Engineering Commons^™

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 …

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 …

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 …

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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Conference Program, Rishi Raj, Olivier Guillon, Hidehiro Yoshida

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

No abstract provided.

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 …

Tensile Strength Of Materials Obtained By Electric Pulse Consolidation Of Powders, Evgeny Grigoryev, Vladimir Goltsev, Andrey Osintsev, Aleksandr Plotnikov

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

A wide range of products of modern technology, obtained by electropulse consolidation of powders, has dimensions that do not exceed 10-15 mm in diameter, and their thickness varies from 1 to 10 mm. Standard mechanical testing methods for such sample sizes are often not applicable.

The article investigates the possibility of determining the resistance to fracture of materials obtained from powders by electric pulse consolidation method using the test method for bending thin disks on an annular support and testing short cylinders according to the "Brazilian test". A numerical simulation of the process of bending a thin disk on an …

Microstructure Evolution During High-Pressure Spark Plasma Sintering (Hpsps) Of Transparent Alumina, Barak Ratzker, Sergey Kalabukhov, Nachum Frage, Avital Wagner

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

Applying high-pressure during spark plasma sintering (so-called HPSPS) enables rapid densification of a ceramic powder at relatively lower temperatures, limiting grain growth and allowing fabrication of fine-grained highly transparent ceramics. The present work focuses on the fabrication of fine submicron transparent alumina from untreated commercial powder by HPSPS and the microstructure evolution during consolidation under high applied pressure. The sintering was conducted at relatively low temperatures (1000-1100°C) under high pressure varied from 250 to 800 MPa. We review unique sintering phenomena such as stress-enhanced grain growth and de-sintering, which are related to creep taking place during the final stage of …

Reprapable Recyclebot: Open Source 3-D Printable Extruder For Converting Plastic To 3-D Printing Filament, Aubrey Woern, Joseph Mccaslin, Adam Pringle, Joshua M. Pearce

Joshua M. Pearce

In order to assist researchers explore the full potential of distributed recycling of post-consumer polymer waste, this article describes a recyclebot, which is a waste plastic extruder capable of making commercial quality 3-D printing filament. The device design takes advantage of both the open source hardware methodology and the paradigm developed by the open source self-replicating rapid prototyper (RepRap) 3-D printer community. Specifically, this paper describes the design, fabrication and operation of a RepRapable Recyclebot, which refers to the Recyclebot’s ability to provide the filament needed to largely replicate the parts for the Recyclebot on any type of RepRap 3-D …

Open Source Low-Cost Power Monitoring System, Shane W. Oberloier, Joshua M. Pearce

Joshua M. Pearce

This study presents an entirely open-source, low-cost power monitoring system capable of many types of measurements including both loads and supplies such as solar photovoltaic systems. In addition, the system can be fabricated using only open source software and hardware. The design revolves around the Digital Universal Energy Logger (DUEL) Node, which is responsible for reading and properly scaling the voltage and current of a particular load, and then serializing it via an on-board ATTiny85 chip. The configuration of the DUEL node allows for custom sensitivity ranges, and can handle up to 50 A and 300 V. Up to 127 …

A National Pragmatic Safety Limit For Nuclear Weapon Quantities, Joshua M. Pearce, David C. Denkenberger

Joshua M. Pearce

This study determines the nuclear pragmatic limit where the direct physical negative consequences of nuclear weapons use are counter to national interests, by assuming all unknowns are conservatively optimistic. The only effect considered is nuclear winter (“nuclear autumn” in the low weapons limits) and the resultant effects on the aggressor nation. First, the ability of low nuclear weapon limits is probed for maintaining deterrence in the worst-case scenario of attacking the most-populous nation. Second, the ability of aggressor nations to feed themselves is assessed without trade and industry resultant from a nuclear attack causing “nuclear autumn” (10% global agricultural shortfall). …

Latex Modified Concrete - Very Early Strength, Bobby Steele

Purdue Road School

INDOT came out with specifications for a very early strength concrete to use on bridge deck overlays. This concrete is fast setting, which allows overlays to be performed over a weekend and benefits the traveling public with a short duration of traffic interference. Cure time to reach the strength requirement is 3 hours. E&B Paving performed the first application with the new spec on August 26, 2018. Many changes were also made to the INDOT Specification Section 722.

Microwave Self-Healing Technology As Airfield Porous Asphalt Friction Course Repair And Maintenance System, Amir Tabakovic, Declan O'Prey, Drew Mckenna, David Woodward

Articles

A problem increasingly faced by airport authorities is the maintenance of runways. Due to their large aircraft loadings associated with take-off and landing operations, runways experience surface deterioration. Poor quality runway surfaces cannot be tolerated in such an environment. Maintenance issues must be carried out to maximise safety and minimise the risk of aircraft damage. A recent development has been the introduction of self-healing technologies such as rejuvenator encapsulation, induction and microwave heating to address these issues. This paper summarises a laboratory investigation to determine the effectiveness of microwave self-healing for crack repair of Porous Friction Course (PFC) used for …

Thermal Transport In Layer-By-Layer Assembled Polycrystalline Graphene Films, David Estrada, Alondra Perez

Materials Science and Engineering Faculty Publications and Presentations

New technologies are emerging which allow us to manipulate and assemble 2-dimensional (2D) building blocks, such as graphene, into synthetic van der Waals (vdW) solids. Assembly of such vdW solids has enabled novel electronic devices and could lead to control over anisotropic thermal properties through tuning of inter-layer coupling and phonon scattering. Here we report the systematic control of heat flow in graphene-based vdW solids assembled in a layer-by-layer (LBL) fashion. In-plane thermal measurements (between 100 K and 400 K) reveal substrate and grain boundary scattering limit thermal transport in vdW solids composed of one to four transferred layers of …

Additive Manufacturing Of Piezoelectric Photopolymer Ferroelectrets, Rami Abu Shammeh

Electronic Thesis and Dissertation Repository

Electroactive polymers are an emerging branch of smart materials that possess the capability to change shape in the presence of an electric field. Particularly, ferroelectrets are films of electrostatically charged dielectric polymer foam that comprise a growing portion of EAP literature. Ferroelectrets are characterized by a piezoelectric response and a quasi-permanent charge polarization owing to the dipoles created when the air cavities in the polymer matrix undergo dielectric breakdown. However, these cavities are often irregular in shape, size, and distribution when produced with conventional preparation methods. To overcome this, we employ a light-based additive manufacturing technique to create a hybrid …

Thermographic Laplacian-Pyramid Filtering To Enhance Delamination Detection In Concrete Structure, Chongsheng Cheng, Ri Na, Zhigang Shen

Department of Construction Engineering and Management: Faculty Publications

Despite decades of efforts using thermography to detect delamination in concrete decks, challenges still exist in removing environmental noise from thermal images. The performance of conventional temperature-contrast approaches can be significantly limited by environment-induced non-uniform temperature distribution across imaging spaces. Time-series based methodologies were found robust to spatial temperature non-uniformity but requires extended period to collect data. A new empirical image filtering method is introduced in this paper to enhance the delamination detection using blob detection method that originated from computer vison. The proposed method employs a Laplacian of Gaussian filter to achieve multi-scale detection of abnormal thermal patterns by …

Corrosion Initiation And Propagation On Carburized Martensitic Stainless Steel Surfaces Studied Via Advanced Scanning Probe Microscopy, Armen Kvryan, Corey M. Efaw, Kari A. Higginbotham, Olivia O. Maryon, Paul H. Davis, Elton Graugnard, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

Historically, high carbon steels have been used in mechanical applications because their high surface hardness contributes to excellent wear performance. However, in aggressive environments, current bearing steels exhibit insufficient corrosion resistance. Martensitic stainless steels are attractive for bearing applications due to their high corrosion resistance and ability to be surface hardened via carburizing heat treatments. Here three different carburizing heat treatments were applied to UNS S42670: a high-temperature temper (HTT), a low-temperature temper (LTT), and carbo-nitriding (CN). Magnetic force microscopy showed differences in magnetic domains between the matrix and carbides, while scanning Kelvin probe force microscopy (SKPFM) revealed a 90–200 …

Roadmap On Biological Pathways For Electronic Nanofabrication And Materials, Reza M. Zadegan

Materials Science and Engineering Faculty Publications and Presentations

Conventional microchip fabrication is energy and resource intensive. Thus, the discovery of new manufacturing approaches that reduce these expenditures would be highly beneficial to the semiconductor industry. In comparison, living systems construct complex nanometer-scale structures with high yields and low energy utilization. Combining the capabilities of living systems with synthetic DNA-/protein-based self-assembly may offer intriguing potential for revolutionizing the synthesis of complex sub-10 nm information processing architectures. The successful discovery of new biologically based paradigms would not only help extend the current semiconductor technology roadmap, but also offer additional potential growth areas in biology, medicine, agriculture and sustainability for the …

Deformation Mechanisms In Mg-Al Nanocomposite, Soodabeh Azadehranjbar, Jian Wang, Jeffrey E. Shield

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

Magnesium is the lightest engineering metal. Replacing steel with Mg based materials in automotive applications would lead to more than 40% weight reduction which significantly boost fuel efficiency. However, conventional Mg alloys typically suffer from low strength and poor deformability due to very few slip systems and easy twinning. Alloying Mg with other materials and microstructural engineering are promising approaches to increase ductility and strength of Mg According to Wang et al. interfaces with low energy and high coherency may effectively constrict the nucleation of twins in Mg In this work, the microstructure of Mg nano layers and nano rods …

Effects Of Steel Type And Sandblasting Pretreatment On The Solid-Liquid Compound Casting Characteristics Of Zinc-Coated Steel/Aluminum Bimetals, Jesik Shin, Taehyeong Kim, Kyoungmook Lim, Hoon Cho, Daeho Yang, Changyeol Jeong, Sung Yi

Mechanical and Materials Engineering Faculty Publications and Presentations

Effects of zinc-coated steel type and steel surface sandblasting pretreatment in the solid-liquid compound casting of layered type steel/aluminum bimetals were investigated. The Zn coating behavior and its effects on interfacial microstructure evolution and fracture mechanism were also discussed. The aluminum fluidity in thin plate type flow channels formed by the steel insert and the mold wall primarily depended on the insert surface roughness and secondarily on the wettability. As-galvanized (GI) steel/aluminum bimetal joints showed the bonding strength of 20 MPa and more, while galvannealed (GA) steels showed poor bonding. The interfacial bonding zone consisted of most Al13Fe4, Al8Fe2Si, Al4.5FeSi …

To Burn-In, Or Not To Burn-In: That’S The Question, Ephraim Suhir

Mechanical and Materials Engineering Faculty Publications and Presentations

In this paper it is shown that the bathtub-curve (BTC) based time-derivative of the failure rate at the initial moment of time can be considered as a suitable criterion of whether burn-in testing (BIT) should or does not have to be conducted. It is also shown that the above criterion is, in effect, the variance of the random statistical failure rate (SFR) of the mass-produced components that the product manufacturer received from numerous vendors, whose commitments to reliability were unknown, and their random SFR might vary therefore in a very wide range, from zero to infinity. A formula for the …

On The Feasibility Of Tailoring Copper-Nickel Functionally Graded Materials Fabricated Through Laser Metal Deposition, Sreekar Karnati, Yunlu Zhang, Frank W. Liou, Joseph William Newkirk

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this study, pulse‐width modulation of laser power was identified as a feasible means for varying the chemical gradient in copper—nickel‐graded materials. Graded material deposits of 70 wt. %. copper‐30 wt. %. nickel on 100 wt. %. nickel and vice versa were deposited and characterized. The 70/30 copper—nickel weight ratio in the feedstock powder was achieved through blending elemental copper and 96 wt. %. Ni—Delero‐22 alloy. At the dissimilar material interface over the course of four layers, the duty cycle of power was ramped down from a high value to optimized deposition conditions. This change was theorized to influence the …