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PROJECTS The technical goals of Propulsion Materials projects are in direct support of the Advanced Combustion Engine Subprogram and the Advanced Power Electronics and Electric Machines Subprogram:
Materials for High Efficiency Engines
Materials for Control of Exhaust Gases and Energy Recovery Systems
Materials by Design
Materials for Electric and Hybrid Drive Systems
Materials for High Pressure Fuel Injection Systems Milestones Contacts Materials for Advanced Engine Valve Train
Milestones Contacts Mechanical Reliability of Piezo-Stack Actuators Enable confident utilization of piezo stack actuator in fuel injectors for heavy vehicle diesel engines. The use of such actuators in diesel fuel injectors has the potential to reduce injector response time, provide greater precision and control of the fuel injection event, and lessen energy consumption. Though piezoelectric function is the obvious primary function of lead zirconium titanate (PZT) ceramic stacks for fuel injectors, their mechanical reliability can be a performance and life limiter because PZT is both brittle, lacks high strength, and is susceptible to fatigue. However, that brittleness, relatively low strength, and fatigue susceptibility can be overcome with the use of appropriate probabilistic design methods. This project combines in-situ micromechanical testing, microstructural-scale finite element analysis, probabilistic design sensitivity, and structural ceramic probabilistic life prediction methods to systematically characterize and optimally design PZT piezoelectric stack actuators that will enable maximized performance and lifetime in diesel fuel injectors.
Milestone Contact Friction and Wear Reduction in Diesel Engine Valve Trains Biodiesel fuels offer significant opportunities to develop cleaner, more energy-efficient vehicles, but their lubricating properties and potentially deleterious effects on rubbing surfaces need to be better understood so that designers can select lubrication strategies and durable materials for fuel systems, exhaust valves, and in-cylinder components. The objectives of this effort are: (1) to establish the compatibility of current and future engine materials with biodiesel fuels, (2) to identify the underlying wear mechanisms that operate in such fuel environments, and (3) to provide engine designers with guidance on choosing materials for surfaces that must move smoothly and reliably in biofueled engines. Experience that was gained from prior OFCVT-supported projects has led to the development of four industry-wide ASTM friction and wear standards. These and related specialized techniques will be applied to investigate effects of biodiesel fuel on the durability of current and promising, new engine materials like titanium alloys, composites, cermets, and nano-composite coatings. Multi-disciplinary studies will include scuffing mitigation strategies for fuel injectors and the effects of the biodiesel content in engine oil on the friction and wear of piston ring and liners materials. Participation with ASTM Committees D2 on “Petroleum Products and Lubricants” and G2 on “Wear and Erosion” will ensure relevance to rapidly-developing biofuels technology and standards. Milestone Contact NDE of Engine Components (ANL) Advanced materials such as ceramics and intermetallics are enabling technologies for heavy-duty engines to achieve higher performance and fuel flexibility. Engine components developed from these materials, however, require rigorous assessment to assure their reliability and durability. The objective of this work is to develop several nondestructive evaluation (NDE) methods to evaluate engine components, such as valve-train and fuel-injection components, that are made from advanced materials. NDE technologies including optical scanning, infrared thermal imaging, and x-ray CT will be evaluated/developed. For ceramic components that permit optical penetration inside the material, the primary NDE methods are laser scattering and 3D confocal microscopy for subsurface-structure examination. Laser scattering is also effective to inspect surface conditions for intermetallic components. Considerable success has been made for NDE of engine valves. Development in these NDE methods will be focused on achieving high-resolution capabilities. The goal of this work is to establish relevant NDE technologies for characterizing material and manufacturing process, and for ensuring component reliability and lifetime. This work is collaborated with Caterpillar Inc. and ORNL. Milestone Contact Materials Testing with ACERT Engine The objective of this Cooperative Research and Development Agreement between UT-Battelle, Inc. (Contractor) and Caterpillar, Inc. (Participant) is to improve diesel engine efficiency by enhancing combustion, and reducing parasitic, frictional, and thermal (PFT) losses by utilizing advanced materials. The proposed CRADA will utilize unique ORNL capabilities in materials and engines research to better understand the interactions between combustion and advanced lightweight materials. The evaluation of the distinct but interrelated technical areas represents a novel application of this technology that may offer efficiency and emissions benefits for multiple engine platforms not simply heavy-duty diesel engines. Research staff from the Engineering Science and Technology (EST) and Materials Science and Technology (MST) Divisions will team with engineers from Caterpillar to evaluate advanced materials for engine use. Caterpillar has provided ORNL with a heavy-duty ACERT engine to serve as a materials evaluation platform and a dynamometer be used as part of their “in-kind” contribution to this CRADA. Caterpillar will also provide guidance to the materials selection and desired operating conditions for evaluation. Staff from the MST Division will perform necessary bench studies and physical characterization of new engine components. Engineers from the EST Division will operate the engine including performing necessary modification and monitoring of the engine performance. This includes optimization of combustion parameters (including modeling) to achieve highest fuel efficiencies and lowest emissions. Key parameters to evaluate include materials durability and wear, combustion effects, and fuel efficiency gained from lowered parasitic losses and reduced heat rejection. Milestone Contact
The goal of this project is to identify and catalog the materials operating conditions in the HCCI engines and utilize computational design concepts and other techniques to develop advanced materials for such applications. The objectives of this project include: (1) interactions with designers of HCCI engines and manufacturers of engine components in order to identify the components that will be affected by the new operating conditions resulting from the HCCI design and mixed-mode or mode switching to conventional combustion, (2) identify the highest priority component(s) that are critical to the implementation of the HCCI concept, (3) identify key properties that need to be improved in materials used in the critical components, and (4) apply computational design concepts to develop high-performance materials that would mitigate the material barrier for use of HCCI engine concepts. Based on discussions with various companies, exhaust valves were identified as one of the highest priority components. Valve materials are needed to operate at temperatures up to 1600oF, higher than the current value of 1400oF. During FY2006, several candidate Ni-based alloys with the potential to have required high temperature properties at 1600oF have been identified for further testing and evaluation. In FY2007, detailed evaluation of microstructure and high temperature mechanical properties of these alloys will be carried out to develop a database on the relationship between composition of alloys, microstructure, and their high temperature fatigue properties. Based upon this database, new alloys with appropriate cost/performance ratio will be developed for this application. Milestone Documents
Contacts More information coming soon. The objective of this agreement is to develop advanced nano-surface engineered systems with innovative properties for applications in high efficiency internal combustion engines. Advanced surface coating techniques, including pulsed laser, magnetron, flame-assisted CVD, and thermal evaporation will be evaluated for specific tribological applications in high-efficiency engines. NCA&T will characterize coatings with techniques including atomic-force microscopy, micro tribometry, X-ray diffraction and Raman spectroscopy. Test specimens for specific applications will also be evaluated by ORNL in collaboration with agreement 13332. Milestone Contact
Milestone Contact Durability of Diesel Engine Particulate Filters The objectives of this agreement are to identify and implement test techniques to characterize the physical and mechanical properties of ceramic substrates used as diesel particulate matter filters (DPFs), to identify the mechanisms responsible for the degradation and failure of DPFs and to develop analysis tools for predicting their reliability and durability. In application, DPFs are coated with catalysts to improve the regeneration process. These catalytic coatings allow particulate matter to be burned out at lower temperatures and more completely. In FY08, the mechanical behavior of coated DPFs will be investigated as a function of temperature. Of particular interest is the influence of these catalyzed coatings to the elastic moduli, which will be measured using the high temperature resonant ultrasound spectroscopy. As needed, strength, fracture toughness, slow crack growth, density/porosity/microstructure, thermal expansion, fractography, etc., will be characterized to understand the overall mechanical behavior of the coated DPFs. In collaboration with Cummins researchers, the results obtained from these tests were used as input data for the implementation of models to predict the service life of DPFs. The ultimate goal of this research agreement is to develop a life prediction methodology for porous cordierite DPFs because the implementation of such methodology would help minimize the risk of cracking and failure of DPFs in the severe thermal environment in which they will operate. During FY08, developing robust real-time monitoring procedures capable of being implemented in full size DPFs and under the aggressive operating conditions experienced by DPFs will continue to be pursued. These monitoring techniques will also be used to validate the service life prediction models that have been developed to date.
Milestone Contact Catalysts via First Principles This objective of this agreement is to develop an integrated approach between computational modeling and experimental development, design and testing of new catalyst materials that we believe will rapidly identify the key physiochemical parameters necessary for improving the catalytic efficiency of these materials. The incentive for this work comes from the fact that the development of new catalytic materials is still dominated by trial and error methods, even though the experimental and theoretical bases for their characterization have improved dramatically in recent years. Experimental catalysis has not benefited from the recent advances in high performance computing that enable more realistic simulations (empirical and first-principles) of large ensemble of atoms, which includes the local environment of a catalyst site in heterogeneous catalysis. These types of simulations, when combined with incisive microscopic and spectroscopic characterization of catalysts, can lead to a much deeper understanding of the reaction chemistry that is difficult to decipher from experimental work alone. We have selected simple well-defined systems Pt/Al2O3 to initiate this work but will extend to other precious metals such as Rh, Pd and supports such as SiO2 and MgO. Theoretical studies on the interaction of small unsupported Pt clusters and Pt clusters supported on MgO with oxygen and CO have been completed. We have synthesized a variety of sol-gel processed alumina, molecular sieve alumina, and commercial alumina supported Pt and Re catalysts with particle sizes of ~ 1 nm and 30 nm. We have carried our preliminary studies of the CO oxidation activities of these catalysts and found that nanostructure of supported clusters consists of single atoms, dimers, trimers, and 10-20 atom clusters. This is very different from the literature models of such catalysts. We have also found that even the initiation of CO oxidation on supported cluster is adequate to introduce particle sintering. We have recorded nanostructural changes as a function of CO oxidation reactions and are correlating the nanostructure of catalysts with activity to identify the catalyst sites responsible for CO oxidation. The results of this work have been presented at several international meetings, invited talk at SAE congress, and the manuscripts have been submitted to refereed journals (some are in press). We have also been invited to submit a review on this topic for Dekker Encyclopedia of Nanoscience & Technology. We plan to extend theoretical studies to supported precious metal clusters on alumina and initiate study of intermediates formed during NO and hydrocarbon oxidation reactions. Simultaneously, we will initiate catalytic testing NO and hydrocarbon oxidation reactions to identify reactive catalyst sites. This will enable us to initiate an iterative process by comparing theoretical and experimental results. Milestones
Contact Characterization of Catalyst Microstructures and Deactivation Mechanisms
Milestones
Contact Life Prediction of Diesel Engine Components
Milestone Contact
Milestone Contact Science Based Approach to Thermoelectric Materials We will use modern science based materials design strategies to find ways to optimize existing thermoelectric materials and to discover new families of high performance thermoelectrics for waste heat recovery applications. We will use first principles methods based on quantum mechanics to calculate thermoelectric properties of materials. The calculations will be done using density functional methods to obtain band structures and vibrational properties of existing and notional thermoelectric compounds. We will use these as input for transport calculations, which will be done with Boltzmann theory. These calculations will include the real structural and chemical complexity of materials, and will therefore yield quantitative predictions, both of the thermoelectric properties and their variation with chemical composition. Trends will be identified and used to suggest other compositions to be tested by detailed calculations. The result will be predictions of compositions with improved thermoelectric performance. These will include new thermoelectric materials and modifications of existing materials. We will interact with experimental groups to obtain feedback on our results. Milestone Contact Materials by Design Utilizing the HTML to Explore Nano-Scale Microstructures of Relevant Materials at Elevated Temperatures Contact Modeling and Testing of Environmental Effects on Automotive PE Devices
Equip existing high temperature test system with humidity control and introduce vibratory test capabilities. Interface this enhanced test system with PE drive and monitoring instrumentation. Evaluate performance of PE devices as a function of temperature, humidity, and vibration. Dissect PE devices as part of their postmortem and evaluate failure initiation location. Cross-section PE devices and use FEA and µ-FEA methods to evaluate their thermal management effectiveness and seek alternative means to achieve improvements to that management, their reliability, and higher temperature use. Milestone Contact Carbon Foam Thermal Management Materials for Electronic Packaging The goal of this program is to develop and demonstrate designs for reducing weight and enhancing heat transfer in power electronic thermal control systems utilizing high thermal conductivity carbon foam. To achieve this goal, an interdisciplinary team of modeling, design and materials development has been assembled. The high thermal conductivity, low density and open-cell structure of ORNL’s graphite foam make it an ideal material for thermal control applications where weight and size are important factors. However, mathematical models indicated that it is necessary to find ways to increase foam permeability in order to increase heat transfer and truly take advantage of the foam thermal properties. Breakthroughs in FY06 and FY07 have shown that graphite foams made by Koppers have larger pores and larger interpore windows and therefore the higher permeability that is required. The objective of this project in FY08 will be to transition the work on graphite foam from ORNL to industry, particularly ThermalCentric, Inc. that has formed a joint venture with Koppers to commercialize graphite foam heat exchangers. The graphite foam team that consists of researchers from the APEEM Program, the APM Program and ThermalCentric will identify specifications for an air-cooled heat sink that will be designed and built by ThermalCentric, will be characterized by APM researchers for heat transfer behavior and evaluated on an inverter or similar component by APEEM researchers. Additionally, during FY08 the collaboration with General Motors Research on evaporative cooling systems will be completed.
Milestone Documents
Contact Materials by Design - Solder Joints of High Performance Power Electronics There is a significant need to study the failures of electronic packages induced by metallurgical changes of solder joints and wire bonds. These failures are induced in solder joints and other components by combination of temperatures, stresses, and current. Coarsening of solder joint microstructures takes place during high temperature use resulting in interdiffusion and the formation of intermetallic compounds. Wire bonds could also be an issue if so determined by our failure analysis work. An understanding of the ceramic and metallic layer failures will empower us to develop a computational-oriented method for the design of materials for packaging applications. The approach would be to analyze simple package designs so that the emphasis is on materials rather than electronic design where complexities of devices may overshadow materials issues. Package designs will be stress tested to see where failures originate. Steady-state exposure at high temperatures, cyclic exposures (thermal fatigue) all affect microstructure of the materials and their properties. IR imaging will be used to show hot spots and perhaps voids. IR imaging will be complemented with radiography and acoustic techniques. Milestone Contact Materials Compatibility of Power Electronics
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U.S. Department of Energy • Office of Vehicle Technologies Program
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Oak Ridge National Laboratory is a national multi-program research and development facility Last modified on
November 20, 2007 8:58 AM
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The demands of meeting new emissions and fuel economy goals are continuing to push heavy-duty truck diesel exhaust component temperatures higher. While normal diesel exhaust valve operate well at temperatures below 750°C, advanced engine applications may push temperatures to 850°C or higher. The materials problem is that such components must also still continue to have similar or better performance or durability, and have similar cost. For normal metals and alloys, higher temperatures reduce performance and shorten life. The purpose of this new CRADA project is to enable close collaboration between ORNL, the engine end-user and their exhaust-valve supplier, to combine innovative valve design, advanced alloys, and possibly coatings, for rapid selection and evaluation. This should enable more efficient production of trial valves with upgraded capability for engine-testing. The critical first step is microcharacterization of engine-tested valves to clearly define the degradation/failure modes. This project will then be structured to perform multiple critical properties screening tests in parallel, in order to provide upgrade valve technology solutions that meet the advanced diesel engine performance requirements, that can be commercially scaled-up, and which are cost-effective. 
Homogeneous Charge Compression Ignition (HCCI) engines appear promising for transportation as well as stationary engines because of the potential for increased efficiency and reduced emissions. Rapid heat release, unthrottled operation, and reduced radiant heat losses are responsible for increased efficiency and highly dilute operation is responsible for reduced NOx and particulate emissions. Power density, however, is currently limited by the peak pressures and the rate of pressure rise that are allowed for a given application and engine design. The materials used for bearings, piston crowns, head gaskets, top of liner, valves/valve seats, turbo-machinery, other air handling and EGR equipment, and even engine blocks may limit the operating conditions. An investigation of advanced materials for use with HCCI engines appears warranted.
The objective of this effort is to produce a quantitative understanding of the interdependence between structure and performance to develop options for an exhaust aftertreatment system with improved final product performance in order to meet the US Environmental Protection Agency emissions requirements for 2010 and beyond. In the FY08 effort, new commercial zeolite urea selective catalytic reduction (SCR) catalysts and model catalysts representing future SCR commercial systems will be characterized at ORNL using transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman Spectroscopy and infrared spectroscopy. The effort will focus on detailed characterization of the selected catalyst formulations, both powder and honeycomb, aged under the well-controlled conditions. This aging will be primarily accomplished by placing the catalysts into an instrumented benchtop reactor and monitoring the performance based on the in-going and out-going gases, looking for reaction reactants, intermediates and products that influence catalyst chemistry. The result will be a quantitative correlation between the materials changes as identified by various characterization techniques and a measure of performance degradation of urea SCR catalysts. These can be then used to develop accelerated aging protocols and laboratory diagnostic methods. An effort will remain to examine Cummins originated samples as needed. 
The advanced sub-Ångström imaging capabilities offered by ORNL’s new aberration-corrected electron microscope (ACEM) will continue to be exploited to provide the highest resolution imaging and spatial resolution energy-loss spectroscopy of catalytic materials in the world. The objective of the proposed research is to study the behavior of monometallic and bimetallic clusters, rafts and nanoparticles on selected oxide support materials, prior to and after systematic treatments in ORNL’s ex-situ catalyst reactor system, in order to better correlate changes in catalyst morphology and chemistry to de-activation mechanisms. This information is essential for proper design of catalysts that can meet critical regulatory requirements. In FY2008, work will also be conducted utilizing novel environmental cell technology, being developed in conjunction with Protochips Co., which will allow studies of changes in catalytic materials in-situ in the ACEM. We will continue to study the mono- and bi-metallic catalyst systems which formed the basis of our studies in FY2007 (e.g., Pt, Au, Pd and alloys of these species on oxide supports such as g-alumina, q-alumina and silica), to correlate results with the ex-situ studies currently underway. This work will continue to be conducted in collaboration with M. Jose-Yacaman, UT-Austin, and S. A. Bradley, UOP Co. Such information is important for fundamental understanding of how a particular catalytic material works, and will be used in future studies to determine the routes through which the growth and coarsening of particles can be controlled to reduce the degradation of the material. 
There are three primary goals of this research agreement, which contribute toward successful implementation: the generation of a mechanical engineering database of candidate advanced materials before and after exposure to simulated engine environments; the microstructural evolution during service in these advanced materials; and the application and verification of probabilistic life prediction methods using diesel engine components as test cases. In FY07 the generation of high-temperature mechanical properties database of TiAl alloys manufactured with modified casting processes by suppliers was completed. Also, evaluations of surface wear characteristics and mechanical properties of TiAl valves after 1000h engine test were also successfully accomplished, which confirmed the probabilistic component design of end users. In FY08, evaluations of mechanical properties as well as surface wear characteristics of potential TiAl engine components after field test in C15 ACERS diesel engine will be carried out. Also, the mechanical properties database of candidate complex-shaped TiAl components (e.g., turbo rotors and valves) will be generated under the test conditions similar to diesel engines. Results will be compared with those generated from the simple-shaped samples. These results provide key inputs to verify the probabilistic component design and life prediction tasks, which are critical to the successful implementation of advanced lightweight components.
Understand the complex relationship between environment (temperature, humidity, and vibration) and automotive power electronic (PE) device performance. There is significant interest in developing more advanced PE devices and systems for transportation applications (e.g., hybrid electric vehicles, plug-in hybrids) that are capable of sustained operation to 200°C. Advances in packaging materials and technology can achieve this but only after their service limitations are better understood.
The use of evaporative cooling for power electronics has grown significantly in recent years as power levels and related performance criteria have increased. As service temperature and pressure requirements are expanded, there is concern among the Original Equipment Manufacturers (OEMs) that the reliability of electrical devices will decrease due to degradation of the electronic materials that come in contact with the liquid refrigerants. Potential forms of degradation are expected to include corrosion of thin metallic conductors as well as physical/chemical deterioration of thin polymer materials and/or the interface properties at the junction between dissimilar materials in the assembled components. Initially, this new project will develop the laboratory methodology to evaluate the degradation of power electronics materials by evaporative liquids. An overall goal for the full project is to develop a database indicating performance boundaries for standard materials and for several candidate coolants.