The objective of Computational and Experimental Development of Novel High Temperature Alloys is to develop alloys with enhanced high temperature oxidation resistance with robust mechanical properties. To accomplish this objective we utilize a novel multi-stage progressive “sieving process.” At this point in time, the most promising alloys are Ni-based, so the efforts will concentrate specifically on designing oxidation-resistant Ni-based alloys that can operate at temperatures close to 2500°F (~1350°C). While intermetallics, like the Mo-silicides, can withstand oxidative environments at very high temperatures, they have poor mechanical properties that preclude their implementation. On the other hand, Ni-based alloys (especially alumina formers) provide good mechanical strength and oxidation resistance. Since the melting point of Ni is 1455°C, the challenge lies in alloy compositions having significantly higher melting points, while maintaining good microstructural, thermodynamic, and chemical stability at elevated temperatures. Our approach would involve using the Miedema model for initial screening of prospective alloys, followed by more detailed thermodynamic assessments, and experiments on oxidation behavior to focus on these potential alloys.
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Current techniques to remove the particulates from hot gases derived from combustion or gasification of coal include the use of porous, rigid, ceramic filter elements intended to remove all particles 1 µm in diameter and larger, and to maintain permeability for extended filtration service by use of gas backflushing. Unfortunately, the use of ceramic filters has limitations, owing primarily to their inherent brittleness, long-term microstructural instabilities at operating temperatures, and poor thermal fatigue resistance. Metal filters of high-temperature corrosion-resistant alloys can offer enhanced thermal and mechanical shock resistance, and high strength—sufficient for filter assembly and operation in high frequency, high-pressure pulsing modes. In addition, alloy filters processed from high-quality spherical powders of a controlled size can utilize unique designs, be processed by many innovative methods, and joined by welding to facilitate filtration system assembly to allow novel filtration system configurations. The objectives of this study are to design and develop metallic filters having uniform, closely controlled porosity, using a unique spherical powder processing and sintering technique. The corrosion resistance of the filter materials (such as Haynes 214, Kanthal AF, and Krupp 602CA) will be evaluated under simulated PFBC/IGCC gaseous environments to determine the optimum alloy composition and filter structure. Corrosion tests also provide a means to estimate the service life of experimental filter materials, when subjected to either normal or abnormal PFBC/IGCC plant operating conditions. Metallic filters are expected to offer the benefits of non-brittle mechanical behavior and improved resistance to thermal fatigue compared to ceramic filter elements, thus improving filter reliability. Moreover, the binder-assisted powder processing and sintering techniques developed from this study will permit additional filter design capability (e.g., highly controlled filter porosity/permeability with greatly enhanced processing simplification), thus enabling more efficient and effective filtration.
Project Leader(s): Iver Anderson Principal Investigators: Iver Anderson
This project has three main objectives.
- Develop high performance permanent magnets (PM) for traction motor with internal PM rotor:
- requires elevated temperature (180-200°C) operation, minimize cooling needs
- increased high temperature magnetic performance more critical than RT
- Reduce manufacturing cost of PM traction motors:
- bonded PM can utilize injection or compression molding technology
- net shape forming for mass production of rotors
- bonded PM can utilize injection or compression molding technology
- Achieve high performance and reliability for bonded magnets:
- increase volumetric loading
- minimize irreversible magnetic losses (oxidation)
This project seeks to enhance the control of metal powder production by gas atomization methods to benefit the implementation of several emerging Fossil Energy technologies that utilize metal powders of specific size ranges and types, not efficiently produced by industrial powder makers. Further improvements in fundamental understanding and design of high efficiency gas atomization nozzles will be directed toward maximizing powder yields in special size classes, including ultrafine (dia. < 10 µm) and mid-range (10 µm < dia. < 44 µm) powders. Efficient production of such powders can eliminate a major technological barrier to the use of new concepts for fabrication, for example, hydrogen membranes, heat exchanger tubing, and oxidation/sulfidation resistant coatings. To provide a direct route for rapid transfer of the atomization technology improvements, powder production tests will be performed in laboratory atomization systems that can demonstrate advanced industrial operation in terms of steady-state operation and controls systems. The laboratory atomization experiments will also involve detailed analysis of atomization process response to alloy and parameter modifications to verify the effect of process innovations. To facilitate investigation of powder processing of the complex alloys involved with Fossil Energy applications, initial work will involve pure metals and simple model alloys for each target area of process or alloy development.
The purpose of this project is to develop the first generation of advanced thin film coatings for high contact stress applications. The results will facilitate domestic energy production through reduced cost of coal gasification, improve fuel efficiency, and lead to novel energy solutions through successful development of materials that are exposed to extreme operating conditions. New research into advanced, nanocomposite materials with an order of magnitude better wear resistance than current offerings has shown great promise. Scale-up efforts will focus on transitioning laboratory-scale, bulk nanocomposite materials research to coated components that perform in environments where all previous coatings have failed. A primary objective will be to transition the superior performance of the bulk, laboratory-scale materials into a thin-film coating that will sustain a target pressure-velocity (PV) product of at least 70,000 MPa-m/s.
Project Leader(s): Marit Nilsen-Hamilton
Principal Investigators: George Kraus
We are developing apatmers to use as cellular receptors for imaging gene expression in a technology termed Gene expression measurement by Revealed Aptamer Based Imaging Technology (GRABIT) that includes two approaches using aptamers to image gene expression: (i) Intracellular Multiaptamer Genetic tags (IMAGEtags), which are aptamer expressing reporter genes, and (ii) Targeted Reversibly Attenuated Probes (TRAPS), which are allosterically regulated aptamer probes. These RNA probes are being developed for imaging in plants and bacterial species.
This research is supported by the U.S. Department of Energy, Office of Biological and Environmental Research through the Ames Laboratory. The Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358
This research is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering.
Uniform magnetic nanoparticles with large magnetic moment and controlled magnetic anisotropy have important technological applications from data storage and quantum computing to catalysis and drug delivery. The Emergent Magnetic and Atomic Structures Group works to determine the nature of macromolecule‐mediated magnetic nanoparticle formation: i.e., the mechanism of particle nucleationand growth, the emergence of crystal structures, and the development of ferromagnetism in the individual bio‐templated magnetic nanocrystals. By utilizing advanced electron microscopy techniques, we work towards gaining a better understanding of how the assembly of biomacromolecules dictates nanoparticle formation and functional properties.
Correlative electron microscopy of magnetotactic bacteria in liquid:
Magnetotactic bacteria biomineralize ordered chains of uniform magnetite or greigite magnetosome nanocrystals with nearly perfect crystal structures and species-specific morphologies. As a result, these microorganisms are one of the best model systems for investigating the molecular mechanisms of biomineralization. Using the liquid cell scanning transmission electron microscopy (STEM) holder, we can image biomineralizing microorganisms in their natural environment with nanometer resolution. This correlative fluid cell STEM and fluorescence microscopy technique is a first step in directly observing biomineralization of magnetite in viable magnetotactic bacteria. We expect this technique to be generally applicable for in vivo imaging of a wide range of biomineralizing organisms.
Tuning the bacterial iron biomineralization:
Iron is biomineralized by many different microorganisms, and tweaking this process exerts control over the magnetic properties of biogenic materials. Biomioneralization can be controlled to yield nanocrystals with tunable composition and magnetic properties. Comprehensive characterization of biominerals reveals the key factors affecting bacterial iron biomineralization.
- Continuous fluid flow Cell Holder Platform, equipped with a turbopumping station (Hummingbird Scientific) and digital camera (Leica)
- Vapor Delivery system Module for use with the continuous fluid flow liquid cell holder(Hummingbird Scientific)
- Nano eNabler Molecular Printer (BioForce Nanosciences)
- Magnetherm V 1.5 AC system (Nanotherics), equipped with a fiber optic thermometer
- Auxiliary equipment: oven; vacuum oven; stand-alone portable RGA module (Stanford Research); controlled temperature circulation bath; Gatan 626 TEM cryo-holder and fully equipped Cryo-Plunger Vitribot (Gatan); glow discharge unit (Pelco); 2 ozone plasma cleaners (BioForce); Midmark 11autoclave sterilizer (Ritter); Shlenk line, glovebox (Vac. Atm.) equipped with a cold storage box and solvent trap; acrylic glovebox unit for cell assembly under argon flow equipped with Leica camera setup unit; two laminar flow hoods; centrifuge and microcentrifuge; direct Immersion ultrasonic horn apparatus (Sonics and Materials)miscellaneous other devices making researchers’ lives a bit easier.
This project will develop Cerium transition-metal (Ce–TM) based permanent magnets for vehicle and wind energy applications. The abundance of Ce (~50% of the rare-earth (RE) content of Molycorp Bastnasite concentrate) is three times that of Nd and Pr combined. Due to an excess of Ce on the market, the development of a Ce–TM permanent magnet would facilitate an increase of the supply of high-energy rare-earth magnets by a factor of 2 to 3 without requiring additional mining or an increase in the amount of separated RE produced. The feature that sets RE elements apart from other elements is the fact that the 4f electron shell is being filled in the series from 1 electron in Ce to 2 in Pr, and so on to 14 for Lu, the last rare earth element. This electron shell has unique magnetic and optical properties. The RE in a permanent magnet plays a key role due to its 4f electrons; unfortunately, in many intermetallic compounds with Fe and Co, Ce atoms lose their local magnetic properties, significantly decreasing the magnetic ordering (Curie) temperature and the saturation magnetization i.e. the strength of the magnet. This project will avoid such effects by controlling the intrinsic ferromagnetic properties through intelligent materials design. The performance goal is to develop a Ce-TM based permanent magnet with a Curie temperature in excess of 300°C, a remnant magnetization in excess of 10 kG, and coercivity in excess of 10 kOe. The project is a combined theoretical and experimental effort to study the potential of Ce intermetallic compounds for use in permanent magnets.
Exploiting the intrinsic ferromagnetic properties Ce-TM based permanent magnets; we will develop a Ce-TM based permanent magnet for use in automotive electric drive motors and wind turbines. Using a combined experimental and theoretical approach, we will develop an understanding of the role of valence and hybridization in determining the Curie temperature, magnetization, and anisotropy of Ce-TM alloys. This will allow us to design nanostructured and aligned hard/semi-hard magnetic alloys with properties suitable for permanent magnet applications and to produce magnets based on those alloys.
A critical benefit of the alternative Ce-TM-based materials will be to provide a market for Ce that is currently under utilized. The development of a high magnetic energy density Ce–TM – based permanent magnet would facilitate an increase of the supply of high-energy rare-earth magnets by a factor of 2 to 3 without requiring additional mining or an increase of RE processing. The effective utilization of the available Ce will drastically alter the economics of rare earth production by effectively doubling the marketable product without incurring additional costs.
This project targets proposes to reduce the content of critical rare earth elements in traction motors to <0.33g/kW. The collaborations with General Motors and NovTorque provide the evaluation of the material for traction motors with a specific power greater than 1.9 kW/Kg. Molycorp, LLC will provide the important materials supply chain and development path for commercialization of these materials.
The U.S. Department of Energy's Ames Laboratory is now the home to a dynamic nuclear polarization (DNP) solid-state nuclear magnetic resonance (NMR) spectrometer that helps scientists understand how individual atoms are arranged in materials