Materials Science and Engineering Commons^™

Scalable Patterning Using Laser-Induced Shock Waves, Saidjafarzoda Ilhom, Khomidkhodza Kholikov, Peizhen Li, Claire Ottman, Dylan Sanford, Zachary Thomas, Omer San, Haluk E. Karaca, Ali O. Er

Mechanical Engineering Faculty Publications

An advanced direct imprinting method with low cost, quick, and minimal environmental impact to create a thermally controllable surface pattern using the laser pulses is reported. Patterned microindents were generated on Ni₅₀Ti₅₀ shape memory alloys and aluminum using an Nd: YAG laser operating at 1064 nm combined with a suitable transparent overlay, a sacrificial layer of graphite, and copper grid. Laser pulses at different energy densities, which generate pressure pulses up to a few GPa on the surface, were focused through the confinement medium, ablating the copper grid to create plasma and transferring the grid pattern onto …

Modeling Of Nitihf Using Finite Difference Method, Nazanin Farjam, Reza Mehrabi, Haluk E. Karaca, Reza Mirzaeifar, Mohammad Elahinia

Mechanical Engineering Faculty Publications

NiTiHf is a high temperature and high strength shape memory alloy with transformation temperatures above 100oC. A constitutive model based on Gibbs free energy is developed to predict the behavior of this material. Two different irrecoverable strains including transformation induced plastic strain (TRIP) and viscoplastic strain (VP) are considered when using high temperature shape memory alloys (HTSMAs). The first one happens during transformation at high levels of stress and the second one is related to the creep which is rate-dependent. The developed model is implemented for NiTiHf under uniaxial loading. Finite difference method is utilized to solve the proposed equations. …

Selective Laser Melting Of Ni-Rich Niti: Selection Of Process Parameters And The Superelastic Response, Narges Shayesteh Moghaddam, Soheil Saedi, Amirhesam Amerinatanzi, Ehsan Saghaian, Ahmadreza Jahadakbar, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Material and mechanical properties of NiTi shape memory alloys strongly depend on the fabrication process parameters and the resulting microstructure. In selective laser melting, the combination of parameters such as laser power, scanning speed, and hatch spacing determine the microstructural defects, grain size and texture. Therefore, processing parameters can be adjusted to tailor the microstructure and mechanical response of the alloy. In this work, NiTi samples were fabricated using Ni_50.8Ti (at.%) powder via SLM PXM by Phenix/3D Systems and the effects of processing parameters were systematically studied. The relationship between the processing parameters and superelastic properties were investigated …

Influence Of Slm On Compressive Response Of Niti Scaffolds, Narges Shayesteh Moghaddam, Soheil Saedi, Amirhesam Amerinatanzi, Ahmadreza Jahadakbar, Sayed Ehsan Saghaian, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Porous Nickel-Titanium shape memory alloys (NiTi-SMAs) have attracted much attention in biomedical applications due to their high range of pure elastic deformability (i.e., superelasticity) as well as their bone-level modulus of elasticity (E≈12-20 GPa). In recent years, Selective Laser Melting (SLM) has been used to produce complex NiTi components. The focus of this study is to investigate the superelasticity and compressive properties of SLM NiTi-SMAs. To this aim, several NiTi components with different level of porosities (32- 58%) were fabricated from Ni_50.8Ti (at. %) powder via SLM PXM by Phenix/3D Systems, using optimum processing parameter (Laser power-P=250 W, …

Application Of Cross-Linked Polyborosiloxanes And Organically Modified Boron Silicate Binders In Silicon-Containing Anodes For Lithium-Ion Batteries, Darius A. Shariaty, Dali Qian, Yang-Tse Cheng, Susan A. Odom

Chemistry Faculty Publications

To determine the effect of cross-linking in polymer binders on gravimetric capacity and retention in charge/discharge cycling of lithium-ion batteries containing silicon anodes, polymers with a varied chemiophysical characters have been studied as electrode binders. Here we report the utilization of cross-linked polyborosiloxanes and a boron-modified organosilicate as binders for nanoparticulate silicon-containing anodes for lithium-ion batteries. We show that highly cross-linked binders enable a large degree of capacity to be accessed and that capacity retention is greater when the electrodes are cycled in half cells. More extensive analysis of the boron-modified organosilicate is further explored.

Orthogonal Photo-Switching Of Supramolecular Patterned Surfaces, Dongsheng Wang, Frank Schellenberger, Jonathan T. Pham, Hans-Jürgen Butt, Si Wu

Chemical and Materials Engineering Faculty Publications

We used Azo/α-CD and ipAzo/γ-CD host–guest complexes to demonstrate that four independent stable states can be orthogonally photo-switched by UV (365 nm), blue (470 nm), green (530 nm) and red light (625 nm). A supramolecular patterned surface was fabricated and orthogonally photo-switched by light with different wavelengths.

A New Hybrid Decision Support Tool For Evaluating The Sustainability Of Mining Projects, S. Kamenopoulos, Zacharias Agioutantis, K. Komnitsas

Mining Engineering Faculty Publications

The integration of sustainable development challenges and opportunities into the decision making process during the design and/or implementation of multi-disciplinary mining projects is generally not supported by decision support systems (DSS). A new hybrid decision support tool, which features an integrated assessment of sustainable development issues as they apply to mining projects, is hereby proposed. The proposed DSS framework, named “Acropolis DSS”, can be used to assist involved stakeholders in critical decisions, especially when addressing issues such as stakeholder participation, transparency, and trade-offs. The proposed DSS is based on a multi-criteria decision analysis combined with the multi-attribute utility theory.

Effect Of Molecular Side Groups And Local Nanoenvironment On Photodegradation And Its Reversibility, Nicole Quist, Mark Li, Ryan Tollefsen, Michael Haley, John Anthony, Oksana Ostroverkhova

Chemistry Faculty Publications

Degradation of organic semiconductors in the presence of oxygen is one of the bottlenecks preventing their wide-spread use in optoelectronic devices. The first step towards such degradation in functionalized pentacene (Pn) derivatives is formation of endoperoxide (EPO), which can either revert back to the parent molecule or proceed to molecule decomposition. We present the study of reversibility of EPO formation through probing the photophysical properties of functionalized fluorinated pentacene (Pn-R-F8) derivatives. Experiments are done in solutions and in films both at the single molecule level and in the bulk. In solutions, degradation of optical absorption and its partial recovery after …

Pit Evolution Around The Fusion Line Of A Nicrmov Steel Welded Joint Caused By Galvanic And Stress-Assisted Coupling Corrosion, Shuo Weng, Yuhui Huang, Fuzhen Xuan, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

The corrosion of NiCrMoV steel welded joints is performed in an aqueous solution of 3.5 wt% NaCl at 180 °C in a container at a pressure of 0.8 MPa. The specimens in the shape of cylindrical tensile rods are immersed in the aqueous solution under the action of tensile stress in a range of 0 to 0.9 of the yield stress of the base metal. The experimental results suggest that there is macro-galvanic corrosion in the welded joint with the coarse-grained heat affected zone (CGHAZ) as anode due to the highest corrosion susceptibility of the CGHAZ. The CGHAZ has the …

Correlation Of Structure, Function And Protein Dynamics In Gh7 Cellobiohydrolases From Trichoderma Atroviride, T. Reesei And T. Harzianum, Anna S. Borisova, Elena V. Eneyskaya, Suvamay Jana, Silke F. Badino, Jeppe Kari, Antonella Amore, Magnus Karlsson, Henrik Hansson, Mats Sandgren, Michael E. Himmel, Peter Westh, Christina M. Payne, Anna A. Kulminskaya, Jerry Ståhlberg

Chemical and Materials Engineering Faculty Publications

Background: The ascomycete fungus Trichoderma reesei is the predominant source of enzymes for industrial conversion of lignocellulose. Its glycoside hydrolase family 7 cellobiohydrolase (GH7 CBH) TreCel7A constitutes nearly half of the enzyme cocktail by weight and is the major workhorse in the cellulose hydrolysis process. The orthologs from Trichoderma atroviride (TatCel7A) and Trichoderma harzianum (ThaCel7A) show high sequence identity with TreCel7A, ~ 80%, and represent naturally evolved combinations of cellulose-binding tunnel-enclosing loop motifs, which have been suggested to influence intrinsic cellobiohydrolase properties, such as endo-initiation, processivity, and off-rate.

Results: The TatCel7A, ThaCel7A, …

Comparison Of Eosin And Fluorescein Conjugates For The Photoinitiation Of Cell-Compatible Polymer Coatings, Jacob L. Lilly, Anuhya Gottipati, Calvin F. Cahall, Mohamed Agoub, Brad J. Berron

Chemical and Materials Engineering Faculty Publications

Targeted photopolymerization is the basis for multiple diagnostic and cell encapsulation technologies. While eosin is used in conjunction with tertiary amines as a water-soluble photoinitiation system, eosin is not widely sold as a conjugate with antibodies and other targeting biomolecules. Here we evaluate the utility of fluorescein-labeled bioconjugates to photopolymerize targeted coatings on live cells. We show that although fluorescein conjugates absorb approximately 50% less light energy than eosin in matched photopolymerization experiments using a 530 nm LED lamp, appreciable polymer thicknesses can still be formed in cell compatible environments with fluorescein photosensitization. At low photoinitiator density, eosin allows more …

Experimental Study On Surface Integrity Of Cryogenically Machined Ti-6al-4v Alloy For Biomedical Devices, M. Hardt, F. Klocke, B. Döbbeler, M. Binder, Ibrahim S. Jawahir

Institute for Sustainable Manufacturing Faculty Publications

Titanium and its alloys are widely used in the biomedical sector. In this field, titanium and its alloys are the material of choice for biomedical devices such as hip and knee replacements. Usually, a Total Hip Replacement (THR) is based on four components, made out of different materials due to the material properties associated with the functional performance. One approach to lower the overall manufacturing costs and enhance the reliability of THR’s is to manufacture the prosthesis out of one material. The titanium alloy Ti-6Al-4V is, therefore, feasible as it exhibits better osseous integration compared to other metallic materials used …

Assisted Development Of Mesophase Pitch With Dispersed Graphene And Its Resulting Carbon Fibers, Aaron Owen

Theses and Dissertations--Mechanical and Aerospace Engineering

The efficacy of dispersed reduced graphene oxide (rGO) as a nucleation site for the growth of mesophase in an isotropic pitch was investigated and quantified in this study. Concentrations of rGO were systematically tested in an isotropic petroleum and coal-tar pitch during thermal treatments and compared to pitch without rGO. The mesophase content of each thermally treated pitch was quantified by polarized light point counting. Further characterization of softening temperature and insolubles were quantified. Additionally, the pitches with and without rGO were melt spun, graphitized, and tensile tested to determine the effects of rGO on graphitized fiber mechanical properties and …

Design And Analysis Of A 3d-Printed, Thermoplastic Elastomer (Tpe) Spring Element For Use In Corrective Hand Orthotics, Kevin Thomas Richardson

Theses and Dissertations--Mechanical and Aerospace Engineering

This thesis proposes an algorithm that determine the geometry of 3D-printed, custom-designed spring element bands made of thermoplastic elastomer (TPE) for use in a wearable orthotic device to aid in the physical therapy of a human hand exhibiting spasticity after stroke. Each finger of the hand is modeled as a mechanical system consisting of a triple-rod pendulum with nonlinear stiffness at each joint and forces applied at the attachment point of each flexor muscle. The system is assumed quasi-static, which leads to a torque balance between the flexor tendons in the hand, joint stiffness and the design force applied to …

Surface Engineering And Monomer Design For Light-Mediated Ring Opening Metathesis Polymerization, Ishan A. Fursule

Theses and Dissertations--Chemical and Materials Engineering

Stimuli-responsive materials are changing the landscape of actuated materials, optoelectronics, molecular machines, solar cells, temporary memory storage, and biomedical materials. Specifically, photo-responsive polymers have gained acceleration in research and application since the last two decades in the form of a surface coating and micro-patterns. Light as a stimulus can be coherent, mono or polychromatic, tunable for power (intensity) and energy (wavelength), and has precise spatiotemporal control. Conventional surface coating techniques such as spin coating are unable to impart properties to the coatings in terms of sturdiness, homogeneity, uniformity over the complex surface, post deposition modification, and process efficiency. Also, in …

Combinatorial Screening Approach In Developing Non-Equiatomic High Entropy Alloys, Azin Akbari

Theses and Dissertations--Chemical and Materials Engineering

High entropy alloys (HEA) are a relatively new group of alloys first introduced in 2004. They usually contain 5 to 6 different principle elements. Each of these elements comprise 5-35 at. % of the chemical composition of the alloy. There is a growing interest in the research community about the development of these alloys as well as their engineering applications. Some HEAs have interesting properties that have made them well suited for higher temperature applications, particularly refractory uses, while some have been shown to maintain their mechanical properties even at cryogenic temperatures.

Initially, the HEA research was focused on developing …

A Microstructure-Based Model Validated Experimentally For Quantification Of Short Fatigue Crack Growth In Three-Dimensions, Pei Cai

Theses and Dissertations--Chemical and Materials Engineering

Built on the recent successes in understanding the crystallographic mechanism for short fatigue crack (SFC) growth across a grain boundary (GB) and developing an experimental method to quantify the GB resistance against short crack growth, a microstructure-based model was developed in this study to simulate the growth behaviors of SFCs in 3-D, by taking into account both the driving force and resistance along at each point along the crack front in an alloy. It was found that the GB resistance was a Weibull function of the minimum twist angle of crack deflection at the boundary in AA2024-T3 Al alloys. In …

Defect Chemistry And Transport Properties Of Solid State Materials For Energy Storage Applications, Xiaowen Zhan

Theses and Dissertations--Chemical and Materials Engineering

Replacing organic liquid electrolytes with nonflammable solid electrolytes can improve safety, offer higher volumetric and gravimetric energy densities, and lower the cost of lithium-ion batteries. However, today’s all-solid-state batteries suffer from low Li-ion conductivity in the electrolyte, slow Li-ion transport across the electrolyte/electrode interface, and slow solid-state Li-ion diffusion within the electrode. Defect chemistry is critical to understanding ionic conductivity and predicting the charge transport through heterogeneous solid interfaces. The goal of this dissertation is to analyze and improve solid state materials for energy storage applications by understanding their defect structure and transport properties.

I have investigated defect chemistry of …

Mixed Matrix Flat Sheet And Hollow Fiber Membranes For Gas Separation Applications, Nicholas W. Linck

Theses and Dissertations--Chemical and Materials Engineering

Mixed matrix membranes (MMM) offer one potential path toward exceeding the Robeson upper bound of selectivity versus permeability for gas separation performance while maintaining the benefits of solution processing. Many inorganic materials, such as zeolites, metal-organic frameworks, or carbon nanotubes, can function as molecular sieves, but as stand-alone membranes are brittle and difficult to manufacture. Incorporating them into a more robust polymeric membrane matrix has the potential to mitigate this issue.

In this work, phase inversion polymer solution processing for the fabrication and testing of asymmetric flat sheet mixed matrix membranes was employed with CVD-derived multiwall carbon nanotubes (MWCNTs) dispersed …

The Formation Mechanism Of Α-Phase Dispersoids And Quantification Of Fatigue Crack Initiation By Experiments And Theoretical Modeling In Modified Aa6061 (Al-Mg-Si-Cu) Alloys, Gongwang Zhang

Theses and Dissertations--Chemical and Materials Engineering

AA6061 Al alloys modified with addition of Mn, Cr and Cu were homogenized at temperatures between 350 ^ºC and 550 ^ºC after casting. STEM experiments revealed that the formation of α-Al(MnFeCr)Si dispersoids during homogenization were strongly affected by various factors such as heating rate, concentration of Mn, low temperature pre-nucleation treatment and homogenization temperature. Through analysis of the STEM results using an image software Image-Pro, the size distributions and number densities of the dispersoids formed during different annealing treatments were quantitatively measured. It was revealed that increasing the heating rate or homogenization temperature led to a reduction of …

Synthesis And Characterization Of Magnesium - Titanium Composites By Severe Plastic Deformation, Baleegh Alobaid

Theses and Dissertations--Chemical and Materials Engineering

Magnesium alloys are widely used in engineering applications, including aerospace and automobile industries, due to their desirable properties, such as lower density, high damping capacity, relatively high thermal conductivity, good machinability, and recyclability. Researchers have, therefore, been developing new magnesium materials. However, mechanical and corrosion properties are still limiting many commercial applications of magnesium alloys. In this Ph.D. thesis research, I developed Mg-Ti composite materials to offer some solutions to further improve the mechanical behavior of magnesium, such as titanium-magnesium (Ti-Mg) claddings, Mg-Ti multilayers, and Ti particle enforced Mg alloys. Low cost manufacturing processes, such as hot roll-bonding (RB) and …

The Physical Behavior And Characterization Of Nanoporous Silicon And Dispenser Cathode Surfaces, Tyler Lucius Corey Maxwell

Theses and Dissertations--Chemical and Materials Engineering

Nanostructured materials have received a surge of interest in recent years since it has become apparent that reducing the size of a material often leads to heightened mechanical behavior. From a fundamental standpoint, this stems from the confinement of dislocations. Applications in microelectromechanical devices, lithium ion batteries, gas sensing and catalysis are realized by combining the improvements in mechanical behavior from material size reduction with the heightened chemical activity offered by materials with a high surface-area-to-volume ratio. In this study, films of nanoporous Si-Mg were produced through magnetron sputtering, followed by dealloying using an environmentally benign process with distilled water. …

Morphological And Energetic Effects On Charge Transport In Conjugated Polymers And Polymer-Nanowire Composites, Zhiming Liang

Theses and Dissertations--Chemistry

Organic semiconductors have wide applications in organic-based light-emitting diodes, field-effect transistors, and thermoelectrics due to the easily modified electrical and optical properties, excellent mechanical flexibility, and solution processability. To fabricate high performance devices, it is important to understand charge transport mechanisms, which are mainly affected by material energetics and material morphology. Currently it is difficult to control the charge transport properties of new organic semiconductors and organic-inorganic nanocomposites due to our incomplete understanding of the large number of influential variables. Molecular doping of π-conjugated polymers and surface modification of nanowires are two means through which charge transport can be manipulated. …

Structural, Transport, And Topological Properties Induced At Complex-Oxide Hetero-Interfaces, Justin K. Thompson

Theses and Dissertations--Physics and Astronomy

Complex-oxides have seen an enormous amount of attention in the realm of Condensed Matter Physics and Materials Science/Engineering over the last several decades. Their ability to host a wide variety of novel physical properties has even caused them to be exploited commercially as dielectric, metallic and magnetic materials. Indeed, since the discovery of high temperature superconductivity in the “Cuprates” in the late 1980’s there has been an explosion of activity involving complex-oxides. Further, as the experimental techniques and equipment for fabricating thin films and heterostructures of these materials has improved over the last several decades, the search for new and …

The Role Of Catalytic Residue PKA On The Hydrolysis/Transglycosylation Partition In Family 3 Β-Glucosidases, Inacrist Geronimo, Christina M. Payne, Mats Sandgren

Chemical and Materials Engineering Faculty Publications

β-Glucosidases (βgls) primarily catalyze the hydrolysis of the terminal glycosidic bond at the non-reducing end of β-glucosides, although glycosidic bond synthesis (called transglycosylation) can also occur in the presence of another acceptor. In the final reaction step, the glucose product or another substrate competes with water for transfer to the glycosyl-enzyme intermediate. The factors governing the balance between the two pathways are not fully known; however, the involvement of ionizable residues in binding and catalysis suggests that their pK_a may play a role. Through constant pH molecular dynamics simulations of a glycoside hydrolase Family 3 (GH3) βgl, we …

Layer-By-Layer Assembled Membranes With Immobilized Porins, Sebastián Hernández, Cassandra Porter, Xinyi Zhang, Yinan Wei, Dibakar Bhattacharyya

Chemical and Materials Engineering Faculty Publications

New and advanced opportunities are arising for the synthesis and functionalization of membranes with selective separation, reactivity, and stimuli-responsive behavior. One such advancement is the integration of bio-based channels in membrane technologies. By a layer-by-layer (LbL) assembly of polyelectrolytes, outer membrane protein F trimers (OmpF) or “porins” from Escherichia coli with central pores ∼2 nm in diameter at their opening and ∼0.7 × 1.1 nm at their constricted region are immobilized within the pores of poly(vinylidene fluoride) microfiltration membranes, in contrast to traditional ruptured lipid bilayer or vesicle processes. These OmpF-membranes demonstrate selective rejection of non-charged organics over ionic solutes, …

Synthesis And Characterization Of Thermoresponsive Hydrogels Based On N-Isopropylacrylamide Crosslinked With 4,4′-Dihydroxybiphenyl Diacrylate, Shuo Tang, Martha Floy, Rohit Bhandari, Manjula Sunkara, Andrew J. Morris, Thomas D. Dziubla, J. Zach Hilt

Chemical and Materials Engineering Faculty Publications

A novel crosslinker [4,4′-dihydroxybiphenyl diacrylate (44BDA)] was developed, and a series of temperature-responsive hydrogels were synthesized through free radical polymerization of N-isopropylacrylamide (NIPAAm) with 44BDA. The temperature-responsive behavior of the resulting gels was characterized by swelling studies, and the lower critical solution temperature (LCST) of the hydrogels was characterized through differential scanning calorimetry. Increased content of 44BDA led to a decreased swelling ratio and shifted the LCST to lower temperatures. These novel hydrogels also displayed resiliency through multiple swelling–deswelling cycles, and their temperature responsiveness was reversible. The successful synthesis of NIPAAm-based hydrogels crosslinked with 44BDA has led to a …

A High Quality And Quantity Hybrid Perovskite Quantum Dots (Cspbx3, X= Cl, Br And I) Powders Synthesis Via Ionic Displacement, Yuhang Yin, Weiling Luan, Chengxi Zhang, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Recently, all-inorganic perovskites CsPbX₃ (X= Cl, Br and I) quantum dots (QDs) have drawn great attentions because of their PL spectra tunable over the whole visible spectral region (400-700 nm) and adjustable bandgap, which revealed a promising potential on the field of photoelectronic devices, such as solar cells, LEDs and sensors. In this paper, CsPbX₃ QDs and hybrid QDs, CsPbClxBr3-x and CsPbBrxI3-x were synthesized via one-step and two-step methods comparably. The optical bandgaps of CsPbCl₃, CsPbBr₃, and CsPbI₃, were calculated as 3.08, 2.36, and 1.73eV, respectively, based on the Tauc's equation and …

Ptfe-Based Microreactor System For The Continuous Synthesis Of Full-Visible-Spectrum Emitting Cesium Lead Halide Perovskite Nanocrystals, Chengxi Zhang, Weiling Luan, Yuhang Yin, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Colloidal perovskite nanocrystals comprised of all inorganic cesium lead halide (CsPbX₃, X = Cl, Br, I or a mixture thereof) have potential as optical gain materials due to their high luminescence efficiency. In this work, cesium lead halide nanocrystals are continuously synthesized via a microreactor system consisting of poly(tetrafluoroethylene) (PTFE) capillaries. The synthesized nanocrystals possess excellent optical properties, including a full width at half maximum of 19–35 nm, high fluorescence quantum yield of 47.8–90.55%, and photoluminescence emission in the range of 450–700 nm. For the same precursor concentrations, the photoluminescence emission peak generally increases with increasing reaction temperature, …

Effect Of Oxide On Surface Tension Of Molten Metal, Chunkai Li, Yu Shi, Yufen Gu, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Oxides as one of the commonly activating fluxes used in active tungsten inert gas welding (A-TIG welding) can dramatically increase the penetration depth to 2–4 times that of conventional welding. Using the oscillation principle of inviscid fluid, a robust method is developed to measure the average surface tension of molten metal during A-TIG welding for four different oxide activating fluxes of B₂O₃, TiO₂, SiO₂, and MgO. The experimental results suggest that the oxygen released from the decomposition of oxides is the dominant factor contributing to the change of the surface tension, which …