be changed by surface modification via the grafting methodologies that have been reported for introducing new and stable functionality to fibrous substrates without changing bulk properties.

Present work is dedicated to synthesis and characterization of macromolecular layers grafted to fiber surface in order to achieve directional liquid transport for the modified fabric. Modification technique used here is based on formation of stable polymer layer on fabric surface using …

Design And Synthesis Of Polymer - Magnetic Nanoparticle Composites For Use In Biomedical Applications, Roland Stone

All Dissertations

The future of diagnostics and therapeutic drugs in biomedicine is nanoparticles. These nanoparticles come in many different shapes, sizes, and combination of materials. Magnetic nanoparticles have been studied for many years for use in biomedicine, not only for their high surface area, but also because of its unique magnetic properties. They can magnetically interact with their environment, be guided to a specific location, and manipulated to release energy in the form of heat. To ensure that these magnetic nanoparticles survive in the circulatory system, they must be modified with materials to make them colloidally stable in water and shield them …

Mode I Fracture Toughness Of Eight-Harness-Satin Carbon Cloth Weaves For Co-Cured And Post-Bonded Laminates, Josh E. Smith

Master's Theses

Mode I interlaminar fracture of 3k 8-Harness-Satin Carbon cloth, with identical fill and weft yarns, pre-impregnated with Newport 307 resin was investigated through the DCB test (ASTM D5528). Crack propagations along both the fill and weft yarns were considered for both post-bonded (co-bonded) and co-cured laminates. A patent-pending delamination insertion method was compared to the standard Teflon film option to assess its applicability to mode I fracture testing. The Modified Beam Theory, Compliance Calibration method, and Modified Compliance Calibration method were used for comparative purposes for these investigations and to evaluate the validity of the proposed Equivalent Stiffness (EQS) method. …

Synthesis And Characterization Of Multi-Component Enrichment Polymer Layers For Chemical Sensor Applications, James Giammarco

All Dissertations

This dissertation presents the building and study of a "universal" enrichment polymer layer system (EPLS). Thin polymer films have been utilized as enrichment layers for evanescent waveguide chemical sensors. The chemical nature of the polymer provides affinity which promotes the analyte to be absorbed. Having one highly sensitive polymer layer is suitable for a single target volatile organic compound (VOC). Here, the development of multi-layered and multi-component thin polymer films has been done to allow for more diverse affinity. Several parameters were identified to make the EPLSs suitable as enrichment layers for chemical sensor devices. The evanescent sensor devices used …

Role Of Air Gap In Scrap Dissolution Process, Ajay Kumar Shukla, Brahma Deo, D. G.C. Robertson

Materials Science and Engineering Faculty Research & Creative Works

The role of the air gap formed between scrap and a solidified metal shell at the beginning of the scrap dissolution process has been investigated. The effect of air gap has been investigated for different Biot numbers (10 to 100) and ratios of air gap to liquid melt heat transfer coefficient (0.1 to 0.9). The predictions of the mathematical model are compared with the experimental results reported elsewhere. The role of air gap is found to be significant only for low Biot numbers (< 50) and for low ratios of air gap to liquid melt heat transfer coefficient (< 0.25). © 2013 The Minerals, Metals & Materials Society and ASM International.