Materials Science and Engineering Commons^™

Thermal And Electrical Properties Of Spark Plasma Sintered (Ti,Cr)B2 Ceramics, Steven M. Smith, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Laura Silvestroni

Materials Science and Engineering Faculty Research & Creative Works

Thermal and electrical properties were measured for TiB2 ceramics containing varying CrB2 contents up to 33 mol%. The room-temperature thermal diffusivity decreased with increasing Cr content from 0.330 ± 0.003 cm2/s for pure TiB2 to 0.060 ± 0.003 cm2/s for (Ti0.66Cr0.33)B2. The amount of anisotropy in the coefficients of thermal expansion increased with increasing Cr content and the c-axis had the greatest dependence on Cr addition, with an increase of more than 25% in the thermal expansion for 33 mol% CrB2 compared to TiB2, whereas the a-axis only increased by about 8%. The electrical conductivity was the lowest for (Ti0.66Cr0.33)B2 …

Compositional Modifications To Alter And Suppress Laves Phases In Alxcrmotayti Alloys, Austin E. Mann, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Herein, the Development of Refractory Complex Concentrated Alloys in the Al–Cr–Mo–Ta–Ti Alloy System is Reported. Alloys with Modified Al and Ta Concentrations Are Designed using CALPHAD Tools and Produced Via Arc Melting and Characterized in Both As-Cast and Annealed Forms. Properties of the Alloys, Nature of the Microstructures, and Phase Transformation Behavior Are Described Via X-Ray Diffraction, Microstructural Characterization, Microhardness, and Differential Scanning Calorimetry. Two Alloys, Namely, Al0.25CrMoTa0.8Ti and Al0.75CrMoTa0.8Ti, Are Represented by a Body-Centered-Cubic Matrix Phase after Annealing, along with a Secondary Cr–Ta Laves Phase of the C15 and C14 Polytypes, respectively. in As-Cast and Annealed Forms, the Al0.75CrMoTa0.45Ti …

High Temperature Confocal Scanning Laser Microscopy Analysis Of Dead-Burned Magnesia Aggregates, Tyler Richards, Viraj Athavale, Jeffrey D. Smith, Ronald J. O'Malley

Materials Science and Engineering Faculty Research & Creative Works

Dead-Burned Magnesia is a Commonly Used Material in the Manufacturing of Refractories for the Steelmaking Industry. Aggregates of Dead-Burned Magnesia Contain Secondary Phases Due to the Impurities within the Magnesite Rock Used in its Production. While These Phases Can Aid in Sintering Magnesia, They May Have Some Impact on the High-Temperature Performance of the Refractory Product. High-Temperature Confocal Scanning Laser Microscopy Was Utilized to Observe the Behavior of Dead-Burned Magnesia Aggregates at Elevated Temperatures (Up to 1550°C). Liquid Formation Was Detected Even at Temperatures Below 1350°C. in Some Cases, This Liquid Quickly Exuded from the Aggregate Surface. This Liquid Phase …

Oxidation Behavior Of Nb-Coated Zirconium Diboride, Jan E. Förster, William Fahrenholtz, Gregory E. Hilmas, Ravisankar Naraparaju

Materials Science and Engineering Faculty Research & Creative Works

Metallic Nb-Coatings Were Deposited on Top of ZrB₂ by Means of Magnetron Sputtering to Improve its Oxidation Resistance. High Temperature Oxidation Tests Have Revealed that the Metallic Nb-Coatings Lead to the Formation of a Dense Solid and Protective Reaction Zone in Addition to a More Stable B₂O₃ Liquid Solution at the Surface. Compared to Baseline ZrB₂, a Reduction in the Oxidation Kinetics, as Well as the Thickness of the Porous Zirconia Layer by 71%, Has Been Achieved with the Help of Nb-Coatings. a Liquid Phase Sintering by Molten Nb₂O₅ Mechanism Was …

Ambient Ammonia Synthesis Via Microwave-Catalytic Materials And Plasma Chemistry, Sean Brown

Graduate Theses, Dissertations, and Problem Reports

Ammonia is critical to supporting human life on earth because of its use as fertilizer. The Haber-Bosch process to produce ammonia has been practiced for over 100 years. This process operates at high pressure and temperature to overcome the thermodynamic and kinetic limitations of the ammonia synthesis reaction thus researchers have tried to overcome it for decades. At present this process represents 1% of global energy usage and 2.5% of global CO₂ emissions. The proposed chemical looping ammonia synthesis approach seeks to reduce the environmental impact of this critical process and to elucidate microwave-catalytic principles.

This research aims to …

Design And Fabrication Of A High-Performance Heat Exchanger Using An Optimized Three-Dimensional Surface Structure Through Additive Manufacturing, Seth T. Waters

Electronic Theses and Dissertations

A heat exchanger is a device used to transfer thermal energy between two intertwining fluid pathways. In this study, the design of a novel heat exchanger is proposed using functional gradient double gyroid structure. The complex internal geometries of the gyroid structure significantly increases the surface area to volume ratio, and potentially could expressively improve efficiency of the heat transfer. The proposed idea provides a new approach for the design of a high-efficiency heat exchanger. In order to fabricate the complex structured heat exchanger system additive manufacturing is adapted instead of traditionally subtractive manufacturing techniques or casting. The prototypes of …

Carrier Transport Engineering In Wide Bandgap Semiconductors For Photonic And Memory Device Applications, Ravi Teja Velpula

Dissertations

Wide bandgap (WBG) semiconductors play a crucial role in the current solid-state lighting technology. The AlGaN compound semiconductor is widely used for ultraviolet (UV) light-emitting diodes (LEDs), however, the efficiency of these LEDs is largely in a single-digit percentage range due to several factors. Until recently, AlInN alloy has been relatively unexplored, though it holds potential for light-emitters operating in the visible and UV regions. In this dissertation, the first axial AlInN core-shell nanowire UV LEDs operating in the UV-A and UV-B regions with an internal quantum efficiency (IQE) of 52% are demonstrated. Moreover, the light extraction efficiency of this …

Damage Stability Study Of A 500 Dw Ro-Ro Ferry Vessel, Zulfaidah Ariany, Budhi Santoso, Sarwoko Sarwoko, Nauval Abdurrahman Prasetyo

Makara Journal of Technology

The development of the crossing transportation industry is currently increasing in the island areas. The use of Ro-Ro type ferry boats is extremely efficient in moving people, goods, and vehicles. The current research focuses on the damage stability of the 500 DWT Ro-Ro ferry, which aims to meet the needs of the Ro-Ro ferry in the archipelago area. The previously existing initial design of a barge hull with a main size Lpp = 40.15 m, B = 12 m, H = 3.2 m, and T = 2.15 m was used to analyze the damage stability condition further. First, the drawings …

Elucidating The Synergic Effect In Nanoscale Mos2/Tio2 Heterointerface For Na-Ion Storage, Chunrong Ma, Dewen Hou, Jiali Jiang, Yanchen Fan, Xiang Li, Tianyi Li, Zifeng Ma, Haoxi Ben, Hui Xiong

Materials Science and Engineering Faculty Publications and Presentations

Interface engineering in electrode materials is an attractive strategy for enhancing charge storage, enabling fast kinetics, and improving cycling stability for energy storage systems. Nevertheless, the performance improvement is usually ambiguously ascribed to the “synergetic effect”, the fundamental understanding toward the effect of the interface at molecular level in composite materials remains elusive. In this work, a well-defined nanoscale MoS₂/TiO₂ interface is rationally designed by immobilizing TiO₂ nanocrystals on MoS₂ nanosheets. The role of heterostructure interface between TiO₂ and MoS₂ by operando synchrotron X-ray diffraction (sXRD), solid-state nuclear magnetic resonance, and density functional …

Engineering Order-Disorder Transitions For High-Performance Thermoelectric Fe2val Heusler Alloys, Cory T. Cline

Dartmouth College Ph.D Dissertations

Fe₂VAl shows great promise as an eco-friendly and low-cost replacement to conventional low-temperature (250-500 K) thermoelectric materials. Current thermoelectric materials use toxic and expensive elements like Te and Sb, whereas Fe₂VAl offers a larger power factor at a lower cost and a reduced risk of environmental pollution. The key issue with Fe₂VAl is the alloy’s relatively large thermal conductivity compared to its semiconductor competitors. This thesis aims to investigate a hierarchical approach to reduce lattice thermal conductivity through a preliminary exploration of heavy element substitutions and mechanical deformation, then through probing order-disorder transitions for …

Computational Symmetric Grain Boundary Energy Of Thorium Dioxide, Brendan J. Carroll

Honors College Theses

With fossil fuels being depleted at a faster rate than ever, there has been an effort to convert fossil fuel energy to different forms of green energy. One of these forms is nuclear power, and while nuclear power itself is not new, new fuel sources for different types of reactors are being developed. This study aims to do computational experiments on Thorium Dioxide (a potential new nuclear fuel source) to look for the lowest grain boundary energy and what the effect of grain boundary conditions on the energy. Different orientations of the materials grain boundary were modeled and molecular dynamic …

Reduction Of Embodied Carbon In Buildings Through Use Of Low Carbon Strategies And Standardization And Enforcement Of Life Cycle Assessment, Bhargavi Sai Sudhakar

Master's Projects and Capstones

The building and construction industry is energy intensive and as of 2021, this industry is responsible for 37% of the total global greenhouse gas emissions. In previous studies of conventional buildings, the operational energy of a building contributed to 80% and the embodied energy contributed to 20% of the total life cycle energy. With increase in policies and standards that focus on reducing the operational energy, low energy and certified green buildings have emerged where the operational energy has considerably reduced. The relative and absolute share of embodied energy in these energy efficient buildings have increased due to excessive use …

Advances On Composite Cathodes For Lithium-Sulfur Batteries, Xi-Yao Li, Chang-Xin Zhao, Bo-Quan Li, Jia-Qi Huang, Qiang Zhang

Journal of Electrochemistry

Lithium-sulfur (Li-S) batteries are deemed as high-promising next-generation energy storage technique due to their ultrahigh theoretical energy density, where the sulfur cathodes with high specific capacity guarantee the energy density advantage and directly determine the battery performances. After decades of exploration, the most promising sulfur cathodes are sulfur/carbon composite (S/C) cathodes and sulfurized polyacrylonitrile (SPAN) cathodes. In this manuscript, recent advances on S/C and SPAN cathodes in Li-S batteries are comprehensively reviewed. The electrochemical reaction circumstances on S/C and SPAN cathodes are firstly introduced and compared to reveal the working mechanisms of the two types of Li-S batteries. The S/C …

Enhanced Performance Of 3d Electroactive Polymer Transducers Via Hierarchical Structures, Frederick B. Holness

Electronic Thesis and Dissertation Repository

Conjugated polymers (CPs) are a class of polymers that exhibit a change in size or shape in response to electrical stimuli. The unique combination of electrical and mechanical properties facilitates the fabrication of novel devices in a broad range of applications including: sensors, actuators, and lab-on-a-chip systems. The alternating single and double bonds along the polymer chain of CPs enables their electroactive properties but is also responsible for processability associated with CPs that has limited fabrication methods. Recently a photosensitive CP composite enabling additive manufacturing (AM) of 3D CP structures was developed. However, the introduction of a copolymer for mechanical …

Dynamic Rbi With Central Difference Method Approach In Calculation Of Uniform Corrosion Rate: A Casestudy On Gas Pipelines, M.Riefqi Dwi Alviansyah, Fernanda Hartoyo, Zahra Nadia Nurullia, Ari Kurniawan

Journal of Materials Exploration and Findings (JMEF)

The oil and gas industry generally uses a piping system to drain fluids. Even though the pipes used have been well designed, the use of pipes as a means of fluid transportation still provides the possibility of failure that can occur at any time, one of which is due to uniform corrosion. The use of standard Risk Based Inspection (RBI) according to the API RBI 581 document has been widely used to anticipate potential failures to pipe components. The use of standard RBI can reduce the risk of failure significantly. Because the standard RBI considers the component risk value to …

Structural Risk-Based Underwater Inspection (Rbui) As A Cost Reduction Of Field’S End Of Production Life, Ivan Fitrian Putra, Johny Wahyuadi Soedarsono, Mirza Mahendra, Yuki Haidir, Faisal Dwiyana Purnawarman, Iwan Sukirna, Widi Hernowo

Journal of Materials Exploration and Findings (JMEF)

Mubadala Petroleum operates offshore platforms in a southern Makassar Straits that needs to be periodically inspected. The cost for the inspection is massive due to the high cost of mobilization and demobilization of vessels including crew and equipment. In response of a new approach to reduce cost, a Risk-Based Underwater Inspection (RBUI) methodology is developed. This RBUI purpose is to reduce the inspection interval of the offshore platform, from every 2 years to a longer period^[1]. There are existing RBUI methodologies, which are already developed and implemented in other companies^[5]. Purpose of this paper is to …

The Comparison Of Pipe Thickness Selection Method Using Full Flange Rating And Non-Full Flange Rating Of Cryogenic Services In An Lng Plant Construction, Ari Agustar, Isdaryanto Iskandar, Wahyuaji Narottama Putra

Journal of Materials Exploration and Findings (JMEF)

Significant growth of gas demand as a source of power generation for domestic use and industries, mainly in the developed countries, has forced the effort to secure the gas supplies located thousands of miles away across the sea as an economical way of gas transportation instead of transporting by pipeline. LNG technology was created as the solution. Natural gas is refrigerated below its boiling point (-160^oC to -162^oC), known as cryogenic temperature or cryogenic service. Material of Construction (MOC) selection report showed that 304/304L and 316/316L Stainless Steel pipe could withstand and be suitable for this …

Investigation Of The Effect Of Corundum Layer On The Heat Transfer Of Sic Slab, Sri Elsa Fatmi, Donanta Dhaneswara, Muhammad Anis, Ahmad Ashari

Journal of Materials Exploration and Findings (JMEF)

Aluminum is the most widely used metal in industry. Aluminum smelting is one of the important steps that needs to be carried out to produce products made of aluminum metal with good quality. In the process of smelting aluminum there are several problems that occur, one of which is the growth of corundum in Si C refractories which affects the quality of aluminum melt and the durability of Si C refractories. This research was conducted to see the heat transfer in Si C and the effect of the presence of Corundum on heat transfer. This research was carried out by …

Platinum-Iridium Alloys In Jewelry, Nathen C. Christa, Seth Walker, Dylan Hallman

ME 4133/6133 Mechanical Metallurgy

One of the most widely used metals on the periodic table is Platinum (Pt). The name is derived from the Spanish Platina, meaning “silver.” This malleable, ductile material is widely used in applications due to its unique chemical properties. A couple of these unique properties include a high melting point and good resistance to corrosion or chemical attack. Platinum materials have alloys that are indispensable in the chemical laboratory for electrodes. This allows for material applications in crucibles and dishes to withstand elevated temperatures. Platinum is used primarily in catalytic converters in vehicles converting emissions from the vehicle’s engine into …

High-Carbon Steel In Additive Manufacturing, Chidi N. Agusiegbe, Devin Morton, Emmanuel Moore

ME 4133/6133 Mechanical Metallurgy

High-carbon steel can be processed through numerous methods. The method that will be focused on primarily is processing high-carbon steel through means of additive manufacturing. Additive manufacturing is the industrial production name for 3D printing, a computer-controlled process that creates three-dimensional objects by depositing materials, usually in layers. AM methods like wire laser additive manufacturing (WLAM) and electron beam melting (EBM) are all common methods for fabricating high carbon steel. The perks associated with these methods are that they improve some drawbacks of the natural properties of high-carbon steel. This paper discusses the uses of these additive manufacturing methods along …