Tag: John & Virginia Towers Lecture Series

Hydrogen Storage in Complex Metal Hydrides and Metal Organic Framework Materials: Challenges and Opportunities

Monday, November 14, 2011 10:00 am – 11:00 am
Room 610, M&M Building

Yves J. Chabal
Department of Materials Science and Engineering University of Texas at Dallas

Abstract

The hydrogen economy critically depends on the ability to store hydrogen safely with high gravimetric and volumetric capacities. Three approaches are being seriously considered by DOE at present: 1) chemical hydrides, 2) complex metal hydrides, and 3) microporous materials. Each approach faces fundamental issues that will require scientific breakthroughs to incorporate them into practical systems. In our group, we are studying two different systems (#2 and 3) and addressing the following fundamental questions: 1) how can hydrogen dissociate on aluminum and what is the nature of mass transport in complex alanates to form complex metal hydrides? and 2) What is the nature of interactions for H2 molecules in microporous metal organic framework (MOF) materials?
To address these questions, we bring to bear a number of characterization methods, such as infrared (IR) absorption spectroscopy, Raman scattering, mass spectrometry, and isotherm measurements. With the help of first principles calculations performed by our collaborators, we derive detailed information on the interaction, dissociation, and product formation for hydrogen on aluminum
surfaces. On aluminum surfaces, the primary objective is to identify the formation of alanes and understand their formation, as well as to understand the role of catalysts such as titanium in dissociation and kinetics of hydrogen. In microporous MOF materials, our primary objectives are to better understand and explain molecule-sorbent interactions within these systems and to provide insight and guidelines toward the design, synthesis and modification of MOF structures for enhanced molecular adsorption strengths, storage capacity and selectivity. Beyond the study of existing and new MOFs, this program is intended to develop novel experimental and theoretical methods to advance the understanding of molecular incorporation into a broader class of microporous materials, to predict improved materials with active metal centers, and to direct the optimized synthesis processes for a variety of applications (storage, separation, sensors).
Work supported by DOE-BES.

Biography

Yves Chabal holds a Texas Instrument Distinguished Chair in Nanoelectronics at the University of Texas at Dallas. He obtained a BA in Physics from Princeton University in 1974, and a Ph.D. in Physics from Cornell University in 1980. He then joined Bell Laboratories where he developed sensitive spectroscopic methods to characterize surfaces and interfaces. He worked at Murray Hill, New Jersey, from 1980 until 2002 for AT&T, Lucent Technologies (1996) and Agere Systems (2001) in the Surface Physics, Optical Physics and Materials Science departments. In 2003, he joined Rutgers University as Professor in Chemistry and Biomedical Engineering, where he expanded his research into new methods of film growth (atomic layer deposition), bio- sensors, and energy (hydrogen storage). He directed the Laboratory for Surface Modification, an interdisciplinary
Center to promote large initiatives. He joined UT Dallas in January 2008 to lead the Materials Science and Engineering department in the Erik Jonsson Engineering School.
He is a Fellow of the American Physical Society and the American Vacuum Society, received a Bell Laboratories Affirmative Action Award (1994), an IBM faculty award (2003), the Rutgers Board of Trustees Award for Excellence in Research (2006), and the Davisson-Germer Prize (2009), the Tech Titan Technology Innovator Award in 2010, and has recently been recognized by the ACS for encouraging women into careers in the Chemical Sciences.

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Understanding Segregation Defect Formation in Remelting Processing of High Temperature Alloys

Friday, October 21, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Matthew John M. Krane
Associate Professor of Materials Engineering Purdue Center for Metal Casting Research Purdue University, West Lafayette, Indiana

Abstract

Remelting processes provide routes to large ingots of specialty metals which have relatively few defects. However, past certain limits on size of the ingots and speed of these processes several types of segregation related defects begin to occur. The heat, mass and momentum transfer and electromagnetics present during electroslag and vacuum arc remelting (ESR and VAR) are modeled and sump profiles and macrosegregation patterns are predicted. These results are studied as functions of process parameters and ingot geometry. During ESR of nickel-based superalloys, a maximum in macrosegregation is found as a function of filling velocity in the flow regime dominated by buoyancy. During VAR of titanium alloys, DC current levels are generally much higher than the AC current in ESR, so the sump flow is controlled by Lorenz forces, leading to different segregation patterns. The numerical simulations include studies of two distinctive flow regimes in VAR: strong counter-clockwise Lorentz driven flow and weak clockwise buoyancy driven flow. The results demonstrate possible influence of process instabilities and the electrode composition on the flow regime and thus macrosegregation. The practice of multiple VAR melts is also simulated, showing the effects of each step on the final solute distribution. Experimental validation of the models and other current projects on remelting processes will also be discussed.

Biography

Dr. Matthew Krane is an Associate Professor of Materials Engineering at Purdue University and a member of the Purdue Center for Metal Casting Research. His research is on design, development, and modeling of materials processes, particularly the solidification of metal alloys. He holds a Ph.D. (1996) from Purdue University in Mechanical Engineering, with a concentration on heat transfer and fluid flow in materials processing. His M.S. (1989) is from the University of Pennsylvania and his B.S. (1986) from Cornell University, both in mechanical engineering. In addition to consulting with the metals processing industry, he also worked for three years (1988-1991) on thermal packaging and manufacturing issues for Digital Equipment Corporation in Andover, Massachusetts. In 2006, he was a Visiting Research Fellow working in the Interdisciplinary Research Centre at the University of Birmingham (UK) and was granted a courtesy appointment in Purdue’s School of Mechanical Engineering in 2008. Serving on several technical committees in the ASME and TMS, including holding the chair of the TMS Process Modeling and Control (2001-2003) and Solidification (2009-2011) Committees, he has organized or co-organized several symposia in his areas of research, including the Tenth International Conference on Modeling of Casting, Welding and Advanced Solidification Processes (MCWASP X) in 2003 and the Liquid Metal Processing and Casting Conference (LMPC) in Nancy, France in 2011. He is on the international technical committees for the MCWASP and the LMPC conference series. Professor Krane’s teaching experience includes heat transfer, fluid mechanics, engineering design, materials processing, numerical modeling, and ethics in engineering practice.

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Ultrafine Grained Ti-6Al-4V for Aerospace Applications

Friday, September 30, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Dr. Judson S. Marte
General Electric Global Research Center Niskayuna, NY

Abstract

Improving the performance and reducing the cost of titanium components is important for aerospace applications, such as gas turbine engines. This presentation will provide an overview of an ongoing collaborative program between ATI Allvac and GE evaluating the production, characterization, and application of ultrafine-grained titanium. Multi-axis forging (MAF) has been used to produce bulk samples with submicron alpha grain size. Extensive characterization of the microstructure shows that, after MAF, the beta phase tends to pin alpha, enhancing thermal stability. Deformation properties have been evaluated and used to make finite element models of near-net shape forging processes. Laboratory-scale near-net shape forgings have been produced to demonstrate feasibility and provide material for microstructural and mechanical evaluation. Tensile and fatigue performance of the sub-scale forgings will be presented, as will a brief discussion of the challenges associated with developing a full-scale forging process.

Biography

Jud is currently the Manager of the Metals Processing and Testing Laboratory at GE Global Research in Niskayuna, NY. He is also a project leader and metallurgist who specializes in the thermomechanical processing of structural metals, low temperature superconductors, and magnetic materials. Prior to joining GE in 1999, he earned his PhD in Materials Science and Engineering at Virginia Tech studying the synthesis and processing of titanium- and titanium aluminide- matrix composites.

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An Overview of Metallurgical Failure Analysis

Friday, September 23, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Joel F. Flumerfelt, PhD
Metallurgist Aspen Research Corporation, St. Paul, MN

Abstract

Materials have been used throughout history for various applications, for example, tools, weapons, buildings, vehicles and ornamentation. Invariably, components used within these products sometimes fail during service before their expected end of life. The past three decades have seen extreme failures that caused human fatalities, for example, the Space Shuttle Challenger explosion shortly after lift-off in 1986, the Space Shuttle Columbia explosion upon re- entry in 2003, and collapse of the Interstate 35W Mississippi River Bridge in Minneapolis, Minnesota, in 2007. When failure happens, there is usually a mandate to identify factors that contributed to the failure to make plans for avoiding failure in the future, i.e. design and build a better mouse trap. A failure analysis investigation satisfies the demand such that the work effort identifies: the failure mode; the immediate primary cause(s) for the failure; the root cause(s) for the failure associated with intentional and unintentional human errors. This presentation will illustrate the principles of the failure analysis process using a recent failure investigation related to a socket head cap screw that failed inside a shaker table.

Biography

Joel is a metallurgist who began his career at Aspen Research Corporation in 2000. As an analyst, he participates in various short term projects that address client inquiries related to failure analysis, foreign residue and deposit identification, microscopic examinations, mechanical testing, customized test method development, material selection and design, material and product quality control measures, and product process development and improvement. As a project manager, he interacts with Aspen’s clients to understand and respond to questions about material and process issues associated with their products, providing customized quotes that define a project’s objective, scope of work, cost, and timeline. He also oversees the operation and maintenance of the metallurgical lab, optical microscopes and SEM-EDS instrumentation.
Prior to joining Aspen Research Corporation, he spent 18 months at Engel Metallurgical, Ltd. (St. Cloud, MN) working on projects related to metallurgical failure analysis and material selection and design.
Joel holds a Bachelor of Science and Master of Science degree in Metallurgical Engineering from Michigan Technological University, and a Doctorate degree in Metallurgical Engineering from Iowa State University. He is a current member of ASM International and SMTA. A hobby of his is playing alto sax with a 17 person swing band, named “Red Rock Swing Band”, which performs at different locales around the Twin City metropolitan area for private and public gigs.

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Ab Initio Investigation and Thermodynamic Modeling of Shape Memory Alloys

Friday, September 9, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Arpita Chari, Navdeep Singh Department of Mechanical Engineering, Texas A&M University

Abstract

Shape Memory Alloys are an interesting class of active materials that undergo reversible shape changes through martensitic transformations that can be triggered by temperature, stress and/or magnetic fields (in the case of ferromagnetic SMAs). Among recently investigated SMAs, Co2NiGa and Co2NiAl alloys have been receiving considerable interest due to their shape memory (SM) properties. While there have been many investigations on the mechanical and magnetic behavior of these materials, very little is known about the fundamental microscopic basis for the observed macroscopic behavior.
In the first part of the talk, we discuss the stability of Co2NiGa and Co2NiAl-based structures. The transformation of the cubic austenite to the tetragonal martensite structure is investigated through Bain distortion paths as well as lattice dynamical calculations. Analysis of the features of the electronic structure are then mapped to the observed metastability of the cubic phases with respect to tetragonal deformations and comparisons are made with the much more studied Ni2MnGa-based SMAs. We also investigate the magnetic behavior of these alloys by using Monte Carlo simulations in combination with ab initio methods.
In the second part of the talk we will focus on the use of the first-principles calculations in combination with experimental information to develop accurate thermodynamic models —based on the CALPHAD approach—for the Co-Ni-Ga ternary system. These thermodynamic models are then used to predict phase constitution as a function of alloy composition and temperature. Reliable thermodynamic models can be used in the computer-aided design of novel shape memory alloys based on this ternary system.

Biography

Dr. Arroyave got his B. S. in Mechanical and Electrical Engineering at ITESM (Monterrey, Mexico). Afterwards, he enrolled at the Massachusetts Institute of Tecnoloogy, where he got his M. S. (2000) and Ph.D. (2004) in Materials Science and Engineering under the supervision of Prof. Thomas W. Eagar. After two and a half years as a Postdoctoral Scholar in Prof. Zi-Kui Liu’s group at Penn State he joined the faculty of Mechanical Engineering and Materials Science at Texas A&M University in 2006. Dr. Arroyave’s expertise is in computational thermodynamics and kinetics of materials (using the CALPHAD method), phase-field methods and use of electronic structure methods to predict the structural/functional properties of materials at the atomic scale. Dr. Arroyave’s group is also working with experimental colleagues to develop Integrated Computational Materials Engineering (ICME) approaches to optimize complex multi-phase, multi-component structural alloys.

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The Future of Automotive Propulsion: One Perspective

Thursday, September 1, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Dr. Edward P. Becker
Materials Technical Specialist General Motors, LLC

Abstract

The worldwide demand for automotive transportation remains strong even as the price of conventional fuels rises. General Motors is committed to providing safe and affordable vehicles which run on whatever fuel is available in a particular market. To assist in extending the current supply of fossil fuels, automakers (including GM) are expanding the use of fuel-saving technologies such as variable valve actuation, cylinder deactivation, additional forward-speed transmissions, and hybrid powertrains. In addition, vehicles which run on Compressed Natural Gas (CNG) and alcohol-gasoline blends (such as E85) are commercially available. GM has also demonstrated a hydrogen fueled, internal combustion engine vehicle and is aggressively pursuing fuel cells for automotive transportation in the future.

Biography

Ed Becker is a Technical Specialist in the Materials Engineering Department at General Motors Powertrain in Pontiac, Michigan. His responsibilities include initiating and managing research and development activities related to innovative materials and processes for GM engines and transmissions. Ed Becker is Past President and a Fellow of the Society of Tribologists and Lubrication Engineers. He has worked for General Motors for over 28 years, mostly in the Powertrain division working on a variety of GM engines and transmissions. He is a licensed Professional Engineer in Michigan.
Ph.D. and M.S., Mechanical Engineering, University of Michigan M.S, Metallurgical Engineering, University of Illinois B.S., Metallurgical Engineering, Illinois Institute of Technology

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Nanoporous Materials for Energy and Environmental Application

Friday, May 6, 2011 10:00 am – 11:00 am
Room 610, M&M Building

Prof. Randall Q. Snurr
Department of Chemical & Biological Engineering
Northwestern University, Evanston, IL

Abstract

Metal-organic frameworks (MOFs) are a new class of nanoporous materials synthesized
in a “building-block” approach by self-assembly of metal or metal-oxide vertices
interconnected by rigid organic linker molecules. The rational synthesis approach opens
up the possibility of incorporating a wide variety of functional groups into the materials,
and these materials may lead to new advances in adsorption separations, gas storage,
sensing, and catalysis. Some of the most intensively studied applications are related to
solving energy and environmental problems, including hydrogen storage for fuel cell
vehicles, capture of CO2 from power plant exhaust, and energy efficient separations.
Because of the predictability of the synthetic routes and the nearly infinite number of
variations possible, molecular modeling is an attractive tool for screening new structures
before they are synthesized. Modeling can also provide insight into the molecular-level
details that lead to observed macroscopic properties. This talk will provide an overview
of MOFs and their potential applications, as well as efforts to predict their properties
using molecular modeling.

Biography

Randy Snurr is a Professor of Chemical and Biological Engineering at Northwestern University. He holds BSE and PhD degrees in chemical engineering from the University of Pennsylvania and the University of California, Berkeley, respectively. From 1994-95, he performed post-doctoral research at the University of Leipzig in Germany supported by a fellowship from the Alexander von Humboldt Foundation. Other honors include a CAREER award from the National Science Foundation and the Leibniz professorship at the University of Leipzig in 2009. He is a Senior Editor of the Journal of Physical Chemistry and has served on the editorial boards of the Journal of Molecular Catalysis A, Catalysis Communications, and Current Nanoscience. His research interests include development of new nanoporous materials for energy and environmental applications, molecular simulation, adsorption separations, diffusion in nanoporous materials, and catalysis.

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The Main Types of Gasar Structure and Production Methods

Monday, April 18, 2011 1:00 pm – 2:00 pm
Room 610, M&M Building

Dr. Vladimir Shapovalov
Department of Materials Science
National Metallurgical Academy of Ukraine

Abstract

This presentation will present a broad classification of gas-eutectic material (gasars) structures, based on experimental data obtained in former USSR, Russia, Ukraine, China, Japan and USA from 1979 to the present time. The presentation will also review gasar production methods and designs of gasar devices for laboratory and industrial manufacturing.

Biography

Dr. Shapovalov is an adjunct professor at the National Metallurgical Academy of Ukraine and seniorresearcher at Materials and Electrochemical Research Corporation of Tuscon, Arizona.  He graduated with a PhDfrom the National Metallurgical Academy of Ukraine in 1972 and has since worked there as a lecturer and professorof Materials Science.  From 1997-2000 he was project manager at Sandia National Laboratory in charge of Gasarmetallic foam research.  He has authored numerous papers on hydrogen equilibrium and advanced materialsprocessing with an emphasis on metallic foam.  His current research interests include advanced plasma processingof Gasar foams for coatings.

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Piezoelectricity and Flexoelectricity in Solid and Soft Materials

Friday, March 25, 2011 3:00 pm – 4:00 pm
Room 610, M&M Building

Dr. John Y. Fu
Department of Mechanical and Aerospace Engineering
State University of New York

Abstract

Historically, the study of flexoelectricity is closely related to that of piezoelectricity though the physicalmechanisms behind these phenomena are completely different [1]. In solid dielectrics, bothpiezoelectricity and flexoelectricity can be derived from the energy coupling in crystalline structures,which are based on equilibrium thermodynamics. However, those phenomena in polymers and liquidcrystals are more complicated due to their complex molecular chains and conformations. Recently, agiant flexoelectric phenomenon has been observed in bent-core nematic liquid crystal elastomers(BCLCEs) [2], which attracts much scientific attention since the nematic phase cannot be regarded asthe ferroelectric phase in most mesomorphic materials. It was believed that the giant flexoelectric effectmight only be observed in certain mesomorphic materials with the chiral smectic C* phase, a ferroelectricphase predicted by Meyer in the 1970s for liquid crystals [3]. Inspired by this study, we investigatedcertain polyvinylidene fluoride (PVDF) polymer films. A giant flexoelectric effect in a PVDF polymer filmwith mixed α- and β-phases has been observed in our group [4], which contradicts the previoustheoretical estimation that the flexoelectric coupling is small, on the order of 10 pC/m. In this seminar, Iwill re-visit the definitions of both piezoelectricity and flexoelectricity in solid dielectrics, and then comparethem with their counterparts in liquid crystals and polymers. Some peculiar physical phenomena relatedto both piezoelectricity and flexoelectricity in polymers will also be discussed. Finally, I will demonstratethat such a giant flexoelectric effect can be exploited to fabricate soft flexoelectric piezoelectriccomposites and devices by using non-piezoelectric soft materials.

References: [1] P. G. de Gennes, Physics of Liquid Crystals (Oxford University Press, London, 1974). [2] J. Hardenet al., Appl. Phys. Lett. 96, 102907 (2010). [3] R. B. Meyer, L. Liebert, L. Strzelecki, P. Keller, J. Phys. Lett. (Paris)36, 69 (1975). [4] J. Y. Fu et al., “Giant flexoelectricity in a polyvinylidene fluoride film”, submitted to Applied PhysicsLetters.

Biography

Dr. John Y. Fu is an assistant professor of mechanical engineering. He came to Buffalo and joined theMAE Department in August 2008. Between 2005 and 2008, Dr. Fu worked as a postdoctoral scholar in a navysponsored materials research laboratory. He completed his college education in China, and received his Ph.D.degree in electrical engineering from the Pennsylvania State University at University Park in December 2004. Dr.Fu holds one American patent and four American and international pending patents. His current research interestsfocus on polymer physics, dielectric polymers, ferroelectric polymers, liquid crystal polymers, flexoelectricpiezoelectric polymer composites and devices, and flexoelectric and flexoviscous phenomena in polymers andbiomaterials.

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The Pressure Dependence of Pore Morphology in Aluminum Gasarite Metallic Foams Produced by Thermal Decomposition

Friday, March 18, 2011 3:00 pm – 3:30 pm
Room 610, M&M Building

Joe Licavoli
Graduate Student
Materials Science and Engineering
Michigan Technological University

Abstract

Gasarite metallic foams are those in which porosity is elongated due to eithergas-metal eutectic growth or evolution of gas from particulate during chillcasting.  Gasarite foams have several superior properties compared to othermetallic foam types, but in general repeatability of experimental results is amajor issue when studying such systems.  The current study replicatesexperiments conducted by other research groups in which ambient pressurewas varied during chill casting of pure aluminum on titanium hydride.According to ideal gas behavior it is expected that decreasing pressure at aconstant temperature will increase pore size and thus porosity, howeverquasi-boiling conditions and subsequent escape of gases from thesolidification front may nullify this effect.  Additional information provided inthis study includes the velocity profile of the solidification front, vacuumlevels, titanium hydride particle size, microstructure around pores andpackaging of the particulate are reported.  In agreement with previousstudies, it was found that operating under vacuum conditions increasesporosity and the tendency to form columnar pores.  Disagreement has beenfound in the propensity to form pores more than 10mm in length and inuniformity of pore radii.  Potential reasons for this disagreement have beendeduced from micro and macrostructural information.  Further studies andintegration of results into process models will be discussed.

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