Materials Science and Engineering Commons^™

Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone, Tara E. Crouch

Theses and Dissertations

Direct numerical simulation (DNS) computational fluid dynamic (CFD) calculations were performed on a 30° slice of 7° half-angle cones with increasing nose radii bluntness at Mach 10 while simulating a distributed roughness pattern on the cone surface. These DNS computations were designed to determine if the non-modal transition behavior observed in testing performed at the Arnold Engineering Development Center (AEDC) Hypervelocity Wind Tunnel 9 was induced via distributed surface roughness. When boundary layer transition is dominated by second mode instabilities, an increase in nose radius delays the transition location downstream. However, blunt nose experiments indicated that as the nose radius …

Interlaminar Shear Performance Of High Temperature Composites, Tyler A. Wallis

Theses and Dissertations

Interlaminar shear properties of a high temperature polymer matrix composite (HTPMC) and a ceramic matrix composite (CMC) were evaluated at elevated tempera- ture. Two variants of the HTPMC were studied. Both consisted of a high-temperature polyimide (AFR-PE-4) matrix reinforced with Astroquartz-III pre-impregnated glass fabric woven in an eight-harness-satin weave. The first HTPMC variant also contained stainless steel foil at the midplane, while the second HTPMC variant did not. The interlaminar shear strength (ILSS) of both variants of the HTPMC was evaluated at 204°C in laboratory air. The addition of the stainless steel foil resulted in significant loss of ILSS for …

Creep Of Nextel 720/Alumina Ceramic Matrix Composite With Diamond-Drilled Effusion Holes At 1200°C In Air And In Steam, Megan L. Harkins

Theses and Dissertations

A recent study evaluated tensile stress-strain and tensile creep behavior of an oxide-oxide composite (Nextel™720/alumina) with laser-drilled effusion holes at 1200°C. It was determined that the presence of laser-drilled holes degraded the mechanical properties and performance of the CMC as a result of damage caused to the composite microstructure by the laser drilling process. Based on these results, the present effort sought to assess the effects of diamond-drilled holes on the mechanical behavior of this CMC. Tensile properties of the N720/A composite at 1200°C in laboratory air were unaffected by the presence of an array of 17 diamond-drilled effusion holes. …

Scaling Film Cooling Adiabatic Effectiveness With Mass Transfer And Thermal Experimental Techniques, Luke J. Mcnamara

Theses and Dissertations

With increasing engine temperatures, it is becoming more important to design effective film cooling schemes. Low temperature, large scale tests are often implemented in the design process to reduce cost and complexity. A nondimensional adiabatic effectiveness can be used as an indication of the performance of a film cooling scheme. However, the coolant flow rate must be properly scaled between the low temperature tests and engine temperatures to accurately predict film cooling effectiveness. This process is complicated by gas property variation with temperature. Tests are commonly conducted using thermal measurement techniques with infrared thermography (IR), but the use of pressure …

Application Of Computational Tools To Spaghetti-Based Truss Bridge Design, Jin Xu, Jiliang Li, Nuri Zeytinoglu, Jinyuan Zhai

ASEE IL-IN Section Conference

Application of Computational Tools to Spaghetti-Based Truss Design

Statics and Strength of Materials are two foundational courses for Mechanical/Civil Engineering. In order to assist students in better understanding and applying concepts to a meaningful design task, SolidWorks and theoretical calculation were used for a spaghetti-bridge design contest with the constraints of given maximum weight and allowable support-material weight. As the first step of this iterative designing process, both extrude feature and structural member were introduced to model planar bridge trusses. Then SolidWorks’ Statics module was used to run FEA analysis of the structural performance in efforts to optimize the …

Design Of A Carburizing Treatment Of Steel Base Gear In The Materials Science Course, Jiliang Li, Jin Xu, Nuri Zeytinoglu, Jinyuan Zhai

ASEE IL-IN Section Conference

Diffusion PDE Application to Carburizing Treatment of Steel Base Gear

An introductory materials-science course is required in the mechanical engineering curriculum of many universities. This article describes an example effort to incorporate programming, diffusion transfer, heat treatment process and mechanical-property determination as an integral part of the materials-science course instruction. This effort was undertaken in order to give students additional experience in Fick’s 1^st and 2^nd laws and in-depth understanding of physics and mathematics involved in diffusion analysis. We chose to focus on Fick’s second law because its applications are not restricted to the materials-science field [1]. As …

Removal Of Synthetic Azo Dye Using Bimetallic Nickel-Iron Nanoparticles, Shelby L. Foster, Katie Estoque, Michael Voecks, Nikki Rentz, Lauren F. Greenlee

Chemical Engineering Faculty Publications and Presentations

Bimetallic nanoparticles comprised of iron (Fe) and nickel (Ni) were investigated for the removal of an azo dye contaminant in water. Morphology (core shell and alloy) and metal molar ratio (Ni2Fe10, Ni5Fe10, and Ni10Fe10) were tested as key nanoparticle properties. The shelf life of the nanoparticles was tested over a 3-week period, and the effect of initial nanoparticle concentration on dye removal was evaluated. The highest initial nanoparticle concentration (1000 mg/L) showed consistent Orange G removal and the greatest extent of dye removal, as compared to the other tested concentrations (i.e., 750 mg/L, 500 mg/L, and 250 mg/L) for the …

Process Parameter Development Of Additively Manufactured Af9628 Weapons Steel, Erin M. Hager

Theses and Dissertations

The manufacture of components in Additive Manufacturing processes is limited by the range of materials available. Qualification of materials for Additive Manufacturing is time intensive, and is often specific to a single type of machine. In this study, an approach to selecting power, speed, and hatch spacing values for a newly powderized material, AF9628 weapons steel, is described that results in highly dense (>99.9%) parts on an MLab 200R Cusing. Initial power and speed values used in a weld track study were selected based on a survey of parameters used on similar materials, with a focus on the energy …

Microscale Metal Forming: Mesoscopic Size Effect, Extrusion And Molding, Bin Zhang

LSU Doctoral Dissertations

The continuing trend of metallic device and product miniaturization has motivated studies on microscale metal forming technologies. A better understanding of materials’ mechanical response and deformation behavior is of importance for the design and operation of micro metal forming processes. In this dissertation, uniaxial compression testing was conducted on Al ring and pillar specimens with characteristic dimensions at meso to micro scales. The experimental data reveal inadequacies of the existing surface layer model and provides a baseline for delineating deformation mechanisms in micro metal forming operations. Microscale reverse extrusion experiment was carried out on Cu and Al rod specimens with …

Investigation Of Methylammonium Lead Halide Perovskite Solar Cells, Natalie Mann

Research Horizons Day Posters

No abstract provided.

Ultra-Rapid Microwave Sintering Of Ceramics And Powder Metals, Kirill I. Rybakov, Yury Bykov, Anatoly Eremeev, Sergei Egorov, Vladislav Kholoptsev, Ivan Plotnikov, Andrei Sorokin

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

Over the recent years, we have demonstrated ultra-rapid microwave sintering of different ceramic materials, including Al₂O₃, ZrO₂, Y₂O₃, MgAl₂O₄, and Yb:(LaO)₂O₃, using a gyrotron system operating at a frequency of 24 GHz with an output microwave power of up to 6 kW [1-3]. The ceramic pellets were sintered to 98-99.5 % of the theoretical density with the duration of the high-temperature sintering stage not exceeding several minutes. We have shown that the absorbed microwave power required for the ultra-rapid sintering regimes is …

Effect Of The Addition Of Doped-Cobalt On The Properties Of Recycled Tungsten Carbide Powder Sintered By Sps, Alexandre Mégret, Véronique Vitry, Fabienne Delaunois

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

A key issue that has appeared in the last twenty years is the availability of certain materials. Cobalt is considered as a critical raw material since it is massively used in batteries for electrical cars [1]. Cobalt is also the usual binder in cemented carbides because it gives excellent hardness to toughness ratio at the tungsten carbide parts. There is a tendency to replace cobalt by other binders such nickel or iron [2] but cobalt remains the best one. Recycling old WC parts is a solution to limit the use of raw cobalt powder and to keep the benefits of …

Kinetics Of Liquid-Assisted Densification During Flash Sintering Of Ceramic Nanoparticles, Rachman Chaim

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The recent liquid film capillary mechanism [1, 2] proposed for the rapid densification during the flash sintering was consistent energetically with the dissipated power during the process. Following this mechanism, melting of contacts with high electric resistance will induce high attractive capillary forces. Wetting of a solid substrate by its own melt is termed homologous wetting with zero wetting (dihedral) angle. Therefore, wetting and spreading of the melt on its own substrate is extremely fast. Here we will show that particle surface softening / melting and the following transient processes associated with it namely local melt wetting and spreading, particle …

Synthesis And Characterization Of LaXBa1-XFeYAl1-YO3, Perovskite Oxides, For Co2 To Co Conversion, Hanzhong Shi

USF Tampa Graduate Theses and Dissertations

As the greenhouse gas effect becomes more serious, it is important to find an effective way to reduce carbon dioxide emissions and/or convert it to value-added products. Based on the catalytic requirements, convert CO₂ to CO using perovskite-type oxides which are suitable for reverse water-gas shift chemical looping (RWGS-CL). The resulting carbon monoxide can be subsequently used for chemical energy storage in the form of hydrocarbon-based fuels and chemicals. This research focuses on the synthesis of the La_xBa_1-xFe_yAl_1-yO₃ perovskite-type oxides, which can form oxygen vacancies, or active sites for CO …

Flash Sintering Of Beta-Alumina Solid Electrolytes For Sodium Battery Applications, Gareth Jones, Y. Hu, S. Ghanizadeh, D. Pearmain, S.N. Heavens, J.S. Blackburn, S. Maclachlan

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The rechargeable sodium batteries, sodium sulphur (NaS) batteries and molten-salt sodium nickel chloride (Na-NiCl₂) are proven commercially available systems, particularly for large-scale energy storage applications and electric vehicle applications respectively. They have attractive properties such as the use of abundant low-cost raw materials, high energy and power density, high faradaic efficiency of charge/discharge, zero self-discharge rate and proven long-term durability. Conventional manufacturing of the core component, the sodium beta”-alumina solid electrolyte, requires a high sintering temperatures, ~ 1600 °C to achieve high density and good ceramic quality, which contributes significantly to battery cost, energy and time consumption in …

Advantages Of The Method Of High-Voltage Consolidation Of Powder Materials, Evgeny Grigoryev, Vladimir Goltsev, Natalya Ermakova, Andrey Osintsev, Aleksandr Plotnikov

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The main features of high-voltage electropulse consolidation (H-VEC) of powder materials and the unique possibilities of the method caused by them are considered. The electro-thermal processes in the H-VEC at the contacts between the powder particles and in the macroscale of the whole consolidated sample are analyzed. The results of calculations of the dynamics of closure (collapse) of interparticle pores in the consolidated material are presented. The experimental results of high voltage consolidation W-based heavy alloys are discussed and a theoretical analysis of the kinetics of compaction of powder materials is made. The results of investigation of the macro- and …

Field Assisted Sintering Of Larger Scaled Ceramic Parts Using Adapted Tool Design And Hybrid Heating, Martin Bram, Moritz Kindelmann, Alexander M. Laptev, Olivier Guillon

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

Field Assisted Sintering/Spark Plasma Sintering (FAST/SPS) is a promising technology for the energy efficient sintering of ceramic, composite and metal powders. The combination of direct current heating and applied pressure enables high heating rates, rapid densification and offers the potential to decrease the sintering temperature significantly. FAST/SPS is of special interest for materials, which are difficult to densify by conventional methods like pressure less sintering. To establish this processing technology on industrial scale, fundamental studies are required to better understand the relationship between processing parameters, specific FAST/SPS boundary conditions and resulting material properties. A challenging task – especially for non-conductive …

Hybrid Sintering – The Beneficial Combination Of Sintering Principles, Juergen Hennicke, Tobias Kessel, Sergio Rivera Monte

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

„Hybrid Sintering“ can be defined as a beneficial combination of different sintering principles, e.g. direct and indirect heating, uniaxial and gas pressure, high and low electrical fields (Figure 1). In the technological context this can be completed by debindering, decoupled pre-heating and cooling as well as rate controlled sintering optionally. Hybrid sintering systems enable the development and production of all new material solutions.

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Photoluminescence In Sps-Processed Transparent Ce:Yag Ceramics, Avital Wagner, Nachum Frage, Sergey Kalabukhov, Barak Ratzker

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

Ceramic phosphors display great promise for the realization of high-power lighting devices. Cerium-doped yttrium aluminum garnet (Ce:YAG) is commonly used as a phosphor in white light emitting diodes. Therefore, it was chosen as a case study to investigate photoluminescence of transparent ceramic phosphors fabricated by spark plasma sintering (SPS). In the present work, 0.5 at.% Ce:YAG nano-powder was synthesized by a co-precipitation method and subsequently consolidated by SPS into highly transparent ceramic samples. The effect of varying sintering parameters (temperature and pressure) and post-sintering treatments (hot isostatic pressing and air atmosphere thermal treatment) on optical properties was investigated. Correlations between …

Β-Sialon-Based Ceramic Composites By Combustion Synthesis And Spark Plasma Sintering, Evgeny Grigoryev, Vladimir Goltsev, Konstantin Smirnov, Dmitriy Moskovskikh, Aleksey Sedegov

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

Spark-plasma sintering (SPS) of composite ceramics in the β-Si₅AlON₇– system (SiC, TiN, BN) was studied. An effective mechanism of intensification of sintering processes was revealed due to the introduction of h-BN, having a scaly structure and playing the role of a solid lubricant, which improves the compressibility of the sintered powder mixtures under load. For composites containing 0–30 wt. % h-BN, 0–40 wt.% β-SiC, and 0–40 wt. % TiN, with different character distribution of components by volume (homogeneous, layered and gradient), the optimal parameters of the PCA were established, ensuring the achievement of a high level …