Materials Science and Engineering Commons^™

Pr3+ Doped Bao:Zno:B2o3:Teo2 Glasses For Laser Host Matrix, R Rajaramakrishna, C Wongdeeying, P Yasaka, P Limkitjaroenporn, N Sangwaranatee, J Kaewkhao

Journal of Metals, Materials and Minerals

In this work, glasses of composition (30-x)TeO2-30B2O3-10ZnO-30BaO-xPr2O3 x=0.00 0.05, 0.10, 0.50, 1.00, 1.50 mol% have been prepared through the melt quenching method. In order to characterize and explore their structural properties, we measured the density, refractive index of the glass which shows increasing trend with increase in Pr2O3 concentration also FTIR and XRD spectrum is used to study the structural properties of the developed glasses. XRD shows amorphous structure of the prepared glasses. FTIR shows B-O stretching (BO3)- units and Symmetrical stretching vibration of Te-O in TeO4. The electronic states belonging to the 4f configuration of trivalent Pr3+ were determined …

Properties Of Uv-Curable Screen Printing Inks Containing Oligolactide Acrylates, S Kulsiriswad, O Saravari, K Srikulkit

Journal of Metals, Materials and Minerals

This study was aimed at investigating the properties of UV-curable screen printing inks prepared from oligolactide acrylates. Those resultant inks were applied on substrates and cured by UV radiation. Then, properties of the cured ink films were evaluated and compared with a commercial acrylate ink. The degradation temperature of ink film was found at around 436°C. In addition, thus obtained films were glossy and transparent without yellowness. The weathering resistance of ink films tested by a Xenon test chamber for 500 h showed that ink films exhibited acceptable outdoor durability. Discoloration due to the degradation of lactide chain was observed, …

Temperature Dependence Of Dielectric Properties For Bfo-Bto-Bzt Ceramics, S Unruan, M Unruan, R Yimnirun

Journal of Metals, Materials and Minerals

In this work, bismuth ferrite-barium titanate-barium zirconate titanate (BFO-BTO-BZT) ceramics were prepared using conventional solid state reaction method. The (1-x)BiFeO3-xBaTiO3 at x = 0.24-0.30 and Ba(Zr,Ti)O3 (Zr = 0.5) systems were separately prepared and calcined at 800 and 1250oC, respectively. All pallets were sintered at temperature of 1100oC. After that, the relationship between phase formation, dielectric and magnetic properties were examined. The XRD patterns revealed that more structural symmetry could be observed in all single-phase perovskite ceramics when more BTO concentration was added. The 0.75(0.70BFO-0.30BTO)-0.25BZT ceramic showed highest dielectric constant with high loss measured at low frequency observed, possibly due …

The Effects Of Concentrations Of Zno Nanoparticles On Dewetting Suppression Of Ps Thin Films, J Thapoung, K Tasurin, N Traiphol, N Pangpaiboon

Journal of Metals, Materials and Minerals

Thin polymer films are widely used in industry, such as protective coating, lubricant and electrical insulator, because of their specific properties. However, thin film in nanoscale tends to separate from substrate; this phenomenon is called Dewetting. In this research, a solution of polystyrenes with a concentration of 0.3 wt% in toluene, providing ~ 21 nm polymeric film, was prepared. Zinc-oxide nanoparticles were added in a polystyrene solution as a Dewetting inhibitor. The concentrations of zinc-oxide were varied from 0 - 1.0 wt%. Thin films were cast by a spin casting machine. After annealing at 90˚C in a vacuum oven for …

Recycled Poly(Ethylene Terephthalate)/Polypropylene/Wollastonite Composites Using Pp-G-Ma As Compatibilizer: Mechanical, Thermal And Morphological Properties, P Chaiwutthinan, S Suwannachot, A Larpkasemsuk

Journal of Metals, Materials and Minerals

Polymers investigated in this study were recycled poly(ethylene terephthalate) (rPET) as a major phase (matrix) and virgin polypropylene (PP) as a minor phase (dispersed phase). Initially, rPET was melt mixed with four different PP contents (10 - 40 wt%) on a co-rotating twin screw extruder and then injection molded. The blend at 30 wt% PP exhibited the highest impact strength and elongation at break and an acceptable tensile strength and Young's modulus. The 70/30 (w/w) rPET/PP blend was then upgraded its compatibility using 1 - 7 parts by weight per hundred of blend resin (phr) of maleic anhydride grafted PP …

Reinventing The Wheel, Esther K. Unti, Ahmed Z. Shorab, Patrick B. Kragen, Adam M. Menashe

Mechanical Engineering

Reinventing the Wheel selected tires and designed wheels for the 2018 Cal Poly, San Luis Obispo Formula SAE combustion vehicle. Available tire options were evaluated for steady-state and transient performance as well as vehicle integration. A single-piece composite wheel with hollow spokes was designed to meet stiffness, strength, and tolerance requirements. A detailed study of wheel loading and geometric structural efficiency was performed. Finite element analysis was used to iterate the geometry and laminate. A two-piece male mold was designed and machined to manufacture the wheel. Removable silicone inserts were used to create the hollow spokes.

Study Of Conduction Behavior In Dielectrics In Chip Level Interconnects: Detection Of Defects In Al/Sio2 Interconnects, Po-Cheng Lu

Material Science and Engineering Dissertations - Archive

This dissertation presents four different electrical measurement techniques to detect structural defects in Al/SiO2 interconnects. These techniques, namely 1) polarity dependence measurement, 2) current voltage measurement, 3) two-point measurement and 4) discharge transient current measurement, can provide simple electrical parameters having direct relationship to defects state (type and quantity) in interconnect structure. All these measurement techniques use the MIM (metal-insulator-metal) structure such as the comb-serpentine structure commonly existing in integrated (IC) devices. This study also presents a newly discovered dielectric failure mechanism, that is the failure by a process of partial discharge dielectric breakdown phenomenon. The goal of the charging …

A Study Of Microcrystalline Cellulose Prepared From Parawood (Hevea Brasiliensis) Sawdust Waste Using Different Acid Types, P Chuayplod, D Aht-Ong

Journal of Metals, Materials and Minerals

Microcrystalline cellulose (MCC) from parawood sawdust (PWS) was successfully prepared by acid hydrolysis method. In this work, parawood sawdust waste was obtained from furniture factory. Initially, PWS was subjected to an alkali pulping and bleaching processes, respectively. After that, the microcrystalline cellulose was prepared from bleached pulp using hydrochloric and sulfuric acid in order to compare the effect of acid type. The parameters for acid hydrolysis process were investigated in terms of reaction time and pulp to acid ratio at constant temperature of 80oC. The properties of obtained MCC such as functional groups, degree of polymerization (DP), crystallinity index (CrI), …

Improved Gas Sensing Performance Of Ald Azo 3-D Coated Zno Nanorods, P. Lin, X. Chen, K. Zhang, H. Baumgart

Electrical & Computer Engineering Faculty Publications

This paper reports an enhancement on the sensing performance of ZnO nanorod ethanol sensors with a new approach by utilizing nested coatings of Aluminum doped ZnO (AZO) thin films by Atomic Layer Deposition (ALD) technology. ZnO nanorods were grown by the hydrothermal method with the ZnO seed layer synthesized on Silicon wafers by ALD. To enhance the sensing performance of ZnO nanorod ethanol sensors, multiple coated AZO thin film 3-D coatings were deposited on the surface of the intrinsic ZnO nanorods by ALD.To investigate the sensing performance of the ZnO nanorods sensor for the detection of ethanol vapor, a gas …

Concentrically Loaded Circular Rc Columns Partially Confined With Frp, Sahar Y. Ghanem, Issam E. Harik

Civil Engineering Faculty Publications

Wrapping reinforced concrete (RC) columns with fiber reinforced polymer (FRP) composites is effective in increasing their capacity. The current state of the art concentrates primarily on fully wrapped columns and few studies dealt with partially wrapped ones. The objective herein is to evaluate the effectiveness of partial wraps (or strips) and to develop a confined concrete compressive stress–strain (f_c − ε_c) model that accounts for partial wrapping. Three-dimensional finite element (FE) models are generated to evaluate the influence of different parameters on the behavior of concentrically loaded RC circular columns that are partially and fully wrapped …

Improving Ductility Of Slender Reinforced Concrete Shear Walls With Frp Sheets And Splay Anchors, Luke M. Ostrom

Architectural Engineering

The Sylmar earthquake of 1971 caused significant damage to slender, non-ductile reinforced concrete (RC) shear wall buildings in California. A later survey by the Concrete Coalition in 2011, under the guidance of EERI members, indicated that there are over 3000 vulnerable concrete buildings in California [8]. This led to City of Los Angeles (LA) Ordinance 193893 enacted in 2015, which requires mandatory upgrades to these concrete buildings by 2035. Current practice to meet the requirements of this ordinance, with respect to RC wall buildings, involves adding new shear walls to the building plan or increasing the cross-sectional area of existing …

Use Of Ultra-High-Performance Fiber-Reinforced Concrete (Uhp-Frc) For Fast And Sustainable Repair Of Pavements, Shih-Ho Chao

Publications

This research presents a new methodology, which enables streets, roads, highways, bridges, and airfields to use an advanced fiber-reinforced concrete material, which can delay or prevent the deterioration of these transportation infrastructure when subjected to traffic and environmental loadings. The major problem of concrete is its considerable deterioration and limited service life due to its brittleness and limited durability. As a result, it requires frequent repair and eventual replacement, which consumes more natural resources. Ultra-high-performance fiber-reinforced concrete (UHP-FRC) introduces significant enhancement in the sustainability of concrete structures due to its dense microstructure and damage-tolerance characteristics. These characteristics can significantly reduce …

A Comprehensive Reliability-Based Framework For Corrosion Damage Monitoring And Repair Design Of Reinforced Concrete Structures, Homero Castaneda, Aydin Karsilaya, Ayman Okeil, Mahmoud Reda Taha

Publications

In this work, we developed a comprehensive framework for corrosion management of reinforced concrete (RC) structures. This framework includes critical steps of an effective approach to quantify the damage evolution as well as providing the timeframe for effective maintenance/repair strategies for corrosion assessment in RC structures. The framework included several activities including the use of indirect and direct inspection tools, theoretical development for damage prediction, experimental measurements and theoretical development of repair time based on reliability. The uniqueness of the framework is the integration of deterministic modeling of corrosion damage evolution by using mechanistic analysis with statistical modeling on corrosion …

Evaluation Of Comparative Damaging Effects Of Multiple Truck Axles For Flexible Pavements, Stefan Romanoschi, Athanassios Papagiannakis

Publications

This study aims at evaluating the effect of overlapping flexible pavement strain responses from truck axles that are not part of multiple axle configurations (i.e., tandem, triple and quad). For this purpose, a newly constructed pavement was instrumented with strain gauges installed at the bottom of the asphalt concrete base layer on US-287 south of Mansfield, TX. This pavement structure is typically used for medium- to high-volume roads in the South-Central region of the United States. The strain gauges were used to measure longitudinal and transverse strains under several passes of a test vehicle. This was a class 6 truck …

Process-Property-Microstructure Relationships In Laser-Powder Bed Fusion Of 420 Stainless Steel., Subrata Deb Nath

Electronic Theses and Dissertations

Laser-powder bed fusion (L-PBF) is an additive manufacturing technique for fabricating metal components with complex design and customized features. However, only a limited number of materials have been widely studied using L-PBF. AISI 420 stainless steel, an alloy with a useful combination of high strength, hardness, and corrosion resistance, is an example of one such material where few L-PBF investigations have emerged to date. In this dissertation, L-PBF experiments were conducted using 420 stainless steel powders to understand the effects of chemical composition, particle size distribution and processing parameters on ensuing physical, mechanical and corrosion properties and microstructure in comparison …

Low Temperature Desiccants In Atmospheric Water Generation., Sunil Gupta

Electronic Theses and Dissertations

Surging global water demand as well as changes to weather patterns and over exploitation of natural water sources, such as ground water, has made potable water a critical resource in many parts of the World already – one rapidly heading towards a crisis situation. Desalination has been adopted as a solution – this is however energy intensive and impractical for most of the developing countries - those most in need of water. A renewable source of energy is solar thermal and solar photovoltaic. A plentiful source of water is the humidity in the atmosphere. This research is to push the …

Plasticity Of Light Metal Matrix Composites Under Anodic Polarization, Y B. Unigovski, E M. Gutman, Z Koren, H Rosenson

Journal of Metals, Materials and Minerals

Light metal matrix composites (MMCs), reinforced with ceramic particles, demonstrate an improvement in strength, elasticity, and wear resistance with regards to matrix alloys. Unfortunately, the plasticity of MMCs is rather low, and their hardness is relatively high. Therefore, there are serious problems in formability and machinability of these materials. In the present study, an improvement in the surface plasticity of such light MMCs as Al 6063-10% SiC (AMC) and Mg AZ31-10% SiC (MgMC) as well as the high-strength Al 7075 T6 alloy under anodic polarization was observed. To assess the effect of polarization on plasticity of composites, the relative Vickers …

Study On Structure And Luminescence Properties Of Labmoo6:Dy3+ Phosphor For Photonic Material Applications, E Kaewnuam, N Wantana, H J. Kim, J Kaewkhao

Journal of Metals, Materials and Minerals

Phosphor powder of LaBMoO6:Dy3+ were prepared to investigate the structure, absorption and luminescence properties. The influence of Dy2O3 concentration on these properties were also studied. XRD characterization represents the main structure of phosphor as monoclinic from LaBMoO6 host matrix. From the reflection spectra, Dy3+ in phosphor can absorb more amount of visible light and near infrared radiation with increasing of Dy2O3 concentration. The energy band gap of LaBMoO6 compound was expanded after doping with Dy2O3 which results to the blue shift of absorption edge. The emission spectra perform the strong yellow and blue light emitting under Dy3+ electric dipole (4F9/2 …

Shape-Controlled Synthesis Of Tungsten Oxide Nanostructures And Characterization, K Petsom, A Kopwitthaya, M Horphathum, Y Ruangtaweep, N Sangwaranatee, J Kaewkhao

Journal of Metals, Materials and Minerals

Synthesis of tungsten oxide nanorods and nanodisks were reported here using hydrothermal method. Our study is focusing on the role of hexadecyltrimethyl-ammonium bromide (CTAB) and silver ions in tungsten oxide nanostructure formation comparing with typical methods. The sodium tungstate dehydrate was used as a precursor. We found that optimum concentration of CTAB and silver ions can provide a rod-like structure. Meanwhile, nanodisks were observed at the absence of silver ion. In addition, concentration of silver ions introduced to growth solution plays an important role in obtained nanostructure dimension. All prepared nanostructures were characterized by X-Ray diffraction (XRD) for crystalline structures …

Characterization And Photocatalytic Activity Of Titanium Dioxide Deposited On Stainless Steel By Pulsed-Pressure Mocvd, K Wirandorn, N Panyayao, V Siriwongrungson

Journal of Metals, Materials and Minerals

Titanium dioxide (TiO2) was deposited on stainless steel 304 by pulsed-pressure metalorganic chemical vapor deposition (PP-MOCVD). Titanium tetraisopropoxide (TTIP) in toluene at the concentration of 0.5 mol% was used as the precursor. The deposition was conducted at the base pressure of 300 Pa and deposition temperatures were varied between 350°C and 400°C. At these deposition temperatures, anatase phase is expected for further photocatalysis study. The deposited TiO2 thin films at the thickness of hundreds nanometers were analyzed using field emission scanning electron microscopy (FESEM) for surface morphology. X-ray diffraction (XRD) was applied for phase analysis. The contact angle was measured …

Effect Of Chromium Content On The Three-Body-Type Abrasive Wear Behavior Of Multi-Alloyed White Cast Iron, J Opapaiboon, M Supradist Na Ayudhaya, P Sricharoenchai, S Inthidech, Y Matsubara

Journal of Metals, Materials and Minerals

The effect of Cr content on three-body-type abrasive wear behavior of multi-alloyed white cast iron was investigated. Multi-alloyed white cast irons were prepared with varying Cr content from 3-9 mass% under basic alloy composition. Annealed specimens were hardened from 1323 and 1373K austenitizing and tempered at three levels of temperatures which were at maximum hardness (HTmax), lower and higher than that at HTmax (L-HTmax and H-HTmax). A rubber wheel wear tester was used to evaluate the abrasive wear resistance. The hardness and volume fraction of the retained austenite (Vγ) varied depending on Cr content and heat treatment condition. The linear …

A Note Of Thanks To John Halloran, William Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

Growth And Characterization Of Silicon-Germanium-Tin Semiconductors For Future Nanophotonics Devices, Bader Saad Alharthi

Graduate Theses and Dissertations

The bright future of silicon (Si) photonics has attracted research interest worldwide. The ultimate goal of this growing field is to develop a group IV based Si foundries that integrate Si-photonics with the current complementary metal–oxide–semiconductor (CMOS) on a single chip for mid-infrared optoelectronics and high speed devices. Even though group IV was used in light detection, such as photoconductors, it is still cannot compete with III-V semiconductors for light generation. This is because most of the group IV elements, such as Si and germanium (Ge), are indirect bandgap materials. Nevertheless, Ge and Si attracted industry attention because they are …

Fabrication And Characterization Of Electrochemical Glucose Sensors, Mohammed Marie

Graduate Theses and Dissertations

Electrochemical sensors based on the nanostructure of the semiconductor materials are of tremendous interest to be utilized for glucose monitoring. The sensors, based on the nanostructure of the semiconductor materials, are the third generations of the glucose sensors that are fast, sensitive, and cost-effect for glucose monitoring.

Glucose sensors based on pure zinc oxide nanorods (NRs) grown on different substrates, such ITO, FTO, and Si/SiO2/Au, were investigated in this research. Silicon nanowire (NW)- based glucose sensors were also studied. First, an enzyme-based glucose sensor was fabricated out of glass/ITO/ZnO NRs/BSA/GOx/nafion membrane. The sensor was tested amperometrically at different glucose concentrations. …

Measuring Characteristic Shrinkage Variability Due To Metal Loading Effects In Low Temperature Co-Fired Ceramic Using Image Processing, John Ezekiel Zumbro

Graduate Theses and Dissertations

Low temperature co-fired ceramic (LTCC) has many benefits when it comes to electronic packaging due to the low dielectric loss, reliability in extreme environments, and high breakdown voltage. Though the ceramic has a lot of benefits it is not widely used due to the high cost and complexities associated with manufacturing. One of these issues with manufacturing is compensating for the shrinkage of the ceramic, this is accomplished by using an expansion factor, creating the “green” or manufactured design. This expansion factor is approximated through knowledge of the ceramic factors such as the metal loading, layers of ceramic tape, firing …

Growth And Behaviors Of Inn/Gan Multiple Quantum Wells By Plasma-Assisted Molecular Beam Epitaxy, Chen Li

Graduate Theses and Dissertations

Fully realizing the potential of InGaN semiconductors requires high quality materials with arbitrary In-content. To this date the growth of In-rich InGaN films is still challenging since it suffers from the low growth temperatures and many detrimental alloying problems. InN/GaN multiple quantum wells (MQWs) and super lattices (SLs) are expected to be promising alternatives to random InGaN alloys since in principle they can achieve the equivalent band gap of InGaN random alloys with arbitrarily high In-content and at the same time bypass many growth difficulties.

This dissertation focuses on studying the growth mechanisms, structural properties and energy structures of InN/GaN …

Comparative Study Of Power Semiconductor Devices In A Multilevel Cascaded H-Bridge Inverter, Kenneth Mordi

Graduate Theses and Dissertations

This thesis compares the performance of a nine-level transformerless cascaded H-bridge (CHB) inverter with integrated battery energy storage system (BESS) using SiC power MOSFETs and Si IGBTs. Two crucial performance drivers for inverter applications are power loss and efficiency. Both of these are investigated in this thesis. Power devices with similar voltage and current ratings are used in the same inverter topology, and the performance of each device is analyzed with respect to switching frequency and operating temperature. The loss measurements and characteristics within the inverter are discussed. The Saber® simulation software was used for the comparisons. The power MOSFET …

Compensation Of Vertical Position Error Using A Force–Deflection Model In Friction Stir Spot Welding, Jinyoung Yoon, Cheolhee Kim, Sehoon Rhee

Mechanical and Materials Engineering Faculty Publications and Presentations

Despite increasing need for friction stir spot welding (FSSW) for high-temperature softening materials, system deflection due to relatively high plunging force remains an obstacle. System deflection results in the vertical position error of a welding tool and insufficient plunge depth. In this study, we used adaptive control to maintain plunge depth, the plunging force was coaxially measured, and the position error was estimated using a force–deflection model. A linear relationship was confirmed between the force and deflection; this relationship is dependent on the stiffness of the welding system while independent of process parameters and base materials. The proposed model was …

Drop Generation Using Cross-Flow In Rigid Body Rotation, Haipeng Zhang

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Inspired by crossflow membrane droplet generation and microfluidic droplet generation, I propose an easy method to generate monodisperse drops using cross-flow caused by rigid body rotation. In this approach, a dispersed phase (DP) liquid was injected through a stationary vertical needle into an immiscible continuous phase (CP) liquid which was in rigid body rotation. A DP drop growing at the end of the needle experienced fluid dynamic forces from the horizontal CP flow, and it was detached from the needle when it had grown to a certain size. This study investigated the relationship between the resultant size of drops and …

Determining The Degree Of [001] Preferred Growth Of Ni(Oh)2 Nanoplates, Taotao Li, Ning Dang, Wanggang Zhang, Wei Liang, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Determining the degree of preferred growth of low-dimensional materials is of practical importance for the improvement of the synthesis methods and applications of low-dimensional materials. In this work, three different methods are used to analyze the degree of preferred growth of the Ni(OH)₂ nanoplates synthesized without the use of a complex anion. The results suggest that the preferred growth degree of the Ni(OH)₂ nanoplates calculated by the March parameter and the expression given by Zolotoyabko, which are based on the analysis and texture refinement of the X-ray diffraction pattern, are in good accordance with the results measured by …