Materials Science and Engineering Commons^™

Architecture Of Heptagonal Metallo-Macrocycles Via Embedding Metal Nodes Into Its Rigid Backbone, A.M.Shashika D. Wijerathna, He Zhao, Qiangqiang Dong, Qixia Bai, Zhiyuan Jiang, Jie Yuan, Jun Wang, Mingzhao Chen, Markus Zirnheld, Rockwell T. Li, Yuan Zhang, Yiming Li, Pingshan Wang

College of Sciences Posters

Metal-organic macrocycles have received increasing attention not only due to their versatile applications such as molecular recognition, compounds encapsulation, anti-bacteria and others, but also for their important role in the study of structure-property relationship at nano scale. However, most of the constructions utilize benzene ring as the backbone, which restricts the ligand arm angle in the range of 60, 120 and 180 degrees. Thus, the topologies of most metallo-macrocycles are limited as triangles and hexagons, and explorations of using other backbones with large angles and the construction of metallo-macrocycles with more than six edges are very rare.

In this study, …

Highly Stretchable And Sensitive Sbs/Gr/Cnts Fibers With Hierarchical Structure For Strain Sensors, Mengsui Liu, Yaping Sheng, Chenggang Huang, Chenggang Huang, Yanfen Zhou, Liang Jiang, Mingwei Tian, Shaojuan Chen, Stephen Jerrams, Fenglei Zhou, Jianyong Yu

Articles

Most of the reported flexible strain sensors can only normally sense external stretch in a quite narrow working range and with low sensitivity. In order to overcome these drawbacks, elastomeric fiber based strain sensors incorporating graphene (Gr) and carbon nanotubes (CNTs) were initially fabricated via coaxial wet spinning. The solution etching method was employed for forming a 1D@2D@1D hierarchical structure, with pores and microcracks on fibers, to reconstruct their conductive networks. The solution etched fiber based strain sensors achieved a significant improvement in obtaining a high maximum gauge factor of 1667 and capability of working over a wide strain range …

Advanced Microstructural Characterization Of Functionally Graded Dental Ceramic Material For Materials-Informed Finishing, Angani Vigneswaran

Theses and Dissertations--Manufacturing Systems Engineering

Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has gained popularity as the choice of material for dental prosthetics. Ivoclar Vivadent’s IPS e.max ZirCAD Prime dental ceramic incorporates a unique gradient technology that varies the yttria content over the thickness of the material. The top layer is composed of 5Y-TZP which is desired for its optical properties while the bottom layer is composed of a much stronger 3Y-TZP. In between the two layers, 5Y-TZP and 3Y-TZP are mixed to form a transition layer. Varying the amount of yttria allows for more esthetically pleasing translucency in the visible areas of the restoration without compromising …

A Deep Learning-Informed Design Scheme For Shear Friction At Concrete-To-Concrete Interface: Recommendations For Inclusion In Aashto Lrfd Guidelines, Tarutal Ghosh Mondal, Nikkolas Edgmond, Lesley Sneed, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Recent advancements in construction technology have led to high-strength concrete and steel. However, these developments have depreciated the accuracy of the design equations in current provisions, which were based on normal-grade materials. To fill such a research gap, this study presents a novel deep learning-based computation scheme that can replace the current design provisions by virtue of its superior accuracy and reliability. The proposed approach exploits Neural Additive Models (NAMs) in which geometric and material properties associated with a normal weight concrete-to-concrete shear interface are inputted to individual neural network blocks. The outputs of the individual blocks are linearly combined …

Achieving Strong Chemical Interface And Superior Energy-Saving Capability At The Crosslinks Of Rubber Composites Containing Graphene Oxide Using Thiol-Vinyl Click Chemistry, Rui Zhang, Jiaye Li, Zongchao Xu, Stephen Jerrams, Shui Hu, Li Lui, Shipeng Wen, Liqun Zhang

Articles

Rapidly developments in international transportation inevitably lead to an increase in the consumption of energy and resources. Minimizing the rolling resistance of tires in this scenario is a pressing challenge. To lower the rolling resistance of tires, enhancing the interaction between fillers and rubber molecules while improving the dispersion of fillers are required to reduce the internal mutual friction and viscous loss of rubber composites. In this study, graphene oxide (GO) was modified using γ-mercaptopropyltrimethoxysilane (MPTMS) with thiol groups. A modified GO/natural rubber (MGO/NR) masterbatch with a fine dispersion of MGO was then introduced into solution-polymerized styrene butadiene rubber (SSBR) …

Comparing Weathering Effects Of Ultraviolet And Xenon Arc Accelerated Aging On Polyvinyl Chloride, Collin Mcinnes

Williams Honors College, Honors Research Projects

As the ubiquitousness of polymers increases and begins seeing use in outdoor settings, the need to fully understand how these materials degrade is also necessary. This study aims to compare two known accelerated aging methods, namely an ultraviolet light chamber and a xenon arc light chamber, to understand what differences, if any, manifest in the mechanical, chemical, and cosmetic deterioration of polyvinyl chloride (PVC) after long-term exposure. The study utilizes Fourier-transform infrared spectroscopy, dynamic mechanical analysis, thermogravimetric analysis, and colorimetry analysis to determine the extent of degradation and potential discrepancies between the aging methods.

Development Of High Current Electromigration Test System For Evaluation Of Novel Solder Structures, Nicholas Pareis

Electronic Theses and Dissertations, 2020-2023

Electromigration reliability of ball-grid-array (BGA) solder joints is emerging as a critical area of research for advanced microelectronic devices, especially those with high power requirements. In this study, a novel high current electromigration test system, including a temperature sensing capability, was designed and developed for the purpose of performing electromigration characterization of various BGA solder joint structures, including features designed for reduced current crowding. This study consisted of two main parts: design and development of a novel high current electromigration test system, and using this novel system for electromigration characterization of BGA solder joints. In the first portion of this …

Xps Study Of Calcium Lanthanum Sulfide Ceramics, Brian E. Butkus

Graduate Thesis and Dissertation 2023-2024

Long wave infrared (LWIR) optics that transmit in the 8 to 14 m wavelength range and, additionally, can withstand severe physical and thermal stresses are needed for advanced remote sensing, guidance and communication-based applications. However, most non-oxide transparent LWIR optics do not have the wider transmission range, nor the hardness and resistance to thermal shock needed for extreme environments. Because of these limitations, research is circling back to a promising material, calcium lanthanum sulfide (CLS), that could meet LWIR needs for extreme environments.

In this thesis, we will demonstrate the abilities of x-ray photoelectron spectroscopy (XPS) as a technique for …

Functionalization Of 1d And 2d Nanostructures And Their Applications, Yuen Yee Li Sip

Graduate Thesis and Dissertation 2023-2024

Material discovery and development has been playing a significant role in shaping human civilizations, by studying and improving materials for appealing observations to aid in our survival as well as to satisfy our curiosity. From the common earthly materials that give us strong building structures and hunting weapons to the Silicon Age that contributes to the creation of modern electronics and computers, the development of novel and enhanced materials continues to grow. Recently, a new field has emerged that is rapidly expanding the engineering circle; these are called nanomaterials. By shrinking bulk materials into structures with nanoscale dimensions, there is …

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 …

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 …

Modeling Phase Selection And Extended Solubility In Rapid Solidified Alloys, Azeez Akinbo, Yijia Gu

Materials Science and Engineering Faculty Research & Creative Works

A new phase selection model based on the time-dependent nucleation theory was developed to investigate the effect of rapid solidification on extended solubility. The model was applied to predict the solubility as a function of undercooling for several binary Al alloys. The predictions of both eutectic and peritectic systems show good agreement with experimental data. It was demonstrated that the developed model is better than the T 0-line method, which neglected the kinetic process of nucleation. Furthermore, the model can also be applied to ternary and multicomponent phases assuming the nucleation is limited by the scarcest species or the slowest …

A Thermal, Mechanical, And Materials Framework For A Shape Memory Alloy Heat Engine For Thermal Management And Energy Recovery, Maria Chikhareva

Electronic Theses and Dissertations, 2020-2023

Shape memory alloy (SMA) heat engines possess an inherent property of sensing a change in temperature, performing work, and rejecting heat through the shape memory effect resulting from a temperature-induced phase transformation. This work presents a framework for the design and implementation of an SMA-based Stirling heat engine for maximum power or speed incorporating and combining mechanical, thermal, and material aspects. The motivation for this work comes from the growing need for reliable thermal management and energy recovery in both ground and space applications of interest to NASA and commercial space companies. In future lunar and Mars missions, an SMA …

Development And Testing Of A Hyperbaric Aerodynamic Levitator For Containerless Materials Research, Sydney Elizabeth Boland

Masters Theses

"This research focused on the development and testing of a hyperbaric aerodynamic levitator for container less materials research of specimens at temperatures greater than 2000°C and pressures up to 10.3 MPa (1500 psi). The effect of specimen size, specimen density, pressure, and flow rate on the levitation behavior was studied. Lightweight specimens demonstrated two stable levitation regimes that were speculated to be associated with a change in the turbulent wake structure. The hyperbaric aerodynamic levitator was also used to determine the effect of pressure on the heat transfer by studying the melting behavior of a levitated 3.0 mm diameter alumina …

Deep Reinforcement Learning For Approximate Policy Iteration: Convergence Analysis And A Post-Earthquake Disaster Response Case Study, Abhijit Gosavi, L. (Lesley) H. Sneed, L. A. Spearing

Engineering Management and Systems Engineering Faculty Research & Creative Works

Approximate Policy Iteration (API) is a Class of Reinforcement Learning (RL) Algorithms that Seek to Solve the Long-Run Discounted Reward Markov Decision Process (MDP), Via the Policy Iteration Paradigm, Without Learning the Transition Model in the Underlying Bellman Equation. Unfortunately, These Algorithms Suffer from a Defect Known as Chattering in Which the Solution (Policy) Delivered in Each Iteration of the Algorithm Oscillates between Improved and Worsened Policies, Leading to Sub-Optimal Behavior. Two Causes for This that Have Been Traced to the Crucial Policy Improvement Step Are: (I) the Inaccuracies in the Policy Improvement Function and (Ii) the Exploration/exploitation Tradeoff Integral …

Laser Powder Bed Fusion Of Bimetallic Structures, Asif Mahmud

Graduate Thesis and Dissertation 2023-2024

Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural development, and nanohardness variations. Constituent intermixing after LPBF was quantitatively estimated using thermo-kinetic coefficients of mass transport and compared with the diffusivity of Ni in the austenitic Fe-Ni system. The intermixing of primary solvents (Ni and Fe) in SS316L/IN718 bimetallic structures was observed for an intermixing zone of approximately 800 µm, and their intermixing coefficient was estimated …

An Experimental Study On The Mechanical Properties And Chemical Composition Of Lcd 3d Printed Specimens, Sebastian Gomez

College of Graduate Studies: Theses & Dissertations

Additive manufacturing technologies have been enhanced throughout the years yet have surprised the manufacturing industry due to their high-end surface finish and dimensional accuracy. Different experiments have been done to identify a specific phenomenon known in the vat-polymerization field. Distortion and dimensional inaccuracy tend to affect the overall properties of the process, either physical or chemical. This approach allows the understanding of how the physical properties have been affected and how to study the chemical properties to avoid this type of phenomenon. The chemical reaction between polymer and UV light has been studied and experimented with to the point that …

Radiation Shielding Effectiveness Of Hafnium Diboride (Hfb2) Reinforced Epoxy Composites For Enhanced Radiation Protection And Safety, Furkan Erdogan

Theses and Dissertations

This thesis investigates the radiation shielding effectiveness of hafnium diboride (HfB2) reinforced epoxy composites, with the aim of enhancing radiation protection and safety in various applications. The study focuses on the development and characterization of HfB2-epoxy composites with varying weight percentages of HfB2 nanoparticles, as well as on the evaluation of their shielding effectiveness against gamma rays and thermal neutrons. The radiation shielding performance of the composites is assessed using gamma-ray spectroscopy and neutron counting, and the neutron attenuation efficacy is compared with that of 5% borated high-dense polyethylene. The results indicate that the HfB2-epoxy composites exhibit promising radiation shielding …

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

College of Graduate Studies: Theses & 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 …

Nanostructured Alloy Thin Film Fabrication And Application For Zinc-Air Battery And Lithium-Ion Battery, Guanzhi Wang

Electronic Theses and Dissertations, 2020-2023

The depletion of unsustainable fossil fuels and growing environmental issues have given rise to scientific challenges and research interests in the development of renewable energy technologies to meet the rising global energy demand. Electrochemical energy storage and conversion technologies (ESCTs), such as lithium-ion batteries, metal-air batteries, supercapacitors, and fuel cells, etc., offer a clean and sustainable strategy for utilizing energy. As the core components, the electrode materials, including anodes, cathodes, and catalysts, play a direct decisive role in the device's performance in practical application. Therefore, the development of high-performance and low-cost electrode materials is critical for the success of these …

Electroanalytical Investigations Of Microrna-Conjugated Cerium Oxide Based Nanomaterials For Biomedical Applications, Chaimae El Ghzaoui

Electronic Theses and Dissertations, 2020-2023

Diabetes patients are increasingly suffering from wound-healing impairments coupled with other severe medical conditions. High levels of oxidative stress and proinflammatory cytokines are predominant pathologic characteristics of diabetic wounds. Applying microRNA (miRNA) in gene therapy often successfully treats various disorders by generating highly specific bio-responses. Studies revealed that microRNA146a (miR146a), a regulator of inflammation, is downregulated in diabetic wounds. However, miR203 is found to be highly-expressed in diabetic foot ulcers in positive correlation with disease severity. We have synthesized Cerium oxide nanoparticles (CNPs) since they are used in various biomedical applications due to their high enzyme-mimetic activities and reactive oxygen …

Investigation Of Manufacturing Techniques For Magnetorheological Elastomers To Expand Feasibility In A Diverse Array Of Applications, Austin S. Robbins

College of Graduate Studies: Theses & Dissertations

Magnetorheological elastomers, or MREs, are smart composite materials with controllable physical and mechanical properties when introduced to an external stimulus of a magnetic field. The controllability of these properties is highly tunable by the selection of the elastomeric matrix, concentration of magnetically permeable particles, introduction of additives, and the alignment of the constituents during the curing process. The fabrication of MREs typically calls for a mold that is filled with an MRE mixture to create the final desired geometry after curing. These molds are frequently placed under a magnetic field which orients the micron sized magnetic particles along the magnetic …

Stability Of Linicoal-Oxide Electrode Material Under High-Temperature Ceramic Fuel Cell Conditions, Wei Zhang

Dissertations, Master's Theses and Master's Reports

LiNi0.8Co0.15Al0.05O2 (LNCA) is an important cathode material for room-temperature operation of lithium-ion batteries (LIBs). As an emerging research area, LNCA was recently applied as electrodes (both cathode and anode) for high-temperature ceramic fuel cells (CFCs) with impressive performances. However, the stability of LNCA electrode material under CFC operating conditions (i.e., reactive atmospheres and high temperatures) remains unknown. In this dissertation: (1) The stability of LNCA in air and H2 atmospheres was systematically evaluated at elevated temperatures (i.e., the operating electrode environments of H2-fueled CFCs). It was found that LNCA exhibited excellent stability in air within a wide temperature range from …

Suppressing Aluminum/Silica Exchange Reaction Between High Aluminum Steel And Mold Flux During Continuous Casting Process, Kuanysh Nurbekuly Yermukhanbetov

Masters Theses

"Mold flux plays one of the critical roles in continuous casting of steel. It performs five primary functions: thermal and chemical insulation, lubrication between the steel strand and mold, absorption of inclusions, and promotion of even heat flux. The aluminum/silica exchange reaction occurring between steel and mold flux during the continuous casting process poses significant challenges in the steel industry. This reaction can lead to various defects in the cast product and adversely affect its surface quality, as well as downstream processing.

In this work, effectiveness of two approaches, namely slag dopant additions and electrochemical techniques, in suppressing the exchange …

Effect Of Platelet Length And Stochastic Morphology On Flexural Behavior Of Prepreg Platelet Molded Composites, Siavash Sattar, Benjamin Beltran Laredo, Sergii G. Kravchenko, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

Prepreg platelet molding compound (PPMC) can be used to create structural grade material with a heterogeneous mesoscale morphology. The present work considered various platelet lengths of the prepreg system IM7/8552 to study the effect of platelet length on the flexural behavior of PPMC composite. A progressive failure finite-element analysis was used to understand competing failure modes in PPMC with the different platelet length. The interlaminar and in-plane damage mechanisms were employed to describe complex failure modes within the mesostructure of PPMCs. Experimental results of the flexural tests of the PPMC with different platelet length sizes were used to validate the …

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 …

Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …

Characterization Of Virgin, Re-Used, And Oxygen-Reduced Copper Powders Processed By The Plasma Spheroidization Process, M. Hossein Sehhat, David Perez-Palomino, Connor Wiedemeier, Tristan Cullom, Joseph William Newkirk

Materials Science and Engineering Faculty Research & Creative Works

Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and …

Boro/Carbothermal Reduction Co-Synthesis Of Dual-Phase High-Entropy Boride-Carbide Ceramics, Lun Feng, William Fahrenholtz, Gregory E. Hilmas, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

Dense, dual-phase (Cr,Hf,Nb,Ta,Ti,Zr)B₂-(Cr,Hf,Nb,Ta,Ti,Zr)C ceramics were synthesized by boro/carbothermal reduction of oxides and densified by spark plasma sintering. The high-entropy carbide content was about 14.5 wt%. Grain growth was suppressed by the pinning effect of the two-phase ceramic, which resulted in average grain sizes of 2.7 ± 1.3 µm for the high-entropy boride phase and 1.6 ± 0.7 µm for the high-entropy carbide phase. Vickers hardness values increased from 25.2 ± 1.1 GPa for an indentation load of 9.81 N to 38.9 ± 2.5 GPa for an indentation load of 0.49 N due to the indentation size effect. Boro/carbothermal …

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 (Ti_0.66Cr_0.33)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 …