The High Temperature Materials Laboratory has expanded into a leading center for transportation innovation.
Conceived in 1973 in the wake of the first Arab oil embargo, Oak Ridge National Laboratory's High Temperature Materials Laboratory (HTML) was originally envisioned as a place where the capabilities of high temperature materials research programs from industry, academia and government laboratories would be brought together to develop structural ceramic materials for use in highly efficient automotive gas turbines and heavy-duty diesel engines. The facility's initial research efforts resulted in several successful collaborations with engine manufacturers, including the development of ceramic turbine components that could withstand the rigors of operating for hundreds of thousands of miles under extreme conditions.
As the price of oil moderated in the early 1980s and the urgency of the energy crisis diminished, HTML director Edgar Lara-Curzio recalls that the general level of interest in high-temperature ceramics also began to wane. "Gradually, HTML's mission evolved from simply studying high-temperature materials to analyzing a greater variety of materials for transportation technologies," he says. This broadened focus has enabled HTML scientists, as well as the users that take advantage of the facilities' unique equipment, to investigate materials-related issues across an array of transportation technologies, including advanced batteries for plug-in electric and hybrid electric vehicles; lighter, stronger vehicle components; and the recovery of waste heat using thermoelectric materials.
The expansion of HTML's research mission proved a boon to users. A large fraction of the facility's users are from industry, while the rest come from universities and other national laboratories. Lara-Curzio is quick to note that HTML continues its close relationships with engine manufacturers who have been interested in structural ceramics for gas turbines and diesel engines since the user facility was first established. "We are working with Cummins on diesel particulate filters and with Caterpillar, General Motors, Ford and others on a range of materials for transportation- related projects."
HTML's user program accommodates both nonproprietary and proprietary research—the main difference being that the former is provided free of charge if users submit the results of their research for publication within six months. Proprietary users pay for the cost of conducting their research but are not required to share their results.
Lara-Curzio maintains that user programs at the national laboratories play an important role in enabling the development and implementation of new technologies by providing users with access to capabilities that are unavailable to universities or commercial research facilities. HTML staff members possess specialized skills in the area of materials characterization. In addition to their involvement in the HTML user program, most conduct research on a variety of materials used for power generation and the distribution, storage and use of energy. The ability of industrial and academic users to share these capabilities benefits both parties. "This is our goal and the role we have played from the beginning," Lara-Curzio says.
A better battery
One of HTML's top priorities in the past year was the development of tools that can be used with microscopes and X-ray and neutron diffractometers to examine the internal structure of batteries at the atomic level as they charge and discharge. Understanding these processes will enable HTML researchers to work with manufacturers to produce batteries that are longer lasting, safer and more efficient. "In one of our projects, we are working with Motorola to study the causes of ‘thermal runaway' in lithium-ion batteries, a condition that causes batteries to overheat and catch fire," Lara-Curzio explains. "We are also seeking ways to enable batteries to store more energy so, for example, an electric vehicle could have a range of hundreds rather than dozens of miles between charges. The challenge is to store as much energy in as little volume with as little weight as possible."
HTML researchers currently are working on increasing the power density of batteries, a process that requires developing batteries that can provide a lot of "juice" quickly and recharge in a relatively short time. Batteries with high power density would enable an electric vehicle to accelerate and merge smoothly into highway traffic or to pass a slower vehicle comfortably. When the vehicle is parked at a charging station, the battery could be charged in a time roughly comparable to the time it takes to fill a car with gasoline.
Lara-Curzio notes that, even with all of the other technical challenges, one of the biggest hurdles on the path to a better battery is keeping the final product affordable. "A large fraction of the cost of electric cars that are available today—or that will be available in the near future— is batteries," he says. "We want inexpensive batteries to last for at least 10 years. Nobody wants to go to the car dealer every three years to replace $10,000 worth of batteries."
The greater use of lightweight materials in vehicles is one of the most straightforward ways of increasing fuel efficiency. HTML researchers are working with several industrial partners to reduce the weight of vehicles without sacrificing safety. One of the biggest success stories to come out of HTML in recent years is Metalsa, a Virginia-based truck component manufacturer that sought to reduce the weight of the truck siderails the company provides to more than 50 percent of the U.S. truck market.
Using instruments at HTML and ORNL's High Flux Isotope Reactor, Metalsa engineers and HTML scientists analyzed how weight and stress were distributed throughout the siderails. They determined the optimal locations for cutting holes in the rails, the best methods for cutting the holes, and the types of steel that would be best suited for this new, lightweight design. As a result, Metalsa modified its manufacturing processes and was able to reduce the weight of several current production models by 10 to 20 percent. In the course of a year, the new designs could save as much as 30 million pounds of steel, resulting in an estimated fuel savings of 3.8 million gallons.
Another approach to designing lightweight vehicle components starts from the ground up, using aluminum, magnesium or fiber-reinforced composites instead of steel. Concerns about these lightweight "replacement" materials often center on their crash worthiness. HTML's specialized equipment not only can assess the amount of energy that a component will absorb in a crash but also can provide information on related issues, such as ways to strengthen welds, better choices for metal alloys and performance of lightweight components under extremes of temperature and stress.
Reflecting on HTML's 25 years as a user facility, Lara-Curzio observes that the facility's wide-ranging materials characterization capabilities have outgrown its name. "HTML continues to play a very important role in addressing one of the Department of Energy's key priorities: to reduce the nation's use of petroleum. We do that by supporting industry, universities and other national laboratories in the development of energy-saving technologies. As we pursued this goal, we expanded our capabilities in materials characterization and were aggressive in developing the infrastructure needed to support the mission of DOE's Office of Transportation Technologies." As a result, HTML today is able to provide the user community with unique analytical capabilities critical to developing safe and efficient vehicles.
Lara-Curzio is optimistic about HTML's future. "Rather than requiring a long proposal process and a long lead time, HTML responds on a timescale that meets users' needs. Our impact is both technologically and application oriented, in keeping with our mission to serve the vehicle technologies community and help solve their materials problems. We are truly a national resource for our industrial and academic users."
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