Materials Science Seminars
2019 Spring Semester
Atom-by-Atom Engineering of Oxide Thin Films and Nanocomposites via Molecular Beam Epitaxy
Dr. Ryan Comes
Assistant Professor, Auburn University
Friday April 12, 2019, 11:15 am – 12:10 pm, ERC 427
Complex oxides comprised of multiple positively charged metal cations exhibit a host of intriguing and useful properties for new technologies. Perovskite oxides with the chemical formula ABO3 and spinel oxides with the formula AB2O4 have some of the richest behavior. These materials may be metallic, semiconducting, or insulating, and exhibit ferroelectricity, with a built-in electric polarization, ferromagnetism, or superconductivity. This combination of properties in a single class of materials offers rich opportunities for engineering of unusual combinations of behavior through the design of multi-layer thin film materials. Through the use of molecular beam epitaxy (MBE), we are able to engineer these materials down to the atomic level so that interfaces between two different perovskites can be controlled to produce desirable properties. In this talk I will present two examples of this type of interfacial engineering, showing how we can design, model, and characterize these properties through a wide variety of techniques. I will discuss our work using interfacial termination in polar/non-polar heterojunctions and superlattices to engineer electric fields in these materials. Using in situ x-ray photoelectron spectroscopy (XPS) characterization of the LaFeO3/n-SrTiO3 junction with differing interfacial termination, we extract the valence and conduction band alignment between the materials and show that we can tune the electronic structure by interfacial engineering. In LaFeO3-NiFe2O4 nanocomposites, we show for the first time that MBE can be used to grow these vertically-aligned nanocomposites that are of interest for magnetic and catalytic applications. Using a combination of atom probe tomography and scanning transmission electron microscopy, we visualize the lateral interfaces down to the atomic level with sensitivity to the elemental composition in each phase. These results open up a wide range of new opportunities to design multilayer and nanostructured materials to achieve specific properties that cannot be found in the bulk.
How Low Can We Go? Unlocking the Potential of Very Small Grain Sizes in Dense Nanocrystalline Ceramics
Dr. James Wollmershauser
U.S. Naval Research Laboratory
Friday April 5, 2019, 11:15 am – 12:10 pm, Baldwin 544/644
Many theoretical and experimental studies boast tremendous enhancements in functional properties of nanostructured materials. In 3-dimensional bulk components (not thin-films) the repeating nanostructure features can bring dramatic improvements to a wide range of properties including magnetic exchange coupling, thermoelectric energy conversion, and mechanical response. However, these improvements are generally only expected when porosity is negligible and the microstructural length scales are well below 50 nm, which is a technological challenge, especially in nanocrystalline ceramics processing. NRL has developed an Environmentally Controlled Pressure Assisted Sintering (EC-PAS) approach to consolidate oxide, metal, and semiconductor nanoparticles into dense 3-dimensional nanostructured materials. EC-PAS incorporates stringent environmental control and utilizes high pressures to break agglomerates while simultaneously exploiting the increased pristine surface potential of nanoparticles for surface-energy-driven densification. Importantly, fully dense nanostructures can be synthesized with negligible change to the pre-sintered crystallite length scales. Using this approach, fully-dense nanocrystalline ceramics with grain sizes <10 nm have been synthesized allowing rigorous evaluation of standing theories in the grain size dependent behavior of ceramics, including Hall Petch break down and indentation size effects. Interestingly, our work suggests that new theories are needed to capture the novel behavior of fully dense nanocrystalline ceramics. Such an understanding of the response of dense bulk ceramics is paramount before seriously considering their use in DOD applications.
Dr. James Wollmershauser is a research scientist at the U.S. Naval Research Laboratory. He received a B.S. in Chemical Engineering in 2005 from the University of Colorado and a PhD in Materials Science and Engineering in 2011 from the University of Virginia. He began work at the U.S. Naval Research Laboratory in 2011 as a Karle Fellow and transitioned to a traditional federal employee in 2013. His work at NRL has focused on synthesis and properties of dense bulk nanostructured materials, including ceramics, semiconductors, and metals. In 2014, he received the Dr. Delores M. Etter Top Scientists and Engineers of the Year Award for his role in the development of a unique method to synthesize new bulk nanocrystalline materials and demonstration of beneficial increases in DoD relevant properties.
Corrosion of Additively Manufactured Stainless Steels: How Stainless are They?
Dr. Eric Schindelholz
Senior member of technical staff, Sandia National Laboratories
Friday March 29, 2019, 11:15 am – 12:10 pm, ERC 427
Additive manufacturing (AM) is of tremendous interest for producing parts with sophisticated, non-traditional 3D geometries from structural alloys. Powder bed selective laser melting (SLM) is a prevalent metal AM process whereby a laser is used to melt a pattern in successive layers of powder material to build a part. Locally high cooling rates with highly non-equilibrium and directional solidification conditions during SLM result in microstructures considerably different from their conventionally processed counterparts. Although the linkage between processing, microstructure and mechanical properties of AM metals has received considerable attention, the corrosion performance of these materials is relatively unexplored – a critical factor for their use in many service environments. In this talk, we will discuss current efforts aimed at understanding how the unique features of SLM stainless steels affect corrosion resistance relative to their conventionally processed counterparts. The electrochemical behavior of SLM 17-4 PH and 304L will be addressed within the context of hierarchal microstructural and surface features governing corrosion across multiple length scales. This includes the deleterious role of lack of fusion porosity, a common SLM feature, and the discovery of exceptional pitting resistance of SLM 304L and its relationship to ultrafine inclusions. Regarding the latter, the development of advanced high-resolution approaches for linking microstructure to corrosion processes, such as in-situ electrochemical transmission electron microscopy, are being developed. Based on these studies, processing and post-processing targets for enhanced corrosion resistance are addressed along with areas for future work.
Eric Schindelholz is a senior staff member in Materials Science and Engineering at Sandia National Laboratories, since 2014. His present work includes basic research in atmospheric corrosion, stress corrosion cracking of nuclear used fuel waste canisters, corrosion of emergent materials and development of nanocomposite corrosion barrier films. He received his PhD in Materials Science and Engineering from the University of Virginia in 2014 and was awarded The Electrochemical Society’s 2015 Morris Cohen award for his contributions to corrosion science. Prior to obtaining his PhD, Eric worked as a corrosion expert on historic monuments and museum artifacts for both private and federal institutions.
Selection and Durability of Polymers Used In Space
Dr. Don Klosterman
Associate Professor, Chemical & Materials Engineering, University of Dayton
Friday March 1st, 2019, 11:15 am – 12:10 pm, Baldwin 544/644
This presentation summarizes the results of an extended literature search on polymers used in spacecraft in earth orbit. First a brief review of the types of spacecraft, common structures, and typical materials (polymers, composites, metals) will be given. Next, the various threats to materials in earth orbit will be described, including chemical (atomic oxygen), physical (micrometeoroids, thermal cycling), and radiation (U.V., various space radiation types). How these threats vary as a function of the orbital parameters will be discussed. Finally, the durability of polymers and composites in orbit will be summarized, including material selection (which polymers are most resistant to atomic oxygen and radiation), issues involved in thermal cycling of composites, how to predict radiation levels and atomic oxygen erosion rates, and where to find information on the long term effect of radiation on polymers and composites. The presentation will focus on structural materials but will NOT include topics such as propulsion materials, batteries / energy generation, heat shields, optics, or thermal protection materials.
Dr. Don Klosterman has 25 years’ experience in processing and characterization of advanced materials, including polymers, polymer matrix composites, ceramics, ceramic matrix composites, and nanocomposites. During these years he participated in the set up and operation of several new laboratory facilities at the University of Dayton Research Institute including rapid prototyping in the 1990s (now referred to as additive manufacturing), electron beam curing of composites around year 2000, and nanocomposite processing pilot plant in the 2000’s. Dr. Klosterman also worked for a brief time at WebCore Technologies Inc. where he helped develop sandwich core composite materials and associated vacuum infusion processes. He is currently an Associate Professor in the Chemical and Materials Engineering Department at University of Dayton (UD). Over the past 15 years, Dr. Klosterman developed four graduate courses in polymer science and engineering, as well as co-developed UD’s first composites lab class, all of which he teaches on an annual basis. Currently he is involved in research on additive manufacturing of carbon nanotube metal matrix composites, and flammability of polymers and composites through the UD Center for Flame Retardant Material Science. Dr. Klosterman is a long time member of SAMPE (Society for the Advancement of Material and Process Engineering) and co-chairs their annual national student symposium.
Volcanoes, teeth, and magnetic nanocomposites: Hidden insights revealed through modern microstructural characterization tools
Dr. Stephen R. Boona
Center for Electron Microscopy and Analysis, The Ohio State University
Friday, February 22nd, 2019, 11:15 am – 12:10 pm, ERC 427
Though it is well known that microstructural material parameters like grain size and compositional homogeneity can have substantial effects on a wide variety of corresponding macro-scale material properties, the significance and range of insights accessible through microstructural characterization are often overlooked. The incorporation of characterization feedback into experimental workflows is never more critical than in studies of material systems where composition and/or processing conditions are systematically varied, or in cases where sample preparation is difficult, expensive, or time consuming. This talk will discuss three examples of challenging material systems where significant benefits were derived from utilizing one or more of the advanced imaging, spectroscopy, and diffraction tools available in modern scanning electron microscopes (SEMs). These examples include studying the factors most relevant to formation of nanoscale inclusions in volcanic rocks; examining the degradation of dentine tubules in human teeth; and tracking the composition dependence of grain growth processes in magnetic nanocomposites annealed in magnetic fields.
Dr. Stephen R. Boona is currently a Research Associate at The Ohio State University (OSU) Center for Electron Microscopy and Analysis (CEMAS), where he specializes in the application of advanced scanning electron microscopy (SEM) techniques toward solving a wide variety of materials science problems. Prior to joining CEMAS, Dr. Boona earned his Bachelor of Science degree Magna Cum Laude in Physics from Northern Illinois University (NIU) in 2008, followed by a Master of Science in Applied Physics from NIU in 2010, and then a Ph.D. in Materials Science & Engineering from Michigan State University in 2013. He joined the staff at CEMAS in 2017 after spending four years working with Profs. Joseph P. Heremans and Fengyuan Yang at the OSU Center for Emergent Materials. Dr. Boona’s published research, which has been cited over 500 times in the last five years, covers topics ranging from prototype high energy particle detectors to the diamagnetism of phonons.
Axis Dependent Carrier Polarity, from Theory to Application
Dr. Bin He
Postdoctoral Researcher, The Ohio State University
Friday, February 8th, 2019 11:15 am – 12:10 pm ERC 427
Most materials generally exhibit a single carrier polarity, either p-type (holes) or n-type (electrons). While some materials and superstructures have been predicted to exhibit axis dependent carrier polarity, most of them have never been experimentally verified and the phenomenon is poorly understood.
Here, based on a novel layered Zintl phase material NaSn2As2, I present the phenomenon of axis dependent carrier polarity, both experimentally and theoretically. Axis dependent carrier polarity can originate from a hyperboloid shape of the Fermi surface topology. In NaSn2As2, the carrier polarity is measured to be in-plane electron and cross-plane hole by thermopower and the exact opposite polarity in the Hall effect. The single band signature is confirmed by a small Nernst coefficient and a magnetoresistance. We name this single carrier axis dependent carrier polarity as ‘goniopolarity’. Moreover, we apply the goniopolar theory to a classic thermoelectric material Re4Si7, which is historically believed to be a multi-carrier system. We proved that, Re4Si7 is another goniopolar material via transport properties measurement and show that the hyperboloid Fermi surface of Re4Si7 is not along the crystallographic axes, which can lead to a misunderstanding of its properties. By extrapolation of the thermal conductivity to high temperature, we predict the thermoelectric figure-of-merit ZT of Re4Si7 to be above 1, which is a promising result for further research.
2018 Fall Semester
The Discovery of Carbon Black / Natural Rubber Vulcanizates for Automobile and Truck Tires and the Mechanism for the Exceptionally High Tear Strength of these Nanocomposites
Dr. Gary Hamed
Professor Emeritus, Department of Polymer Science University of Akron, OH, USA Email: firstname.lastname@example.org
Friday, September 7th, 2018 11:15 pm – 12:10 pm Zimmer 413
Natural rubber vulcanizates containing 0-50 phr of a fine carbon black (N115, d ≈ 27 nm) were prepared and tensile strengths of normal (no pre-cut) and edge pre-cut specimens were determined. Normal tensile strengths of all vulcanizates were similar. At the relatively slow strain rate experienced wholesale by normal uncut specimens, all vulcanizates, prior to crack initiation, strain-crystallized sufficiently to be strong. However, pre-cut specimens experience increased strain rate at a cut tip. Magnification of the strain rate increases as cut depth c increases. Fracture in the gum NR and vulcanizates with up to 14 phr of black occurred by simple forward crack growth from a cut tip, and all exhibited a critical cut size ccr, where strength dropped abruptly. Furthermore, for these lightly filled samples, strength and ccr decreased with increased black content. This indicates less strain-crystallization before rupture of pre-cut specimens when levels of black are low. This effect is attributed to rapid straining at a cut tip and hindering of the chain mobility necessary for crystallization. When black content was increased to 15 phr, with 1 mm < c < 2 mm, about 50% of specimens retained simple lateral fracture and were weak, but, the other 50% developed deviated cracks (knotty tearing) and were much stronger. With 50 phr of black, all pre-cut specimens exhibited knotty tearing and were significantly stronger than corresponding pre-cut gum specimens, especially at large c. High strengths with sufficient black levels are attributed to increased strain-crystallization and super-blunting (multiple cracks) at a cut tip. These inhibit forward crack growth. For carbon black to enhance strain-crystallization relative to the gum, it appears there must be enough of it to form a bound rubber/black network. If the black concentration is less than this percolation threshold, strain-crystallization is hindered at a cut tip.
PhD in Polymer Science, Univ. of Akron 1976; 4 years at Firestone Central Research; 1980-2015 professor of Polymer Science at the Univ. of Akron (currently professor emeritus); research on the mechanical properties of rubber, especially fracture; 110 publications; mentored 108 graduate students.
Thermomagnetic Transport in Topological Weyl Semimetals
Dr. Sarah Watzman
Assistant Professor, University of Cincinnati Email: email@example.com
Friday, September 14th, 2018 11:15 pm – 12:10 pm Zimmer 413
The majority of the world’s energy comes from nonrenewable sources, with over 60% rejected as waste-heat. If waste-heat could be recovered, the effect on humanity would be equivalent to that of adding a renewable energy source, majorly increasing society’s energy conversion efficiency. This can be accomplished through the use of thermoelectric materials, which convert a temperature gradient (like that from waste-heat) into a usable voltage output. Conventional thermoelectric materials have not increased in commercial efficiency in recent years, therefore a different approach is taken in this work. Here, novel transport is explored by tuning the electronic band structure to have unique topological transport signatures, found in the recently experimentally-realized class of materials called Weyl semimetals. Predicted to have large transverse transport coefficients, NbP is experimentally proven to effectively convert a temperature gradient into a perpendicular output voltage. Transverse thermoelectric devices have technological advantages over conventional Peltier or Seebeck longitudinal modules (in which the applied temperature gradient is parallel to the output voltage), but they require an externally applied magnetic field. Further control over the band structure in Weyl semimetals offers a solution, where YbMnBi2 is experimentally proven to effectively utilize a transverse geometry without the need for an external magnetic field. This effect is proven to arise from the Berry curvature of the electronic band structure, which functions like an internal magnetic field. The novel and unique signatures of Weyl semimetals indicate their strong potential as candidate materials for thermoelectric energy generation and cooling.
Dr. Sarah Watzman began as an assistant professor in the Department of Mechanical and Materials Engineering in August of 2018. Her research focuses on characterizing energy conversion between heat and electricity and how magnetization can enhance this transport. Specifically, she focuses on thermomagnetic transport in topological materials including Weyl semimetals. Sarah completed her PhD in mechanical engineering at The Ohio State University in May of 2018. At Ohio State, she was a National Science Foundation Graduate Research Fellow, a University Fellow, and a Future Academic Scholar Training Fellow from OSU’s Department of Mechanical and Aerospace Engineering. Sarah has worked with elemental metals studying magnon-drag, and her dissertation focused on characterizing transverse thermomagnetic transport in Weyl semimetals. Sarah has also worked as a visiting researcher (summer 2017) at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, and she continues to collaborate with those colleagues on novel transport in Weyl semimetals. Sarah is actively involved in the Society of Women Engineers, having served on the Board of Directors as Collegiate Director and on the Society’s senate. Sarah is originally from Cincinnati and is excited to return as a professor at UC!
Additive Manufacturing of Nickel Superalloys
Dr. Andrew Wessman
Friday September 28th, 2018 11:15 pm – 12:10 pm Zimmer 413
Additive manufacturing is a burgeoning area of research in both mechanical and materials engineering as a number of industries are rapidly increasing the use of 3D printing to make engineered components. Adoption in the aerospace industry is especially rapid, where the combination of part complexity and low volumes is well suited to the current state of the additive manufacturing technologies. Nickel superalloys, a class of materials used at high temperatures in applications such as turbine engines and rocket nozzles, are being increasingly used in additive manufacturing to produce complex structural components to improve performance, reduce weight and reduce system costs. This presentation will provide an overview of GE Additive, one of the world’s leading providers of additive manufacturing machines, materials and services, and will discuss some of the materials science aspects of additive manufacturing of the nickel superalloy Rene 65.
Dr. Andrew Wessman is a Staff Engineer at GE Additive. During 13 years at GE, he worked at GE Aviation to develop polycrystalline nickel superalloys for use in turbine engine rotating parts. This work also included developing the forging, welding and ICME capabilities necessary to utilize these materials in safety critical components. Dr. Wessman moved to GE Additive prior to the launch of the new GE business in early 2017, and is currently leading development of high temperature materials and processes for additive manufacturing. He has B.S. and M.S. degrees in Metallurgical Engineering from the University of Utah and a Ph.D. in Materials Science from the University of Cincinnati. He also serves as an Adjunct Professor of Materials Science and Mechanical Engineering at The Ohio State University.
Assessing Additive Manufacturing Process Heterogeneity
Dr. Eddie Schwalbach
Research Materials Engineer, Air Force Research Laboratory
Friday October 26th, 2018 11:15 am – 12:10 pm Zimmer 413
There has been increasing complexity in both additive manufacturing processes themselves (e.g. scan path planning, systems with multiple independent sources, and multiple heating modes) as well as the component geometries to which they are being applied. Fundamental questions about how these details combine to produce heterogeneity in local processing state, and therefore structure, will be addressed. Fast acting models and analytics procedures to assess and screen thermal history will be described. Potential applications for such capabilities include process-structure-property correlation development, processing equivalency testing, and potentially process design.
Additionally, we will describe a series of experimental activities and associated processing-to-structure modeling prediction challenge problems being performed within the Materials Informed Digital Design Demonstration for Additive Structures (MIDAS) program.
Bioinspired Nanomaterials: Discovery, Design, Applications and Manufacture.
Dr. Siddharth Patwardhan
Department of Chemical and Biological Engineering, University of Sheffield UK
Tuesday October 30th, 2018 10:00 am – 11:00 am
Inorganic nanomaterials are widely used in industry and in consumer products with a global production of the order of several million tons per annum and worth several $billions. Current methods for nanomaterials synthesis or manufacturing suffer from extremely adverse environmental burden leading to high costs and unsustainable production. In contrast, biological organisms, through biomineralisation, produce elaborate and ordered nanomaterials under physiological conditions. Taking inspiration from organisms and understanding the molecular principles in biomineralisation, we have developed green nanomaterials (GN) synthesis. This green method (mild, one-pot and rapid synthesis in water, at room temperature and neutral pH) offers substantial reductions in resources, time and energy usage when compared to traditional routes, yet offers excellent control over the properties and function of the materials.
This presentation will illustrate how such bioinspired materials can be designed and fine-tuned with examples from various applications/sectors such as drug delivery systems and water treatment. We will show how key synthetic parameters were identified systematically in order to modulate silica formation, its physicochemical properties and its function. Extensive materials characterisation using spectroscopy and microscopy, we are able to gain understanding of the synthesis-structure-property relationships which enable materials design/discovery. Finally, results from experiments and economic analysis on scaling-up the synthesis from mg to kg will be presented.
Siddharth V. Patwardhan is a Professor of Sustainable Chemical and Materials Engineering and Head of the Green Nanomaterials Research Group (www.svplab.com, @GreenNanoRes ) at the University of Sheffield, UK. He graduated from UC's MSE department with a PhD in 2003. Siddharth, a chemical engineering and materials chemistry, with a vision to develop sustainable, scalable and economical routes to functional nanostructured materials. He has experience of bioinspired synthesis of nanomaterials for applications in energy, environmental, biomedical and engineering sectors. He has over 70 publications with an h-index of 33. Siddharth's EPSRC Fellowship in Manufacturing and a multi-university EPSRC project are developing the tools for assessing scalability of and developing manufacturing technologies for various nanomaterials.
2018 Spring Semester
Application of Crystal Plasticity Modeling: Thermal Ratcheting
Dr. Jonathan Nickels
University of Cincinnati
Department of Chemical & Environmental Engineering Email: firstname.lastname@example.org
Friday, January 19th, 2018 2:30 pm – 3:25 pm Zimmer 413
The structure and function of biological membranes is far more complex than the classical view of a homogeneous fluid mosaic. Though it has been studied for more than 100 years, the role of lateral organization stemming from its rich compositional diversity a is still being unraveled. Often, the lipid raft hypothesis is invoked to contextualize the observations of lateral heterogeneities in the plane of the membrane. The lipid raft hypothesis suggests that these nanoscopic and transient lateral structures facilitate the organization, assembly and regulation of multi-molecular protein complexes. Provides a compelling rationale for numerous observations relating to complex biological functions such as membrane trafficking, endocytosis, signal transduction, and other processes. There is an unrealized potential to unlock new understanding and therapies to a variety of diseases based on an improved grasp of the structure and biophysical basis of lipid raft formation and properties.
I will discuss recent work establishing a platform for systematic in vitro and in vivo investigations of cell membrane organization; setting the stage to both understand and access the potential of these enigmatic membrane structures. Using both neutron scattering as well as simulation based approaches, we first accessed the bending modulus of the ‘raft’ structures in model lipid mixtures. This result provides fundamental information about the underlying physical mechanisms of raft formation and stability. These observations relied upon neutron ‘contrast matching’ approaches to resolve scattering signals from the co-existing lipid phases. This work lead into current efforts to probe the structure and organization of the cell membrane in a living organism, B. subtilis, by extending these scattering based approaches in combination with a number of innovative genetic and biochemical strategies. Ultimately, we have been able to isotopically label a living bacterial system to present neutron contrast between the cell membrane and the rest of the cell/extracellular space in order to directly observe the cell membrane of a living organism. This approach has already yielded the first direct in vivo observations of bilayer hydrophobic thickness as well as evidence for the existence of lipid rafts in this organism.
Laser-material interactions to pave the way for functional materials
Advanced Manufacturing Processes Laboratory Department of Mechanical Engineering Northwestern University
Friday, January 19, 2018; 11:15 AM – 12:10 PM; 544 Baldwin Hall
Powder-blown and laser-based additive manufacturing processes provide unique opportunities for novel materials design of functional materials with complex component geometries and improved mechanical behavior due to its unprecedented rapid solidification. The nature of the process opens doors to multi-material capability at many length scales. However, the complex physical phenomena that occur during the process leads to uncertainties in structure and mechanical behavior. Research that couples experiments and thermal modeling aims to investigate the relations between the process, thermal history, microstructure and final mechanical behavior of additively manufactured materials. Some of the very first experiments of in-situ high-speed X-ray imaging of the powder deposition process at Argonne National Laboratory illuminate how processing conditions influence the build. Thermal monitoring, structural characterization and mechanical testing show what mechanisms in the process lead to final part properties. Optimal process control requires thorough understanding of these process-structure-property relationships so that the same part could be built by various machines and systems. Future work includes manipulating laser- matter interactions with external magnetic fields, adaptive optics and reheating so that the complex phenomena in the process will not only be isolated and understood, but also used to build new functional materials.
Sarah Wolff is finishing up her PhD in mechanical engineering from the Advanced Manufacturing Processes Laboratory with Professors Jian Cao and Kornel Ehmann at Northwestern University. After completing a B.S. degree in environmental engineering at Northwestern and working in the aerospace industry, she transitioned to research sustainable manufacturing systems and later advanced processes. Sarah studies the underlying physics of laser-material interactions in both subtractive and additive processes and their influence on resulting microstructure and mechanical behavior. She is also building an open-architecture hybrid processing rapid prototyping machine in hopes to design new materials.
Understanding and Controlling the Bond Surface in Manufacturing for Reliable Adhesive Bonding
Dr. Giles Dillingham
CEO and Chief Scientist, BTG Labs Email: email@example.com
Friday, February 2nd, 2018 2:30 pm – 3:25 pm Zimmer 413
The interactions between a bond surface and an adhesive that determine the strength and reliability of a bonded structure occur in a zone that is perhaps 1 nanometer thick. This seminar provides a comprehensive look at the molecular level characteristics of a bond surface that determine bond performance, how to establish the desired characteristics through surface preparation, and how to quantify them for process development, quality assurance, and failure analysis. We will provide an overview of the basic scientific principles involved in measuring surface composition and surface energy and how these relate to bond performance in manufacturing and repair.
Giles Dillingham, CEO and Chief Scientist of BTG Labs, has worked in the areas of materials, surfaces, interfaces, and adhesive bonding since receiving his Ph.D. in Materials Science from UC in 1987. BTG Labs, established by Dr. Dillingham in the late 1990’s, performs basic and applied research in surface science, surface treatments and adhesion, and develops instrumentation for development and process control of surface engineering processes. Recent work by BTG Labs is helping pave the way to certifiable adhesively bonded primary aircraft structures. Dr. Dillingham has over 40 publications and patents in the areas of surface treatments, surface energetics, and adhesion.
Application of Crystal Plasticity Modeling: Thermal Ratcheting
Dr. Christopher A. Calhoun
Engineer, Technical Data Analysis, Inc. Email: firstname.lastname@example.org
Friday, February 9th, 2018 2:30 pm – 3:25 pm Zimmer 413
α-Uranium’s orthorhombic crystal structure leads to many unique phenomena. Most interestingly, textured polycrystals exhibit thermal ratcheting, which is defined as the accumulation of permanent deformation through repeated stress-free thermal cycling. The driving force for the ratcheting stems from the anisotropy of the single crystal thermal expansion coefficient of the single crystal, which possesses one direction with a negative CTE. Despite having been reported in the literature in the 1950’s and 60’s, a thorough modeling explanation of ratcheting has not been presented. This talk will present a combined experimental and modeling effort to explain the mechanisms for the thermal ratcheting. A brief overview of plasticity modeling, with a focus on crystal plasticity will be included.
Dr. Calhoun grew up in Reno, NV, where he discovered that careers can be dedicated to breaking metal and making sense of it. In an effort to pursue that goal, he went to Virginia Tech to obtain a Bachelor’s in Engineering Science and Mechanics, where he worked on fatigue in aircraft aluminum. After that, he went onto obtain a Master’s in Aerospace Engineering from Texas A&M studying thermo-mechanical fatigue of shape memory alloys. In an effort to return to return to Virginia, Chris enrolled obtained a PhD in Materials Science and Engineering at the University of Virginia. There he focused on the polycrystalline plasticity. He went on to work two years at NIST in the Center for Automotive Lightweighting studying plasticity as applied to shaping and forming. Recently, he started at Technical Data Analysis, Inc. working on a variety of projects with a primary focus on metal fatigue in aerospace structures. In his free time, Dr. Calhoun teaches “Introduction to Finite Element Analysis” as an adjunct faculty member in the mechanical engineering department at George Mason University.
Printed Homes: Additive Manufacturing Reforming Construction Technology
Dr. Seyed Allameh
Professor of Physics, Geology and Engineering Technology Northern Kentucky University
Friday, February 23rd, 2018 2:30 pm – 3:25 pm Zimmer 413
Imagine you draw a house with a desired shape, send it to a printer and it gets printed, not on small prototype one from polymers, rather, a life-size, real home that you can move in! Imagine a home that resists earthquakes and fire so we do not see the collapse of buildings causing human casualties, Imagine construction under hazardous conditions, in cold and hot weather in very short periods of time and at very affordable costs! All these are becoming feasible with the advent of new 3D printing technology associated with advances in construction composites with intricate micro- and macrostructures such as cellular, lattice block, and sandwich structures. Biomimicking, as the new enabling technology and its incorporation in 3D printing of houses written from bioinspired materials will be discussed and its implications on the current construction technology will be elucidated.
Dr. Seyed Allameh is currently is professor of Physics, Geology and Engineering Technology at Northern Kentucky University. He joined NKU in 2004 after 5 years of research in the areas of MEMS, and advanced materials at Princeton University as research staff scientist. Prior to Princeton, he worked on the synthesis and characterization of electronic ceramics at The Ohio State University as research associate and postdoctoral fellow. He received his PhD in 1993 from OSU in the field of Materials Science and Engineering. For his PhD, he worked on the energy and structure of interphase interfaces
Dr. Allameh has worked on the fabrication and characterization of nano-crystalline materials, microelectromechanical systems (MEMS), thin film bimorphs, biomaterials, and nanostructures with applications in nanotechnology. He has a special interest in surfaces and
interfaces, electron microscopy, nano-crystalline materials, nano-scale and microscale devices, and microtesting systems for mechanical behavior of MEMS and NEMS. He has developed state of the art microtesting systems for evaluation of mechanical behavior of MEMS components. These included tensile, compression, bending, buckling, fatigue and creep tests using laser interferometry and image correlation techniques. At Princeton, he developed a simple method for growing nano-scale structures including nanofins, nanorods, and thin-walled lightweight nanostructures.
Dr. Allameh has authored or co-authored over 80 peer- reviewed journal articles, conference proceedings papers and book chapters. Further, he has given 46 conference presentations including invited talks at various universities and international conferences. He was the guest editor of a special issue of Journal of Materials Science and Engineering. He organizes symposia on Bio materials, Bioinspired materials and biofuels at the ASME international conference and exhibition. He is the recipient of awards and recognitions including the 2017 NKU outstanding research award. His current research is focused on biomimicked composites and micromechanical characterization of MEMS components.
Understanding the Physical Metallurgy of Ni-Based Alloy Haynes 244
Dr. Jie Song
Research Associate, Colorado School of Mines Email: email@example.com
Friday, March 2nd , 2018 2:30 pm – 3:25 pm Zimmer 413
Ni-based superalloys display excellent mechanical properties at high temperatures as well as superior oxidation and corrosion resistance. They are widely used in gas turbines, and chemical plants. In this talk, the morphology and development of precipitate-free zones (PFZs) near grain boundaries (GBs) in low coefficient of thermal expansion (CTE) Ni-15.6Mo-10.2Cr- 2.2W at.% (based on Haynes 244) will be discussed as a function of thermal history and composition using electron microscopy techniques. The formation of wide, continuous PFZs adjacent to GBs can be largely attributed to vacancy depletion in the vicinity of the GBs. The crystallography of grain boundary precipitates has been investigated using transmission electron diffraction. The space group of previously unreported cubic precipitate is Pm3̅m with lattice parameter a=6.42Å.The μ phase that formed during this heat treatment contains a high density of finely spaced (0001) nanotwins, which give rise to pseudo 6/mmm symmetry (instead of 3̅m, expected for the μ phase R3̅m space group) in CBED patterns. In addition, variant selection of intragranular Ni2(Mo,Cr) precipitates will be discussed.
Jie Song received his Master’s degree in materials science and engineering from the Tsinghua University, in 2009, and PhD degree in Engineering Technology from Purdue University in 2014. He conducted his postdoctoral studies at Colorado School of Mines and Purdue University. Jie Song’s research interests lie in the area of material characterization based on advanced microscopies as well as material processing and properties.
Dr. Pulickel M. Ajayan
Department of Materials Science and NanoEngineering Rice University, Houston, Texas,
Friday, March 30th, 2018 12:20 - 1:15 pm
Rec Center 3250
The past two decades has belonged to truly innovative discoveries in the area of nanotechnology. Although basic science in the area has progressed significantly, there are still challenges related to engineering and integration of nanomaterials into applications and commercial products. This talk will discuss some of the challenges and opportunities in the field, with particular reference to engineered nanomaterials that include carbon nanostructures, two dimensional materials, and several other nanomaterials and hybrids. Our group has made pioneering contributions to this field in relevance to developing these materials for applications such as energy storage and conversion, catalysis, low power devices, coatings and light-weight materials. Several aspects that include synthesis, characterization and modifications will be explored with the objective of achieving functional nanostructures for future technologies. The intrinsic challenges in the area of nano-engineering will be highlighted, particularly for bottom-up creation of nanostructured materials.
Dr. Pulickel M. Ajayan, the Benjamin M. and Mary Greenwood Anderson Professor of Engineering, is the founding Chair of the Materials Science and NanoEngineering Department in the Brown School of Engineering at Rice University. Prof. Ajayan started out as a metallurgist, and moved quickly into carbon nanotechnology as his major area of focus, with world-leading research into multi- and single-walled carbon nanotubes - their growth in vertical arrays and their uses in composites and other materials - and in graphene and hybrid carbon nanomaterials. Prof. Ajayan has published one book and 600 journal papers with > 130,000 citations and an h-index of 151, based on ISI database. He has received a number of rewards among which including the 2016 Lifetime Achievement Award in Nanotechnology from the Houston Technology Center, 2016 NANOSMAT Prize, Spiers Memorial Award by the Royal Society of Chemistry (UK), Senior Humboldt Prize, MRS medal, and Scientific American 50 recognition. He has been elected as a fellow of the Royal Society of Chemistry (UK) and other academies, as well as serving as visiting and guest faculty positions across the globe.
A Chemical Engineer’s Adventures in the Semiconductor Industry
Dr. George P. Fotou
Principal Engineer, Cabot Microelectronics Email: George_Fotou@cabotcmp.com
Friday, March 30th, 2018 2:30 pm – 3:25 pm Zimmer 413
Chemical Mechanical Planarization (CMP) is a technology not broadly known but a very important step in the fabrication of IC semiconductor devices. A brief introduction of this technology will be provided as well as how it is enabling the miniaturization of the chips that are used in semiconductor devices. Slurries made from highly engineered abrasive particles and designed to operate within very tight performance limits of removal rate, defectivity and uniformity are integral part of CMP. Polishing pads play an equally important role in the CMP process. These are materials based on either thermoplastic or thermoset polyurethane polymers and manufactured by various processes to achieve specific physical characteristics and mechanical properties that are important in the CMP process
A message that I would like to convey with my talk is that transitions from traditional technical fields to “non-traditional” ones can be exciting and rewarding.
Dr. Fotou earned his doctorate degree from the University of Cincinnati, Department of Chemical Engineering in 1995. After a post-doctoral appointment at the University of New Mexico, he joined Cabot Corporation in 1996. In his 14 year R&D career with Cabot, Dr. Fotou developed, scaled up and commercialized several processes for nanoparticle production and filed several patents. He joined Cabot Microelectronics in 2010 where he is currently a Principal Engineer. For the past 7 years Dr. Fotou developed and commercialized polishing pads for Chemical Mechanical Planarization (CMP) of advanced semiconductor materials. He is currently managing the supply of abrasive particles for the manufacture of CMP slurries.
Characterizing the Age of Ancient Egyptian Manuscripts through microRaman Spectroscopy
Dr. Sarah Goler
Columbia Nano Initiative, Columbia University, New York Email: firstname.lastname@example.org
Friday, March 23rd, 2018 2:30 pm – 3:25 pm Zimmer 413
We have established scientific basis for a new, nondestructive methodology for dating ancient Egyptian papyri based on Raman spectroscopy. Egypt’s dry climate has preserved thousands of handwritten documents which provide insight into ancient cultures, but most of these manuscripts are not dated. Currently, the only scientific method for estimating the date is radiocarbon dating, which is destructive and cannot be used to date the ink separate from the support. In contrast, microRaman spectroscopy, a nondestructive light scattering technique, can distinguish physical and chemical properties of materials. We discovered, for a study of well dated ancient Egyptian papyri covering the date range from 300BCE to 900CE, the Raman spectra (20-40 measurements per manuscript) of black ink all show the spectrum of carbon black characterized by two broad features, the G and D bands indicative of crystalline and amorphous carbon. The G band, 1585cm-1, is a Raman allowed transition arising from the E2g inplane vibration of sp2 bonded carbon. The D band at ~1350cm-1 is a forbidden Raman transition that occurs when the lattice symmetry is broken due to disorder, vacancies, crystalline edges, etc. We observed the spectra exhibit systematic change as a function of manuscript date, unexpected given these papyri span 1,200 years and the fact that each manuscript has a unique provenance, archeological, and storage history. We conclude Egyptian black ink pigments were manufactured using similar processes over this time period. We attribute the systematic changes in Raman spectrum to two concurrent oxidation processes: slow oxidation of crystalline carbon and faster oxidation of amorphous carbon. Oxidative degradation proceeds over time altering the Raman response of the material, providing a direct experimental indicator for manuscript age. This research establishes the basis for a simple, rapid, nondestructive method for dating ancient manuscripts from Egypt as well as the ability to differentiate between modern forgeries and authentic ancient manuscripts. To validate this method we performed a blind study where the scientific team performed the measurements and provided predicted dates without knowing the true dates which were revealed later.
Sarah Goler completed her undergraduate studies in applied physics at Columbia University's School of Engineering and Applied Science and Mathematics. She went on to complete a PhD in Condensed Matter Physics at the Scuola Normale Superiore di Pisa in Italy where she focused on graphene for hydrogen storage using STM, microRaman and CVD processes. She then continued her studies of carbon while completing a postdoctoral position at Columbia University as a member of the Ancient Ink Laboratory. She won a year-long research scientist fellowship with the Italian Academy at Columbia University in 2014/2015 and won the Dan David Prize for young scholars in 2017.
Simulating Microstructural Evolution during Metal Additive Manufacturing
Dr. Theron Rodgers
Sandia National Laboratories Email: email@example.com
Friday, April 20th, 2018 2:30 pm – 3:25 pm Zimmer 413
With the rapid growth of additive manufacturing, rapid solidification phenomena have become increasingly important in the materials community. Recently, we have introduced a novel Monte Carlo-based method of simulating microstructural evolution during process such as additive manufacturing, welding, and thin film solidification. Here, we will discuss recent work with the model including coupling it to thermal conduction simulations, incorporating crystallographic texture, and using synthetic microstructures in simulations of mechanical behavior.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Closed-Loop Research and Development of Gas Atomization and Selective Laser Melting for Additive Manufacturing of Metallic Alloys
Dr. Yongho Sohn
Professor, Department of Materials Science and Engineering University of Central Florida, Orlando, FL, USA
Friday, April 13th, 2018 2:30 pm – 3:25 pm Zimmer 413
Additive manufacturing of metallic alloys is emerging as a disruptive technology to produce net- shape components with nearly unlimited geometrical complexity and customization. This technology also represents an opportunity to design new and modified alloys that can desensitize inherent process variables and take advantage of thermo-kinetic environments associated with additive manufacturing. In this presentation, in-laboratory, hands-on, closed-loop research capability of gas atomization and selective laser melting for alloy development established at UCF will be introduced. Exploration and optimization of process parameters will be documented for gas atomization (e.g., flow rate, atomizing pressure, melt temperature and orifice temperature) and selective laser melting (e.g., laser power, scanning speed, hatch spacing and slice thickness) using microstructure and mechanical properties. Demonstrative results from commercially available and new/modified Al-, Ni-, and Fe-alloys will be discussed to identify scientific understanding required to mature additive manufacturing technology including solidification, micro-segregation, homogenization, and precipitation via multicomponent phase equilibria and diffusion.
Dr. Yongho Sohn is a Pegasus Professor of Materials Science and Engineering, and Associate Director for Materials Characterization Facility (MCF) at University of Central Florida. MCF is a FL-state user facility for academics and industry with over $20M in analytical instrumentation and 3 full-time staff engineers. He received his B.S. with honors and M.S. from Worcester Polytechnic Institute, Worcester, MA in mechanical and materials engineering, respectively. He graduated in 1999 with a Ph.D. in materials science and engineering from Purdue University and spent two years as a post-doctoral research scholar at the University of Connecticut. He joined University of Central Florida in 2001 as an assistant professor. His research and teaching interests includes microstructural analysis and control, multicomponent intrinsic and
interdiffusion in multiphase alloys, powder processing and additive manufacturing, thermal barrier coatings and other protective metallic/ceramic coatings, and light-weight metallic alloys and metal-matrix composites. He has published 8 book chapters, over 140 journal papers and 60 proceedings papers. He gave over 400 presentations including 100 invited lectures at conferences around the globe. He is a Fellow of ASM International (FASM), recipient of NSF CAREER Award (2003), Outstanding Materials Engineer Award from Purdue University (2016), UCF’s 2017, 2012 and 2006 research incentive awards, UCF’s 2007 and 2013 teaching incentive award. He is an associate editor for Journal of Phase Equilibria and Diffusion and a member of editorial board for Metallurgical and Materials Transactions. He has supervised to completion, 11 Ph.D. students, 29 M.S. students and 8 post-doctoral scholars, and currently supervises 4 Ph.D. students, 1 research associate, and 4 undergraduate research assistants. Details on his research and teaching activities can be found at http://mse.ucf.edu/sohn.