Materials Science and Engineering Commons^™

Sintering Techniques For Microstructure Control In Ceramics, Andrew T. Rosenberger

Open Access Dissertations

Sintering techniques can be manipulated to enhance densification in difficult to sinter materials and to produce property enhancing microstructures. However, the interplay between materials, sintering techniques, and end properties is not fully understood in many material systems, and some fundamental aspects of sintering such as the nature of the effects of electric fields remains unknown. The processing property relationships were examined in two classes of materials; zirconium diboride ultra high temperature ceramic composites, and all solid lithium-ion battery phosphate materials. ^ Investigation of zirconium diboride ceramics focused on the effects of zirconium carbide as a secondary or tertiary phase in …

Surface Modification Of Traditional And Bioresorbable Metallic Implant Materials For Improved Biocompatibility, Emily Kristine Walker

Open Access Dissertations

Due to their strength, elasticity, and durability, a variety of metal alloys are commonly used in medical implants. Traditionally, corrosion-resistant metals have been preferred. These permanent materials can cause negative systemic and local tissue effects in the long-term. Permanent stenting can lead to late-stent thrombosis and in-stent restenosis. Metallic pins and screws for fracture fixation can corrode and fail, cause loss of bone mass, and contribute to inflammation and pain at the implant site, requiring reintervention. Corrodible metallic implants have the potential to prevent many of these complications by providing transient support to the affected tissue, dissolving at a rate …

Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson

Open Access Dissertations

The unparalleled quality of GaAs/AlGaAs heterostructures grown by molecular beam epitaxy has enabled a wide range of experiments probing interaction effects in two-dimensional electron and hole gases. This dissertation presents work aimed at further understanding the key material-related issues currently limiting the quality of these 2D systems, particularly in relation to the fractional quantum Hall effect in the 2^nd Landau level and spin-based implementations of quantum computation.^ The manuscript begins with a theoretical introduction to the quantum Hall effect which outlines the experimental conditions necessary to study the physics of interest and motivates the use of the semiconductor growth …

Encapsulation Of Chemical Catalyst And Structural Epoxy In Microcapsules Generated Via Microcapillary Devices, Congwang Ye

Open Access Dissertations

Protection and controlled release of chemicals through encapsulation have been extensively used in daily applications such as drug delivery, food processing, enzyme stabilization, and chemical storage. A significant need for further development in this area is to reduce the capsule size and to obtain more predictable performance by narrowing the capsule geometry distribution. For the past decade, microfluidics have been rapidly developed to become a popular technique for the generation of monodisperse single/double/multiple emulsion drops in the micrometer to millimeter size range. With this technique, polymeric microcapsules with a narrow size distribution can be fabricated by adding different polymer blends …

Experimental And Modeling Investigation Of Cellulose Nanocrystals Polymer Composite Fibers, Si Chen

Open Access Dissertations

Cellulose nanocrystals (CNCs) are a class of newly developed and sustainable nanomaterial derived from cellulose-based materials such as wood. There have been substantial research efforts to utilize these materials as reinforcing agents. However, in order to develop CNC nanocomposites with industrial applications, it is necessary to understand how addition of CNCs affect the properties of the polymer nanocomposite. In the present work, several approaches, experimental and theoretical, are presented in an effort to characterize and understand the effect of CNCs on the properties of polymer CNC fibers. ^ Two experimental methods were used to develop cellulose acetate (CA) and CNC …

Tunable Organization Of Cellulose Nanocrystals For Controlled Thermal And Optical Response, Jairo A. Diaz Amaya

Open Access Dissertations

The biorenewable nature of cellulose nanocrystals (CNCs) has opened up new opportunities for cost-effective, sustainable materials design. By taking advantage of their distinctive structural properties and self-assembly, promising applications have started to nurture the fields of flexible electronics, biomaterials, and nanocomposites. CNCs exhibit two fundamental characteristics: rod-like morphology (5-20 nm wide, 50-500 nm long), and lyotropic behavior (i.e., liquid crystalline mesophases formed in solvents), which offer unique opportunities for structural control and fine tuning of thermal and optical properties based on a proper understanding of their individual behavior and interactions at different length scales. In the present work, we attempt …

Unveiling The Mechanical Behavior Of The Rod-Like Microstructure In The Radular Teeth Of Cryptochiton Stelleri, Enrique Escobar De Obaldia

Open Access Dissertations

Natural ceramics provided with high volume fractions of mineralized materials that are surrounded by a weak organic interface combine the stiff mechanical behavior of building blocks, like hydroxyapatite or aragonite, and the compliance of the organic surroundings. Unique mechanical properties (e.g. light density and toughness) distinguish bio-composites from common engineering materials. A key example is the highly mineralized shell of the radular teeth of the Crypochiton stelleri. Nature has provided the radular teeth with a highly oriented rod-like microstructure of nano-scale dimensions embedded in a matrix of chitin sheaths. Compared to other biological materials, the external iron oxide layer of …

Seebeck Coefficient Of Soi Layer Induced By Phonon Transport, Faiz Salleh, Takuro Oda, Yuhei Suzuki, Yoshinari Kamakura, Hiroya Ikeda

Makara Journal of Technology

The Seebeck coefficient of a patterned Si wire on P-doped SOI (Si-on-insulator) layer with a carrier concentration of 1018 cm-3 was measured near room temperature. The Seebeck coefficient is found to be smaller than that in the SOI layer and to be closer to the calculated Seebeck coefficient including the electronic contribution. The decrease in the Seebeck coefficient of Si wire is likely to occur due to the elimination of the contribution of phonon drag part. From the theoretical calculation of scattering rates by considering the scattering processes in phonon system, it is considered that an increase in phonon-boundary scattering …

Construction Of A Novel Method Of Measuring Thermal Conductivity For Nanostructures, Hiroya Ikeda, Shoma Yoshida, Yuhei Suzuki, Veerappan Manimuthu, Faiz Salleh, Fujio Kuwahara, Masaru Shimomura, Kenji Murakami

Makara Journal of Technology

With the aim of characterizing the thermal conduction in a nanometer-scaled materials, we have constructed a novel method on the basis of an ac calorimetric method. In this method, periodic sample heating is performed by light irradiation and the corresponding periodic temperature is detected by infrared irradiative thermometer. This makes us measure the thermal diffusivity out of contact with the objective sample. In the present study, we confirm to measure the thermal diffusivity of bulk Si and Cu by this non-contact method with halogen-lamp irradiation. In determining the thermal diffusivity from the relationship between distance deviation and delay time, the …

Phonon-Drag Contribution To Seebeck Coefficient Of Ge-On-Insulator Substrate Fabricated By Wafer Bonding Process, Veerappan Manimuthu, Shoma Yoshida, Yuhei Suzuki, Faiz Salleh, Mukannan Arivanandhan, Yoshinari Kamakura, Yasuhiro Hayakawa, Hiroya Ikeda

Makara Journal of Technology

In order to build high-sensitivity infrared photodetectors using SiGe nanowires, we investigate the thermoelectric characteristics of Ge-on-insulator (GOI) layers as a reference for SiGe. We fabricate p-type GOI substrates with an impurity concentration of 1016-1018cm-3 by a wafer-bonding process using Ge and oxidized Si wafers. Annealing treatment is performed in order to further increase the bonding strength of Ge/SiO2 interface. We measure the Seebeck coefficient in the temperature range of 290-350 K. The Seebeck coefficient of the GOI layers is very close to the theoretical value for Ge, calculated on the basis of carrier transport. Hence, there is a small …

Fiber Optic Ring Resonator Sensor Detection Technique Based On Spectral Intensity Integration, Purnomo Sidi Priambodo, Sasono Rahardjo, Gunawan Witjaksono, Djoko Hartanto

Makara Journal of Technology

Resonant field phenomenon in optical ring resonator has been a major theme for various studies and can be used for various sensor applications. The spectral response shape changes are subjects to be discussed and analyzed for detection in optical sensor system. The spectral response changes are caused by various factors ranging from refractive index of the surrounding medium, medium loss due to absorption and scattering, and coupling variation between waveguides. These optical phenomena are mostly used for bio-sensor applications, since it is free from electromagnetic interference (EMI) and non-physically destructive. In this paper, we discuss our current research in developing …

The Effects Of The Types Of Milk (Cow, Goat, Soya) And Enzymes (Rennet, Papain, Bromelain) Toward Cheddar Cheese Production, Ariestya Arlene, Anastasia Prima Kristijarti, Ivana Ardelia

Makara Journal of Technology

The objectives of this research are to study the effects of different types of milk and enzymes toward the yield and quality (moisture, ash, protein, fat content, and texture) of cheddar cheese and the interaction between those two variables during the process. The types of milk are cow, goat, and soya milk, while the types of enzymes are rennet, papain, and bromelain enzymes. Regarding the procedure, the milk is first pasteurized before CaCl2 and Lactobacillus lactis that acts as the acidifier starter as much as 0.2% (w/v) and 0.5% of the milk volume are added respectively. The amount of enzyme …

Hazard-Driven Drivers’ Behaviours Towards Vehicle-To-Median Safe Distances, Martha Leni Siregar

Makara Journal of Technology

A median is required for a two-way road to separate traffic from opposing lanes and to prevent head-on collisions. However, studies indicate that medians are also perceived as hazards which need to be avoided during driving. This hazard perception is manifested in drivers’ changing behavior towards various types of medians along the driving lanes inform of their tendency to allow various safe distances to the medians. The Indonesian Highway Capacity Manual (IHCM) does not differentiate between types of medians and the influence on the drivers’ choice of safe margin to the medians. Therefore, this study looks into how the existence …

Energy And Exergy Analysis Of Kalina Cycle For The Utilization Of Waste Heat In Brine Water For Indonesian Geothermal Field, Nasruddin Nasruddin, Agus Noor Sidiq, Abdulmajeed Mohamad, Rama Usvika

Makara Journal of Technology

The utilization of waste heat in a power plant system—which would otherwise be released back to the environment—in order to produce additional power increases the efficiency of the system itself. The purpose of this study is to present an energy and exergy analysis of Kalina Cycle System (KCS) 11, which is proposed to be utilized to generate additional electric power from the waste heat contained in geothermal brine water available in the Lahendong Geothermal power plant site in North Sulawesi, Indonesia. A modeling application on energy and exergy system is used to study the design of thermal system which uses …

Surface Oxidation Energetics And Kinetics On Mos2 Monolayer, Santosh Kc, Roberto Longo, Robert Wallace, Kyeongjae Cho

Faculty Publications

In this work, surface oxidation of monolayer MoS2 (one of the representative semiconductors in transition-metal dichalcogenides) has been investigated using density functional theory method. Oxygen interaction with MoS2 shows that, thermodynamically, the surface tends to be oxidized. However, the dissociative absorption of molecular oxygen on the MoS2 surface is kinetically limited due to the large energy barrier at low temperature. This finding elucidates the air stability of MoS2 surface in the atmosphere. Furthermore, the presence of defects significantly alters the surface stability and adsorption mechanisms. The electronic properties of the oxidized surface have been examined as a function of oxygen …

The Use Of Lanthanum (La+3) And Cerium (Ce+3) Ions As Phosphate Activators In Low Grade Phosphate Flotation, Salah Al-Thyabat, Patrick Zhang

Beneficiation of Phosphates VII

No abstract provided.

Application Of Custofloat® Carbonate Collectors In Beneficiating Phosphate Ores In China, Guoxin Wang, Zhengguo Jiang, Lingyi Du

Beneficiation of Phosphates VII

Custofloat® 813 (CF-813) is a collector specially designed and manufactured by ArrMazz for reverse flotation of phosphate ores with carbonate impurities. It was used to process phosphate ores from several mines in China with great success. The paper will present the process flowsheets and flotation results of phosphate ores in three commercial beneficiation plants.

Processing Florida Dolomitic Phosphate Pebble With Custofloat® Carbonate Collectors, Guoxin Wang, Zhengxing (James) Gu

Beneficiation of Phosphates VII

It was estimated that phosphate reserves associated with high carbonate minerals are greater than those with siliceous gangues worldwide. It has been long recognized that separation of carbonate from phosphate is difficult because those minerals contain same or similar alkaline earth cations which lead them to exhibit similar surface behavior in flotation. With the depletion of easy-to-process phosphate reserves, phosphate deposits with high carbonate impurities must be mined and processed to meet the demand. Crushing, grinding and flotation are considered the most efficient process to recover phosphate from phosphate ores associated with carbonate gangue minerals. Therefore, flotation reagents, especially collectors, …

Recovery Of Ree From An Apatite Concentrate In The Nitrophosphate Process Of Fertilizer Production, Mahmood Alemrajabi, Kerstin Forsberg, Ake Rasmuson

Beneficiation of Phosphates VII

No abstract provided.

The Surface And Colloid Chemistry Of Layered Silicate Minerals, J.D. Miller, Jing Liu

Beneficiation of Phosphates VII

No abstract provided.

Upgrading Phosphate Flotation Tailings For Rare Earths Extraction, Salah Al-Thyabat, Patrick Zhang

Beneficiation of Phosphates VII

No abstract provided.

Preface, Patrick Zhang

Beneficiation of Phosphates VII

No abstract provided.

Beneficiation Of Phosphates Vii Conference Program, Patrick Zhang

Beneficiation of Phosphates VII

No abstract provided.

A Tailor Made Approach For The Beneficiation Of Phosphate Rock, Leonid Lisiansky, Mike Baker, Keren Larmour-Ship, Olga Elyash

Beneficiation of Phosphates VII

Tenova Bateman Technologies (TBT), part of Tenova Mining & Minerals is known as a provider of advanced process technologies in solvent extraction, phosphate beneficiation and fertilizer production.

TBT has participated in a number of phosphate projects and offers a comprehensive range of phosphate treatment technologies: from beneficiation to the production of purified phosphoric acid and downstream salts.

The beneficiation of phosphate rock can often be simplified and made more economic by taking into account the distribution of P₂O₅ and impurities as a function of their deportment between the size fractions resulting from mined and comminuted sedimentary phosphates. …

Fatigue Behavior Of Im7/Bmi 5250-4 Composite At Room And Elevated Temperatures, James T. Tipton

Theses and Dissertations

The tension-tension fatigue and tension-compression fatigue behaviors of the IM7/BMI 5250-4 composite were investigated. The tension-tension fatigue of the composite with 0/90 and ±45 fiber orientations was studied at 23, 170, and 190°C. The tension-compression fatigue of the composite with 0/90 fiber orientation was examined at 23°C. The tensile and compressive properties of the composite were also evaluated at room and elevated temperatures for both 0/90 and ±45 fiber orientations. Elevated temperature had little effect on the tensile properties of the 0/90 fiber orientation, but strongly influenced the ±45 tensile properties as well as the compressive properties of both fiber …

Adhesion Of Germanium Electrode On Nickel Substrate For Lithium Ion Battery Applications, Aadithya Jeyaranjan

USF Tampa Graduate Theses and Dissertations

Lithium ion batteries (LIBs) have gained increasing popularity due to their high potential, low self-discharge, zero priming and minimal memory effect. However, the emergence of electrical vehicles and hybrid electrical vehicles in the automobile industry, where LIBs are predominantly in use, instilled a need to improve LIB batteries by experimenting with new materials. Graphite, the commonly used anode material for LIBs suffers from low theoretical capacity (372 mA h g-1) and torpid rate performance. Germanium (Ge) seems to be a promising substitute of carbon due to its high theoretical capacity, high Li+ diffusivity and electrical conductivity. However, Ge undergoes large …

Plastic Deformation Of A Model Glass Induced By A Local Shear Transformation, Nikolai V. Priezjev

Mechanical and Materials Engineering Faculty Publications

The effect of a local shear transformation on plastic deformation of a three-dimensional amorphous solid is studied using molecular dynamics simulations. We consider a spherical inclusion, which is gradually transformed into an ellipsoid of the same volume and then converted back into the sphere. It is shown that at sufficiently large strain amplitudes, the deformation of the material involves localized plastic events that are identified based on the relative displacement of atoms before and after the shear transformation. We find that the density profiles of cage jumps decay away from the inclusion, which correlates well with the radial dependence of …

Continual Cell Deformation Induced Via Attachment To Oriented Fibers Enhances Fibroblast Cell Migration, Sisi Qin, Vincent Ricotta, Marcia Simon, Richard A. F. Clark, Miriam Rafailovich

Department of Biomedical Engineering Faculty Publications

Fibroblast migration is critical to the wound healing process. In vivo, migration occurs on fibrillar substrates, and previous observations have shown that a significant time lag exists before the onset of granulation tissue. We therefore conducted a series of experiments to understand the impact of both fibrillar morphology and migration time. Substrate topography was first shown to have a profound influence. Fibroblasts preferentially attach to fibrillar surfaces, and orient their cytoplasm for maximal contact with the fiber edge. In the case of en-mass cell migration out of an agarose droplet, fibroblasts on flat surfaces emerged with an enhanced velocity, v …

Synthesis, Characterization, And Electrochemical Properties Of Polyaniline Thin Films, Soukaina Rami

USF Tampa Graduate Theses and Dissertations

Conjugated polymers have been used in various applications (battery, supercapacitor, electromagnetic shielding, chemical sensor, biosensor, nanocomposite, light-emitting-diode, electrochromic display etc.) due to their excellent conductivity, electrochemical and optical properties, and low cost. Polyaniline has attracted the researchers from all disciplines of science, engineering, and industry due to its redox properties, environmental stability, conductivity, and optical properties. Moreover, it is a polymer with fast electroactive switching and reversible properties displayed at low potential, which is an important feature in many applications. The thin oriented polyaniline films have been fabricated using self-assembly, Langmuir-Blodgett, in-situ self-assembly, layer-by-layer, and electrochemical technique. The focus of …

Thermodynamic Analysis Of Rare Earth Chlorination And Bromination Processes, Katie Lyons, Jerome Downey, Dan Gaede, Bryce Ruffier

2015 Undergraduate Research

Research funded by the Army Research Laboratory (ARL), the Metallurgical and Materials Engineering Department at Montana Tech investigated various methods of extracting and refining rare earth elements (REEs) from mineral ores and concentrates. Extensive thermodynamic, thermogravimetric and differential thermal analyses were performed to evaluate the relative stabilities of various REE compounds in order to assess potential methods for selective separation and recovery of specific REEs. Conversion of rare earth oxides (REO) to rare earth chlorides or bromides is a possible initial step in pyrometallurgical and hydrometallurgical processing of REEs. REO can be converted to chlorides or bromides by roasting in …