To improve the efficiency of the continuous casting process and the quality of its products, this dissertation mainly investigated fluid flow related phenomena and inclusion motion in continuous casting. Mathematical simulation was performed for this purpose. Both a slab caster and a billet caster were investigated. In the study of the slab caster, the application …
Tag Archive: Materials Science
Mar
13
Low temperature constrained sintering of cerium gadolinium oxide films for solid oxide fuel cell applications
Cerium gadolinium oxide CGO) has been identified as an acceptable solid oxide fuel cell SOFC) electrolyte at temperatures 500-700°；C) where cheap, rigid, stainless steel interconnect substrates can be used. Unfortunately, both the high sintering temperature of pure CGO, ＞1200°；C, and the fact that constraint during sintering often results in cracked, low density ceramic films, have …
Mar
13
Viscosity effects on the flow and fracture of metallic glasses and other viscous materials
The purpose of this study was to further understand the effects of changes in viscosity on the flow and fracture of metallic glasses. The viscosity of metallic glasses under various testing conditions were measured via three types of experiments. Estimates of global sample viscosity were made from tensile test data at temperatures from room temperature …
Mar
13
Interstitial diffusion in lithium-ion battery electrodes and structural phase transitions in crystalline solids from first principles
We perform first-principles investigations of thermally activated phase transitions and diffusion in solids. The atomic scale energy landscapes are evaluated with first-principles total energy calculations for different structural and configurational microstates. Effective Hamiltonians constructed from the total energies are subjected to Monte Carlo simulations to study thermodynamic and kinetic properties of the solids at finite …
Mar
12
On novel uses of sub-micron probes: piezoelectric and mechanical measurement of nanocrystalline zinc oxide and other electronic materials
This study sought to investigate novel uses of sub-micron probes. One such application was to measure the piezoelectric strain coefficient of nanocrystalline zinc oxide. Zinc oxide, as a piezoelectric semiconductor, may be developed as a nanogenerator, transducing mechanical motion into electrical energy. To design these nanogenerators, it is necessary to measure their piezoelectric characteristics and …
Mar
12
Effect of Material Properties on High Frequency Signal Propagation and Partial Discharge Detection in Solid Dielectric Shielded Power Cables
High frequency signal propagation characteristics of shielded power cables, including attenuation, electromagnetic propagation velocity, and characteristic impedance, are determined mainly by the dielectric properties of cable insulation and semiconductive shields, as well as the metallic sheath structure. High frequency attenuation in two transmission class XLPE cables with differing ground structures is studied by computation and …
Mar
12
Effect of accelerated aging on mechanical properties and structure of nano-scale composite systems
Nano-scale composites are being investigated by academic, industrial, and national laboratories for potential applications such as wear resistant coatings and high strength foils. These structures are of interest due to their as-fabricated mechanical properties, such as high strength for nanolaminates. However, there have only been limited studies of the long-term mechanical stability. A greater understanding …
Mar
12
The Low-Temperature Redox-Assisted Seeded Growth of Cadmium Selenide Nanocrystals
Semiconducting CdSe nanocrystals NCs) are a unique class of materials that exhibit properties that are dependant on their size, morphology and composition. When the radius of a nanocrystal is decreased below its Bohr exciton radius, the nanocrystal exhibits quantum confinement, and the bandgap of the material increases as the radius decreases. When the morphology of …
Mar
12
Materials selection and evaluation of Copper-Tungsten particulate composites for extreme electrical contacts
Materials for extreme electrical contacts need to have high electrical conductivity coupled with good structural properties. Potential applications include motor contacts, high power switches, and the components of electromagnetic launch EML) systems. The lack of durability experienced with these contact materials limits service life. Due to extreme current densities coupled with the local sliding, electrical …
Mar
12
Quantitative microstructural characterization of microalloyed steels
Microalloyed steels are widely used in oil and gas pipelines. They are a class of high strength, low carbon steels containing small additions in amounts less than 0.1 wt%) of Nb, Ti and/or V. The steels may contain other alloying elements, such as Mo, in amounts exceeding 0.1wt%. Microalloyed steels have good strength, good toughness …